CN220492696U - Power-down holding circuit and power supply device - Google Patents
Power-down holding circuit and power supply device Download PDFInfo
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- CN220492696U CN220492696U CN202322007612.0U CN202322007612U CN220492696U CN 220492696 U CN220492696 U CN 220492696U CN 202322007612 U CN202322007612 U CN 202322007612U CN 220492696 U CN220492696 U CN 220492696U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The utility model discloses a power-down holding circuit and a power supply device, wherein the power-down holding circuit comprises: switching tubes Q1 and Q2, a diode D1, a capacitor C1, a capacitor charging circuit, an input voltage detection circuit, a control circuit, a reverse-filling prevention driving circuit, a capacitor discharging driving circuit and a reverse-filling prevention detection circuit; when the switching power supply works normally, the capacitor C1 is charged; when the input voltage of the switching power supply drops out of a normal range, the input voltage detection circuit outputs a first voltage signal representing the input voltage of the switching power supply, the control circuit compares the first voltage signal with a first reference voltage to generate a second voltage signal, the anti-reverse-filling driving circuit controls the switching tube Q2 to be turned off according to the second voltage signal, the capacitor discharging driving circuit controls the switching tube Q1 to be turned on according to the second voltage signal after delay time, the capacitor C1 is discharged, and the anti-reverse-filling detection circuit keeps the states of the switching tubes Q2 and Q1 until the input voltage of the switching power supply drops to an under-voltage protection point. The utility model realizes the prolongation of the power-down holding time.
Description
Technical Field
The present utility model relates to the field of electronic technologies, and in particular, to a power-down holding circuit and a power supply device.
Background
In some fields with high reliability requirements, such as railway power supplies, in order to reliably operate the electronic devices, it is required that when power supply is cut off, that is, when input voltage of the switch power supply suddenly drops, energy can still be output for a certain time, and the electronic devices need to store power-down state data and orderly switch to a standby power supply, so that a switch power supply system is required to have a long power-down holding time. For example, in the field of railway power supply, a power-down holding time of not less than 10ms is required.
In the prior art, two modes are generally adopted to realize the maintenance of longer power failure retention time, and firstly, a switching power supply adopting a single-stage topological design such as flyback is generally adopted to store energy by directly connecting electrolytic capacitors in parallel at an input side, and the energy is stored according to a capacitance energy storage formula w=1/2×c×u 2 It can be seen that the higher the input voltage U of the switching power supply, the more energy W is stored, and the longer the power-down hold time is with the same capacitance value C. This approach results in a larger capacitance value at low voltage input in order to maintain the same power down hold time, which presents difficulties for the system design of the switching power supply.
The second scheme adopts a two-stage topology series connection mode, the front stage adopts a BOOST circuit to BOOST the input voltage to a certain value, and the rear stage adopts a normal topology to perform conversion, such as flyback, half-bridge and the like. The external energy storage capacitor is connected with the middle node of the two-stage topology, namely the output end of the BOOST circuit, and when the input energy is cut off, the external energy storage capacitor can continuously provide energy for the later stage to realize the power-down holding time. Although the stored energy is improved greatly, because of the two stages connected in series, the circuit is complex, the reliability is reduced, the efficiency is much lower than that of a single-stage scheme, and the advantages of the size and the performance of the switching power supply product are completely lost.
The Chinese patent publication No. CN112615425A, published on 4/6/2021, proposes a power-down delay circuit and a detection control circuit thereof, wherein the circuit shown in FIG. 1 is adopted, an auxiliary winding of a transformer T1 in a DC-DC switching power supply product is utilized to charge a holding capacitor C3, when an input voltage is powered down, a control switch Q1 is closed, and the holding capacitor discharges to the input side of the product to provide power-down holding time. Taking the railway power supply as an example, if the scheme is adopted to charge the holding capacitor to the highest input voltage of 160VDC, the output power of the railway power supply is 250W, the efficiency is 90%, and the S1 level requirement of the full input voltage range of 60-160 VDC can be met only by 253uF electrolytic capacitors, so that the power-down holding capacitor value requirement is greatly reduced, and the problem of input surge current is also solved.
The scheme also has the following problems:
problem 1: the application range is narrow, no auxiliary winding special for power failure maintenance is available in the mainstream DC-DC railway power supply products in the current market, the transformer auxiliary winding is needed to be newly added when the scheme is specifically applied, the original form of the product is changed, and the scheme cannot be applied to the existing products without the auxiliary winding or the switching power supply without a transformer. Problem 2: d1 is a reverse-flow preventing diode, for a railway power supply system with 250W output power, 90% efficiency and 14.4-154 VDC ultra-wide voltage input, when the input voltage is 14.4V, the average input current is as high as 19.29A, at the moment, the reverse-flow preventing diode is still a diode, the forward conduction voltage drop of the diode at the moment is as high as 1V, the diode loss is as high as 19.29W, and the diode accounts for 7.7% of the output power, so that the efficiency of the railway power supply is seriously influenced, the temperature rise of the diode is extremely high, the high-temperature working characteristic and reliability of the railway power supply are influenced, and the like.
Even though the railway power supply system with the nominal input voltage of 110VDC is universal, the problems that the diode loss is large, the temperature rises, the high-temperature working characteristics and the reliability of the railway power supply are affected and the like still exist when the diode is adopted as an anti-reverse-filling device for a high-power railway power supply. For a railway power supply with an output power of 1000W, the efficiency is 90%, the input average current is 16.83A at a low voltage 66VDC input, the forward conduction voltage drop of the diode is calculated as 1V, and the diode loss is also as high as 16.83W.
It should be noted that the above information disclosed in the background section is only for enhancement of understanding of the general background of the present application and should not be taken as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
Disclosure of Invention
In view of the above, the present utility model provides a power-down holding circuit and a power supply device, which at least solve one of the technical problems in the prior art to a certain extent.
