CN210898926U - Switching power supply output load discharge circuit - Google Patents
Switching power supply output load discharge circuit Download PDFInfo
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- CN210898926U CN210898926U CN201921556096.4U CN201921556096U CN210898926U CN 210898926 U CN210898926 U CN 210898926U CN 201921556096 U CN201921556096 U CN 201921556096U CN 210898926 U CN210898926 U CN 210898926U
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Abstract
The utility model discloses a switch power supply output load discharge circuit, which comprises a detection circuit, an isolation connection unit, a switch unit and a discharge power resistor which are connected in sequence; the detection circuit is connected with the input positive end and used for detecting the voltage value of the input positive end and setting the rear-stage circuit to work when the input voltage value is lower than the lowest working voltage of the switching power supply; the isolation connection unit isolates the detection circuit from the switch unit, so that the detection circuit is not electrically and directly connected with the switch unit; the discharge power resistor is connected with the positive output terminal and used for adjusting the discharge time of the discharge circuit. The utility model discloses a switching power supply output discharge circuit is through the resistance of change R1, R2, can set for when input voltage is less than switching power supply's minimum operating voltage, and the back stage circuit begins to discharge, and the adjustable discharge time of resistance of change discharge resistance, circuit are simple, low cost, safety and stability, and application prospect is wide.
Description
Technical Field
The utility model relates to a circuit, specific theory relates to a switching power supply output load discharge circuit.
Background
When a general multi-output switch power supply is shut down, the output voltages of all paths are random disordered power failure, and when the voltage of one path is required to be adjusted to an index required value within a certain time, the switch power supply does not have the control function and needs to be realized by an additional circuit. At present, the conventional method is realized by connecting a power output end in parallel with a load resistor, the circuit is simple, but a part of power of the switching power supply is consumed, and the efficiency of the switching power supply is reduced.
Disclosure of Invention
An object of the utility model is to provide a switching power supply output load discharge circuit, especially a switching power supply output load discharge circuit to current electronic switch's not enough.
In order to achieve the above purpose, the utility model discloses the technical scheme who takes includes:
a switching power supply output load discharge circuit comprises a detection circuit, an isolation connection unit, a switching unit and a discharge power resistor which are connected in sequence;
the detection circuit is connected with the input positive end and used for detecting the voltage value of the input positive end and setting the rear-stage circuit to start to act when the voltage value is lower than the lowest working voltage of the switching power supply;
the isolation connection unit isolates the detection circuit from the switch unit, so that the detection circuit is not electrically and directly connected with the switch unit;
the discharge power resistor is connected with the positive output terminal and used for adjusting the discharge time of the discharge circuit.
Furthermore, the detection circuit comprises a divider resistor, an operation comparator and a diode which are connected in sequence, the isolation connection unit is an isolation optocoupler U1,
the voltage dividing resistor is used for setting an input voltage sampling signal; when the input voltage is lower than the minimum working voltage of the switching power supply, the operation comparator generates low-level voltage; and if the low level voltage generated by the operation comparator is lower than the voltage of the isolation optocoupler U1, the diode is conducted to enable the diode of the isolation optocoupler U1 to emit light.
Furthermore, the voltage dividing resistor comprises a resistor R1 and a resistor R2 which are connected in series, one end of the resistor R1 is connected with the positive input terminal, and the other end of the resistor R2 is connected with the ground input terminal.
Furthermore, the detection circuit further comprises a capacitor C1 and a capacitor C2, the operational comparator is an operational comparator OP1, the homodromous input end of the operational comparator OP1 is connected with the common end connected with the resistor R1 and the resistor R2, the reverse input end of the operational comparator OP1 is connected with one end of the capacitor C1 connected with Vref, the other end of the capacitor C1 is connected with an input ground, the pin 5 of the operational comparator OP1 is connected with one end of the capacitor C2, the common ends of the operational comparator OP1 and the capacitor C2 are connected with the end of the working voltage VCC1, the pin 2 of the operational comparator OP1 is connected with the other end of the capacitor C2 in a chip-ground manner and is connected with the input ground, the 1-pin chip output end of the OP1 is connected with the cathode of the diode D1, and the anode of the diode D1 is connected with the isolation connection unit.
