CN112566343A - No-load protection circuit - Google Patents
No-load protection circuit Download PDFInfo
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- CN112566343A CN112566343A CN202011399644.4A CN202011399644A CN112566343A CN 112566343 A CN112566343 A CN 112566343A CN 202011399644 A CN202011399644 A CN 202011399644A CN 112566343 A CN112566343 A CN 112566343A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/20—Responsive to malfunctions or to light source life; for protection
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Abstract
The invention discloses a no-load protection circuit. The problem of no-load protection under the condition of not influencing the work of a power supply in the prior art is solved; the driving circuit comprises a driving chip U1 with a protection function, a voltage stabilizing module, a driving output module, a pull-up resistor, a pull-down resistor, a transformer and a triode QS 43; the output end of the driving chip is connected with a driving output module, and the driving output module comprises a primary side of a transformer; the secondary side of the transformer is connected with a base electrode of a triode QS43 through a voltage stabilizing module, a collector electrode of the triode QS43 is connected with a protection trigger end of a driving chip, an emitter electrode of the triode QS43 is connected with a first end of a pull-down resistor, and a second end of the pull-down resistor is connected with the secondary side of the transformer; the first end of the pull-up resistor is connected with the base electrode of the triode QS43, and the second end of the pull-up resistor is connected with the first end of the pull-down resistor. The circuit is used as a peripheral circuit of the driving chip, has a simple circuit structure, does not influence the working condition of a power supply when triggering protection, and is suitable for driving chips of different models.
Description
Technical Field
The invention relates to the field of protection circuits, in particular to a no-load protection circuit.
Background
When the circuit is unloaded, if the circuit is not protected, the voltage rises all the time and exceeds the withstand voltage value of components, such as an output diode, so that the circuit is damaged. With the improvement of the safety requirements of people on the power supply, the requirement that the power supply can be protected under the condition of no load is increasingly normalized, even if the lamp is an integrated lamp, the risk of no load exists, and the fact that the no-load protection function is added under the condition that the working condition of the power supply is not influenced is particularly important.
Most of the existing no-load protection circuits are coupled with a power supply circuit, and the start of no-load protection can influence the work of the power supply. For example, a publication No. CN211352541U of "an overcurrent no-load protection circuit, an emergency lamp device, and a lighting system" disclosed in chinese patent literature includes a plurality of overcurrent no-load protection branches and a control circuit having a plurality of control terminals, where each overcurrent no-load protection branch includes an LED operating circuit, a voltage detection module, a short-circuit detection module, and a short-circuit protection module, the voltage detection module detects an operating voltage of an LED, the short-circuit detection module outputs a corresponding detection signal according to the operating voltage, the short-circuit protection module receives the detection signal and outputs a corresponding preset voltage, the control circuit outputs a control signal according to the operating voltage and the detection signal, and the LED operating circuit operates according to the preset voltage and/or the control signal. The circuit can affect the working state of the power supply when no-load protection is carried out.
Disclosure of Invention
The invention mainly solves the problem that the prior art carries out no-load protection under the condition of not influencing the work of a power supply; the no-load protection circuit is used as a peripheral circuit of a driving chip, detects the change of output voltage to control the starting protection function of the driving chip, and does not influence the working condition of a power supply.
The technical problem of the invention is mainly solved by the following technical scheme:
the no-load protection circuit comprises a driving chip U1 with a protection function and a voltage stabilizing module, and the no-load protection circuit further comprises a pull-up resistor, a pull-down resistor, a transformer and an NPN triode QS 43; the output end of the driving chip U1 is connected with a driving output module, and the driving output module comprises a primary side L41A of a transformer; the secondary side L41C of the transformer is connected with a voltage stabilizing module, the output end of the voltage stabilizing module is connected with the base electrode of a triode QS43 through a mirror image input source, the collector electrode of the triode QS43 is connected with the protection trigger end of a driving chip U1, the emitter electrode of the triode QS43 is connected with the first end of a pull-down resistor, and the second end of the pull-down resistor is connected with the secondary side L41C of the transformer; a first end of the pull-up resistor is connected to the base of the transistor QS43, and a second end of the pull-up resistor is connected to a first end of the pull-down resistor.
