TWI398758B - Intelligent clamping circuit and power supply with this clamping circuit - Google Patents

Abstract

An intelligent clamping circuit is adapted for configuring in a power supply and receiving an alternating voltage switchingly to control a clamped switch. The clamping circuit includes a switch, a voltage-passing unit and a detector. The switch is controlled by the alternating voltage to switch between turn-on status and turn-off status. The voltage-passing unit is controlled by the switch to output a coupling voltage based on a standby voltage generating from the alternating voltage. The detector controls the clamped switch according to the coupling voltage and a power-good signal. When entering AC-OFF mode from AC-ON mode, the power supply switches to stop receiving the alternating voltage, and the switch turns off to make the coupling voltage low-potential. Therefore, the power-good signal is switched to be low-potential due to entering AC-OFF mode, and the detector turns off the clamped switch.

Description

Smart clamp circuit and power supply including the same

The present invention relates to a power supply technology, and more particularly to a smart clamp circuit capable of controlling power supply timing and a power supply including the clamp circuit.

The power supply usually operates in four working modes according to the plugging and unplugging of a plug and the switching of a power switch: power-on mode, standby mode, virtual off mode (also known as AC OFF & remote ON mode), and indeed shutdown mode (again Called AC OFF & remote OFF mode).

If the plug is connected to receive an AC voltage, it will enter the power-on mode when the power switch is switched to the remote on state, and enter the standby mode when switching to the remote off state. On the other hand, if the plug is pulled out and cannot receive the AC voltage (AC OFF), it will enter the virtual shutdown mode when the power switch is switched to the receiving state, and enter the true shutdown mode when switching to the blocking state.

Referring to FIG. 1 to FIG. 3, in order to ensure that a passive device 95 can maintain a high potential output voltage Vout during a high power supply (PG) signal high potential, a common power supply standard is to first make a PG signal. After switching to the low potential, the output voltage Vout of the passive device 95 is switched to the low potential, and the switching time difference (from the low potential starting point of the PG signal to the time point when the high potential output voltage Vout is stepped down by 5%) is A warning time T4. In the virtual shutdown mode of FIG. 3, the standby voltage is also changed to a low potential after the output voltage Vout is switched to a low potential, and this time difference is generally referred to as a Turn off-Standby time T5. More specifically, this period of time T5 refers to a time point from when the high-potential output voltage Vout is stepped down by 90% to when the high-potential standby voltage is stepped down by 5%.

In order to meet the specifications, the conventional circuit uses an optocoupler 92 to delay the switching of the passive device 95, wherein the delay modes of the standby mode and the virtual shutdown mode are respectively described below. Referring to FIG. 1 and FIG. 2, if the power switch is switched to the blocking state in the power-on mode, the standby mode is entered. At this time, a supervisor device 93 emits a high potential while emitting a low-level PG signal. With the fault protection (FP) signal, the optocoupler 92 is thus turned off and the operating voltage cannot be transferred to a control device 94, and the output voltage Vout of the passive device 95 is thereby switched to a low potential to achieve the aforementioned specifications. Among them, the passive device 95 is a common topology of general power electronics, such as a forward/flyback converter and a half bridge converter.

Moreover, referring to FIG. 1 and FIG. 3, if the plug is pulled out in the boot mode, the virtual shutdown mode is entered. At this time, the monitoring device 93 emits a low potential FP signal and emits a low potential FP signal to make a voltage. The generating device 91, the optical coupler 92, a resistor R1 and the monitoring device 93 form a loop. The energy of the standby voltage is gradually released by the photocoupler 92 and the resistor R1, and since the photocoupler 92 is still in an on state during the release, the passive device 95 continues to output a high potential. Passive device 95 switches to a low potential until optical coupler 92 is turned off due to energy release. However, such a circuit design prolongs the energy release time as the load of the standby voltage (eg, mouse, keyboard, etc.) is reduced, resulting in an extended warning time T4. Taking FIG. 4 and FIG. 5 as an example, it can be observed that the warning time T4 difference caused by the different loads is more than 100 milliseconds (ms).