As a first aspect of the present utility model, a technical solution of an embodiment of a power-down holding circuit is provided as follows:
a power-down holding circuit applied to a power supply device, the power supply device comprising a switching power supply which is turned off to enter a protection state when an input voltage of the switching power supply drops to an under-voltage protection point, wherein the power-down holding circuit comprises:
the switching tube Q1, the switching tube Q2, the diode D1, the capacitor C1, the capacitor charging circuit, the input voltage detection circuit, the control circuit, the anti-reverse-filling driving circuit, the capacitor discharging driving circuit and the anti-reverse-filling detection circuit;
one end of the switching tube Q2 is used for being connected with an input positive end of the power supply device, the other end of the switching tube Q2 and a cathode of the diode D1 are connected together and used for being connected with the input positive end of the switching power supply, an anode of the diode D1 is connected with one end of the switching tube Q1, the other end of the switching tube Q1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is used for being connected with an input negative end of the power supply device and an input ground end of the switching power supply;
When the switching power supply works normally, the switching tube Q2 is turned on, the switching tube Q1 is turned off, and the capacitor charging circuit charges and stores energy for the capacitor C1;
when the input voltage of the switching power supply drops out of a normal input range, the input voltage detection circuit outputs a first voltage signal representing the input voltage of the switching power supply, the control circuit compares the first voltage signal with a first reference voltage to generate a second voltage signal, the anti-reverse-filling driving circuit controls the switching tube Q2 to be turned off according to the second voltage signal, after a delay time, the capacitor discharging driving circuit controls the switching tube Q1 to be turned on according to the second voltage signal, the capacitor C1 starts to discharge, and the anti-reverse-filling detection circuit is used for generating a third voltage signal to keep the switching tube Q2 in a turned-off state under the state and generating a fourth voltage signal to keep the switching tube Q1 in the turned-on state until the input voltage of the switching power supply drops to the under-voltage protection point.
Preferably, the capacitor charging circuit includes a first non-isolated voltage stabilizing circuit, where the first non-isolated voltage stabilizing circuit includes three ports, that is, an input positive port, an output positive port and a ground port, the first non-isolated voltage stabilizing circuit is configured to convert a variable voltage input by the input port and the ground port of the first non-isolated voltage stabilizing circuit into a relatively stable voltage, and output the relatively stable voltage through the output port and the ground port of the first non-isolated voltage stabilizing circuit, the input positive port of the first non-isolated voltage stabilizing circuit is configured to be connected to the other end of the switch Q2, the output positive port of the first non-isolated voltage stabilizing circuit is connected to one end of the capacitor C1, and the ground port of the first non-isolated voltage stabilizing circuit is configured to be connected to the input ground end of the switch power supply.
Preferably, the input voltage detection circuit includes a resistor R1 and a resistor R2, one end of the resistor R1 is connected to the other end of the switching tube Q2, the other end of the resistor R1 is connected to one end of the resistor R2 and is used for outputting the first voltage signal, and the other end of the resistor R2 is connected to the input ground end of the switching power supply.
Preferably, the control circuit includes an operational amplifier IC3, a resistor R12, a diode D3 and a capacitor C2, where a positive input end of the operational amplifier IC3 is used for inputting the first reference voltage, a negative input end of the operational amplifier IC3 is used for inputting the first voltage signal, an output end of the operational amplifier IC3 is connected with an anode of the diode D3, a cathode of the diode D3, one end of the resistor R12 and one end of the capacitor C2 are connected together to output the second voltage signal, and the other end of the resistor R12 and the other end of the capacitor C2 are used for connecting an input ground end of the switching power supply.
Preferably, the anti-reverse-filling driving circuit comprises a resistor R19, a chip IC6 and a first isolation voltage stabilizing circuit; the first isolation voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the first isolation voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port of the first isolation voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the first isolation voltage stabilizing circuit, the input positive port of the first isolation voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, and the input negative port of the first isolation voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply; the chip IC6 is an isolation driving chip, the chip IC6 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, the input end of the chip IC6 is used for simultaneously inputting the second voltage signal and the third voltage signal, the output end of the chip IC6 is connected with the grid electrode of the switch tube Q2, the power supply end of the chip IC6 is used for inputting the power supply voltage, the grounding end of the chip IC6 is used for being connected with the input ground end of the switch power supply, the isolation power supply positive end of the chip IC6 is connected with the output positive end of the first isolation voltage stabilizing circuit, the isolation power supply negative end of the chip IC6 is connected with the output negative end of the first isolation voltage stabilizing circuit and is used for being connected with the input positive end of the power supply device, and the resistor R19 is connected between the output end of the chip IC6 and the isolation power supply negative end of the chip IC 6.
Preferably, the anti-reverse-filling driving circuit comprises a resistor R19, a chip IC6, a diode D6, a capacitor C5 and a second non-isolated voltage stabilizing circuit; the second non-isolated voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, and is used for converting the variable voltage input by the input positive port and the input negative port into relatively stable voltage and outputting the relatively stable voltage through the output positive port and the output negative port; the anode of the diode D6 is used for being connected with one end of a first auxiliary winding Lf1 of the switching power supply, the cathode of the diode D6 and one end of the capacitor C5 are simultaneously connected with an input positive port of the second non-isolated voltage stabilizing circuit, and the other end of the capacitor C5 and an input negative port of the second non-isolated voltage stabilizing circuit are connected together and then are used for being connected with the other end of the first auxiliary winding Lf1 of the switching power supply; the chip IC6 is an isolation driving chip, the chip IC6 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, the input end of the chip IC6 is used for simultaneously inputting the second voltage signal and the third voltage signal, the output end of the chip IC6 is connected with the grid electrode of the switch tube Q2, the power supply end of the chip IC6 is used for inputting power supply voltage, the grounding end of the chip IC6 is used for being connected with the input ground end of the switch power supply, the isolation power supply positive end of the chip IC6 is connected with the output positive end of the second non-isolation voltage stabilizing circuit, the isolation power supply negative end of the chip IC6 is connected with the output negative end of the second non-isolation voltage stabilizing circuit and is used for being connected with the input positive end of the power supply device, and the resistor R19 is connected between the output end of the chip IC6 and the isolation power supply negative end of the chip IC 6.
Preferably, the capacitor discharge driving circuit comprises a resistor R13, a resistor R14, a capacitor C3, a chip IC4 and a second isolation voltage stabilizing circuit; the second isolation voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the second isolation voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port of the second isolation voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the second isolation voltage stabilizing circuit, the input positive port of the second isolation voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, and the input negative port of the second isolation voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply; the chip IC4 is an isolation driving chip, the chip IC4 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, one end of the resistor R13 is used for simultaneously inputting the second voltage signal and the fourth voltage signal, the other end of the resistor R13 is simultaneously connected with one end of the capacitor C3 and the input end of the chip IC4, the output end of the chip IC4 is connected with the grid electrode of the switch tube Q1, the power supply end of the chip IC4 is used for inputting power supply voltage, the grounding end of the chip IC4 is used for being connected with the input grounding end of the switch power supply, the isolation power supply positive end of the chip IC4 is connected with the output positive end of the second isolation voltage stabilizing circuit, and the isolation power supply negative end of the chip IC4 and the output negative end of the second isolation voltage stabilizing circuit are simultaneously connected with the anode of the diode D1.