When a load exists, the secondary side of the transformer outputs 3.3V to the base electrode of a triode QS43 through a voltage stabilizing module, the voltage of the emitter of the triode QS43, namely the connection part of a pull-up resistor and a pull-down resistor, is more than 1V, the triode QS43 is cut off, and the protection trigger end of a driving chip U1 flows constant current; when the circuit is in no-load state, the output voltage of the driving output module rises, the voltage and the negative current on the secondary side L41C winding coupled to the transformer rise, the voltage at the connection position of the pull-up resistor and the pull-down resistor drops to 0V, the triode QS43 is conducted, at the moment, the current on the protection trigger end of the driving chip U1 is reduced, the voltage drops, and meanwhile, the frequency is controlled to rise, so that the circuit enters a protection state. The circuit is used as a peripheral circuit of the driving chip, has a simple circuit structure, detects the change of the output voltage to control the starting protection function of the driving chip, and does not influence the working condition of the power supply.
Preferably, the mirror image input source comprises an NPN transistor QS41A and an NPN transistor QS 41B; the collector of the transistor QS41A is connected with the output end of the voltage stabilizing module, and the collector of the transistor QS41B is connected with the collector of the transistor QS 43; the base of the transistor QS41A is connected to the base of the transistor QS41B, the emitter of the transistor QS41A is connected to the emitter of the transistor QS41B, and the emitter of the transistor QS41A is connected to the emitter of the transistor QS 43. The mirror image source input is adopted to provide a stable small current, and in the scheme, the input voltage is 3.3V.
Preferably, the no-load protection circuit further includes a backflow prevention protection module, and the backflow prevention protection module is disposed between the transistor QS43 and the protection trigger terminal of the driver chip U1. The backflow prevention protection module prevents current in the circuit from flowing backwards into the driving chip U1, and protects normal operation of the driving chip U1.
Preferably, the backflow prevention protection module comprises an NPN transistor QS42B, a collector of the transistor QS42B is connected with a base of the transistor QS42B, a base of the transistor QS42B is connected with a protection trigger end of the driving chip U1, and an emitter of the transistor QS42B is connected with a collector of the transistor QS 43. And an NPN triode is used as a backflow prevention element to protect the normal operation of the driving chip.
Preferably, the backflow prevention protection module comprises an NPN transistor QS42A, a collector of the transistor QS42A is connected with a base of the transistor QS42A, a base of the transistor QS42A is grounded, and an emitter of the transistor QS42A is connected with a collector of the transistor QS 43. Transistor QS42A protects the line.
Preferably, the pull-up resistor comprises a resistor RS45A and a resistor RS45B which are connected in series, the pull-down resistor comprises a resistor RS46A and a resistor RS46B which are connected in parallel, a diode DS42 is arranged between the pull-down resistor and the secondary side L41C of the transformer, the anode of the diode DS42 is connected with the second end of the pull-down resistor, and the cathode of the diode DS42 is connected with the secondary side L41C of the transformer. The resistance values of the pull-up resistor and the pull-down resistor are changed to change the magnitude of the no-load voltage, so that the requirements of different no-load voltages are met.
The invention has the beneficial effects that:
1. the no-load protection circuit is used as a peripheral circuit of the driving chip, the circuit structure is simple, the output voltage change is detected to control the starting protection function of the driving chip, and the working condition of a power supply is not influenced.
2. And the mirror image source input is adopted, so that the input current is stable.
3. As a peripheral circuit of the driving chip, the driving circuit is suitable for various driving chips and has strong universality.
Drawings
Fig. 1 is a schematic connection diagram of a no-load protection circuit of the present invention.
