JP2006034025A - DC stabilized power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC stabilizing power supply that can always minimize loss irrespective of how much current is consumed by a load in a DC stabilizing power supply in which a chopper regulator is arranged at a pre-stage and a series regulator at a post-stage. <P>SOLUTION: This DC stabilizing power supply, in which the chopper regulator CR1 is arranged at the pre-stage and the series regulator SR1 at the post-stage, is provided with an output current detecting portion (22) that detects an output current of the series regulator SR1; circuits (including 10, 11) that set an output voltage of the chopper regulator CR1 to a given value; and output voltage regulating circuits (23, 24) that change and regulate the set voltage according to the detected output current of the series regulator SR1 in such a way that a voltage difference between the input and output of the series regulator SR1 becomes a minimum value that corresponds to the output current of the series regulator SR1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stabilized DC power supply device that converts a DC input voltage that is not necessarily stable into a stabilized DC voltage and outputs the stabilized DC voltage. In particular, the present invention relates to a high-efficiency DC stable circuit in which a chopper regulator is disposed in the front stage and a series regulator is disposed in the rear stage. The present invention relates to an integrated power supply.

  In general, the power supply voltage inside a computer or digital AV equipment is two systems of DC (direct current) 12V and DC5V. From this power supply voltage, a stabilized power supply device on the digital board side uses a memory, a microcomputer, a DSP (Digital Signal Processor), etc. Voltages such as 3.3V and 1.8V that are used in the above are made.

  However, with the recent increase in data transfer speed and processing speed of computers and digital AV devices, power supply voltage and current demanded by memories, microcomputers, and DSPs are increasing. For example, in the case of a DSP, the required voltage is lowered to 1.2V, and the current consumption is increased to about 1A.

  The stabilized power supply apparatus is mainly classified into two types, a dropper regulator and a switching regulator. In the case of a series regulator which is a kind of dropper regulator, the loss P is approximated by P = (Vin−Vo) × Io. (Vin, Vo, and Io are the input voltage, output voltage, and output current of the series regulator, respectively). Therefore, for example, in a series regulator that obtains an output of DC 1.2 V, 1 A (ampere) from DC 5 V, a loss of P = (5-1.2) × 1 = 3.8 W (Watt) occurs, and also in terms of heat generation In terms of energy consumption, it will be very large.

  Conventional examples for reducing the heat generation and the like are disclosed in Patent Document 1 and Patent Document 2 below. FIG. 14 is a circuit showing the conventional example. The stabilized power supply device in FIG. 14 has a chopper regulator CR0, which is a kind of switching regulator, disposed in the previous stage and a series regulator SR0 disposed in the subsequent stage, and a DSP to which the output voltage of the series regulator SR0 is connected to the outside. Is supplied to the load.

(Fig. 14: Explanation of configuration and operation)
First, the chopper regulator CR0 will be described. An output voltage DC5V of the power supply 1 is applied to the collector of the switching transistor 2 composed of an NPN type bipolar transistor, and its emitter is commonly connected to the cathode of the diode 3 whose anode is grounded and one end of the coil 4. . The other end of the coil 4 is grounded via a series circuit composed of a smoothing capacitor 5 and voltage dividing resistors 10 and 11, respectively.

  A connection point between the voltage dividing resistor 10 and the voltage dividing resistor 11 is connected to an inverting input terminal (−) of an error amplifier 8 formed of an operational amplifier. The reference voltage Vref output from the reference voltage generation circuit 9 is applied to the non-inverting input terminal (+) of the error amplifier 8, and the output of the error amplifier 8 is the non-inverting input terminal ( +). The inverting input terminal (−) of the comparator 6 is given a triangular wave output from the oscillation circuit 7, and the output of the comparator 6 is given to the base of the switching transistor 2. The output voltage of the power supply 1 is supplied to the comparator 6, the error amplifier 8, and the reference voltage generation circuit 8 as the respective power supply voltages.

  Thus, the chopper regulator CR0 includes the switching transistor 2, the diode 3, the coil 4, the smoothing capacitor 5, the comparator 6, the oscillation circuit 7, the error amplifier 8, the reference voltage generating circuit 9, the voltage dividing resistor 10, and the voltage dividing resistor 11. It is equipped with.

  The switching transistor 2 switches DC5V from the power supply 1, and the diode 3, the coil 4, and the smoothing capacitor 5 rectify the switched output. This rectified voltage is the output voltage of the chopper regulator CR0 (also the output voltage of the smoothing capacitor 5), and this output voltage is given as an input voltage to the subsequent series regulator SR0.

  The error amplifier 8 compares the voltage obtained by dividing the output voltage by the voltage dividing resistors 10 and 11 with the reference voltage Vref, and outputs a higher level (high potential) voltage as the divided voltage is lower. The comparator 6 compares the output voltage from the error amplifier 8 with the triangular wave from the oscillation circuit 7 and turns on the switching transistor 2 when the output voltage from the error amplifier 8 is higher than the triangular wave. Therefore, the lower the output voltage of the smoothing capacitor 5 is, the longer the switching transistor 2 is turned on, that is, the duty of the switching transistor 2 is increased. In this way, the chopper regulator CR0 outputs the voltage whose voltage value is set by the voltage dividing resistors 10 and 11 to the subsequent series regulator SR0.

  Next, the series regulator SR0 will be described. The output voltage of the chopper regulator CR0 is given to the emitter of the output transistor 12 composed of a PNP type bipolar transistor, and its collector is grounded via a series circuit comprising a smoothing capacitor 18 and voltage dividing resistors 16 and 17, respectively. ing.

  A connection point between the voltage dividing resistor 16 and the voltage dividing resistor 17 is connected to an inverting input terminal (−) of the error amplifier 14 formed of an operational amplifier. The non-inverting input terminal (+) of the error amplifier 14 is supplied with the reference voltage Vref output from the reference voltage generation circuit 15, and the output of the error amplifier 14 is the base of the control transistor 13 formed of an NPN type bipolar transistor. Is given to. In the control transistor 13, the collector is connected to the base of the output transistor 12, and the emitter is grounded. The output voltage of the chopper regulator CR0 is supplied to the error amplifier 14 and the reference voltage generation circuit 15 as the respective power supply voltages.

  As described above, the series regulator SR0 includes the output transistor 12, the control transistor 13, the error amplifier 14, the reference voltage generation circuit 15, the smoothing capacitor 18, the voltage dividing resistor 16, and the voltage dividing resistor 17.

  The series regulator SR0 steps down the output voltage of the preceding chopper regulator CR0 by the output transistor 12, stabilizes it by the smoothing capacitor 18, and outputs the stabilized voltage to a load 19 such as a microcomputer or DSP. This output voltage is divided by the voltage dividing resistors 16 and 17 and supplied to the error amplifier 14. The error amplifier 14 compares the voltage obtained by dividing the output voltage by the voltage dividing resistors 16 and 17 with the reference voltage Vref. The lower the divided voltage is, the higher the voltage of the control transistor 13 is. Output to the base to increase the base current of the output transistor 12. In this way, the series regulator SR0 supplies a stabilized output voltage to the load 19 whose voltage value is set by the voltage dividing resistors 10 and 11.

  Now, for example, assuming that the output voltage of the power source 1, the output voltage of the chopper regulator CR0, the output voltage of the series regulator SR0, and the current Io flowing through the load 19 are DC5V, DC1.8V, DC1.2V, and 1A, respectively, FIG. The loss of the entire stabilized power supply shown in Fig. 1 is verified. First, the loss P1 in the chopper regulator CR0 is approximated by P1 = Vsat × Io × (the output voltage of the chopper regulator / the input voltage of the chopper regulator) (where Vsat is the saturation voltage between the collector and the emitter of the switching transistor 2). ) And Vsat = 1.5V, P1 = 1.5 × 1 × (1.8 / 5) = 0.54W. Further, the loss P2 in the series regulator SR0 is P2 = (1.8−1.2) × 1 = 0.6 W, so the loss of the entire stabilized power supply is 0.54 + 0.6 = 1.14 W. Thus, compared to a case where the series regulator is operated alone (P = 3.8 W), heat generation and energy consumption can be greatly reduced.

