CN220368603U - Output discharging circuit of switching power supply - Google Patents
Output discharging circuit of switching power supply Download PDFInfo
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- CN220368603U CN220368603U CN202321774735.0U CN202321774735U CN220368603U CN 220368603 U CN220368603 U CN 220368603U CN 202321774735 U CN202321774735 U CN 202321774735U CN 220368603 U CN220368603 U CN 220368603U
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- 238000007599 discharging Methods 0.000 title claims description 16
- 238000002955 isolation Methods 0.000 claims abstract description 55
- 230000000087 stabilizing effect Effects 0.000 claims abstract description 26
- 238000004804 winding Methods 0.000 claims abstract description 12
- 239000003990 capacitor Substances 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 abstract description 4
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
Abstract
The utility model discloses an output discharge circuit of a switching power supply, which comprises a voltage stabilizing circuit, an optical coupler isolation circuit, an electronic switching circuit and a discharge circuit, wherein the voltage stabilizing circuit is connected with the optical coupler isolation circuit; the input end of the voltage stabilizing circuit is connected with an auxiliary winding of a transformer T502 of the switching power supply, the output end of the voltage stabilizing circuit is connected with the input positive electrode of the optocoupler isolation circuit, the input negative electrode of the optocoupler isolation circuit is connected with the primary ground of the switching power supply, the output positive electrode of the optocoupler isolation circuit and the control end of the electronic switching circuit are connected with the output end of the switching power supply through the pull-up circuit, the output negative electrode of the optocoupler isolation circuit and the output end of the electronic switching circuit are connected with the secondary ground of the switching power supply, and the input end of the electronic switching circuit is connected with the output end of the switching power supply through the discharge circuit. The utility model can enable the switching power supply to discharge rapidly when the switching power supply is powered off, and meanwhile, the efficiency of the switching power supply is not affected.
Description
Technical Field
The utility model relates to the field of power supply of electronic equipment, in particular to an output discharge circuit of a switching power supply.
Background
The functions of the current electronic devices are more and more, the functional modules of the main board of the electronic device are more and more, and the power supply types of the functional modules are more and more, so that the power-on and power-off time sequence of each functional module is important, especially in some operations (such as quick power-off and the like), if the time sequence is improper, the phenomenon of dead halt is caused, and when the voltage sag occurs due to the fluctuation of a power grid, the electronic device may not work normally or cannot be restarted automatically for recovery and the like.
The capacity of the output filter electrolytic capacitor of the switching power supply used for supplying power to each functional module of the existing electronic is very large (generally thousands uF), thus the switching power supply discharges slowly when the power is off, and the time sequence disorder of each functional module is easy to occur when the power is on or off.
In view of the above, there is a need to develop an output discharge circuit of a switching power supply, which can rapidly discharge the switching power supply when the switching power supply is powered off, without affecting the efficiency of the switching power supply.
Disclosure of Invention
The utility model aims to provide an output discharging circuit of a switching power supply, which can enable the switching power supply to discharge rapidly when the switching power supply is powered off and can not influence the efficiency of the switching power supply.
In order to achieve the above object, the solution of the present utility model is:
an output discharge circuit of a switching power supply comprises a voltage stabilizing circuit, an optical coupling isolation circuit, an electronic switching circuit and a discharge circuit; the input end of the voltage stabilizing circuit is connected with an auxiliary winding of a transformer T502 of the switching power supply, the output end of the voltage stabilizing circuit is connected with the input positive electrode of the optocoupler isolation circuit, the input negative electrode of the optocoupler isolation circuit is connected with the primary ground of the switching power supply, the output positive electrode of the optocoupler isolation circuit and the control end of the electronic switching circuit are connected with the output end of the switching power supply through a pull-up circuit, the output negative electrode of the optocoupler isolation circuit and the output end of the electronic switching circuit are connected with the secondary ground of the switching power supply, and the input end of the electronic switching circuit is connected with the output end of the switching power supply through a discharge circuit; when the switching power supply works normally, the auxiliary winding of the transformer T502 supplies power to the input positive electrode of the optocoupler isolation circuit through the voltage stabilizing circuit, so that the output positive electrode and the output negative electrode of the optocoupler isolation circuit are conducted, and the control end level of the electronic switching circuit is pulled down to turn off the electronic switching circuit, so that the discharging circuit does not work; when the switching power supply is powered off, the auxiliary winding of the transformer T502 is powered off to power off the input positive electrode of the optocoupler isolation circuit, so that the output positive electrode and the output negative electrode of the optocoupler isolation circuit are turned off, the control end level of the electronic switching circuit is pulled up to conduct the electronic switching circuit, and the discharging circuit works to enable the output end of the switching power supply to discharge rapidly.
