JP2013042571A - Switching power supply device - Google Patents

Abstract

Even if an organic semiconductor capacitor is used, it is possible to prevent the occurrence of an overshoot in which the output voltage exceeds the target voltage and to prevent the generation of high-frequency noise before the output voltage reaches the target voltage. Enable.
When a switching power supply device 20 uses an input voltage Vin as an output voltage Vout through an organic semiconductor capacitor C2, the output voltage Vout is fed back to the switching power supply controller 13 through voltage dividing resistors R3 and R2. Then, switching control is performed to increase or decrease the frequency of the input voltage to the capacitor C2 in accordance with the level of the feedback voltage. The power inductor L2 is connected to the input side of the capacitor C2 in a state where an LC filter is formed by the power inductor L2 and the capacitor C2, and the voltage after switching control by the control unit 13 is fed back to the input side of the power inductor L2. An RC circuit including a resistor R4 and a capacitor C5 is provided.
[Selection] Figure 1

Description

  The present invention relates to a switching power supply device that uses an organic semiconductor capacitor to remove noise from an output voltage.

  As a conventional switching power supply, there is a circuit configuration shown in FIG. The switching power supply device 10 shown in FIG. 4 includes a power supply 11, a switching power supply control unit 13, a phase correction unit 15 formed by connecting a resistor R1 and an electrolytic capacitor (also simply referred to as a capacitor) C1, and an electrolytic capacitor C3. , C4, an inductor L1, a Zener diode (also simply referred to as a diode) D1, an organic semiconductor capacitor C2 for removing noise from the output voltage Vout, and resistors R2, R3, and R5.

  The switching power supply control unit 13 includes a control unit 13 a and a power unit 13 b using a power transistor, and the control unit 13 a appropriately corrects the phase of the input voltage Vin from the power supply 11 using the phase correction unit 15. Control and control to increase or decrease the switching frequency according to the level of a feedback voltage Vfb described later are performed. The power unit 13b repeats a switching operation for short-circuiting / opening the passing voltage output side of the inductor L1 connected to the power supply 11 with GND (ground) at predetermined intervals according to the vertical control of the switching frequency by the control unit 13a. The frequency of the passing voltage is varied.

  An electrolytic capacitor C3 is connected between the power supply 11 and the input terminal in to which the input voltage Vin of the switching power supply control unit 13 is input. The electrolytic capacitor C3 is connected between the input terminal in and the capacitor C3. Is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the switching frequency control terminal SW of the power unit 13b and to the anode of the diode D1.

  A resistor R5 serving as an output unit of the switching power supply device 10 is connected between the cathode of the diode D1 and GND. Between the resistor R5 and the cathode of the diode D1, an electrolytic capacitor C4 and a capacitor are sequentially connected from the cathode side. An organic semiconductor capacitor C2 is connected between GND, and resistors R3 and R4 as voltage dividing resistors are connected between GND, and a switching power supply controller between these resistors R3 and R4. Thirteen feedback terminals FB are connected. That is, the output voltage Vout output from both ends of the resistor R5 is divided by the voltage dividing resistors R3 and R4 and fed back to the switching power supply controller 13 as the feedback voltage Vfb.

  In the switching power supply 10 having such a configuration, if the level of the feedback voltage Vfb input to the switching power supply control unit 13 is high, the control unit 13a controls the switching frequency to be low, and power is controlled according to this control. The part 13b is controlled so that the frequency of the passing voltage of the inductor L1 is lowered, and the level of the output voltage Vout is lowered accordingly. On the other hand, if the level of the feedback voltage Vfb is low, the control unit 13a is controlled to increase the switching frequency, and in response to this control, the power unit 13b is controlled to increase the frequency of the passing voltage of the inductor L1. Accordingly, the level of the output voltage Vout increases. As a result, the output voltage Vout is controlled to a predetermined constant voltage value.

  In such a switching power supply device 10, an organic semiconductor capacitor C2 for removing noise of the output voltage Vout is used. As a device using this type of organic semiconductor capacitor, there is a technique described in Patent Document 1.