  Further, Patent Document 2 discloses a base current of an output transistor of a dropper-type stabilized power supply circuit in a DC-stabilized power supply device including a switching-type stabilized power supply circuit on a front stage side and a dropper-type stabilized power supply circuit on a rear stage side. A method of controlling the switching element of the switching-type stabilized power supply circuit (hereinafter, “method A”) so that the voltage generated across the detection resistor matches the reference voltage generated by the reference voltage source by flowing through the detection resistor via the control transistor. ") Is exemplified.

JP-A-7-95765 JP 2000-354365 A

  As shown in FIG. 14, when the chopper regulator CR0 is arranged at the front stage and the series regulator SR0 is arranged at the rear stage, the output voltage of the chopper regulator CR0 is the minimum input-output voltage difference Vi-o of the series regulator SR0 and the output voltage of the series regulator SR0. Is set with a slight margin, and is about 1.8V. The voltage difference between the input and output of the series regulator SR0 here is equal to the voltage difference between the input and output of the output transistor 12 (collector-emitter voltage difference), and the minimum input / output voltage difference Vi-o of the series regulator SR0 is It means the minimum value of the voltage difference between the input and output of the series regulator SR0 necessary for supplying the desired output current Io to the load 19.

  FIG. 15 shows the relationship between the output current Io and the minimum input / output voltage difference Vi-o. As shown in FIG. 15, the minimum input / output voltage difference Vi-o is large when the output current Io is relatively large, but the minimum input / output voltage difference Vi-o can be small when the output current Io is relatively small. . For example, the current consumption of the DSP fluctuates depending on the operating state. However, in the operating state (maximum load state) in which the current consumption is maximum, a current of about 1 A is consumed, so the minimum input / output voltage difference Vi-o is 0. .6V (that is, a voltage difference between input and output of 0.6V or more is required). On the other hand, since the current is hardly consumed in the standby state (light load state) where the current consumption is minimized, the minimum input / output voltage difference Vi-o is about 0.1 V (that is, the input / output voltage difference is 0). .1V is enough).

  However, the conventional stabilized power supply device shown in FIG. 14 needs to set the characteristics of each element so that a predetermined voltage (rated voltage of the load 19) can be obtained even in the assumed maximum load state. That is, it is necessary to set the voltage difference between the input and output corresponding to the minimum input / output voltage difference Vi-o at the maximum load, and there is a problem that the efficiency is poor at a light load.

  In view of the above points, the present invention provides a direct current stabilized power supply device in which a chopper regulator is disposed in the front stage and a series regulator is disposed in the rear stage. The direct current can always minimize the loss regardless of the current consumption of the load. An object is to provide a stabilized power supply.

  In order to achieve the above object, a first DC stabilized power supply apparatus according to the present invention includes a chopper regulator disposed in a front stage and an output transistor disposed in a rear stage and stepping down and outputting an output voltage of the chopper regulator. The series regulator includes a first output current detection unit that detects an output current of the series regulator, and the chopper regulator includes an input voltage to the chopper regulator. A switching transistor for switching and outputting the output voltage, an output voltage setting means for setting the output voltage of the chopper regulator to a predetermined value, and an input / output of the series regulator according to a detection result by the first output current detection means The voltage difference between As a minimum value corresponding to the current, and an output voltage adjustment means for adjusting by changing the set output voltage.

  According to the above configuration, the output voltage of the chopper regulator set to a predetermined value is changed according to the output current of the series regulator, that is, the current consumption of the load, and the voltage difference between the input and output of the series regulator is The minimum value corresponds to the output current of the series regulator. As a result, the loss in the DC stabilized power supply device can always be minimized regardless of the current consumption of the load, and heat generation can also be minimized.

  Further, a second DC stabilized power supply device according to the present invention includes a chopper regulator disposed in a preceding stage, and a series regulator disposed in a subsequent stage and including an output transistor that steps down the output voltage of the chopper regulator and outputs the voltage. In the stabilized DC power supply apparatus, the series regulator includes base current detection means for detecting a base current of the output transistor, and the chopper regulator switches a voltage input to the chopper regulator and outputs the switching transistor. The voltage difference between the input and output of the series regulator corresponds to the output current of the series regulator according to the detection result by the output voltage setting means for setting the output voltage of the chopper regulator to a predetermined value and the base current detection means The minimum value Sea urchin, and an output voltage adjustment means for adjusting by changing the set output voltage.

  When the load consumption current increases and the output current of the series regulator increases, the base current of the output transistor also increases. Therefore, according to the above configuration, the output voltage of the chopper regulator set to a predetermined value is changed according to the base current of the output transistor, that is, the current consumption of the load, and the voltage difference between the input and output of the series regulator is changed. Is the minimum value corresponding to the output current of the series regulator. As a result, the loss in the DC stabilized power supply device can always be minimized regardless of the current consumption of the load, and heat generation can also be minimized.

  In the method A exemplified in Patent Document 2, the input voltage of the output transistor of the dropper-type stabilized power supply circuit is {(voltage generated across the detection resistor) + (saturation voltage between the collector and emitter of the control transistor). ) + (Saturation voltage between the base and emitter of the output transistor)}, and the reference voltage by the reference voltage source is at least 0.6 V or more (generally 1.25 V or more). Even when the output voltage of the dropper-type stabilized power supply circuit is low, the input voltage of the output transistor of the dropper-type stabilized power supply circuit is {(0.6V) + (the collector-emitter saturation voltage of the control transistor) + (output transistor The base-emitter saturation voltage)} cannot be reduced below. As a result, the loss increases when the output voltage to the load is low.

  On the other hand, unlike the method A in which the voltage generated between both ends of the detection resistor is matched with the reference voltage, the second DC stabilized power supply device is provided with the output voltage setting means separately, and the chopper regulator After setting the output voltage, the output voltage of the chopper regulator is adjusted based on the detection result of the base current detection means. As the base current detection means, for example, similarly to the above-described method A, even when a method of passing a base current through a base current detection resistor and converting it into a voltage is used, the base current detection resistor includes the above-described method A. It is not necessary to generate a large voltage (minimum 0.6 V) such as the reference voltage at. This is because the voltage generated in the base current detection resistor can be used as the signal voltage to adjust the output voltage of the chopper regulator. Therefore, in the second stabilized DC power supply, the loss can be suppressed even when the output voltage to the load is low.

  Further, a third DC stabilized power supply device according to the present invention includes a chopper regulator disposed in the preceding stage, and a series regulator disposed in the subsequent stage and including an output transistor that steps down the output voltage of the chopper regulator and outputs the voltage. In the stabilized DC power supply apparatus, the chopper regulator includes a switching transistor that switches and outputs an input voltage to the chopper regulator, an output voltage setting unit that sets an output voltage of the chopper regulator to a predetermined value, and The second output current detection means for detecting the output current of the chopper regulator, and the voltage difference between the input and output of the series regulator corresponds to the output current of the series regulator according to the detection result by the second output current detection means. Set the output so that the And an output voltage adjustment means for adjusting by changing the voltage.

  The output current of the chopper regulator is substantially equal to the output current of the subsequent series regulator. Therefore, according to the above configuration, the output voltage of the chopper regulator set to a predetermined value is changed according to the output current of the chopper regulator, that is, the current consumption of the load, and the voltage difference between the input and output of the series regulator is changed. Is the minimum value corresponding to the output current of the series regulator. As a result, the loss in the DC stabilized power supply device can always be minimized regardless of the current consumption of the load, and heat generation can also be minimized.

  Further, a fourth DC stabilized power supply device according to the present invention includes a chopper regulator disposed in a preceding stage, and a series regulator disposed in a subsequent stage and including an output transistor that steps down an output voltage of the chopper regulator and outputs the voltage. In the stabilized DC power supply apparatus, the chopper regulator includes a switching transistor that switches and outputs an input voltage to the chopper regulator, an output voltage setting means that sets the output voltage of the chopper regulator to a predetermined value, and an external Output voltage adjusting means for receiving and changing the set output voltage so that the voltage difference between the input and output of the series regulator becomes a minimum value corresponding to the output current of the series regulator; It has.

  According to the above configuration, in response to an externally applied signal, the output voltage of the chopper regulator set to a predetermined value is changed, and the voltage difference between the input and output of the series regulator is the minimum corresponding to the output current of the series regulator. Value. As a result, the loss in the DC stabilized power supply device can always be minimized regardless of the current consumption of the load, and heat generation can also be minimized.

