CN221202362U - Input voltage quick discharging circuit in switching power supply - Google Patents
Input voltage quick discharging circuit in switching power supply Download PDFInfo
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- CN221202362U CN221202362U CN202323225454.2U CN202323225454U CN221202362U CN 221202362 U CN221202362 U CN 221202362U CN 202323225454 U CN202323225454 U CN 202323225454U CN 221202362 U CN221202362 U CN 221202362U
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- input voltage
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- power supply
- switching
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- 238000007599 discharging Methods 0.000 title claims abstract description 16
- 238000001514 detection method Methods 0.000 claims abstract description 9
- 239000003990 capacitor Substances 0.000 claims description 17
- 206010014357 Electric shock Diseases 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
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Abstract
The utility model provides an input voltage quick discharge circuit in a switching power supply, which comprises an input voltage detection circuit, a digital signal processor and a quick discharge circuit, wherein a voltage division point of the input voltage detection circuit is connected with an input port of the digital signal processor and is used for detecting input voltage, the digital signal processor outputs a voltage signal to the quick discharge circuit, the quick discharge circuit comprises a first switching tube and a second switching tube, the digital signal processor outputs the voltage signal to a grid electrode of the first switching tube, a drain electrode of the first switching tube is connected with a grid electrode of the second switching tube, and a drain electrode of the second switching tube is connected with a positive end of the input voltage through a fifth resistor; the input voltage discharging circuit provided by the utility model controls the second switching tube to be turned on after the digital signal processor detects that the input voltage is powered off, so that the quick discharging of the input voltage is realized, the reliability of the switching power supply is improved, the circuit structure is simple, and the universality is strong.
Description
Technical Field
The utility model relates to the field of switching power supplies, in particular to a fast input voltage discharging circuit in a switching power supply.
Background
In a switching power supply, especially in a high-voltage input vehicle-mounted switching power supply, the input voltage is up to 600V or even kilovolts, a plurality of high-voltage filter capacitors are arranged at the input end, when the input voltage is powered off, as the capacitance value of the input capacitor is large, the voltage on the capacitors is high, if the voltage on the capacitors is discharged only by means of resistors, the voltage on the capacitors can be discharged slowly, the time required for discharging the safety voltage which can be contacted by a human body is long, in actual operation, after the input voltage is powered off, an operator touches a power supply module, the operator touches the switching power supply which is not completely discharged yet, and the risk of electric shock exists, so that a circuit for rapidly discharging the input voltage after the input power is powered off is needed.
In order to solve the above problems, the present utility model provides a fast input voltage discharging circuit in a switching power supply.
Disclosure of utility model
The utility model solves the technical problem of providing a fast discharge circuit for input voltage in a switching power supply.
The technical scheme adopted by the utility model for solving the technical problems is as follows:
The input voltage quick discharge circuit comprises an input voltage detection circuit, a digital signal processor and a quick discharge circuit, wherein the input voltage detection circuit is formed by connecting a plurality of resistors in parallel and then connecting the resistors in series, the resistors are connected across the input capacitor and the two ends of the input voltage, a voltage division point is connected with one input port of the digital signal processor and used for detecting the input voltage, the digital signal processor outputs a voltage signal to the quick discharge circuit, and outputs a PWM signal to a power switch tube in the switch power supply;
The rapid discharging circuit comprises a first switching tube and a second switching tube, voltage signals output by the digital signal processor are supplied to a grid electrode of the first switching tube, the grid electrode of the first switching tube is further connected with one end of a third resistor and one end of a first capacitor, a drain electrode of the first switching tube is connected with the grid electrode of the second switching tube, one end of a fourth resistor, one end of a sixth resistor and one end of a second capacitor, a drain electrode of the second switching tube is connected with a positive end of input voltage through a fifth resistor, source electrodes of the first switching tube and the second switching tube are grounded, and the other ends of the first capacitor, the sixth resistor and the second capacitor are grounded.
Further, the first switching tube and the second switching tube are N-type MOS tubes, the first switching tube is a small MOS tube with a rated voltage of about 30V and low voltage, and the rated voltage of the second switching tube is at least 1.2 times of the input voltage.
Further, the other end of the third resistor and the power supply end of the digital signal processor are connected with a stable voltage of 3.3V, the other end of the fourth resistor is connected with a stable voltage of 15V, and the stable voltage of 3.3V and the stable voltage of 15V are provided by an auxiliary power supply circuit of the switching power supply.
Compared with the prior art, the utility model has the following technical effects:
According to the input voltage discharging circuit provided by the utility model, after the input voltage is powered off, the digital signal processor controls the second switching tube to be turned on, so that the rapid discharging of the input voltage is realized, the reliability of the switching power supply is improved, the circuit structure is simple, and the universality is strong.
Drawings
Fig. 1 is a schematic diagram of an input voltage fast discharging circuit in a switching power supply provided by the utility model.
Description of the embodiments
Embodiments of the circuit of the present utility model are described below in detail with reference to the accompanying drawings.