Preferably, the capacitor discharge driving circuit comprises a resistor R13, a resistor R14, a capacitor C3, a chip IC4, a diode D7, a capacitor C7 and a third non-isolated voltage stabilizing circuit; the third non-isolated voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the third non-isolated voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port of the third non-isolated voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the third non-isolated voltage stabilizing circuit, the anode of the diode D7 is used for being connected with one end of a second auxiliary winding Lf2 of the switching power supply, the cathode of the diode D7 and one end of the capacitor C7 are simultaneously connected with the input positive port of the third non-isolated voltage stabilizing circuit, and the other end of the capacitor C7 and the input negative port of the third non-isolated voltage stabilizing circuit are connected together and are used for being connected with the other end of the second auxiliary winding Lf2 of the switching power supply; the chip IC4 is an isolation driving chip, the chip IC4 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, one end of the resistor R13 is used for simultaneously inputting the second voltage signal and the fourth voltage signal, the other end of the resistor R13 is simultaneously connected with one end of the capacitor C3 and the input end of the chip IC4, the output end of the chip IC4 is connected with the grid electrode of the switching tube Q1, the power supply end of the chip IC4 is used for inputting power supply voltage, the grounding end of the chip IC4 is used for being connected with the input ground end of the switching power supply, the isolation power supply positive end of the chip IC4 is connected with the output positive end of the third non-isolation voltage stabilizing circuit, and the isolation power supply negative end of the chip IC4 is simultaneously connected with the anode of the diode D1.
Preferably, the anti-reverse-filling detection circuit comprises a diode D4, a zener diode D5, a resistor R15 and a resistor R16, wherein one end of the resistor R15 is connected with the anode of the diode D1, the other end of the resistor R15 is simultaneously connected with one end of the resistor R16, the anode of the diode D4 and the cathode of the zener diode D5, the cathode of the diode D4 simultaneously outputs the third voltage signal and the fourth voltage signal, and the other end of the resistor R16 and the anode of the zener diode D5 are connected together to be used for connecting the input ground end of the switching power supply.
Further, the power failure holding circuit further comprises an inductor L1, the other end of the switching tube Q2 is connected with the cathode of the diode D1 and then connected with one end of the inductor L1, and the other end of the inductor L1 is used for being connected with the input positive end of the switching power supply.
As a second aspect of the present utility model, an embodiment of the power supply device is provided as follows:
the power supply device comprises a switching power supply, and the switching power supply can be turned off to enter a protection state when the input voltage drops to an under-voltage protection point, wherein: the power supply device includes the power-down holding circuit described in any one of the first aspects.
Further, the capacitor C1 is externally arranged.
Compared with the prior art, the utility model has at least the following beneficial effects:
1. the capacitor C1 is charged and stored by the capacitor charging circuit, so that the existing switch power supply product without an auxiliary winding or the switch power supply product without a transformer can be met, and the application range of the power-down holding circuit is widened;
2. the reverse-filling prevention diode is replaced by the switching tube Q2, so that the problem of temperature rise of the reverse-filling prevention diode device is solved, the efficiency of the switching power supply is improved, the high-temperature working characteristic of the railway power supply is optimized, and the railway power supply and the same reliability are improved;
3. when the switching power supply works normally, the switching tube Q1 is turned off, and the energy storage process of the energy storage capacitor C1 does not influence the work of the switching power supply, so that the problems of efficiency and reliability reduction are not caused;
4. the energy stored by the energy storage capacitor C1 is not changed by the change of the input voltage, so that the energy storage capacitor C is very suitable for a power supply solution which is ultra-wide in input voltage and has a low-voltage input condition;
5. for the isolated DC-DC converter, an auxiliary winding and a secondary winding can be coupled, and a single-stage topology realization circuit is adopted;
6. the voltage of the energy storage capacitor C1 can be raised to be higher, and the energy storage capacitor with smaller capacity can be selected to realize the prolongation of the power-down holding time, so that the volume of the power supply device is reduced;
7. When the input voltage of the switching power supply falls out of the normal input range, the switching tube Q2 is turned off and then is controlled to be turned on after a delay time, so that the discharge of the energy storage capacitor C1 to the input positive end of the power supply device can be avoided, and compared with a two-stage scheme, the control logic is adopted, and the reliability and the efficiency of the circuit are greatly improved;
8. for the application of the ultra-wide input switching power supply, no matter how much input voltage is, the same set of peripheral circuits can be adopted to solve the problem of power failure holding time, and great convenience is brought to the application of a power supply device;
9. when the input voltage of the switching power supply drops out of the normal input range, the anti-reverse-filling detection circuit can keep the state that the switching tube Q2 is turned off and the state that the switching tube Q1 is turned on until the input voltage of the switching power supply drops to an undervoltage protection point, so that follow-up adjustment can be automatically carried out according to the undervoltage point adjustment of the switching power supply product, and the power-down delay control can be realized under various undervoltage states.
Drawings
Fig. 1 is a circuit configuration diagram of a conventional CN112615425 a.
Fig. 2 is a circuit block diagram of a power-down holding circuit according to a first embodiment of the present utility model applied to a power supply device.
FIG. 3 is a circuit diagram of a first implementation of the circuit block diagram of FIG. 2;
Fig. 4 is a circuit diagram of a second implementation of the circuit block diagram of fig. 2.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present utility model can be understood in detail, a more particular description of the utility model, briefly summarized below, may be had by reference to embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "comprising" and "having," and any variations thereof, as described in the specification and claims of this application are intended to cover a non-exclusive inclusion, such as an inclusion of a list of elements, unit circuits, or control sequences that are not necessarily limited to those elements, unit circuits, or control sequences explicitly listed, but may include elements, unit circuits, or control sequences not explicitly listed or inherent to such circuits.
In addition, embodiments and features of embodiments in this application may be combined with each other without conflict.
It will be understood that, in the description and in the claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element; when it is described that a step is continued to another step, the step may be continued directly to the another step or through a third step to the another step.