  Specifically, the voltage difference between the input and output of the series regulator, which is the difference between the output voltage of the chopper regulator and the output voltage of the series regulator, is made equal to the collector-emitter saturation voltage in the output transistor.

  Further, for example, the series regulator includes an output control unit that controls the output transistor in accordance with the output voltage of the series regulator, and the output control unit operates using the input voltage to the chopper regulator as its own power supply voltage. You may make it do.

  When the output control unit operates using the input voltage of the series regulator as its power supply voltage, the output control unit will not operate normally if the input voltage decreases and falls below the minimum operating voltage of the output control unit. There is a fear. However, if the input voltage to the chopper regulator is applied as a power supply voltage to the output control unit as described above, there is no possibility that the above-described malfunction occurs. Further, since the output voltage of the chopper regulator can be set lower than the minimum operating voltage of the output controller of the series regulator, the loss in the stabilized power supply device can be further reduced.

  Further, for example, the chopper regulator includes a switching control unit that controls the switching transistor according to the output voltage of the chopper regulator, and the series regulator controls the output transistor according to the output voltage of the series regulator. And a single reference voltage generation circuit may be used as both the reference voltage generation circuit constituting the switching control unit and the reference voltage generation circuit constituting the output control unit. .

  As a result, it is not necessary to provide a plurality of reference voltage generation circuits, and the number of elements constituting the stabilized DC power supply device can be reduced.

  Further, for example, the series regulator may include a plurality of series regulators connected in parallel to the subsequent stage of the chopper regulator, and the plurality of series regulators may output voltages having different voltage values.

  Thereby, a plurality of voltages having different voltage values can be supplied to the load with a small number of elements and a small space.

  Further, for example, the chopper regulator includes a switching control unit that controls the switching transistor according to the output voltage of the chopper regulator, and the series regulator controls the output transistor according to the output voltage of the series regulator. An output control unit, wherein the DC stabilized power supply unit shuts off power supply to the switching control unit in response to a first control signal from the outside, and shuts off the switching transistor, and / or According to a second control signal from the outside, power supply to the output control unit may be cut off, and a second cutoff unit that cuts off the output transistor may be further provided.

  When supply of voltage to the load is unnecessary, it is possible to contribute to energy saving by stopping the operation of the chopper regulator and / or the series regulator.

  In addition, for example, when the output transistor is shut off by the second shut-off means that shuts off the output transistor in response to a second control signal from the outside, and through the series regulator There may be provided first bypass means for supplying the output voltage of the chopper regulator to a load connected to the series regulator.

  When some noise is allowed to enter the load, the operation of the series regulator is stopped and the operation is switched to the operation of the chopper regulator alone, thereby further reducing the loss in the DC stabilized power supply device.

  In addition, for example, when the switching transistor is shut off by the first shut-off means according to a first control signal from the outside, and when the switching transistor is shut off by the first shut-off means, via the chopper regulator There may be provided a second bypass means for supplying the input voltage to the chopper regulator as an input voltage to the series regulator.

  When the input voltage to the chopper regulator has dropped to such an extent that it would hinder the application of the rated voltage to the load, the chopper regulator operation is stopped by the first on / off control means, and the series regulator alone is operated. By switching to, it becomes possible to continue supplying the rated voltage to the load. Further, reduction of radiation noise and further reduction of loss in the DC stabilized power supply device are realized.

  In addition, for example, when the input voltage to the chopper regulator is detected and the magnitude of the input voltage becomes smaller than a predetermined threshold, the switching transistor is shut off and the chopper regulator is not passed through the chopper regulator. There may be provided a third bypass means for supplying the input voltage to the series regulator as an input voltage.

  When configured as described above, when it is detected that the input voltage to the chopper regulator has dropped to such an extent that, for example, the rated voltage is applied to the load, the operation of the chopper regulator is automatically turned off. The operation can be switched to the series regulator alone. This makes it possible to continue supplying the rated voltage to the load. Further, reduction of radiation noise and further reduction of loss in the DC stabilized power supply device are realized.

  Also, for example, when the on-time duty of the switching transistor included in the chopper regulator becomes larger than a predetermined threshold value, the input voltage to the chopper regulator is supplied to the series regulator as the input voltage without going through the chopper regulator. You may make it provide the 4th detour means.

  As the input voltage to the chopper regulator decreases, the on-time duty of the switching transistor increases. By using this relationship and configuring as described above, when the input voltage to the chopper regulator drops, for example, to the extent that it would interfere with giving the rated voltage to the load, the chopper regulator automatically operates. It can be switched to the operation of the series regulator alone as off. This makes it possible to continue supplying the rated voltage to the load. Further, reduction of radiation noise and further reduction of loss in the DC stabilized power supply device are realized.

  Further, for example, when the input voltage to the chopper regulator is supplied as an input voltage to the series regulator without passing through the chopper regulator by the third bypass means or the fourth bypass means, a reset signal is externally supplied. An emitting circuit may be provided.

  Thereby, it is possible to notify the load, an external device, or the like that the input voltage to the chopper regulator has decreased.

  For example, the chopper regulator may be a boost chopper regulator that boosts and outputs an input voltage to the chopper regulator.

  For example, the chopper regulator may be a step-up / step-down chopper regulator that boosts or steps down an input voltage to the chopper regulator and outputs the boosted voltage.

  As described above, according to the stabilized DC power supply device of the present invention, it is always possible to minimize the loss regardless of the current consumption of the load.

  Embodiments of a stabilized DC power supply apparatus according to the present invention will be described below with reference to the drawings. In all the DC stabilized power supply devices in the following embodiments, a chopper regulator is arranged at the front stage and a series regulator is arranged at the rear stage as in FIG. 14, and the chopper regulator inputs its output voltage to the series regulator. The series regulator supplies its output voltage to a load 19 connected to the outside. Further, in all series regulators in the following embodiments, the relationship between the output current Io and the minimum input / output voltage difference Vi-o is the same as that shown in FIG.

<< First Embodiment >>
FIG. 1 is a circuit diagram showing a first embodiment of a direct current stabilized power supply apparatus according to the present invention. In the stabilized power supply device of FIG. 1, a chopper regulator CR1 is disposed at the front stage and a series regulator SR1 is disposed at the rear stage. The stabilized power supply device in FIG. 1 is similar to the stabilized power supply device in FIG. 14. In FIG. 1, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR1 is different from the chopper regulator CR0 in FIG. 14 in that the collector of the NPN-type bipolar transistor 24 is connected to the connection point between the voltage dividing resistors 10 and 11, and is identical in other points. ing. The series regulator SR1 is the same as the series regulator SR0 in FIG. However, the output voltage of the series regulator SR1 is applied to the load 19 via the detection resistor 22, and the connection point between the smoothing capacitor 18 and one end of the detection resistor 22 (first output current detection means) is compared. The connection point between the other end of the detection resistor 22 and the load 19 is connected to the inverting input terminal (−) of the comparator 23. The output of the comparator 23 is given to the base of the transistor 24, and the emitter of the transistor 24 is grounded.

  The comparator 23 supplies a higher voltage to the base of the transistor 24 as the output current of the series regulator SR1 increases, that is, as the voltage difference generated between both ends of the detection resistor 22 increases. When the base voltage of the transistor 24 increases and the base current increases, the current flowing through the voltage dividing resistor 10 increases while the current flowing through the voltage dividing resistor 11 decreases. Therefore, the voltage is divided by these voltage dividing resistors. As a result, the output voltage of the chopper regulator CR1 is increased. Conversely, the comparator 23 supplies a lower voltage to the base of the transistor 24 as the output current of the series regulator SR1 becomes smaller. As a result, the output voltage of the chopper regulator CR1 tends to decrease.

  That is, the output voltage of the chopper regulator CR1 increases as the output current of the series regulator SR1 increases, and the output voltage of the chopper regulator CR1 decreases as the output current of the series regulator SR1 decreases. Reduction of power loss in the device is realized.

  Here, if the characteristics of the detection resistor 22, the comparator 23, the transistor 24, and the like are appropriately set, the voltage difference between the input and output of the series regulator SR1 becomes a minimum value corresponding to the output current of the series regulator SR1. The output voltage of the chopper regulator CR1 set by the voltage dividing resistors 10 and 11 is changed (adjusted), and power loss in the stabilized power supply device is always minimized regardless of the current consumption of the load 19. Can be suppressed.