JP-A-7-263276

  By the way, according to the conventional switching power supply device 10 described above, the organic semiconductor capacitor C2 is used on the voltage output side for noise removal. This is because the organic semiconductor capacitor C2 has a noise removal capability that is smaller than that of the electrolytic capacitor. The difference is large. Compared with ESR (equivalent series resistance value), the electrolytic capacitor is 100 mΩ, whereas the organic semiconductor capacitor (for example, 2.5V 820 μF product) is remarkably small at 5 mΩ. It has come to be adopted on the output side of the power supply device because of its large noise removal capability.

  However, the ESR of the organic semiconductor capacitor C2 is reduced, high frequency components are removed, and stable feedback control by the feedback voltage Vfb cannot be performed. As a solution to this, stability has been ensured by increasing the amount of delay compensation of the phase correction unit 15 and reducing the loop gain at a high frequency, but for this reason, fluctuations at a high frequency on the voltage output side. It was a lot. That is, as shown in FIG. 5, an overshoot occurs in which the output voltage Vout exceeds the target voltage V0 (= 12V), and the output voltage Vout has an amplitude (between the voltage V1 higher than the target voltage V0 and the voltage V2 lower than the target voltage V0). In the worst case, the oscillation state occurs), and there is a problem that the output voltage Vout of the constant target voltage V0 cannot be output.

  Further, as shown in FIG. 5, the rising curve between about 6V and about 13V of the output voltage Vout is represented by a thick line, which causes a problem that the harmonic noise increases before the output voltage Vout reaches the overshoot.

  The present invention has been made to solve the above-described problems. Even when an organic semiconductor capacitor is used, it is possible to prevent the occurrence of an overshoot in which the output voltage exceeds the target voltage and the output voltage reaches the target. An object of the present invention is to provide a switching power supply device that can prevent the generation of high-frequency noise in the previous stage leading to a voltage.

  In order to solve the above-described problem, the present invention provides a switching power supply unit that uses an organic semiconductor capacitor to perform switching control for increasing and decreasing the frequency of a voltage input to the organic semiconductor capacitor, and the organic semiconductor A power inductor is provided on the input side of the capacitor.

  In the present invention, the switching power supply control unit performs the switching control based on an output side voltage of the organic semiconductor capacitor.

  In the present invention, the switching power supply control unit performs the switching control based on an input side voltage of the power inductor.

  According to the present invention, even when an organic semiconductor capacitor is used, it is possible to prevent the occurrence of overshoot in which the output voltage exceeds the target voltage and the generation of high frequency noise in the previous stage where the output voltage reaches the target voltage. A switching power supply device that can be prevented can be provided.

It is a figure which shows the circuit structure of the switching power supply device which concerns on this embodiment. It is a figure showing the level change of the output voltage at the time of power activation in the switching power supply concerning this embodiment. It is a figure which shows the circuit structure of the switching power supply device which concerns on the modification of this embodiment. It is a figure which shows the circuit structure of the conventional switching power supply device. It is a figure showing the level change of the output voltage at the time of power activation in the conventional switching power supply device.

Hereinafter, an embodiment for carrying out the present invention (hereinafter simply referred to as the present embodiment) will be described in detail with reference to the accompanying drawings. However, the same parts are denoted by the same reference symbols throughout the drawings, and the description thereof is omitted as appropriate.
(Configuration of the embodiment)
FIG. 1 is a diagram illustrating a circuit configuration of a switching power supply device 20 according to the present embodiment. The switching power supply 20 according to the present embodiment is characterized by a power inductor on the power supply 11 side (hereinafter also referred to as the front stage side or input side) of the organic semiconductor capacitor C2 in the switching power supply 10 shown in FIG. 4 described above. L2 is connected such that L2 and C2 are in series to form an LC filter (LC circuit), and a resistor is provided between the front stage side of the power inductor L2 and the feedback terminal FB of the switching power supply control unit 13. R4 and electrolytic capacitor C5 are connected in series.

  The power inductor L2 has a resistance value that increases as the frequency of the voltage signal input to the power inductor L2 increases, and cuts off the high frequency. This action prevents the ESR of the organic semiconductor capacitor C2 from decreasing. To do. Furthermore, since the power inductor L2 forms an LC filter with the organic semiconductor capacitor C2, it has an action of removing high frequency noise.