First embodiment
Fig. 2 is a circuit block diagram of a power-down holding circuit applied to a power supply device according to a first embodiment of the present utility model, please refer to fig. 2, the power-down holding circuit of the present embodiment is applied to the power supply device, the power supply device includes a switching power supply, and the switching power supply is turned off to enter a protection state when an input voltage drops to an under-voltage protection point, wherein the power-down holding circuit includes:
the switching tube Q1, the switching tube Q2, the diode D1, the capacitor C1, the capacitor charging circuit, the input voltage detection circuit, the control circuit, the anti-reverse-filling driving circuit, the capacitor discharging driving circuit and the anti-reverse-filling detection circuit;
one end of the switching tube Q2 is used for being connected with an input positive end +vin of the power supply device, the other end of the switching tube Q2 is connected with a cathode of the diode D1 and is used for being connected with the input positive end of the switching power supply, an anode of the diode D1 is connected with one end of the switching tube Q1, the other end of the switching tube Q1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is used for being connected with an input negative end-Vin of the power supply device and an input ground end GND of the switching power supply;
When the switching power supply works normally, the switching tube Q2 is turned on, the switching tube Q1 is turned off, and the capacitor charging circuit charges and stores energy for the capacitor C1;
when the input voltage of the switching power supply drops out of a normal input range, the input voltage detection circuit outputs a first voltage signal Vin1 representing the input voltage of the switching power supply, the control circuit compares the first voltage signal Vin1 with a first reference voltage REF1 to generate a second voltage signal Vin2, the anti-reverse-filling driving circuit controls the switching tube Q2 to be turned off according to the second voltage signal Vin2, the capacitor discharging driving circuit controls the switching tube Q1 to be turned on according to the second voltage signal Vin2 after a delay time, the capacitor C1 starts to discharge, and the anti-reverse-filling detection circuit is used for generating a third voltage signal Vf1 to keep the switching tube Q2 in a turned-off state under the state and generating a fourth voltage signal Vf2 to keep the switching tube Q1 in the turned-on state until the input voltage of the switching power supply drops to an under-voltage protection point.
Wherein the switching tube Q1 and the switching tube Q2 are MOS tubes, and other devices for realizing the same function can be modified by those skilled in the art, including but not limited to IGBT, silicon controlled rectifier, relay and the like.
The capacitor C1 may be a ceramic capacitor or an electrolytic capacitor, and is preferably an electrolytic capacitor, and the embodiment is not limited in terms of how to select the capacitor.
The switching power supply in the power supply device to which the power-down holding circuit of the present embodiment is applied includes, but is not limited to, a flyback topology type single-stage switching power supply, and may also be a two-stage type switching power supply, including, but not limited to, a BOOST topology circuit+flyback topology circuit, a BOOST topology circuit+half-bridge topology circuit, as long as conversion of a wide input voltage into a relatively stable output voltage can be achieved. The switching power supply is provided with an undervoltage control port BO, when the control circuit outputs a low level, the switching power supply is turned off through the switching power supply undervoltage control port BO, and no output is generated.
Fig. 3 is a circuit diagram of a first implementation of the circuit block diagram of fig. 2, and fig. 4 is a circuit diagram of a second implementation of the circuit block diagram of fig. 2.
Referring to fig. 3 and fig. 4, the capacitor charging circuit includes a first non-isolated voltage stabilizing circuit, the first non-isolated voltage stabilizing circuit includes three ports, which are an input positive port, an output positive port and a ground port, respectively, the first non-isolated voltage stabilizing circuit is configured to convert a variable voltage input by the input port and the ground port thereof into a relatively stable voltage to be output by the output port and the ground port thereof, the input positive port of the first non-isolated voltage stabilizing circuit is configured to be connected to the other end of the switching tube Q2, the output positive port of the first non-isolated voltage stabilizing circuit is connected to one end of the capacitor C1, and the ground port of the first non-isolated voltage stabilizing circuit is configured to be connected to the input ground end of the switching power supply; the first non-isolated voltage stabilizing circuit can convert the variable voltage input by the positive input port and the negative input port into relatively stable voltage, and the relatively stable voltage is output by the positive output port and the negative output port of the first non-isolated voltage stabilizing circuit, and the first non-isolated voltage stabilizing circuit comprises but is not limited to flyback topology type circuits, FLY-BUCK circuits and the like.
Referring to fig. 3 and fig. 4, the input voltage detection circuit includes a resistor R1 and a resistor R2, wherein one end of the resistor R1 is used for connecting with the other end of the switching tube Q2, the other end of the resistor R1 and one end of the resistor R2 are connected together for outputting a first voltage signal, and the other end of the resistor R2 is connected with an input ground end of the switching power supply.
Referring to fig. 3 and fig. 4, the control circuit includes an operational amplifier IC3, a resistor R12, a diode D3 and a capacitor C2, wherein a positive input end of the operational amplifier IC3 is used for inputting a first reference voltage, a negative input end of the operational amplifier IC3 is used for inputting a first voltage signal, an output end of the operational amplifier IC3 is connected with an anode of the diode D3, a cathode of the diode D3, one end of the resistor R12 and one end of the capacitor C2 are connected together to output a second voltage signal, and the other end of the resistor R12 and the other end of the capacitor C2 are connected with an input ground end of the switching power supply; the operational amplifier IC3 can select an independent operational amplifier or an integrated dual operational amplifier, such as LM2904; further, the control circuit further comprises a resistor R11, one end of the resistor R11 is connected with the positive input end of the operational amplifier IC3, the other end of the resistor R11 is connected with the output end of the operational amplifier IC3, the resistor R11 plays a role in return difference, misoperation caused by voltage fluctuation of the positive input end +vin of the power supply device is avoided, and the performance of the power supply device is improved.