<< Second Embodiment >>
FIG. 2 is a circuit diagram showing a second embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 2, a chopper regulator CR2 is disposed at the front stage and a series regulator SR2 is disposed at the rear stage. The stabilized power supply device in FIG. 2 is similar to the stabilized power supply device in FIG. 14. In FIG. 2, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR2 is different from the chopper regulator CR0 in FIG. 14 in that the collector of the NPN-type bipolar transistor 27 is connected to the connection point between the voltage dividing resistors 10 and 11, and is identical in other points. ing. In the series regulator SR2, the emitter of the control transistor 13 is grounded via the base current detection resistor R25 (base current detection means) of the output transistor 12, and the emitter is connected to the non-inverting input terminal (+ ) Is different from the series regulator SR0 in FIG. 14 and is the same in other points. The inverting input terminal (−) of the comparator 26 is grounded, and its output is connected to the base of the transistor 27. The emitter of the transistor 27 is grounded.

  The comparator 26 supplies a higher voltage to the base of the transistor 27 as the base current of the output transistor 12 increases, that is, as the voltage difference generated between both ends of the base current detection resistor 25 increases. When the base voltage of the transistor 27 increases and the base current increases, the current flowing through the voltage dividing resistor 10 increases, while the current flowing through the voltage dividing resistor 11 decreases. Therefore, the voltage is divided by these voltage dividing resistors. As a result, the output voltage of the chopper regulator CR2 is increased. Conversely, the comparator 26 supplies a lower voltage to the base of the transistor 27 as the base current of the output transistor 12 decreases. As a result, the output voltage of the chopper regulator CR2 tends to decrease.

  When the consumption current of the load 19 increases and the output current of the series regulator SR2 increases, the base current of the output transistor 12 also increases. Therefore, the output voltage of the chopper regulator CR2 increases due to the operation of the comparator 26 and the like. To do. On the other hand, when the current consumption of the load 19 is reduced and the output current of the series regulator SR2 is reduced, the base current of the output transistor 12 is also reduced. Therefore, the output of the chopper regulator CR2 is caused by the operation of the comparator 26 and the like. The voltage drops.

  That is, as the output current of the series regulator SR2 increases, the output voltage of the chopper regulator CR2 increases, and as the output current of the series regulator SR2 decreases, the output voltage of the chopper regulator CR2 decreases. Reduction of power loss in the device is realized.

  Here, if the characteristics of the detection resistor 25, the comparator 26, the transistor 27, etc. are appropriately set, the voltage difference between the input and output of the series regulator SR2 becomes a minimum value corresponding to the output current of the series regulator SR2. The output voltage of the chopper regulator CR2 set by the voltage dividing resistors 10 and 11 is changed (adjusted), and power loss in the stabilized power supply device is always minimized regardless of the current consumption of the load 19. Can be suppressed.

  Next, the present embodiment and the method A exemplified in Patent Document 2 are compared. In the above method A, the input voltage of the output transistor of the dropper type stabilized power supply circuit is {(voltage generated across the detection resistor) + (saturation voltage between the collector and emitter of the control transistor) + (between the base and emitter of the output transistor). Saturation voltage)}, and the reference voltage from the reference voltage source is at least 0.6 V or higher (generally 1.25 V or higher), so that the output voltage of the dropper-type stabilized power supply circuit Even if the voltage is low, the input voltage of the output transistor of the dropper-type stabilized power supply circuit should be lowered to {0.6V + (control transistor collector-emitter saturation voltage) + (output transistor base-emitter saturation voltage)} or less. I can't. For example, if (the collector-emitter saturation voltage of the control transistor) and (the base-emitter saturation voltage of the output transistor) are 0.5 V and 1 V, respectively, the input voltage of the output transistor of the dropper type stabilized power supply circuit is 2 .1V or more is required, and when the output voltage to the load is low (for example, 1.5V), the loss increases.

  On the other hand, in this embodiment, the transistor 27 can be driven even when the voltage generated in the detection resistor 25 is 0.01 V, for example, the collector-emitter saturation voltage of the control transistor 13 and the base voltage of the output transistor 12- When the saturation voltage between the emitters is 0.5 V and 1 V, respectively, the input voltage to the series regulator SR2 can be suppressed to 0.01V + 0.5V + 1V = 1.51V. Thereby, even when the output voltage to the load 19 is low (for example, 1.5 V), the loss can be reduced.

  In addition, even if the comparator 26 is omitted in FIG. 2 and the connection point between the detection resistor 25 and the collector of the control transistor 13 is directly connected to the base of the transistor 27, the necessary voltage to be generated by the detection resistor 25 is Since the base-emitter saturation voltage of the transistor 27 is about 0.5 V, the loss can be made smaller than that of the method A.

<< Third Embodiment >>
FIG. 3 is a circuit diagram showing a third embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 3, a chopper regulator CR3 is disposed at the front stage and a series regulator SR3 is disposed at the rear stage. The stabilized power supply device in FIG. 3 is similar to the stabilized power supply device in FIG. 14. In FIG. 3, the same parts as those of the stabilized power supply device in FIG. .

  In the chopper regulator CR3, the collector of the NPN bipolar transistor 30 is connected to the connection point between the voltage dividing resistors 10 and 11, and the connection point between the smoothing capacitor 5 and the coil 4 is the detection of the output current of the chopper regulator CR3. A point connected to the connection point between one end of the voltage dividing resistor 10 and the emitter of the output transistor 12 via the resistor 28 (second output current detecting means), and the smoothing capacitor 5 and one end of the detection resistor 28 The connection point is connected to the non-inverting input terminal (+) of the comparator 29, and the connection point between the other end of the detection resistor 28 and one end of the voltage dividing resistor 10 is the inverting input terminal (− ) Is different from the chopper regulator CR0 in FIG. 14, and the other points are the same. The series regulator SR3 is the same as the series regulator SR0 in FIG. The output of the comparator 29 is given to the base of the transistor 30, and the emitter of the transistor 30 is grounded.

  The comparator 29 supplies a higher voltage to the base of the transistor 30 as the output current of the chopper regulator CR3 increases, that is, as the voltage difference generated between both ends of the detection resistor 28 increases. When the base voltage of the transistor 30 increases and the base current increases, the current flowing through the voltage dividing resistor 10 increases, while the current flowing through the voltage dividing resistor 11 decreases. Therefore, the voltage is divided by these voltage dividing resistors. As a result, the output voltage of the chopper regulator CR3 increases. Conversely, the comparator 29 supplies a lower voltage to the base of the transistor 30 as the output current of the chopper regulator CR3 becomes smaller. As a result, the output voltage of the chopper regulator CR3 tends to decrease. Further, since the output current of the series regulator SR3 is substantially equal to the input current of the series regulator SR3, if the output current of the series regulator SR3 increases, the output current of the chopper regulator CR3 also increases.

  That is, as the output current of the series regulator SR3 increases, the output voltage of the chopper regulator CR3 increases, and as the output current of the series regulator SR3 decreases, the output voltage of the chopper regulator CR3 decreases. Reduction of power loss in the device is realized.

  Here, if the characteristics of the detection resistor 28, the comparator 29, the transistor 30, and the like are appropriately set, the voltage difference between the input and output of the series regulator SR3 becomes a minimum value corresponding to the output current of the series regulator SR3. The output voltage of the chopper regulator CR3 set by the voltage dividing resistors 10 and 11 is changed (adjusted), and power loss in the stabilized power supply device is always minimized regardless of the current consumption of the load 19. Can be suppressed.

<< Fourth Embodiment >>
FIG. 4 is a circuit diagram showing a fourth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 4, a chopper regulator CR4 is arranged at the front stage, and a series regulator SR4 is arranged at the rear stage. The stabilized power supply device in FIG. 4 is similar to the stabilized power supply device in FIG. 14. In FIG. 4, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR4 is different from the chopper regulator CR0 in FIG. 14 in that the collector of the NPN bipolar transistor 31 is connected to the connection point between the voltage dividing resistors 10 and 11, and is the same in other points. ing. The series regulator SR4 is the same as the series regulator SR0 in FIG. An external signal applied to the base terminal 32 is applied to the base of the transistor 31, and the base current of the transistor 31 is controlled by the external signal. The emitter of the transistor 31 is grounded.