In addition, if the restarting procedure is not completed within a certain inspection time after resetting the power supply 900, the passive device 95 will be prone to a crash phenomenon, even if the plug is connected and the power switch is switched to the receiving state, Outputs a high potential output voltage Vout.

The so-called reset and reboot means that in the virtual shutdown mode, the power supply 900 is further brought into the true shutdown mode, and then the virtual shutdown mode is returned, and then the plug is changed to the boot mode. Assuming no load or very light load, the standby voltage will cause the high voltage source (ie standby) after the virtual shutdown mode is replied to a check time (for example, 300 milliseconds) due to the slow release of energy. Voltage). However, at this time, the output voltage Vout is low, so the monitoring device 93 judges that the condition is abnormal and the passive device 95 is tied to cause the crash.

Therefore, by synthesizing the above warning time T4 and the problem of the crash, it can be found that the stability of the conventional power supply 900 is not good, and the process yield cannot be improved.

Accordingly, it is an object of the present invention to provide a smart clamp circuit for improving stability and improving production yield and a power supply including the same, which can shorten the warning time in the virtual shutdown mode and ensure resetting The subsequent reboot process can proceed smoothly.

Therefore, the power supply of the present invention is adapted to switchably receive an AC voltage and cause a passive device to generate an output voltage, comprising: a voltage generating device, generating a standby voltage and an operating voltage according to the AC voltage; a monitoring device, Sending a power good signal indicating the power supply condition of the power supply; a smart clamp circuit, outputting a clamp signal based on the AC voltage and the power good signal; and a clamped switch controlled by the clamp signal to switch to a conductive state And an off state; and a first optocoupler controlled by the clamped switch to determine an output voltage of the passive device; when the power supply enters a stop mode from a power on mode, it switches to stop receiving The AC voltage and the power good signal will change from a high potential to a low potential, the clamp signal is turned from a low potential to a high potential and the clamped switch is turned off, the first optical coupler is thus turned off and the signal is well turned on. The low voltage is low and the output voltage is low after a warning time.

The smart clamp circuit of the present invention is adapted to be disposed in a power supply and switchably receiving an AC voltage to control a clamped switch, comprising: a switch switch controlled by the AC voltage to be switched to a conductive state And a cut-off state; the voltage transfer unit is controlled by the switch switch to transmit a coupled voltage according to a standby voltage generated from the AC voltage; and a detector based on the coupled voltage and a good power supply signal Controlling the clamped switch; when the power supply enters a stop mode from a power-on mode, it switches to stop receiving the AC voltage, and the switch switch is switched from on to off and causes a coupling voltage sent by the pressure transmitting unit It is low and the power good signal will be at a low potential due to entering the shutdown mode, and the detector thus cuts off the clamped switch.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to FIG. 6, the smart clamp circuit 7 of the present invention determines the output voltage Vout of an external passive device 200 to detect when the PG signal is switched to a low level by detecting an AC voltage and a good power supply (PG) signal change. Effectively control the length of the warning time T4, and output a monitoring voltage to make the reset boot process go smoothly.

The preferred embodiment of the power supply 100 of the present invention is adapted to receive an AC voltage controlled by a plug (not shown), including a voltage generating device 1, a first optical coupler 2, a first resistor 3, and a first The second resistor 4, a monitoring device 5, a control device 6, a smart clamp circuit 7, and a clamped switch 8. The clamping circuit 7 includes a switching device 71, a switching switch 72 (implemented by a transistor in this embodiment), a voltage transmitting unit 73 (in this example, a second optical coupler), and a detector 74. The clamped switch 8, the switch switch 72, and the optical couplers 2, 73 can be switched between the on state and the off state, respectively. With reference to FIG. 7, each of the optical couplers 2, 73 has a primary side unit 21, 731 and a secondary side unit 22, 732, and the conversion device 71 has a full bridge rectifier 711 and a filter regulator 712, and The detector 74 has a first transistor M1, a second transistor M2, a third transistor M3, and a fourth transistor M4. The filter regulator 712 is well known to those of ordinary skill in the art to which the present invention pertains, and will not be described again.