Further, keep apart pin 2 of opto-coupler U1 with diode D1 positive pole connect, 1 external resistor R3 of pin of isolation opto-coupler U1, VCC1 end is connected to the other end of resistor R3, pin 3 link switch unit of isolation opto-coupler U1, VCC2 end is connected to pin 4 of isolation opto-coupler U1.
Further, the switching unit is a switching MOS transistor Q1, a G-pole external resistor R4 of the switching MOS transistor Q1 is connected to a common terminal connected to the 3 rd pin of the optocoupler U1, and the other end of the resistor R4 is connected to an output ground terminal.
Furthermore, the S pole of the switching MOS transistor Q1 is connected to the output ground, the D pole of the switching MOS transistor Q1 is connected to one end of the regulating discharge unit, and the MOS transistor D, S pole is connected in parallel to the resistor R5.
Specifically, when the voltage of the input positive terminal is reduced to a set voltage value when the switching power supply is turned off, the detection circuit is triggered, the operational comparator OP1 outputs a low level, the diode D1 is conducted, the primary light emitting diode of the isolation optocoupler U1 is conducted to emit light, then the secondary of the isolation optocoupler U1 is conducted, the voltage of the VCC2 terminal is applied to the G pole of the switching MOS transistor, the switching MOS transistor Q1 is conducted, and the output positive terminal of the switching power supply discharges to the input ground terminal through the discharge power resistor.
The utility model has the advantages that:
the utility model provides a pair of switching power supply output load discharge circuit has defined in switching power supply shutdown in the twinkling of an eye, and input detection circuitry triggers when input positive terminal voltage reduces below the minimum operating voltage of switching power supply, and discharge circuit starts work, and discharge resistance discharges to the output positive terminal. The utility model discloses a switching power supply output discharge circuit is through the resistance of change R1, R2, can set for after input voltage is less than switching power supply's minimum operating voltage, the back level circuit begins to discharge, the adjustable discharge time of resistance of change discharge resistance, and the circuit is simple, low cost, safety and stability, and application prospect is wide.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention;
the reference numerals in the figures denote:
1. an input detection circuit; 2. an isolated connection unit; 3. a switch unit; 4. discharging the power resistor.
Detailed Description
The invention will be described in further detail with reference to the accompanying drawings:
with reference to fig. 1, the utility model discloses a switching power supply output load discharge circuit, which comprises a detection circuit 1, an isolation connection unit 2, a switching unit 3 and a discharge power resistor 4, which are connected in sequence;
the detection circuit 1 is connected with the input positive terminal and used for detecting the voltage value of the input positive terminal and setting the output low level of the operation comparator when the input voltage value is lower than the lowest working voltage of the switching power supply; the isolation connecting unit 2 isolates the detection circuit 1 from the switch unit 3, so that the detection circuit 1 is not electrically and directly connected with the switch unit 3; the discharge power resistor 4 is connected with the positive output terminal and used for adjusting the discharge time of the discharge circuit.
The detection circuit 1 comprises a divider resistor, an operation comparator and a diode which are connected in sequence, the isolation connection unit 2 is an isolation optocoupler U1,
the divider resistor is used for setting an input voltage sampling signal; when the input voltage is lower than the minimum working voltage of the switching power supply, the operation comparator generates low-level voltage; if the low level voltage generated by the operation comparator is lower than the voltage of the isolation optocoupler U1, the diode is conducted to enable the diode of the isolation optocoupler U1 to emit light.
Specifically, the voltage dividing resistor comprises a resistor R1 and a resistor R2 which are connected in series, one end of the resistor R1 is connected with the positive input terminal, and the other end of the resistor R2 is connected with the ground input terminal.