  A main control unit (not shown) that can recognize the current consumption of the load 19 while controlling the operation of the load 19 varies the signal applied to the base terminal 32 to control the base current of the transistor 31, whereby a chopper regulator The output voltage of CR4 can be adjusted.

  For example, when the output current of the series regulator SR4 increases, a signal is given to the base terminal 32 so that the output voltage of the chopper regulator CR4 increases, and when the output current of the series regulator SR4 decreases, the chopper regulator CR4. A signal is applied to the base terminal 32 so that the output voltage of the signal is reduced. Thereby, reduction of the power loss in the stabilized power supply device is realized.

  Here, if an appropriate signal is given to the base terminal 32, the voltage difference between the input and output of the series regulator SR4 is set by the voltage dividing resistors 10 and 11 so as to be the minimum value corresponding to the output current of the series regulator SR4. The output voltage of the chopper regulator CR4 is changed (adjusted), so that the power loss in the stabilized power supply device can always be minimized regardless of the current consumption of the load 19.

<< Fifth Embodiment >>
FIG. 5 is a circuit diagram showing a fifth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 5, a chopper regulator CR5 is arranged at the front stage and a series regulator SR5 is arranged at the rear stage. The stabilized power supply device in FIG. 5 is similar to the stabilized power supply device in FIG. 4. In FIG. 5, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR5 and the series regulator SR5 are configured such that the collector of the switching transistor 2 is further commonly connected to the power supply terminal of the error amplifier 14 and the power supply terminal of the reference voltage generation circuit 15 of the series regulator SR5. It is different from the regulator CR4 and the series regulator SR4, and is identical in other points. That is, in FIG. 4, the output voltage of the chopper regulator CR4 is given to the error amplifier 14 and the reference voltage generation circuit 15 as the respective power supply voltages, but in FIG. The input voltage to the chopper regulator CR5 is supplied to the error amplifier 14 and the reference voltage generation circuit 15 as the respective power supply voltages, instead of being supplied to the reference voltage generation circuit 15 as the respective power supply voltages.

  An output control unit, which includes at least an error amplifier 14 and a reference voltage generation circuit 15 and controls the amount of base current of the output transistor 12 in accordance with the output voltage of the series regulator SR5, uses the input voltage of the series regulator as the power supply voltage. When operating, if the input voltage decreases (for example, 2 V or less) and falls below the minimum operating voltage of the output control unit, the output control unit may not operate normally.

  However, if it is configured as shown in FIG. 5 and the input voltage to the chopper regulator CR5 is supplied to the output control unit as the power supply voltage, there is no possibility that the above-described malfunction occurs. Further, with the configuration as shown in FIG. 5, the output voltage of the chopper regulator CR5 can be set lower than the minimum operating voltage of the output control unit of the series regulator SR5. Can be further reduced.

<< Sixth Embodiment >>
FIG. 6 is a circuit diagram showing a sixth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 6, a chopper regulator CR6 is arranged at the front stage and a series regulator SR6 is arranged at the rear stage. The stabilized power supply device in FIG. 6 is similar to the stabilized power supply device in FIG. 5. In FIG. 6, the same parts as those of the stabilized power supply device in FIG. .

  In the chopper regulator CR6 and the series regulator SR6, the reference voltage generation circuit 15 is omitted, and the reference voltage output from the reference voltage generation circuit 9 of the chopper regulator CR6 is applied to the non-inverting input terminal (+) of the error amplifier 14. This is different from the chopper regulator CR5 and the series regulator SR5 in FIG. 5, and is the same in other points.

  As described above, the ON time (or duty) of the switching transistor 2 is controlled by comparing the voltage corresponding to the output voltage of the chopper regulator CR6 with the reference voltage, and the base current of the output transistor 12 is The voltage is controlled by comparing a voltage corresponding to the output voltage of the series regulator SR6 with a reference voltage.

  In this embodiment, the single reference voltage generation circuit 9 is a reference voltage generation circuit that is a component of a circuit that controls the switching transistor 2 and a component of a circuit that controls the base current of the output transistor 12. It is also used as a reference voltage generation circuit.

  Thereby, it is not necessary to provide a plurality of reference voltage generation circuits, and the number of elements constituting the stabilized power supply device can be reduced.

<< Seventh Embodiment >>
FIG. 7 is a block diagram showing a seventh embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 7, a chopper regulator CR is arranged in the front stage, and series regulators SRa, SRb, and SRc are arranged in parallel in the rear stage. Any of the above-described chopper regulators CR1 to CR6 may be employed for the circuit configuration of the chopper regulator CR, or any of the chopper regulators CR8 to CR13 described later may be employed. Any of the above-described series regulators SR1 to SR6 or any of series regulators SR8 to SR13 described later may be employed for the circuit configuration of each of the series regulators SRa, SRb, and SRc.

  The chopper regulator CR receives an input voltage of DC 5V and supplies the converted voltage to each of the series regulators SRa, SRb, and SRc. The series regulators SRa, SRb, and SRc step down the supplied voltage and supply voltages of DC 1.8V, DC 1.5V, and DC 1.2V to a load (not shown) connected to the outside, respectively. In this case, for example, the output voltage of the chopper regulator CR is set so that the voltage difference between the input and output of the series regulator SRa having the largest output voltage supplied to the load (not shown) becomes the minimum value corresponding to the output current of the series regulator SRa. Is adjusted.

  In many cases, it is necessary to supply a plurality of input voltages having different voltage values to a microcomputer or DSP as a load. However, if configured as in this embodiment, the voltage value can be reduced with a small number of elements and a small space. It is possible to supply a plurality of different input voltages. In FIG. 7, there are three series regulators in the subsequent stage, but any number can be changed as necessary.

<< Eighth Embodiment >>
FIG. 8 is a circuit diagram showing an eighth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 8, a chopper regulator CR8 is disposed at the front stage and a series regulator SR8 is disposed at the rear stage. The stabilized power supply device in FIG. 8 is similar to the stabilized power supply device in FIG. 4. In FIG. 8, the same parts as those of the stabilized power supply device in FIG. .

  In the chopper regulator CR8, the collector of the switching transistor 2 is connected to the collector of the NPN bipolar transistor 33 (first cutoff means), and the power supply terminals of the comparator 6, the error amplifier 8 and the reference voltage generation circuit 9 are connected. Is connected to the emitter of the transistor 33, that is, the output voltage of the power source 1 is supplied as the power source voltage to the comparator 6, the error amplifier 8 and the reference voltage generation circuit 9 via the transistor 33. This is different from the chopper regulator CR4 in FIG. 4 and is identical in other points. The base of the transistor 33 is connected to the control terminal 35.

  In the series regulator SR8, the emitter of the output transistor 12 is connected to the collector of the NPN bipolar transistor 34 (second cutoff means), and the power supply terminals of the error amplifier 14 and the reference voltage generation circuit 15 are the transistors 34, respectively. Connected to the emitter, that is, the output voltage of the chopper regulator CR8 (the input voltage to the series regulator SR8) is supplied as a power supply voltage to each of the error amplifier 14 and the reference voltage generation circuit 15 via the transistor 34. 4 is different from the series regulator SR4 in FIG. 4 and is identical in other points. The base of the transistor 34 is connected to the control terminal 36.

  Then, for example, a main control unit (not shown) that controls the operation of the load 19 gives a signal for controlling on / off of the output of the voltage from the chopper regulator CR8 to the control terminal 35, and the voltage from the series regulator SR8. A signal for ON / OFF control of the output of is supplied to the control terminal 36.

  When the signal applied to the control terminal 35 is at a high level, the transistor 33 is turned on to supply the power supply voltage to each of the comparator 6, the error amplifier 8, and the reference voltage generation circuit 9, and the chopper regulator CR8 has been described above. As described above, the voltage is output to the subsequent series regulator SR8 (the voltage output is turned on). On the other hand, when the signal applied to the control terminal 35 is at a low level, the transistor 33 is turned off, the supply of the power supply voltage to each of the comparator 6, the error amplifier 8 and the reference voltage generation circuit 9 is cut off, and the switching transistor 2 Is turned off, the voltage output from the chopper regulator CR8 is stopped (turned off).