With continued reference to fig. 3 and 4, the control circuit further provides a switching power supply input undervoltage protection circuit and a reference voltage generation circuit. Specifically:
the input undervoltage protection circuit includes: the positive phase input end of the operational amplifier IC2 is used for inputting a first voltage signal Vin1, the negative phase input end of the operational amplifier IC2 is used for inputting a second reference voltage REF2, the output end of the operational amplifier IC2 is connected with the cathode of the diode D2, the resistor R10 is connected between the positive phase input end of the operational amplifier IC2 and the output end of the operational amplifier IC2, and the anode of the diode D2 is connected with the undervoltage control port BO of the switching power supply, so that when the first voltage signal Vin1 is smaller than the second reference voltage REF2 (namely, when the input voltage of the switching power supply drops to an undervoltage protection point), the switching power supply is turned off to enter a protection state; the operational amplifier IC2 can select an independent operational amplifier or an integrated dual operational amplifier, such as LM2904;
the reference voltage generating circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9 and a chip IC1, wherein one end of the resistor R3 is used for inputting a stable power supply voltage VDD, the other end of the resistor R3 is connected with the cathode of the chip IC1, the anode of the chip IC1 is connected with the input ground end GND of the switching power supply, the chip IC1 is a comparator chip, and the cathode of the chip IC1 can obtain a stable output voltage, such as a TL431 chip, through comparison with an internal reference voltage. The resistor R4 is connected between the cathode of the chip IC1 and the reference end of the chip IC1, and the resistor R5 is connected between the reference end of the chip IC1 and the input ground end GND of the switching power supply; the resistor R6 is connected between the cathode of the chip IC1 and the output end of the first reference voltage REF1, and the resistor R7 is connected between the output end of the first reference voltage REF1 and the input ground end GND of the switching power supply; the resistor R8 is connected between the cathode of the chip IC1 and the output terminal of the second reference voltage REF2, and the resistor R9 is connected between the output terminal of the second reference voltage REF2 and the input ground GND of the switching power supply.
Referring to fig. 3, the anti-reverse-filling driving circuit includes a resistor R19, a chip IC6 and a first isolation voltage stabilizing circuit; the first isolation voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, and is used for converting the variable voltage input by the input positive port and the input negative port of the first isolation voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the first isolation voltage stabilizing circuit, wherein the input positive port of the first isolation voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, and the input negative port of the first isolation voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply; the chip IC6 is an isolated driving chip, the chip IC6 comprises six ports, namely an input end HI, an output end HO, a power supply end VDD, a ground end GND, an isolated power supply positive end VB and an isolated power supply negative end VS, the input end of the chip IC6 is simultaneously input with a second voltage signal and a third voltage signal, the output end of the chip IC6 is connected with the grid electrode of the switch tube Q2, the power supply end of the chip IC6 is used for inputting power supply voltage, the ground end of the chip IC6 is used for being connected with the input ground end of the switch power supply, the isolated power supply positive end of the chip IC6 is connected with the output positive end of the first isolated voltage stabilizing circuit, the isolated power supply negative end of the chip IC6 is connected with the output negative end of the first isolated voltage stabilizing circuit to be used for being connected with the input positive end of the power supply device, and the resistor R19 is connected between the output end of the chip IC6 and the isolated power supply negative end of the chip IC6 to play a role of discharging; the first isolation voltage stabilizing circuit can convert the variable voltage input by the input positive port and the input negative port into relatively stable voltage which is output by the output positive port and the output negative port of the first isolation voltage stabilizing circuit, and the first isolation voltage stabilizing circuit comprises but is not limited to a flyback topology type circuit, an FLY-BUCK isolation circuit and the like; further, the anti-backflow driving circuit further comprises a capacitor C6, and the capacitor C6 is connected between the isolated power supply positive end of the chip IC6 and the isolated power supply negative end of the chip IC6, and plays a role in filtering and reduces interference.
Referring to fig. 4, the anti-reverse-filling driving circuit is another scheme, and includes a resistor R19, a chip IC6, a diode D6, a capacitor C5, and a second non-isolated voltage stabilizing circuit; the second non-isolated voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, and is used for converting the variable voltage input by the input positive port and the input negative port of the second non-isolated voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the second non-isolated voltage stabilizing circuit; the anode of the diode D6 is used for connecting one end of a first auxiliary winding Lf1 of the switching power supply, the cathode of the diode D6 and one end of the capacitor C5 are simultaneously connected with an input positive port of the second non-isolated voltage stabilizing circuit, and the other end of the capacitor C5 and an input negative port of the second non-isolated voltage stabilizing circuit are simultaneously connected with the other end of the first auxiliary winding Lf1 of the switching power supply; the chip IC6 is an isolated driving chip, the chip IC6 comprises six ports, namely an input end HI, an output end HO, a power supply end VDD, a ground end GND, an isolated power supply positive end VB and an isolated power supply negative end VS, the input end of the chip IC6 is simultaneously input with a second voltage signal and a third voltage signal, the output end of the chip IC6 is connected with the grid electrode of the switch tube Q2, the power supply end of the chip IC6 is used for inputting power supply voltage, the ground end of the chip IC6 is used for being connected with the input ground end of the switch power supply, the isolated power supply positive end of the chip IC6 is connected with the output positive end of the second non-isolated voltage stabilizing circuit, the isolated power supply negative end of the chip IC6 is connected with the output negative end of the second non-isolated voltage stabilizing circuit and is connected with the input positive end of the power supply device, and the resistor R19 is connected between the output end of the chip IC6 and the isolated power supply negative end of the chip IC6 to play a role in discharging; the first auxiliary winding Lf1 is preferably coupled to the output voltage of the switching power supply, so that a relatively stable voltage is obtained after rectification by the diode D6 and the capacitor C5 and is supplied to the second non-isolated voltage stabilizing circuit, and the second non-isolated voltage stabilizing circuit only needs to convert the voltage of the first auxiliary winding Lf1 after full-half-wave rectification into the relatively stable output voltage, which includes but is not limited to a linear voltage stabilizing circuit, a BUCK circuit and the like; further, the anti-backflow driving circuit further comprises a capacitor C6, and the capacitor C6 is connected between the isolated power supply positive end of the chip IC6 and the isolated power supply negative end of the chip IC6, and plays a role in filtering and reduces interference.
Referring to fig. 3, the capacitor discharge driving circuit includes a resistor R13, a resistor R14, a capacitor C3, a chip IC4 and a second isolation voltage stabilizing circuit; the second isolation voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, and is used for converting the variable voltage input by the input positive port and the input negative port of the second isolation voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the second isolation voltage stabilizing circuit, wherein the input positive port of the second isolation voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, and the input negative port of the second isolation voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply; the chip IC4 is an isolated driving chip, the chip IC4 comprises six ports, namely an input end HI, an output end HO, a power supply end VDD, a ground end GND, an isolated power supply positive end VB and an isolated power supply negative end VS, one end of a resistor R13 is simultaneously input with a second voltage signal and a fourth voltage signal, the other end of the resistor R13 is simultaneously connected with one end of a capacitor C3 and the input end of the chip IC4, the output end of the chip IC4 is connected with a grid electrode of a switch tube Q1, the power supply end of the chip IC4 is used for inputting power supply voltage, the ground end of the chip IC4 is used for connecting with the input ground end of a switch power supply, the isolated power supply positive end of the chip IC4 is connected with the output positive end of a second isolated voltage stabilizing circuit, and the isolated power supply negative end of the chip IC4 is simultaneously connected with the anode of the diode D1; the second isolation voltage stabilizing circuit can convert the variable voltage input by the positive input port and the negative input port into relatively stable voltage which is output by the positive output port and the negative output port of the second isolation voltage stabilizing circuit, and the second isolation voltage stabilizing circuit comprises but is not limited to a flyback topology type circuit, an FLY-BUCK isolation circuit and the like; further, the capacitor discharging driving circuit further comprises a capacitor C4, and the capacitor C4 is connected between the isolated power supply positive end of the chip IC4 and the isolated power supply negative end of the chip IC4, and has a filtering function to reduce interference.