  Since the resistor R4 and the capacitor C5 connected in series are connected between the front stage side of the power inductor L2 and the feedback terminal FB, the switching power supply control is performed from the front stage of the power inductor L2 via the resistor R4 and the capacitor C5. Feedback is applied to the section 13.

At this time, a part of the voltage signal is extracted by the resistor R4 according to the time constant determined by the RC circuit including the resistor R4 and the capacitor C5, and a high frequency component is further extracted by the capacitor C5 from the extracted signal. Is fed back to the feedback terminal FB as a feedback voltage Vfb1. As a result, high frequency components are fed back. However, the output voltage Vout1 in the output-side resistor R5 is fed back to the feedback terminal FB as a divided signal (feedback voltage) Vfb by the voltage dividing resistors R3 and R2.
(Operation of the embodiment)
Hereinafter, the operation of the switching power supply device 20 according to the present embodiment shown in FIG. 1 will be described. The input voltage Vin from the power supply 11 is input to the control unit 13a of the switching power supply control unit 13, and is also input to the power inductor L2 through the inductor L1 and the diode D1, and is further output from the resistor R5 as the output voltage Vout1. The At this time, the output voltage Vout1 is divided by the voltage dividing resistors R3 and R4 before the resistor R5 and fed back to the feedback terminal FB of the switching power supply controller 13 as the feedback voltage Vfb.

  In the switching power supply control unit 13, the control unit 13 a performs control for appropriately correcting the phase of the input voltage Vin by the phase correction unit 15, and performs control for increasing or decreasing the switching frequency in accordance with the level of the feedback voltage Vfb. Done. In accordance with this control, the switching operation in which the passing voltage of the inductor L1 is shorted or opened with the GND in the power unit 13b is repeated at predetermined intervals, and the frequency of the passing voltage is varied.

  Here, if the level of the feedback voltage Vfb input to the switching power supply control unit 13 is high, the control unit 13a controls the switching frequency to be low, and according to this control, the power unit 13b controls the passing voltage of the inductor L1. The frequency is controlled to be lowered, and the level of the output voltage Vout1 is lowered accordingly. On the other hand, if the level of the feedback voltage Vfb is low, the control unit 13a is controlled to increase the switching frequency, and in response to this control, the power unit 13b is controlled to increase the frequency of the passing voltage of the inductor L1. Accordingly, the level of the output voltage Vout1 increases. As a result, the output voltage Vout1 is controlled to a predetermined constant voltage value.

  Further, the passing voltage of the inductor L1 is input to the power inductor L2 via the diode D1, but the higher the frequency of the voltage signal input to the power inductor L2, the higher the resistance value and the higher frequency is cut off. By this action, the ESR of the organic semiconductor capacitor C2 is not reduced. At this time, in the preceding stage of the power inductor L2, a part of the voltage signal is extracted by the resistor R4 according to the time constant determined by R × C of the resistor R4 and the capacitor C5, and the capacitor C5 is further extracted from the extracted portion. Thus, a high frequency component is extracted and fed back to the feedback terminal FB as a feedback voltage Vfb1. That is, high frequency components are fed back.

  When the high-frequency component is fed back in this way, the control unit 13a controls the switching frequency to be lowered, and according to this control, the power unit 13b is controlled to lower the frequency of the passing voltage of the inductor L1. The level of the output voltage Vout1 decreases. By this control, as shown in FIG. 2, the output voltage Vout1 does not exceed the target voltage V0 (= 12V). That is, no overshoot occurs, and the output voltage Vout1 converges to a constant target voltage V0.

Further, since the high frequency component is fed back via the resistor R4 and the capacitor C5 in the previous stage of the power inductor L2 as described above, the rising curve between about 5.6 V and about 11.5 V shown in FIG. 2 is represented by a thin line. In addition, almost no harmonic noise is generated in the output voltage Vout1 before the target voltage V0.
(Effect of embodiment)
As described above, when the switching power supply device 20 according to the present embodiment outputs the input voltage Vin as the output voltage Vout through the organic semiconductor capacitor C2, the voltage dividing resistor as the voltage dividing resistor circuit is used as the output voltage Vout. This is fed back to the switching power supply control unit 13 via the devices R3 and R2, and performs switching control to increase or decrease the frequency of the voltage input to the organic semiconductor capacitor C2 according to the level of the feedback voltage.