The voltage generating device 1 generates a standby voltage and an operating voltage in accordance with the alternating voltage. When the first photocoupler 2 is switched to the on state, the standby voltage can be transmitted to the monitoring device 5 through the first resistor 3, and the operating voltage is transmitted to the second resistor 4 through the second resistor 4. The control device 6 is operative to cause the passive device 200 to generate an output voltage Vout.

Moreover, the monitoring device 5 is controlled by an external power switch (not shown) to issue a fault protection (FP) signal, wherein the power switch can be switched between a receiving state and a blocking state. Moreover, the monitoring device 5 emits a PG signal, and the PG signal exhibits a high potential during the high potential of the output voltage Vout to indicate that the power supply condition is normal, and exhibits a low potential when the power switch is switched to the blocking state or the plug is pulled out. The clamp circuit 7 determines a clamp signal for turning on the clamped switch 8 based on changes in the AC voltage, the PG signal, and the FP signal.

In the clamp circuit 7, the conversion device 71 converts the AC voltage into a rectified signal by the full bridge rectifier 711 to supply the filter regulator 712 to output a filtered signal. The switch switch 72 is controlled by the filtered signal to determine whether to turn on the primary side unit 731 of the second optical coupler 73, and thereby cause the secondary side unit 732 to output a coupled voltage to the detector 74. The detector 74 then outputs the clamp signal based on the coupling voltage, the PG signal, and the FP signal. In addition, the detector 74 also outputs a priority signal, and when the priority signal is low, the output voltage Vout of the passive device 200 can be forced to be low, without being limited by the control device 6.

The detector 74 is activated in such a manner that the first transistor M1 determines whether to turn on the second transistor M2 according to the coupling voltage and the FP signal, and the third transistor M3 is controlled by the PG signal to determine the conduction state. The conduction state of the second transistor M2 and the third transistor M3 will affect the conduction state of the fourth transistor M4. Wherein, when one of the second transistor M2 and the third transistor M3 is turned on, the clamp signal is caused to exhibit a low potential, and the fourth transistor M4 is caused to be turned off to output a high-potential priority signal. When both the second transistor M2 and the third transistor M3 are turned off, the clamp signal exhibits a high potential, and the fourth transistor M4 outputs a low potential priority signal due to the conduction.

More specifically, the power supply 100 presents four operating modes as the plug is plugged and unplugged and the power switch is switched: a power-on mode, a standby mode, a virtual power-off mode, and a true power-off mode. In this example, the virtual shutdown mode and the actual shutdown mode are generally referred to in a shutdown mode.

Boot mode

At this time, the plug is connected and the power switch is in the receiving state, so that the power supply 100 can receive the AC voltage and the monitoring device 5 emits the low potential FP signal.

In the clamp circuit 7, the switching means 71 outputs a filtered signal sufficient to turn the switching switch 72 on because it receives an alternating voltage. This will cause the primary side unit 731 of the second photocoupler 73 to be turned on with the secondary side unit 732, and the standby voltage as the coupling voltage transmitted to the detector 74. Also, since the FP signal exhibits a low potential, the first transistor M1 遂 enters an on state and causes the second transistor M2 to be turned on. Therefore, the clamp signal (low potential) turns on the clamped switch 8 so that the primary side unit 21 of the second optical coupler 2 receives the standby voltage. In addition, the priority signal is at a high potential due to the fourth transistor M4 being turned off, so that the operation of the passive device 200 is not affected.

After receiving the standby voltage, the primary side unit 21 is turned on because the FP signal exhibits a low potential, and causes the secondary side unit 22 to transmit the operating voltage to the control device 6, so that the output voltage Vout will exhibit a high potential and further promote the monitoring device. 5 A high-potential PG signal is output (the power supply is normal).