The voltage stabilizing circuit comprises a diode D556, a resistor R799 and a capacitor C733, wherein the positive electrode of the diode D556 is connected with the output end of the voltage stabilizing circuit, the negative electrode of the diode D556 is connected with the first end of the resistor R799, the second end of the resistor R799 and the first end of the capacitor C733 are connected with the output end of the voltage stabilizing circuit, and the second end of the capacitor C733 is connected with the primary ground of the switching power supply.
The optocoupler isolation circuit comprises a resistor R797, a resistor R798 and an optocoupler TD1018, wherein a first end of the resistor R798 is connected with an input positive electrode of the optocoupler isolation circuit, a second end of the resistor R798 and a first end of the resistor R797 are connected with an input positive electrode of the optocoupler TD1018, a second end of the resistor R797 and an input negative electrode of the optocoupler TD1018 are connected with an input negative electrode of the optocoupler isolation circuit, an output positive electrode of the optocoupler TD1018 is connected with an output positive electrode of the optocoupler isolation circuit, and an output negative electrode of the optocoupler TD1018 is connected with an output negative electrode of the optocoupler isolation circuit.
The pull-up circuit includes a resistor R796.
The electronic switching circuit comprises a MOS tube V708, and a grid electrode, a drain electrode and a source electrode of the MOS tube V708 are respectively connected with a control end, an input end and an output end of the electronic switching circuit.
The discharge circuit includes a resistor R793, a resistor R794, and a resistor R795 connected in parallel.
After the scheme is adopted, when the switching power supply works normally, the auxiliary winding of the transformer T502 supplies power to the input positive electrode of the optocoupler isolation circuit through the voltage stabilizing circuit, so that the output positive electrode and the output negative electrode of the optocoupler isolation circuit are conducted, the control end level of the electronic switching circuit is pulled down to turn off the electronic switching circuit, the discharging circuit does not work, and the discharging circuit does not work and has no loss at the moment, so that the efficiency of the switching power supply cannot be reduced; when the switching power supply is powered off, the auxiliary winding of the transformer T502 is powered off to power off the input positive electrode of the optocoupler isolation circuit, the output positive electrode and the output negative electrode of the optocoupler isolation circuit are turned off, the control end level of the electronic switching circuit is pulled up to enable the electronic switching circuit to be conducted, and accordingly the discharging circuit works to enable the output end of the switching power supply to discharge rapidly.
Therefore, the output discharging circuit of the switching power supply can enable the switching power supply to discharge rapidly when the switching power supply is powered off, and meanwhile the efficiency of the switching power supply is not affected.
Drawings
Fig. 1 is a schematic circuit diagram of the present utility model.
FIG. 2 is a schematic representation of the use of the present utility model.
Detailed Description
In order to further explain the technical scheme of the utility model, the utility model is explained in detail by specific examples.
As shown in fig. 1 and 2, the present utility model discloses an output discharge circuit of a switching power supply, which includes a voltage stabilizing circuit, an optocoupler isolation circuit, an electronic switching circuit and a discharge circuit; the input end of the voltage stabilizing circuit is connected with an auxiliary winding of a transformer T502 of the switching power supply, the output end of the voltage stabilizing circuit is connected with the input positive electrode of the optocoupler isolation circuit, the input negative electrode of the optocoupler isolation circuit is connected with the primary ground of the switching power supply, the output positive electrode of the optocoupler isolation circuit and the control end of the electronic switching circuit are connected with the output end of the switching power supply through the pull-up circuit, the output negative electrode of the optocoupler isolation circuit and the output end of the electronic switching circuit are connected with the secondary ground of the switching power supply, and the input end of the electronic switching circuit is connected with the output end of the switching power supply through the discharge circuit.