  An LC filter is formed by the switching power supply control unit 13 that performs switching control to increase and decrease the frequency of the voltage input to the organic semiconductor capacitor C2, and the power inductor L2 on the input side of the organic semiconductor capacitor C2.

  According to this configuration, the voltage after the switching control is input to the power inductor L2. At this time, the higher the frequency of the voltage, the larger the resistance value of the power inductor L2, and the high frequency is cut off by the LC filter. As a result, the ESR of the organic semiconductor capacitor C2 does not decrease. At this time, since the high frequency component cut off by the power inductor L2 is fed back on the input side of the power inductor L2, in switching control, the voltage frequency is controlled to be low. Since control is performed so that the output voltage Vout1 does not exceed the target voltage V0 during this control, no overshoot occurs, and the output voltage Vout1 converges to a constant target voltage V0. Accordingly, a constant target voltage V0 can be output from the switching power supply device 20.

  In addition, the feedback is preferably performed via an RC circuit including a resistor R4 and a capacitor C5 that extract a part of the voltage after switching control and extract a high-frequency component from the extracted voltage.

According to this configuration, high-frequency components can be properly fed back, so that switching control can be performed so that the output voltage Vout1 does not exceed the target voltage V0, and thereby the output voltage Vout1 is set to a constant target voltage V0. It can be converged. Furthermore, since high frequency components are fed back via the resistor R4 and the capacitor C5, it is possible to prevent harmonic noise from being substantially generated in the output voltage Vout1 before the output voltage Vout converges to the target voltage V0.
(Modification of the embodiment)
FIG. 3 is a diagram illustrating a circuit configuration of a switching power supply device 30 according to a modification of the present embodiment. The switching power supply 30 is characterized in that, in the switching power supply 10 shown in FIG. 4, a power inductor L2 is connected to the front side of the organic semiconductor capacitor C2 so as to form an LC filter at L2 and C2, and the power inductor L2 The voltage dividing resistors R3 and R2 on the output side are moved and connected between the previous stage side and the feedback terminal FB of the switching power supply control unit 13, and the input voltage to the power inductor L2 is changed to the voltage dividing resistor R3 and R3. This is because the voltage is divided by R4 and fed back as a feedback voltage Vfb2.

  According to this configuration, the voltage after switching control in the switching power supply control unit 13 is input to the power inductor L2, and at this time, the higher the frequency of the voltage, the higher the frequency is blocked by the power inductor L2, and this The high frequency component is divided by the voltage dividing resistors R3 and R2 and fed back. Therefore, in the switching control, the output voltage Vout2 can be controlled so as not to exceed the target voltage V0, and the stability of the output voltage Vout can be maintained.

  As mentioned above, although preferred embodiment of this invention was explained in full detail, it cannot be overemphasized that the technical range prediction of this invention is not limited to the range prediction as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. In addition, it is apparent from the description of the scope of claims that embodiments to which such changes or improvements are added can also be included in the scope of prediction of the present invention.

  11..Power supply, 13..Switching power supply control unit, 13a..Control unit, 13b..Power unit, 15..Phase correction unit, 20,30..Switching power supply device, R1, R2, R3, R4, R5 ..Resistors, C1, C3, C4, C5 ..Electrolytic capacitors, C2 ..Organic semiconductor capacitors, L1 ..Inductors, L2 ..Power inductors, D1 ..Zener diodes, Vin ..Input voltage, Vout1, Vout2 -Output voltage, Vfb, Vfb1, Vfb2-Feedback voltage.

Claims (3)

In a switching power supply using an organic semiconductor capacitor,
A switching power supply controller that performs switching control to increase and decrease the frequency of the voltage input to the organic semiconductor capacitor;
A power inductor on the input side of the organic semiconductor capacitor;
A switching power supply device comprising:   The switching power supply device according to claim 1, wherein the switching power supply control unit performs the switching control based on an output side voltage of the organic semiconductor capacitor.   The switching power supply device according to claim 1, wherein the switching power supply control unit performs the switching control based on an input side voltage of the power inductor.