Standby mode

At this time, the plug is connected and the power switch is in a blocking state, so that the power supply 100 receives the AC voltage and the monitoring device 5 emits a high potential FP signal, and the monitoring device 5 also sets the PG signal because the power switch is in the blocking state. Switch to low potential (display power supply abnormality).

Since the clamp switch 8 remains in the on state during the period when the power switch has just switched to the blocking state and the clamp signal has not yet changed the potential, the second photocoupler 2 is turned off due to the high potential FP signal, and the output voltage Vout is also Then quickly drop to a low potential.

Virtual shutdown mode

If the plug is unplugged in the power-on mode, the power supply 100 will enter the virtual power-off mode, at which time the AC voltage cannot be received and the FP signal remains low. The monitoring device 5 also switches the PG signal to a low level (displaying a power supply abnormality).

In the clamping circuit 7, since the switching device 71 does not receive the AC voltage, the filtered signal is insufficient to turn the switching switch 72 on, and the coupling voltage is zero at this time, so that the second transistor M2 cannot be turned on regardless of the FP signal. . The third transistor M3 is also turned off because the PG signal is at a low potential. Therefore, after a delay of a resistor Ra, a resistor Rb and a capacitor Ca, the clamp signal will turn to a high potential, so that the clamped switch 8 is turned off, and the primary side unit 21 cannot receive the standby voltage, of course, the passive device 200 The output voltage Vout is also reduced to a low potential. In order to further ensure the timing of the output voltage Vout, the fourth transistor M4 further outputs a low potential signal to force the output voltage Vout to be low.

Since the output voltage Vout of the conventional circuit is reduced to a low potential until the energy is released, and the load is reduced, the energy release time is longer. The output voltage Vout of the present invention is then lowered to a low potential after the delay of the resistor Ra, the resistor Rb and the capacitor Ca, or after the passive device 200 receives the low potential priority signal. Therefore, the warning time T4 is much shorter than the conventional technique and does not vary greatly with the size of the load. In addition, as the warning time T4 is shortened, the off standby mode time T5 is elongated, which will help increase the hold-up time of the power supply 100.

Referring to Figures 8 and 9, it can be seen that at the same operating voltage, the power supply 100 can shorten and maintain a similar warning time T4 despite the different load sizes, unlike the conventional technique gap of more than 100 milliseconds. Similarly, the warning time T4 of FIGS. 10 and 11 is not too large due to the load. Referring to Figures 8 and 11, even if the operating voltage and load are different, the warning time T4 is not much different.

Indeed shutdown mode

If the power switch is switched to the blocking state in the virtual shutdown mode, the power supply 100 will enter the true shutdown mode. At this time, the PG signal outputted by the monitoring device 5 is maintained at a low potential (display power supply abnormality), and the operation of the clamp circuit 7 is similar to the virtual shutdown mode.

Referring back to FIG. 7, in order to avoid a possible crash phenomenon after resetting, the power supply 100 of the present invention changes the voltage source of the monitoring device 5 from the conventionally used standby voltage to the clamped switch 8 to the primary side unit. 21 monitoring voltage. When in the shutdown mode, the clamped switch 8 is turned off to cause the monitoring voltage to exhibit a low potential; thereafter, switching to the power-on mode, the clamped switch 8 is turned on to cause the monitoring voltage to assume a high potential, and the first optical coupler 2 The output voltage Vout can be changed in accordance with the operating voltage. Therefore, the resetting action causes the monitoring voltage to drop to a low potential, and the monitoring device 5 does not catch the passive device 200 at the time of rebooting, causing the crash.

It should be noted that the second transistor M2 and the third transistor M3 form a circuit equivalent to a logical inverse (NOR) gate, because only at least one of the transistors M2 and M3 is turned on, the clamp is clamped. The signal is low. Of course, in other embodiments, other circuits that can perform a logical inverse (NOR) gate function can be used instead.