Referring to fig. 4, the capacitive discharge driving circuit is another scheme, and includes a resistor R13, a resistor R14, a capacitor C3, a chip IC4, a diode D7, a capacitor C7, and a third non-isolated voltage stabilizing circuit; the third non-isolated voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the third non-isolated voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port into relatively stable voltage to be output by the output positive port and the output negative port, the anode of the diode D7 is used for being connected with one end of a second auxiliary winding Lf2 of the switching power supply, the cathode of the diode D7 and one end of the capacitor C7 are simultaneously connected with the input positive port of the third non-isolated voltage stabilizing circuit, and the other end of the capacitor C7 and the input negative port of the second non-isolated voltage stabilizing circuit are connected together and are used for being connected with the other end of the second auxiliary winding Lf2 of the switching power supply; the chip IC4 is an isolated driving chip, the chip IC4 comprises six ports, namely an input end HI, an output end HO, a power supply end VDD, a ground end GND, an isolated power supply positive end VB and an isolated power supply negative end VS, one end of a resistor R13 is simultaneously input with a second voltage signal and a fourth voltage signal, the other end of the resistor R13 is simultaneously connected with one end of a capacitor C3 and the input end of the chip IC4, the output end of the chip IC4 is connected with a grid electrode of a switching tube Q1, the power supply end of the chip IC4 is used for inputting power supply voltage, the ground end of the chip IC4 is used for connecting with the input ground end of a switching power supply, the isolated power supply positive end of the chip IC4 is connected with the output positive end of a third non-isolated voltage stabilizing circuit, and the output negative end of the chip IC4 is simultaneously connected with the anode of the diode D1; the second auxiliary winding Lf2 is preferably coupled to the output voltage of the switching power supply, so that a relatively stable voltage is obtained after rectification by the diode D7 and the capacitor C7 and is supplied to the third non-isolated voltage stabilizing circuit, and the third non-isolated voltage stabilizing circuit only needs to convert the voltage of the second auxiliary winding Lf2 after full-half-wave rectification into the relatively stable output voltage, including but not limited to a linear voltage stabilizing circuit, a BUCK circuit and the like; further, the capacitor discharging driving circuit further comprises a capacitor C4, and the capacitor C4 is connected between the isolated power supply positive end of the chip IC4 and the isolated power supply negative end of the chip IC4, and has a filtering function to reduce interference.
Referring to fig. 3 and fig. 4, the anti-reverse-filling detection circuit includes a diode D4, a zener diode D5, a resistor R15 and a resistor R16, one end of the resistor R15 is connected to the anode of the diode D1, the other end of the resistor R15 is simultaneously connected to one end of the resistor R16, the anode of the diode D4 and the cathode of the zener diode D5, the cathode of the diode D4 simultaneously outputs a third voltage signal and a fourth voltage signal, and the other end of the resistor R16 and the anode of the zener diode D5 are connected together for connecting the input ground terminal of the switching power supply. The signal detection of the anti-reverse-filling detection circuit is independent of the working state of the switching tube Q2, and when the capacitor C1 is in a discharging state, the switching tube Q2 is still in a conducting state, so that the problem of signal detection failure is avoided.
Referring to fig. 2 to 4, further, the power-down holding circuit further includes an inductor L1, the other end of the switching tube Q2 is connected with the cathode of the diode D1, and then connected to one end of the inductor L1, the other end of the inductor L1 is used for being connected to the input positive end of the switching power supply, and the purpose of increasing the inductor L1 is to reduce the impact current of discharging the capacitor C1, so as to avoid damaging the internal devices of the switching power supply.
The principle of operation of the circuits of fig. 3 and 4 is as follows:
when the switching power supply product works normally, the capacitor charging circuit charges and stores energy for the energy storage capacitor C1. The input detection circuit performs voltage detection on the input port Vg, and when the input port Vg falls out of a normal input range, the input detection circuit outputs a first voltage signal Vin1. The control circuit receives the first voltage signal Vin1 and compares the first voltage signal Vin1 with a first reference voltage REF1 to generate a high-level second voltage signal Vin2. The anti-reverse-filling driving circuit receives the second voltage signal Vin2 and outputs a low-level signal VG2 to turn off the switching tube Q2. Meanwhile, the capacitor discharge driving circuit receives a second voltage signal Vin2, delays and generates a high-level voltage signal VG1 driven in an isolated manner through a delay circuit formed by a resistor R13 and a capacitor C3, and the switching tube Q1 is conducted. The energy storage capacitor C1 discharges the switching power supply through the inductor L1, and at the moment, the switching tube Q2 is switched off in advance, so that the energy storage capacitor C1 is prevented from discharging the input positive end +vin of the power supply device. When the energy storage capacitor C1 discharges the switching power supply, the voltage Vg at the other end of the switching tube Q2 rises firstly and then falls, when the voltage of the first voltage signal Vin1 is larger than the first reference voltage REF1, the chip IC3 outputs a low level, the voltage of the second voltage signal Vin2 gradually falls, the switching tube Q1 is turned off, and the energy storage capacitor C1 stops discharging. In order to solve this problem, the anti-reverse-filling detection circuit is added, when the energy storage capacitor C1 discharges, the diode D1 is turned on in the forward direction, so that the cathode voltage VD1 of the diode D1 rises, the anti-reverse-filling detection circuit outputs a high level, and further, the fourth voltage signal Vf2 of the capacitor discharge driving circuit and the third voltage signal Vf1 of the anti-reverse-filling driving circuit are maintained to be in a high level, so that the switch tube Q1 continues to keep on state and the switch tube Q2 continues to keep off state, the energy storage capacitor C1 is ensured to continue to keep on discharging state, the switching power supply is turned off until the voltage Vg at the other end of the switch tube Q2 drops to the under-voltage protection point of the switching power supply, the under-voltage control port of the switching power supply is controlled to enable the switching power supply to be turned off, the under-voltage point adjustment of the switching power supply product is automatically performed to follow adjustment, and the power down delay control can be realized under various under-voltage states. The resistor R10 and the resistor R11 play a role in regulating undervoltage return difference, and abnormal operation of the control circuit caused by small fluctuation of input voltage is avoided.