The detection circuit 1 further comprises a capacitor C1 and a capacitor C2, the operational comparator is an operational comparator OP1, the homodromous input end of the operational comparator OP1 is connected with the common end connected with the resistor R1 and the resistor R2, the reverse input end of the operational comparator OP1 is connected with one end of the capacitor C1 connected with Vref, the other end of the capacitor C1 is grounded, a pin 5 of the operational comparator OP1 is connected with one end of the capacitor C2, the common end of the operational comparator OP1 and the capacitor C2 is connected with a working voltage VCC1, a pin 2 of the operational comparator OP1 is connected with the other end of the capacitor C2 in a chip mode and is connected with an input ground terminal, the output end of a pin 1 of the OP1 is connected with the cathode of the diode D1, and the anode of the diode D1 is connected with the isolation connection unit 2.
The pin 2 of the isolation optocoupler U1 is connected with the anode of the diode D1, the pin 1 of the isolation optocoupler U1 is externally connected with a resistor R3, the other end of the resistor R3 is connected with a VCC1 end, the pin 3 of the isolation optocoupler U1 is connected with a switch unit 3, and the pin 4 of the isolation optocoupler U1 is connected with a VCC2 end.
The switch unit 3 is a switch MOS transistor Q1, a G pole of the switch MOS transistor Q1 is externally connected with a common end of a resistor R4 connected with a 3 rd pin of an optocoupler U1, and the other end of the resistor R4 is connected with an output ground end.
The S pole (source) of the switch MOS tube Q1 is connected with the output ground, the D pole (drain) of the MOS tube Q1 is connected with one end of the adjusting discharge unit 4, and the MOS tube D, S pole is connected with the resistor R5 in parallel. When the MOS transistor Q1 is turned on, the positive output terminal forms a discharge path to the input ground through the discharge power resistor 4.
The utility model discloses a theory of operation does: when the switching power supply is powered off, the detection circuit 1 is triggered when the voltage of the input positive end of the switching power supply output load discharge circuit is reduced to be lower than the lowest working voltage of the switching power supply, the operational comparator OP1 outputs a low level, the diode D1 is conducted, the primary light emitting diode of the isolation optocoupler U1 is conducted to emit light, then the secondary of the isolation optocoupler U1 is conducted, the voltage of the VCC2 end is applied to the G pole (grid electrode) of the switching MOS transistor, the switching MOS transistor Q1 is conducted, and the output positive end of the switching power supply discharges to the input ground end through the discharge power resistor 4. The voltage of the output positive terminal is reduced to the index value required by the user in a short time. When the input voltage is set to be reduced to the lowest operating voltage of the switching power supply by changing the resistance values of the resistors (R1, R2), the subsequent circuit operates. The resistance value of the discharge power resistor 4 is changed to set the discharge time of the output voltage.
The utility model provides a pair of switching power supply output discharge circuit is through changing R1, R2's resistance, can set for when input voltage is less than switching power supply's minimum operating voltage, triggers back-stage discharge circuit and begins to discharge, and the adjustable discharge time of resistance of change discharge power resistance 4, simple, low cost, safety and stability of circuit, application prospect is wide.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can change or replace the present invention without creative efforts within the technical scope of the present invention.
Claims (8)
1. A switching power supply output load discharge circuit is characterized by comprising a detection circuit (1), an isolation connection unit (2), a switching unit (3) and a discharge power resistor (4) which are sequentially connected;
the detection circuit (1) is connected with the input positive end and used for detecting the voltage value of the input positive end and setting the rear-stage circuit to start to act when the voltage value is lower than the lowest working voltage of the switching power supply;
the isolation connecting unit (2) isolates the detection circuit (1) from the switch unit (3) so that the detection circuit (1) is not electrically and directly connected with the switch unit (3);
and the discharge power resistor (4) is connected with the positive output end and is used for adjusting the discharge time of the discharge circuit.
2. The switching power supply output load discharging circuit according to claim 1, wherein the detection circuit (1) comprises a divider resistor, an operation comparator and a diode which are connected in sequence, the isolation connection unit (2) is an isolation optocoupler U1,
the voltage dividing resistor is used for setting an input voltage sampling signal; when the input voltage is lower than the minimum working voltage of the switching power supply, the operation comparator generates low-level voltage; and if the low level voltage generated by the operation comparator is lower than the voltage of the isolation optocoupler U1, the diode is conducted to enable the diode of the isolation optocoupler U1 to emit light.