In summary, the power supply device 100 of the present invention can shorten the length of the warning time T4 and reduce the influence of the load size by the smart clamp circuit 7, and can ensure that the power supply 100 is successfully restarted after the reset of the monitoring device 5. The program is indeed capable of achieving the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

100. . . Power Supplier

200. . . Passive device

1. . . Voltage generating device

2. . . First optocoupler

twenty one. . . Primary side unit

twenty two. . . Secondary side unit

3. . . First resistance

4. . . Second resistance

5. . . Monitoring device

6. . . Control device

7. . . Smart clamp circuit

71. . . Conversion device

711. . . Full bridge rectifier

712. . . Filter regulator

72. . . Switch switcher

73. . . Second optocoupler

731. . . Primary side unit

732. . . Secondary side unit

74. . . Detector

8. . . Clamped switch

Ca. . . capacitance

M1. . . First transistor

M2. . . Second transistor

M3. . . Third transistor

M4. . . Fourth transistor

Ra. . . resistance

Rb. . . resistance

Figure 1 is a block diagram of a conventional power supply;

Figure 2 is a timing diagram illustrating the warning time;

Figure 3 is a timing diagram, further illustrating the time to turn off the standby mode;

Figure 4 is a timing diagram illustrating the warning time at the time of conventional overloading;

Figure 5 is a timing chart illustrating the warning time at the time of conventional light load;

Figure 6 is a block diagram of a power supply of the present invention;

Figure 7 is a circuit diagram of a smart clamp circuit of the present invention;

Figure 8 is a timing diagram illustrating the reload warning time of the low operating voltage;

Figure 9 is a timing diagram illustrating the light load warning time of a low operating voltage;

Figure 10 is a timing diagram illustrating the reload warning time of a high operating voltage;

Figure 11 is a timing diagram illustrating the light load warning time for high operating voltages.

100. . . Power Supplier

200. . . Passive device

1. . . Voltage generating device

2. . . First optocoupler

twenty one. . . Primary side unit

twenty two. . . Secondary side unit

3. . . First resistance

4. . . Second resistance

5. . . Monitoring device

6. . . Control device

7. . . Smart clamp circuit

71. . . Conversion device

72. . . Switch switcher

73. . . Second optocoupler

74. . . Detector

8. . . Clamped switch

Claims (13)