  When the signal applied to the control terminal 36 is at a high level, the transistor 34 is turned on, and the power supply voltage is supplied to each of the error amplifier 14 and the reference voltage generation circuit 15, and the series regulator SR8 has been described above. Voltage is output to the load 19 (voltage output is turned on). On the other hand, when the signal applied to the control terminal 36 is at a low level, the transistor 34 is turned off, the supply of the power supply voltage to the error amplifier 14 and the reference voltage generation circuit 15 is cut off, and the output transistor 12 is turned off. Therefore, the output of the voltage from the series regulator SR8 is stopped (off).

  Therefore, when it is not necessary to supply voltage to the load 19, if a low level signal is supplied to at least one of the control terminal 35 and the control terminal 36, output of voltage to the load 19 is stopped. Can contribute. In consideration of the power loss caused by the on / off control of the switching transistor 2 and the power consumption of the error amplifiers 8 and 14 and the like, if the supply of voltage to the load 19 is unnecessary, the control terminal 35 and It is desirable to supply a low level signal to both of them. Alternatively, the control terminal 35 and the control terminal 36 may be connected so that the transistor 33 and the transistor 34 are simultaneously on / off controlled in accordance with an external signal.

<< Ninth Embodiment >>
FIG. 9 is a circuit diagram showing a ninth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 9, a chopper regulator CR9 is arranged at the front stage and a series regulator SR9 is arranged at the rear stage. The stabilized power supply device in FIG. 9 is similar to the stabilized power supply device in FIG. 8. In FIG. 9, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR9 is different from the chopper regulator CR8 in FIG. 8 in that the emitter of a PNP bipolar transistor 37 (first bypass means) is connected to the connection point between the smoothing capacitor 5 and the voltage dividing resistor 10. In other respects. Series regulator SR9 is the same as series regulator SR8 in FIG. However, the collector of the transistor 37 is connected to the connection point between the smoothing capacitor 18 and the load 19. The base of the transistor 37 is connected to the control terminal 36.

  When a high level signal is applied to the control terminal 36, the transistor 34 is turned on and the series regulator SR9 outputs a voltage. At this time, the transistor 37 is turned off.

  On the other hand, when a low level signal is applied to the control terminal 36, the transistor 34 is turned off and the voltage output from the series regulator SR9 is turned off. At this time, since the transistor 37 is turned on, the voltage output from the chopper regulator CR9 is supplied to the load 19 without passing through the series regulator SR9.

  As described above, when the voltage output from the chopper regulator CR9 is supplied to the load 19 without passing through the series regulator SR9, the input to the load 19 is compared with the case where the voltage is supplied to the load 19 via the series regulator SR9. There will be more noise in the voltage. However, when a slight amount of noise is permitted, a low level signal is supplied to the control terminal 36 to switch to the operation of the chopper regulator CR9 alone, thereby further reducing the power loss in the stabilized power supply device. .

<< Tenth Embodiment >>
FIG. 10 is a circuit diagram showing a tenth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 10, a chopper regulator CR10 is arranged at the front stage and a series regulator SR10 is arranged at the rear stage. The stabilized power supply device in FIG. 10 is similar to the stabilized power supply device in FIG. 8. In FIG. 10, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR10 is different from the chopper regulator CR8 in FIG. 8 in that the collector of the PNP bipolar transistor 38 (second bypass means) is connected to the connection point between the smoothing capacitor 5 and the voltage dividing resistor 10. In other respects. Further, the output voltage of the power supply 1 is given to the emitter of the transistor 38, and its base is connected to the control terminal 35. Series regulator SR10 is the same as series regulator SR8 in FIG.

  When a high level signal is applied to the control terminal 35, the transistor 33 is turned on and the chopper regulator CR10 outputs a voltage. At this time, the transistor 38 is turned off.

  On the other hand, when a low level signal is applied to the control terminal 35, the transistor 33 is turned off and the voltage output from the chopper regulator CR10 is turned off. At this time, since the transistor 38 is turned on, the output voltage of the power source 1 (input voltage to the chopper regulator CR10) is supplied as an input voltage to the series regulator SR10 without passing through the chopper regulator CR10.

  Thus, if the voltage output from the chopper regulator CR10 is turned off (when the operation of the chopper regulator CR10 is stopped), the radiation noise is reduced. Therefore, when reduction of radiation noise is required, a low level signal may be given to the control terminal 35 to switch to the operation of the series regulator SR10 alone. Thereby, further reduction of the power loss in the stabilized power supply device can also be realized.

Since the loss in the chopper regulator CR10 is approximated by Vsat × Io × (output voltage of the chopper regulator CR10 / input voltage of the chopper regulator CR10) (Vsat: saturation voltage between the collector and the emitter of the switching transistor 2), the chopper regulator When the input voltage to the CR 10 becomes low, the loss increases. Furthermore, the voltage difference between the input voltage to the chopper regulator CR10 and the rated voltage V _{L of the} load 19 (the input voltage to the load 19 required by the load 19) is the minimum input / output of the saturation voltage Vsat and the series regulator SR10. When the input voltage to the chopper regulator CR10 becomes lower as it becomes smaller than the sum of the voltage differences Vi-o, the rated voltage is supplied to the load 19 when both the regulators CR10 and SR10 are operated. Can not be.

Therefore, when the input voltage of the chopper regulator CR10 becomes low, it is preferable to provide a low level signal to the control terminal 35 to bypass the chopper regulator CR10 and switch to the operation of the series regulator SR10 alone. Thereby, even when the input voltage to the chopper regulator CR10 becomes (Vsat + Vi−o + V _L ) or less, the rated voltage V _L can be continuously supplied to the load 19.

<< Eleventh Embodiment >>
FIG. 11 is a circuit diagram showing an eleventh embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 11, a chopper regulator CR11 is arranged at the front stage, and a series regulator SR11 is arranged at the rear stage. The stabilized power supply device in FIG. 11 is similar to the stabilized power supply device in FIG. 10. In FIG. 11, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR11 is the same as the chopper regulator CR10 in FIG. However, the control terminal 35 in the stabilized power supply device of FIG. 10 is omitted, the base of the transistor 33 is connected to the collector of the transistor 33 via the resistor 50, and the transistor 38 (third bypass means). Connected to the base. The series regulator SR11 is the same as the series regulator SR10 in FIG.

  The output voltage of the power source 1 is grounded through a series circuit composed of voltage dividing resistors 39 and 40, and a connection point between the voltage dividing resistor 39 and the voltage dividing resistor 40 is an inverting input terminal (− )It is connected to the. The non-inverting input terminal (+) of the error amplifier 41 is supplied with the reference voltage Vref output from the reference voltage generation circuit 42, and the output of the error amplifier 41 is supplied to the base of the NPN bipolar transistor 43. Yes. The collector of the transistor 43 is connected to the base of the transistor 38, and the emitter of the transistor 43 is grounded.

When the output voltage of the power supply 1 is higher than the predetermined voltage V _A , the voltage divided by the voltage dividing resistors 39 and 40 becomes higher than the reference voltage output from the reference voltage generating circuit 42, and the error amplifier 41 is low level. The transistor 43 is turned off in response to the low level output. As a result, the transistor 33 is turned on, the chopper regulator CR11 operates to output a voltage, and the transistor 38 is turned off.

On the other hand, when the output voltage of the power supply 1 is lower than the predetermined voltage V _A , the voltage divided by the voltage dividing resistors 39 and 40 becomes lower than the reference voltage output from the reference voltage generating circuit 42 and the error amplifier 41. Outputs a high level signal, and the transistor 43 is turned on in response to the high level output. As a result, the transistor 33 is turned off, the chopper regulator CR11 stops outputting the voltage, and the transistor 38 is turned on, so that the output voltage of the power source 1 (input voltage to the chopper regulator CR11) passes through the chopper regulator CR11. Instead, it is supplied as an input voltage to the series regulator SR11.

Therefore, for example, if the predetermined voltage V _A is set to be equal to (Vsat + Vi−o + V _L ), when the input voltage to the chopper regulator CR11 becomes (Vsat + Vi−o + V _L ) or less, it is automatically set. The input voltage to the chopper regulator CR11 is supplied to the subsequent series regulator SR11 via the transistor 38, and the operation is switched to the operation of the series regulator SR11 alone. That is, even when the input voltage to the chopper regulator CR11 becomes (Vsat + Vi−o + V _L ) or less, the rated voltage V _L can be continuously supplied to the load 19 automatically.