Second embodiment
The embodiment provides a power supply device, the power supply device includes switching power supply, and the input voltage of switching power supply drops to under-voltage protection point and can turn off and get into the protection state, wherein: the power supply apparatus further comprising any of the power-down holding circuits of the first embodiment.
Further, the capacitor C1 is externally arranged, that is, the power supply device is packaged into a product, the capacitor C1 is not arranged inside, and the capacitor C1 is arranged on a circuit board of a user.
The above is only a preferred embodiment of the present utility model, and it should be noted that the above-mentioned preferred embodiment should not be construed as limiting the present utility model, and that it is possible for a person skilled in the art to make several modifications and alterations to all the circuits implementing this function without departing from the spirit and scope of the present utility model, and it should be considered as the protection scope of the present utility model, which is defined by the scope of the appended claims.
Claims (12)
1. A power-down holding circuit applied to a power supply device, the power supply device comprising a switching power supply, the switching power supply being turned off to enter a protection state when an input voltage drops to an undervoltage protection point, the power-down holding circuit comprising:
The switching tube Q1, the switching tube Q2, the diode D1, the capacitor C1, the capacitor charging circuit, the input voltage detection circuit, the control circuit, the anti-reverse-filling driving circuit, the capacitor discharging driving circuit and the anti-reverse-filling detection circuit;
one end of the switching tube Q2 is used for being connected with an input positive end of the power supply device, the other end of the switching tube Q2 and a cathode of the diode D1 are connected together and used for being connected with the input positive end of the switching power supply, an anode of the diode D1 is connected with one end of the switching tube Q1, the other end of the switching tube Q1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is used for being connected with an input negative end of the power supply device and an input ground end of the switching power supply;
when the switching power supply works normally, the switching tube Q2 is turned on, the switching tube Q1 is turned off, and the capacitor charging circuit charges and stores energy for the capacitor C1;
when the input voltage of the switching power supply drops out of a normal input range, the input voltage detection circuit outputs a first voltage signal representing the input voltage of the switching power supply, the control circuit compares the first voltage signal with a first reference voltage to generate a second voltage signal, the anti-reverse-filling driving circuit controls the switching tube Q2 to be turned off according to the second voltage signal, after a delay time, the capacitor discharging driving circuit controls the switching tube Q1 to be turned on according to the second voltage signal, the capacitor C1 starts to discharge, and the anti-reverse-filling detection circuit is used for generating a third voltage signal to keep the switching tube Q2 in a turned-off state under the state and generating a fourth voltage signal to keep the switching tube Q1 in the turned-on state until the input voltage of the switching power supply drops to the under-voltage protection point.
2. The power-down holding circuit according to claim 1, wherein the capacitor charging circuit comprises a first non-isolated voltage stabilizing circuit, the first non-isolated voltage stabilizing circuit comprises three ports, namely an input positive port, an output positive port and a ground port, the first non-isolated voltage stabilizing circuit is used for converting a variable voltage input by the input port and the ground port of the first non-isolated voltage stabilizing circuit into a relatively stable voltage to be output by the output port and the ground port of the first non-isolated voltage stabilizing circuit, the input positive port of the first non-isolated voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, the output positive port of the first non-isolated voltage stabilizing circuit is connected with one end of the capacitor C1, and the ground port of the first non-isolated voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply.
3. The power down holding circuit according to claim 1, wherein: the input voltage detection circuit comprises a resistor R1 and a resistor R2, one end of the resistor R1 is used for being connected with the other end of the switching tube Q2, the other end of the resistor R1 and one end of the resistor R2 are connected together to be used for outputting the first voltage signal, and the other end of the resistor R2 is connected with the input ground end of the switching power supply.
4. The power down holding circuit according to claim 1, wherein: the control circuit comprises an operational amplifier IC3, a resistor R12, a diode D3 and a capacitor C2, wherein the positive phase input end of the operational amplifier IC3 is used for inputting the first reference voltage, the negative phase input end of the operational amplifier IC3 is used for inputting the first voltage signal, the output end of the operational amplifier IC3 is connected with the anode of the diode D3, the cathode of the diode D3, one end of the resistor R12 and one end of the capacitor C2 are connected together to output the second voltage signal, and the other end of the resistor R12 and the other end of the capacitor C2 are used for being connected with the input ground end of the switching power supply.
5. The power down holding circuit according to claim 1, wherein: the anti-reverse-filling driving circuit comprises a resistor R19, a chip IC6 and a first isolation voltage stabilizing circuit; the first isolation voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the first isolation voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port of the first isolation voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the first isolation voltage stabilizing circuit, the input positive port of the first isolation voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, and the input negative port of the first isolation voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply; the chip IC6 is an isolation driving chip, the chip IC6 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, the input end of the chip IC6 is used for simultaneously inputting the second voltage signal and the third voltage signal, the output end of the chip IC6 is connected with the grid electrode of the switch tube Q2, the power supply end of the chip IC6 is used for inputting the power supply voltage, the grounding end of the chip IC6 is used for being connected with the input ground end of the switch power supply, the isolation power supply positive end of the chip IC6 is connected with the output positive end of the first isolation voltage stabilizing circuit, the isolation power supply negative end of the chip IC6 is connected with the output negative end of the first isolation voltage stabilizing circuit and is used for being connected with the input positive end of the power supply device, and the resistor R19 is connected between the output end of the chip IC6 and the isolation power supply negative end of the chip IC 6.