As shown in fig. 1 below, an input voltage rapid discharge circuit in a switching power supply includes an input voltage detection circuit 10, a digital signal processor, and a rapid discharge circuit 20, where R1 and R2 in the input voltage detection circuit are respectively a plurality of resistors connected in parallel, one end of R1 is connected to a positive end of the input voltage, the other end is connected in series with R2 and then connected to a negative end Vin-, of the input voltage, and a voltage division point a of R1 and R2 is connected to an input port of the digital signal processor for detecting the input voltage; the rapid discharging circuit comprises a first switching tube Q1 and a second switching tube Q2, the digital signal processor outputs a voltage signal to the grid electrode of the first switching tube Q1, one end of a third resistor R3 and one end of a first capacitor C1, the drain electrode of the first switching tube Q1 is connected with the grid electrode of the second switching tube Q2, one end of a fourth resistor R4, one end of a sixth resistor R6 and one end of a second capacitor C2, the drain electrode of the second switching tube Q2 is connected with the positive end vin+ of an input voltage after passing through a fifth resistor R5, the source electrode of the Q1, the source electrode of the Q2, the other ends of the R6 and the C2 are grounded, the other end of the R3 and the power supply end of the digital signal processor are connected with one stable voltage of 3.3V, the other end of the R4 is connected with one stable voltage of 15V, and the stable voltage of 3.3V and 15V is provided by the auxiliary power supply circuit of the switching power supply.
The supply voltage of the digital signal processor is 3.3V, so the voltage provided by the digital signal processor to the gate of the Q1 is not higher than 3.3V, the threshold voltage of the first switching tube Q1 is low enough, usually about 1V to 2V, so the Q1 needs to be selected as a low-voltage small MOS tube, for example, the rated voltage can be about 30V, the drain electrode of the second switching tube Q2 is connected with the input voltage, and the rated voltage is at least 1.2 times of the input voltage.
When the switching power supply works normally, namely the PWM signal output by the digital signal processor is normal, the digital signal processor outputs a high level to the first switching tubes Q1 and Q1 to be switched on, the grid voltage of the second switching tube Q2 is pulled down, and the second switching tube Q2 is switched off; when the digital signal processor does not output PWM signals, the voltage at the detection point A of the digital signal processor confirms that the input voltage is gradually reduced after a plurality of times of sampling and comparison, the input voltage is indicated to be powered off, at the moment, the digital signal processor outputs a low level to the first switching tube Q1, Q1 is turned off, the voltage of the grid electrode of the Q2 is raised, Q2 is turned on, the input voltage is rapidly pulled down, and rapid discharging of the input voltage is completed.
While particular implementations of the present utility model have been described above, it will be appreciated by those skilled in the art that these are merely illustrative, and that many changes and modifications may be made to these implementations without departing from the principles and spirit of the utility model. Accordingly, the scope of the utility model is defined by the appended claims.
Claims (3)
1. The input voltage quick discharge circuit in the switching power supply is characterized by comprising an input voltage detection circuit, a digital signal processor and a quick discharge circuit, wherein the input voltage detection circuit is formed by connecting a plurality of resistors in parallel and then in series, is connected with two ends of an input capacitor and the input voltage in a bridging way, is connected with one input port of the digital signal processor at a voltage dividing point and is used for detecting the input voltage, the digital signal processor outputs a voltage signal to the quick discharge circuit, and outputs a PWM signal to a power switch tube of the switching power supply;
The rapid discharging circuit comprises a first switching tube and a second switching tube, voltage signals output by the digital signal processor are supplied to a grid electrode of the first switching tube, the grid electrode of the first switching tube is further connected with one end of a third resistor and one end of a first capacitor, a drain electrode of the first switching tube is connected with the grid electrode of the second switching tube, one end of a fourth resistor, one end of a sixth resistor and one end of a second capacitor, a drain electrode of the second switching tube is connected with a positive end of input voltage through a fifth resistor, source electrodes of the first switching tube and the second switching tube are grounded, and the other ends of the first capacitor, the sixth resistor and the second capacitor are grounded.
2. The rapid discharge circuit of input voltage in a switching power supply according to claim 1, wherein the first and second switching transistors are N-type MOS transistors, the first switching transistor is a small MOS transistor with a rated voltage of about 30V, and the rated voltage of the second switching transistor is at least 1.2 times the input voltage.
3. The rapid discharging circuit of input voltage in a switching power supply according to claim 1, wherein the other end of the third resistor and the power supply end of the digital signal processor are connected with a stable voltage of 3.3V, the other end of the fourth resistor is connected with a stable voltage of 15V, and the stable voltage of 3.3V and the stable voltage of 15V are provided by the auxiliary power supply circuit of the switching power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323225454.2U CN221202362U (en) | 2023-11-29 | 2023-11-29 | Input voltage quick discharging circuit in switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323225454.2U CN221202362U (en) | 2023-11-29 | 2023-11-29 | Input voltage quick discharging circuit in switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN221202362U true CN221202362U (en) | 2024-06-21 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202323225454.2U Active CN221202362U (en) | 2023-11-29 | 2023-11-29 | Input voltage quick discharging circuit in switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN221202362U (en) |
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2023
- 2023-11-29 CN CN202323225454.2U patent/CN221202362U/en active Active
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