3. The output load discharge circuit of claim 2, wherein the voltage dividing resistor comprises a resistor R1 and a resistor R2 connected in series, one end of the resistor R1 is connected to the positive input terminal, and the other end of the resistor R2 is connected to the ground input terminal.
4. A switching power supply output load discharging circuit according to claim 3, wherein said detection circuit (1) further comprises a capacitor C1 and a capacitor C2, said operational comparator is an operational comparator OP1, the same-direction input terminal of the operational comparator OP1 is connected to the common terminal of the connection of the resistor R1 and the resistor R2, the reverse input terminal of the operational comparator OP1 is connected to the Vref terminal of the capacitor C1, the other terminal of the capacitor C1 is grounded, the pin 5 of the operational comparator OP1 is connected to one terminal of the capacitor C2, the common terminal of the operational comparator OP1 and the capacitor C2 is connected to the operating voltage VCC1 terminal, the pin 2 of the operational comparator OP1 is connected to the other terminal of the capacitor C2 by chip ground and to the input ground terminal, the 1-pin output terminal of the OP1 is connected to the cathode of a diode D1, and the anode of the diode D1 is connected to the isolation connection unit (2).
5. A switching power supply output load discharge circuit according to claim 4, characterized in that pin 2 of the isolating optocoupler U1 is connected with the anode of the diode D1, pin 1 of the isolating optocoupler U1 is connected with an external resistor R3, the other end of the resistor R3 is connected with the VCC1 terminal, pin 3 of the isolating optocoupler U1 is connected with the switch unit (3), and pin 4 of the isolating optocoupler U1 is connected with the VCC2 terminal.
6. The switching power supply output load discharge circuit according to claim 5, wherein the switching unit (3) is a switching MOS transistor Q1, a G-pole external resistor R4 of the switching MOS transistor Q1 is connected to a common terminal of the 3-pin isolation optocoupler U1, and the other end of the resistor R4 is connected to the output ground terminal.
7. The output load discharge circuit of claim 6, wherein the S pole of the switching MOS transistor Q1 is connected to the output ground, the D pole of the MOS transistor Q1 is connected to one end of the discharge power resistor (4), and the MOS transistor D, S is connected in parallel with the resistor R5.
8. The switching power supply output load discharging circuit according to claim 6, wherein when the voltage of the input positive terminal decreases to the set voltage value when the switching power supply is turned off, the detection circuit (1) is triggered, the operational comparator OP1 outputs a low level, the diode D1 is turned on, the primary light emitting diode of the isolating optocoupler U1 is turned on to emit light, then the secondary of the isolating optocoupler U1 is turned on, the voltage of the VCC2 is applied to the G pole of the switching MOS transistor, the switching MOS transistor Q1 is turned on, and the output positive terminal of the switching power supply discharges to the input ground terminal through the discharging power resistor (4).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921556096.4U CN210898926U (en) | 2019-09-18 | 2019-09-18 | Switching power supply output load discharge circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921556096.4U CN210898926U (en) | 2019-09-18 | 2019-09-18 | Switching power supply output load discharge circuit |
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| Publication Number | Publication Date |
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| CN210898926U true CN210898926U (en) | 2020-06-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201921556096.4U Active CN210898926U (en) | 2019-09-18 | 2019-09-18 | Switching power supply output load discharge circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111983957A (en) * | 2020-09-03 | 2020-11-24 | 中国兵器工业集团第二一四研究所苏州研发中心 | Combined power supply and power-on time sequence control method thereof |
-
2019
- 2019-09-18 CN CN201921556096.4U patent/CN210898926U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111983957A (en) * | 2020-09-03 | 2020-11-24 | 中国兵器工业集团第二一四研究所苏州研发中心 | Combined power supply and power-on time sequence control method thereof |
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