When the switching power supply works normally, the auxiliary winding of the transformer T502 supplies power to the input positive electrode of the optocoupler isolation circuit through the voltage stabilizing circuit, so that the output positive electrode and the output negative electrode of the optocoupler isolation circuit are conducted, the control end level of the electronic switching circuit is pulled down to turn off the electronic switching circuit, the discharging circuit does not work, and the discharging circuit does not work and has no loss at the moment, so that the efficiency of the switching power supply is not reduced; when the switching power supply is powered off, the auxiliary winding of the transformer T502 is powered off to power off the input positive electrode of the optocoupler isolation circuit, the output positive electrode and the output negative electrode of the optocoupler isolation circuit are turned off, the control end level of the electronic switching circuit is pulled up to enable the electronic switching circuit to be conducted, and accordingly the discharging circuit works to enable the output end of the switching power supply to discharge rapidly. The output discharging circuit of the switching power supply can enable the switching power supply to discharge rapidly when the switching power supply is powered off, and meanwhile the efficiency of the switching power supply is not affected.
In an embodiment of the present utility model, the voltage stabilizing circuit includes a diode D556, a resistor R799 and a capacitor C733, where a positive electrode of the diode D556 is connected to an output terminal of the voltage stabilizing circuit, a negative electrode of the diode D556 is connected to a first terminal of the resistor R799, a second terminal of the resistor R799 and a first terminal of the capacitor C733 are connected to an output terminal of the voltage stabilizing circuit, and a second terminal of the capacitor C733 is connected to a primary ground of the switching power supply; the resistor R799 and the capacitor C733 form an RC circuit to convert alternating current into direct current to supply power to the input positive electrode of the optocoupler isolation circuit, and the diode D556 can prevent the optocoupler circuit from being damaged due to reverse voltage.
In an embodiment of the present utility model, the optocoupler isolation circuit includes a resistor R797, a resistor R798, and an optocoupler TD1018, where a first end of the resistor R798 is connected to an input positive electrode of the optocoupler isolation circuit, a second end of the resistor R798 and a first end of the resistor R797 are connected to an input positive electrode of the optocoupler TD1018, a second end of the resistor R797 and an input negative electrode of the optocoupler TD1018 are connected to an input negative electrode of the optocoupler isolation circuit, an output positive electrode of the optocoupler TD1018 is connected to an output positive electrode of the optocoupler isolation circuit, and an output negative electrode of the optocoupler TD1018 is connected to an output negative electrode of the optocoupler isolation circuit. The optocoupler isolation circuit mainly plays a role in isolating primary and secondary of the switching power supply, so that interference is prevented.
In the embodiment of the utility model, the pull-up circuit comprises a resistor R796, and the pull-up circuit is arranged so that the on-off energy between the output positive electrode and the output negative electrode of the optical coupler isolation circuit influences the control end level of the electronic switch circuit.
In the embodiment of the utility model, the electronic switching circuit comprises a MOS tube V708, and a grid electrode, a drain electrode and a source electrode of the MOS tube V708 are respectively connected with a control end, an input end and an output end of the electronic switching circuit. When the switching power supply is powered off, the MOS tube V708 enables the discharge circuit to work and discharge, and when the Vgs voltage of the MOS tube V708 reaches the pinch-off voltage, the discharge is stopped, the pinch-off voltage of the MOS tube V708 needs to meet the discharge voltage requirement lower than the switching power supply, for example, the output voltage of the switching power supply is required to be rapidly discharged from 12V to below 5V, and then the pinch-off voltage of the MOS tube V708 needs to be below 5V.
In an embodiment of the present utility model, the discharging circuit includes a resistor R793, a resistor R794 and a resistor R795 connected in parallel, and resistance values of the resistor R793, the resistor R794 and the resistor R795 may be calculated according to time required by actual time sequence and output electrolytic capacity, specifically according to V t =V 0 *e （-t/RC） Performing calculation, wherein V 0 Is the rated output voltage of the switching power supply. Vt is the pinch-off voltage of MOS tube V708, t is the required discharge time, C is the output electrolytic capacity, and R is the total resistance of resistor R793, resistor R794 and resistor R795.