6. The power down holding circuit according to claim 1, wherein: the anti-reverse-filling driving circuit comprises a resistor R19, a chip IC6, a diode D6, a capacitor C5 and a second non-isolated voltage stabilizing circuit; the second non-isolated voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, and is used for converting the variable voltage input by the input positive port and the input negative port into relatively stable voltage and outputting the relatively stable voltage through the output positive port and the output negative port; the anode of the diode D6 is used for being connected with one end of a first auxiliary winding Lf1 of the switching power supply, the cathode of the diode D6 and one end of the capacitor C5 are simultaneously connected with an input positive port of the second non-isolated voltage stabilizing circuit, and the other end of the capacitor C5 and an input negative port of the second non-isolated voltage stabilizing circuit are connected together and then are used for being connected with the other end of the first auxiliary winding Lf1 of the switching power supply; the chip IC6 is an isolation driving chip, the chip IC6 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, the input end of the chip IC6 is used for simultaneously inputting the second voltage signal and the third voltage signal, the output end of the chip IC6 is connected with the grid electrode of the switch tube Q2, the power supply end of the chip IC6 is used for inputting power supply voltage, the grounding end of the chip IC6 is used for being connected with the input ground end of the switch power supply, the isolation power supply positive end of the chip IC6 is connected with the output positive end of the second non-isolation voltage stabilizing circuit, the isolation power supply negative end of the chip IC6 is connected with the output negative end of the second non-isolation voltage stabilizing circuit and is used for being connected with the input positive end of the power supply device, and the resistor R19 is connected between the output end of the chip IC6 and the isolation power supply negative end of the chip IC 6.
7. The power down holding circuit according to claim 1, wherein: the capacitor discharge driving circuit comprises a resistor R13, a resistor R14, a capacitor C3, a chip IC4 and a second isolation voltage stabilizing circuit; the second isolation voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the second isolation voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port of the second isolation voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the second isolation voltage stabilizing circuit, the input positive port of the second isolation voltage stabilizing circuit is used for being connected with the other end of the switch tube Q2, and the input negative port of the second isolation voltage stabilizing circuit is used for being connected with the input ground end of the switch power supply; the chip IC4 is an isolation driving chip, the chip IC4 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, one end of the resistor R13 is used for simultaneously inputting the second voltage signal and the fourth voltage signal, the other end of the resistor R13 is simultaneously connected with one end of the capacitor C3 and the input end of the chip IC4, the output end of the chip IC4 is connected with the grid electrode of the switch tube Q1, the power supply end of the chip IC4 is used for inputting power supply voltage, the grounding end of the chip IC4 is used for being connected with the input grounding end of the switch power supply, the isolation power supply positive end of the chip IC4 is connected with the output positive end of the second isolation voltage stabilizing circuit, and the isolation power supply negative end of the chip IC4 and the output negative end of the second isolation voltage stabilizing circuit are simultaneously connected with the anode of the diode D1.
8. The power down holding circuit according to claim 1, wherein: the capacitor discharge driving circuit comprises a resistor R13, a resistor R14, a capacitor C3, a chip IC4, a diode D7, a capacitor C7 and a third non-isolated voltage stabilizing circuit; the third non-isolated voltage stabilizing circuit comprises four ports, namely an input positive port, an input negative port, an output positive port and an output negative port, wherein the third non-isolated voltage stabilizing circuit is used for converting the variable voltage input by the input positive port and the input negative port of the third non-isolated voltage stabilizing circuit into relatively stable voltage to be output by the output positive port and the output negative port of the third non-isolated voltage stabilizing circuit, the anode of the diode D7 is used for being connected with one end of a second auxiliary winding Lf2 of the switching power supply, the cathode of the diode D7 and one end of the capacitor C7 are simultaneously connected with the input positive port of the third non-isolated voltage stabilizing circuit, and the other end of the capacitor C7 and the input negative port of the third non-isolated voltage stabilizing circuit are connected together and are used for being connected with the other end of the second auxiliary winding Lf2 of the switching power supply; the chip IC4 is an isolation driving chip, the chip IC4 comprises six ports, namely an input end, an output end, a power supply end, a grounding end, an isolation power supply positive end and an isolation power supply negative end, one end of the resistor R13 is used for simultaneously inputting the second voltage signal and the fourth voltage signal, the other end of the resistor R13 is simultaneously connected with one end of the capacitor C3 and the input end of the chip IC4, the output end of the chip IC4 is connected with the grid electrode of the switching tube Q1, the power supply end of the chip IC4 is used for inputting power supply voltage, the grounding end of the chip IC4 is used for being connected with the input ground end of the switching power supply, the isolation power supply positive end of the chip IC4 is connected with the output positive end of the third non-isolation voltage stabilizing circuit, and the isolation power supply negative end of the chip IC4 is simultaneously connected with the anode of the diode D1.
9. The power down holding circuit according to claim 1, wherein: the anti-reverse irrigation detection circuit comprises a diode D4, a voltage stabilizing diode D5, a resistor R15 and a resistor R16, wherein one end of the resistor R15 is connected with the anode of the diode D1, the other end of the resistor R15 is simultaneously connected with one end of the resistor R16, the anode of the diode D4 and the cathode of the voltage stabilizing diode D5, the cathode of the diode D4 simultaneously outputs a third voltage signal and a fourth voltage signal, and the other end of the resistor R16 and the anode of the voltage stabilizing diode D5 are connected together to be used for connecting the input ground end of the switching power supply.
10. The power down holding circuit according to any one of claims 1 to 9, wherein: the power failure holding circuit further comprises an inductor L1, the other end of the switching tube Q2 is connected with the cathode of the diode D1 and then connected with one end of the inductor L1, and the other end of the inductor L1 is used for being connected with the input positive end of the switching power supply.
11. A power supply device, the power supply device comprising a switching power supply, the switching power supply being turned off to enter a protection state when an input voltage drops to an under-voltage protection point, characterized in that: the power supply device further includes the power-down holding circuit of any one of claims 1 to 10.
12. The power supply apparatus according to claim 11, wherein: and externally arranging the capacitor C1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322007612.0U CN220492696U (en) | 2023-07-28 | 2023-07-28 | Power-down holding circuit and power supply device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322007612.0U CN220492696U (en) | 2023-07-28 | 2023-07-28 | Power-down holding circuit and power supply device |
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| Publication Number | Publication Date |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118842152A (en) * | 2024-09-20 | 2024-10-25 | 深圳市振华微电子有限公司 | Circuit of DC-DC power supply maintaining module and discharging method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118842152A (en) * | 2024-09-20 | 2024-10-25 | 深圳市振华微电子有限公司 | Circuit of DC-DC power supply maintaining module and discharging method |
| CN118842152B (en) * | 2024-09-20 | 2025-05-09 | 深圳市振华微电子有限公司 | Circuit of DC-DC power supply maintaining module and discharging method |
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