<< Twelfth Embodiment >>
FIG. 12 is a circuit diagram showing a twelfth embodiment of the DC stabilized power supply device according to the present invention. In the stabilized power supply device of FIG. 12, a chopper regulator CR12 is arranged at the front stage and a series regulator SR12 is arranged at the rear stage. The stabilized power supply device in FIG. 12 is similar to the stabilized power supply device in FIG. 8. In FIG. 12, the same parts as those of the stabilized power supply device in FIG. .

  In the chopper regulator CR12, the transistor 33 in FIG. 8 is omitted (therefore, the control terminal 35 is not provided), and the output of the error amplifier 8 is connected to the base of the NPN bipolar transistor 43, so that the smoothing capacitor 5 8 is different from the chopper regulator CR8 in FIG. 8 in that the collector of the PNP bipolar transistor 38 is connected to the connection point between the voltage dividing resistor 10 and the voltage dividing resistor 10, and the other points are the same. Series regulator SR12 is the same as series regulator SR8 in FIG. In the transistor 43, the collector is connected to the base of the transistor 38, and the emitter is grounded. Further, the output of the power source 1 is connected to the emitter of the transistor 38 and the output voltage of the power source 1 is directly supplied.

  The operation of the stabilized power supply configured as described above will be described. When the current consumption of the load 19 is constant, when the input voltage to the chopper regulator CR12 decreases, the output voltage of the error amplifier 8 increases, and accordingly the output voltage of the comparator 6 becomes high level. The ratio, that is, the duty of the ON time of the switching transistor 2 increases.

  When the output voltage of the error amplifier 8 increases as the duty of the ON time of the switching transistor 2 exceeds a certain threshold value, the transistor 43 is turned on, and the transistor 38 is turned on. When the transistor 38 is turned on, the output voltage of the power source 1 (input voltage to the chopper regulator CR12) is supplied as an input voltage to the series regulator SR12 via the transistor 38 without passing through the chopper regulator CR12.

As described above, the loss in the chopper regulator CR12 increases as the input voltage to the chopper regulator CR12 decreases. However, the input voltage to the chopper regulator CR12 decreases as a result of the configuration as in this embodiment. (For example, if it becomes (Vsat + Vi−o + V _L ) or less), the transistor 38 is automatically turned on, and the operation is switched to the operation of the series regulator SR12 alone. Thereby, the power loss in the stabilized power supply device can be reduced. Further, the lower limit of the output voltage of the power source 1 for supplying the rated voltage V _L to the load 19 is reduced, and when the power source 1 is a storage battery or the like, the life of the storage battery (the rated current _L can be supplied to the load 19). Time).

  Even when the transistor 38 is on, the potential of the inverting input terminal (−) of the error amplifier 8 rises when the output voltage of the power supply 1 rises. If the transistor 43 is shut off along with this rise, then the transistor 38 is shut off. As a result, the chopper regulator CR12 resumes its original operation, and the input voltage to the series regulator SR12 is supplied by the switching operation of the switching transistor 2.

  When the transistor 38 is turned on and the output voltage of the power source 1 is supplied to the connection point between the voltage dividing resistor 10 and the smoothing capacitor 5 via the transistor 38, an error occurs due to the increase in the voltage at the connection point. The transistor 38 may be immediately turned off when the output voltage of the amplifier 8 decreases. In this case, the transistor 38 is repeatedly turned on and off, and the voltage at the connection point between the voltage dividing resistor 10 and the smoothing capacitor 5 becomes unstable. However, the series regulator SR12 is connected to the input voltage (the voltage dividing resistor 10 and the smoothing capacitor). Since the stable voltage can be output even if the voltage at the connection point with the terminal 5 becomes unstable, there is no problem as a whole. The unstable operation as described above is transient, and the transistor 38 is kept off if the output voltage of the power source 1 is sufficiently high. The transistor 38 is maintained if the output voltage of the power source 1 is sufficiently low. Keeps on.

<< Thirteenth Embodiment >>
FIG. 13 is a circuit diagram showing a thirteenth embodiment of the direct current stabilized power supply according to the present invention. In the stabilized power supply device of FIG. 13, a chopper regulator CR13 is arranged at the front stage and a series regulator SR13 is arranged at the rear stage. The stabilized power supply device in FIG. 13 is similar to the stabilized power supply device in FIG. 12. In FIG. 13, the same parts as those of the stabilized power supply device in FIG. .

  The chopper regulator CR13 is different from the chopper regulator CR12 in FIG. 12 in that the output of the error amplifier 8 is connected to the base of the transistor 43 and to the base of the NPN type bipolar transistor 44. In terms of The series regulator SR13 is the same as the series regulator SR12 in FIG. In the transistor 44, the collector is connected to the reset output terminal 45, and the emitter is grounded.

  The transistor 44 is turned on and off in synchronization with the turning on and off of the transistor 43, respectively. If the reset output terminal 45 is connected to a connection point between the smoothing capacitor 18 and the load 19 via a pull-up resistor (not shown), for example, the transistor 43 is turned on and the transistor 38 is turned on. At the same time, the transistor 44 is turned on and the reset output terminal 45 becomes low level. When the transistor 43 is turned off and the transistor 38 is turned off, the transistor 44 is also turned off and the reset output terminal 45 becomes high level.

  Therefore, if the reset output terminal 45 is connected to the load 19 or an external device, the load 19 or an external device can be informed that the input voltage to the chopper regulator CR13 has decreased. Needless to say, the transistor 44 and the reset output terminal 45 may be provided in the stabilized power supply device in FIG.

<< Deformation, etc. >>
It should be noted that all the embodiments described above can be implemented in any combination as long as no contradiction occurs. As a result, a stabilized power supply device that performs optimum operation while realizing maximum efficiency according to the output voltage of the power supply 1 (input voltage to the chopper regulator) and the consumption current of the load 19 (output current of the series regulator). Is configured.

(Replacement with boost chopper regulator)
All the chopper regulators in FIGS. 1 to 13 are step-down chopper regulators that step down and output an input voltage, but may be replaced with step-up chopper regulators that output a desired voltage by stepping up the input voltage. . In particular, in portable devices such as cellular phones, the power source 1 is composed of a low-voltage output storage battery (eg, rated output voltage is DC 3.6 V), and a liquid crystal backlight driving voltage of DC 12 V is created from the low-voltage output. There are many things that must be done. In such a case, if it is replaced with a boost chopper regulator, a stable supply of DC 12 V can be achieved with a minimum power loss.

(Replacement with buck-boost chopper regulator)
All the chopper regulators in FIGS. 1 to 13 are step-down chopper regulators that step down and output an input voltage, but are step-up / step-down chopper regulators that output a desired voltage by stepping up or stepping down the input voltage, respectively. It may be replaced. When the storage battery mounted on the automobile is the power source 1 in FIGS. 1 to 13, the output voltage of the power source 1 fluctuates relatively greatly. For example, when the rated voltage of the load 19 of DC12V is created, if the output voltage of the storage battery is relatively high, the chopper regulator needs to step down the output voltage of the storage battery, and the output voltage of the storage battery is relatively low In other words, the chopper regulator needs to boost the output voltage of the storage battery. In such a case, if the step-up / step-down chopper regulator is replaced, it is possible to supply a stable DC 12 V with a minimum power loss.

  Further, in all the embodiments described above, the same code Vref is used as a code representing the reference voltage Vref output from the reference voltage generation circuits 9 and 15, but the voltage output from the reference voltage generation circuits 9 and 15 is Different voltage values may be used. Similarly, the voltage output from the reference voltage generation circuit 42 in FIG. 11 may be different from the voltage output from the reference voltage generation circuits 9 and 15.

  Compared with the stabilized power supply device shown in FIG. 14, the parts (transistor 24 and the like in FIG. 1) and wiring newly added in FIGS. 1 to 13 are provided inside the chopper regulator in each embodiment. It can also be understood that it is disposed, and can be regarded as disposed outside the chopper regulator. Similarly, it can be considered that it is disposed inside the series regulator in each embodiment, or can be regarded as disposed outside the series regulator.

  In addition, although all the chopper regulators in FIGS. 1 to 13 employ bipolar transistors as switching transistors, synchronous rectification chopper regulators using MOSFETs (insulated gate type field effect transistors) are employed. It may be. 1 to 13 employs PNP type bipolar transistors as output transistors, but may employ NPN type bipolar transistors.