A power supply device adapted to switchably receive an AC voltage and cause a passive device to generate an output voltage, comprising: a monitoring device that sends a good signal indicating the power supply of the power supply; and a smart clamp circuit based on The AC voltage and the power good signal output a clamp signal; a clamped switch is controlled by the clamp signal to switch between an on state and an off state; and a first optocoupler is controlled by the clamped switch Determining the output voltage of the passive device; when the power supply enters a shutdown mode from a power-on mode, it switches to stop receiving the AC voltage and the power good signal changes from a high potential to a low potential, and the clamp signal is The low potential turns to a high potential and causes the clamped switch to turn off, the first optical coupler thus turning off and causing the output voltage to be low after the power good signal turns to a low potential for a warning time. The power supply device of claim 1, further comprising a voltage generating device for generating a standby voltage according to the alternating voltage, wherein the smart clamp circuit comprises: a switch switch controlled by the alternating current voltage Switching between a conducting state and an off state; a voltage transmitting unit controlled by the switching switch to transmit a coupling voltage according to the standby voltage; and a detector outputting the signal based on the coupling voltage and the power good signal Clamping a signal; when the power supply enters the shutdown mode from the power-on mode, the switching switch is turned off to cause the coupling voltage sent by the voltage transmitting unit to be low, and the power good signal is low because entering the shutdown mode At the potential, the clamp signal thus turns to a high potential and causes the clamped switch to be turned off. The power supply device of claim 2, wherein the detector further outputs a priority signal, and when the priority signal is low, the output voltage of the passive device is forced to be low. The power supply device of claim 1, wherein the clamped switch outputs a monitoring voltage; when the power supply enters the power-on mode from the shutdown mode, the clamped switch is switched from an off state to an off state. The conduction state, and the monitoring voltage is changed from a low potential to a high potential, and the first optical coupler further changes an output voltage of the passive device according to an operating voltage. According to the power supply device of claim 2, wherein the monitoring device is further controlled by an external control, and the detector has a first transistor, a second transistor and a first a third transistor; the first transistor determines an on state of the second transistor according to the coupling voltage and the error protection signal, and the third transistor is controlled by the power good signal to determine a conduction state; When the at least one of the second transistor and the third transistor are turned on, the clamp signal exhibits a low potential; when both the second transistor and the third transistor are turned off, the clamp signal exhibits a high potential. The power supply device of claim 3, wherein the monitoring device is further controlled by an external control and has a fault protection signal, and the detector has a first transistor, a second transistor, and a first a third transistor and a fourth transistor; the first transistor determines an on state of the second transistor according to the coupling voltage and the error protection signal, and the third transistor is controlled by the power good signal a conducting state, wherein a conductive state of the second transistor and the third transistor determines an on state of the fourth transistor; and when the second transistor is in conduction with one of the third transistors, the fourth The transistor will turn off and output the high potential signal; when the second transistor and the third transistor are both turned off, the fourth transistor outputs a low potential signal due to conduction. The power supply device of claim 2, wherein the voltage generating device generates an operating voltage according to the alternating voltage; the detector only when the coupling voltage and the power good signal are high. The clamp signal of the low potential is output, and the clamped switch is turned on to cause the first optical coupler to change the output voltage to a high potential according to the operating voltage. A smart clamp circuit adapted to be disposed in a power supply and switchably receiving an AC voltage to control a clamped switch, comprising: a switch switch controlled by the AC voltage to switch to a conducting state and a An off-voltage unit is controlled by the switch switch to transmit a coupling voltage according to a standby voltage generated from the AC voltage; and a detector for controlling the signal based on the coupling voltage and a power good signal The clamped switch; when the power supply enters a stop mode from a power-on mode, it switches to stop receiving the AC voltage, and the switch switch is switched from on to off and causes the coupling voltage sent by the pressure transmitting unit to be low. The potential, and the power good signal will be at a low potential due to entering the shutdown mode, and the detector thus turns off the clamped switch. The clamp circuit according to claim 8 is more suitable for controlling a passive device, wherein the detector further outputs a priority signal, and when the priority signal is low, the output voltage of the passive device is forced to be presented. Low potential. The clamp circuit according to claim 8 is more suitable for electrically connecting a passive device, and the power supply comprises a first optical coupler coupled to the passive device, and the clamped switch outputs a monitoring Using a voltage, wherein when the power supply enters the power-on mode from the shutdown mode, the detector switches the clamped switch from an off state to an on state, and the monitoring voltage is changed from a low level to a high level, The first optocoupler in turn varies the output voltage of the passive device based on an operating voltage generated from the alternating voltage. The clamp circuit according to item 8 of the patent application scope is more suitable for picking up Receiving a fault protection signal, wherein the detector has a first transistor, a second transistor, and a third transistor; the first transistor determines the second power according to the coupling voltage and the error protection signal a conducting state of the crystal, and the third transistor is controlled by the power good signal to determine an on state; when the second transistor is electrically connected to at least one of the third transistor, the clamped off is turned on; The second transistor and the third transistor are both turned off, and the clamped off is turned off. The clamp circuit according to claim 9 is more suitable for receiving a fault protection signal, wherein the detector has a first transistor, a second transistor, a third transistor and a fourth battery. a crystal; the first transistor determines an on state of the second transistor according to the coupling voltage and the error protection signal, and the third transistor is controlled by the power good signal to determine an on state, and the second transistor The conduction state of the crystal and the third transistor determines an on state of the fourth transistor; when the second transistor is in conduction with one of the third transistors, the fourth transistor is turned off and a high potential is output The priority signal; when the second transistor and the third transistor are both turned off, the fourth transistor outputs a low potential of the priority signal due to conduction. The clamp circuit of claim 8, wherein the detector turns on the clamped switch only when the coupling voltage and the power good signal are both high.