The above examples and drawings are not intended to limit the form or form of the present utility model, and any suitable variations or modifications thereof by those skilled in the art should be construed as not departing from the scope of the present utility model.
Claims (6)
1. An output discharge circuit of a switching power supply is characterized in that: the circuit comprises a voltage stabilizing circuit, an optocoupler isolation circuit, an electronic switch circuit and a discharge circuit;
the input end of the voltage stabilizing circuit is connected with an auxiliary winding of a transformer T502 of the switching power supply, the output end of the voltage stabilizing circuit is connected with the input positive electrode of the optocoupler isolation circuit, the input negative electrode of the optocoupler isolation circuit is connected with the primary ground of the switching power supply, the output positive electrode of the optocoupler isolation circuit and the control end of the electronic switching circuit are connected with the output end of the switching power supply through a pull-up circuit, the output negative electrode of the optocoupler isolation circuit and the output end of the electronic switching circuit are connected with the secondary ground of the switching power supply, and the input end of the electronic switching circuit is connected with the output end of the switching power supply through a discharge circuit;
when the switching power supply works normally, the auxiliary winding of the transformer T502 supplies power to the input positive electrode of the optocoupler isolation circuit through the voltage stabilizing circuit, so that the output positive electrode and the output negative electrode of the optocoupler isolation circuit are conducted, and the control end level of the electronic switching circuit is pulled down to turn off the electronic switching circuit, so that the discharging circuit does not work;
when the switching power supply is powered off, the auxiliary winding of the transformer T502 is powered off to power off the input positive electrode of the optocoupler isolation circuit, so that the output positive electrode and the output negative electrode of the optocoupler isolation circuit are turned off, the control end level of the electronic switching circuit is pulled up to conduct the electronic switching circuit, and the discharging circuit works to enable the output end of the switching power supply to discharge rapidly.
2. An output discharge circuit of a switching power supply as claimed in claim 1, wherein: the voltage stabilizing circuit comprises a diode D556, a resistor R799 and a capacitor C733, wherein the positive electrode of the diode D556 is connected with the output end of the voltage stabilizing circuit, the negative electrode of the diode D556 is connected with the first end of the resistor R799, the second end of the resistor R799 and the first end of the capacitor C733 are connected with the output end of the voltage stabilizing circuit, and the second end of the capacitor C733 is connected with the primary ground of the switching power supply.
3. An output discharge circuit of a switching power supply as claimed in claim 1, wherein: the optocoupler isolation circuit comprises a resistor R797, a resistor R798 and an optocoupler TD1018, wherein a first end of the resistor R798 is connected with an input positive electrode of the optocoupler isolation circuit, a second end of the resistor R798 and a first end of the resistor R797 are connected with an input positive electrode of the optocoupler TD1018, a second end of the resistor R797 and an input negative electrode of the optocoupler TD1018 are connected with an input negative electrode of the optocoupler isolation circuit, an output positive electrode of the optocoupler TD1018 is connected with an output positive electrode of the optocoupler isolation circuit, and an output negative electrode of the optocoupler TD1018 is connected with an output negative electrode of the optocoupler isolation circuit.
4. An output discharge circuit of a switching power supply as claimed in claim 1, wherein: the pull-up circuit includes a resistor R796.
5. An output discharge circuit of a switching power supply as claimed in claim 1, wherein: the electronic switching circuit comprises a MOS tube V708, and a grid electrode, a drain electrode and a source electrode of the MOS tube V708 are respectively connected with a control end, an input end and an output end of the electronic switching circuit.
6. An output discharge circuit of a switching power supply as claimed in claim 1, wherein: the discharge circuit includes a resistor R793, a resistor R794, and a resistor R795 connected in parallel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321774735.0U CN220368603U (en) | 2023-07-07 | 2023-07-07 | Output discharging circuit of switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321774735.0U CN220368603U (en) | 2023-07-07 | 2023-07-07 | Output discharging circuit of switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220368603U true CN220368603U (en) | 2024-01-19 |
Family
ID=89513840
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202321774735.0U Active CN220368603U (en) | 2023-07-07 | 2023-07-07 | Output discharging circuit of switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220368603U (en) |
-
2023
- 2023-07-07 CN CN202321774735.0U patent/CN220368603U/en active Active
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