(Other)
The voltage dividing resistor 10, the voltage dividing resistor 11, and the reference voltage generating circuit 9 mainly function as output voltage setting means for setting an output voltage of a chopper regulator (chopper regulator CR1 or the like). The comparator 6, the error amplifier 8, and the reference voltage generation circuit 9 mainly include a switching control unit that controls on / off (switching pulse width) of the switching transistor 2 in accordance with the output voltage of the chopper regulator (chopper regulator CR1, etc.). Function as. The control transistor 13, the error amplifier 14, and the reference voltage generation circuit 15 mainly function as an output control unit that controls the output transistor 12 in accordance with the output voltage of a series regulator (such as the series regulator SR1).

  The stabilized power supply device according to the present invention is suitable as a power supply device for electrical equipment such as a computer and an optical disk playback device, and in particular, portable equipment (portable electrical equipment such as a mobile phone and a digital camera) that requires low loss. ).

1 is a circuit diagram showing a first embodiment of a stabilized DC power supply device according to the present invention. It is a circuit diagram which shows 2nd Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 3rd Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 4th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 5th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 6th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a block diagram which shows 7th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 8th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 9th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 10th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 11th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 12th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit diagram which shows 13th Embodiment of the direct current | flow stabilized power supply device which concerns on this invention. It is a circuit which shows the conventional direct current | flow stabilized power supply device. It is a figure which shows the relationship between the output current in the series regulator of FIG. 14, and the minimum voltage difference between input and output.

Explanation of symbols

CR0 to CR6, CR8 to CR13, CR Chopper regulator SR0 to SR6, SR8 to SR13 Series regulator SRa, SRb, SRc Series regulator 1 Power supply 2 Switching transistor 3 Diode 4 Coil 5, 18 Smoothing capacitor 10, 11, 16, 17, 39 , 40 Voltage dividing resistor 6, 23, 26, 29 Comparator 7 Oscillation circuit 8, 14, 41 Error amplifier 9, 15, 42 Reference voltage generation circuit 12 Output transistor 13 Control transistor 19 Load 22, 25, 28 Detection resistor 32 Base terminal 35, 36 Control terminal

Claims (17)

In a DC stabilized power supply device including a chopper regulator disposed in a front stage and a series regulator that is disposed in a rear stage and includes an output transistor that steps down and outputs an output voltage of the chopper regulator.
The series regulator includes first output current detection means for detecting an output current of the series regulator,
The chopper regulator includes a switching transistor that switches and outputs an input voltage to the chopper regulator, output voltage setting means that sets an output voltage of the chopper regulator to a predetermined value,
The set output voltage is changed so that the voltage difference between the input and output of the series regulator becomes a minimum value corresponding to the output current of the series regulator according to the detection result by the first output current detecting means. A stabilized DC power supply device comprising output voltage adjusting means for adjusting the output voltage. In a DC stabilized power supply device including a chopper regulator disposed in a front stage and a series regulator that is disposed in a rear stage and includes an output transistor that steps down and outputs an output voltage of the chopper regulator.
The series regulator includes base current detection means for detecting a base current of the output transistor,
The chopper regulator includes a switching transistor that switches and outputs an input voltage to the chopper regulator, output voltage setting means that sets an output voltage of the chopper regulator to a predetermined value,
According to the detection result by the base current detection means, the set output voltage is changed and adjusted so that the voltage difference between the input and output of the series regulator becomes a minimum value corresponding to the output current of the series regulator. A stabilized DC power supply device comprising: an output voltage adjusting unit. In a DC stabilized power supply device including a chopper regulator disposed in a front stage and a series regulator that is disposed in a rear stage and includes an output transistor that steps down and outputs an output voltage of the chopper regulator.
The chopper regulator includes a switching transistor that switches and outputs an input voltage to the chopper regulator, output voltage setting means that sets an output voltage of the chopper regulator to a predetermined value,
Second output current detection means for detecting the output current of the chopper regulator;
The set output voltage is changed so that the voltage difference between the input and output of the series regulator becomes a minimum value corresponding to the output current of the series regulator according to the detection result by the second output current detecting means. A stabilized DC power supply device comprising output voltage adjusting means for adjusting the output voltage. In a DC stabilized power supply device including a chopper regulator disposed in a front stage and a series regulator that is disposed in a rear stage and includes an output transistor that steps down and outputs an output voltage of the chopper regulator.
The chopper regulator includes a switching transistor that switches and outputs an input voltage to the chopper regulator, output voltage setting means that sets an output voltage of the chopper regulator to a predetermined value,
Output voltage adjusting means for receiving and changing the set output voltage so that the voltage difference between the input and output of the series regulator becomes a minimum value corresponding to the output current of the series regulator in response to an external signal A stabilized DC power supply device comprising: 2. A voltage difference between input and output of the series regulator, which is a difference between an output voltage of the chopper regulator and an output voltage of the series regulator, is made equal to a collector-emitter saturation voltage in the output transistor. The DC stabilized power supply device according to claim 4. The series regulator includes an output control unit that controls the output transistor in accordance with an output voltage of the series regulator, and the output control unit operates using the input voltage to the chopper regulator as its power supply voltage. The direct-current stabilized power supply device according to any one of claims 1 to 5. The chopper regulator includes a switching control unit that controls the switching transistor according to an output voltage of the chopper regulator,
The series regulator includes an output control unit that controls the output transistor according to an output voltage of the series regulator,
6. A single reference voltage generation circuit is used as both a reference voltage generation circuit constituting the switching control unit and a reference voltage generation circuit constituting the output control unit. The direct current | flow stabilized power supply device in any one of. The series regulator includes a plurality of series regulators connected in parallel to the subsequent stage of the chopper regulator, and the plurality of series regulators output voltages having different voltage values, respectively. Item 6. The stabilized direct-current power supply device according to any one of Items 5. The chopper regulator includes a switching control unit that controls the switching transistor according to an output voltage of the chopper regulator,
The series regulator includes an output control unit that controls the output transistor according to an output voltage of the series regulator,
The DC stabilized power supply device cuts off power supply to the switching control unit in response to a first control signal from the outside, and cuts off the switching transistor and / or second control from outside. 6. The direct current according to claim 1, further comprising a second shut-off unit that shuts off power supply to the output control unit according to a signal and shuts off the output transistor. Stabilized power supply. A second blocking means for blocking the output transistor in response to a second control signal from the outside;
First bypass means for supplying the output voltage of the chopper regulator to a load connected to the series regulator without passing through the series regulator when the output transistor is shut off by the second cutoff means. 6. The stabilized direct-current power supply device according to claim 1, wherein First blocking means for blocking the switching transistor in response to a first control signal from the outside;
When the switching transistor is cut off by the first cut-off means, a second bypass means is provided for supplying the input voltage to the chopper regulator as an input voltage to the series regulator without going through the chopper regulator. The stabilized DC power supply device according to any one of claims 1 to 5. When the input voltage to the chopper regulator is detected, and the magnitude of the input voltage becomes smaller than a predetermined threshold, the switching transistor is shut off and the input voltage to the chopper regulator is not passed through the chopper regulator. 6. The stabilized DC power supply device according to claim 1, further comprising third bypass means for supplying the series regulator as an input voltage. A fourth detour for supplying an input voltage to the series regulator as an input voltage without going through the chopper regulator when the on-time duty of the switching transistor included in the chopper regulator becomes larger than a predetermined threshold value The direct-current stabilized power supply device according to any one of claims 1 to 5, further comprising means. When the third bypass means or the fourth bypass means supplies the input voltage to the chopper regulator as an input voltage to the series regulator without going through the chopper regulator, a circuit for generating a reset signal is provided. 14. The stabilized DC power supply device according to claim 12, wherein the stabilized DC power supply device is provided. 6. The DC stabilized power supply device according to claim 1, wherein the chopper regulator is a boost chopper regulator that boosts and outputs an input voltage to the chopper regulator. 6. The stabilized DC power supply device according to claim 1, wherein the chopper regulator is a step-up / step-down chopper regulator that steps up or steps down an input voltage to the chopper regulator and outputs the boosted voltage.   An electric apparatus comprising the DC stabilized power supply device according to any one of claims 1 to 16.

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