Fig. 2 is a schematic circuit diagram of the regulator module of the present invention.
Fig. 3 is a schematic connection diagram of an exemplary circuit for driving an output module according to the present invention.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.
Example (b):
as shown in fig. 1 to 3, the no-load protection circuit of this embodiment includes a driving chip U1 with a protection function, a voltage stabilizing module, a driving output module, a pull-up resistor, a pull-down resistor, a transformer, a backflow prevention protection module, an NPN transistor QS43, an NPN transistor QS41A, and an NPN transistor QS 41B.
The backflow prevention protection module is arranged between the transistor QS43 and a protection trigger end of the driving chip U1. The backflow prevention protection module prevents current in the circuit from flowing backwards into the driving chip U1, and protects normal operation of the driving chip U1.
The driving chip U1 with protection function can perform protection action according to the signal of the protection trigger terminal. The model of the driver chip U1 may be ICL5101, ICL5102, TEA19161T, and the like, and in the present embodiment, the model of the driver chip U1 is UBA1313, and the protection trigger terminal is 5 pins.
The output end of the driving chip U1 is connected with a driving output module, and the driving output module comprises a primary side L41A of a transformer.
The secondary side L41C of the transformer outputs a stable 3.3V voltage through the voltage stabilizing module. The secondary side L41C of the transformer is flowing a negative current.
The pull-up resistor comprises a resistor RS45A and a resistor RS45B which are connected in series; the pull-down resistor comprises a resistor RS46A and a resistor RS46B which are connected in parallel, a diode DS42 is arranged between the pull-down resistor and the secondary side L41C of the transformer, the anode of the diode DS42 is connected with the second end of the pull-down resistor, and the cathode of the diode DS42 is connected with the secondary side L41C of the transformer. The two ends of the pull-up resistor are connected with the capacitor CS45 in parallel, the first end of the pull-up resistor is connected with the first end of the capacitor CS46, and the second end of the pull-down resistor is connected with the second end of the capacitor CS 46.
The resistance values of the pull-up resistor and the pull-down resistor are changed to change the magnitude of the no-load voltage, so that the requirements of different no-load voltages are met.
The output end of the voltage stabilizing module is connected with the base electrode of a triode QS43 through a resistor RS40, the collector electrode of the triode QS43 is connected with the protection trigger end of a driving chip U1, the emitter electrode of the triode QS43 is connected with the first end of a pull-down resistor, and the second end of the pull-down resistor is connected with the secondary side L41C of the transformer; a first end of the pull-up resistor is connected to the base of the transistor QS43, and a second end of the pull-up resistor is connected to a first end of the pull-down resistor.
A 0 ohm resistor RS42 is arranged between the connection position of the pull-up resistor and the pull-down resistor and the emitter of the transistor QS 43.
Transistor QS41A and transistor QS41B form mirror image input sources. The mirror source input is used to provide a stable small current, in this embodiment, the input voltage is 3.3V, and the RS40 resistance is 120K Ω.
The collector of the transistor QS41A is connected with the output end of the voltage stabilizing module through a resistor RS40, and the collector of the transistor QS41B is connected with the collector of the transistor QS 43; the base of the transistor QS41A is connected to the base of the transistor QS41B, the emitter of the transistor QS41A is connected to the emitter of the transistor QS41B, and the emitter of the transistor QS41A is connected to the emitter of the transistor QS 43.
An emitter of the transistor QS41B is connected with an anode of a diode DS41, a first end of a resistor RS41 and a first end of a capacitor CS41 respectively, and a cathode of the diode DS41, a second end of a resistor RS41 and a second end of a capacitor CS41 are connected with an emitter of a transistor QS41 respectively. A capacitor CS42 is provided between the emitter of the transistor QS41A and the emitter of the transistor QS 43. The second terminal of the pull-down resistor is connected to the first terminal of the capacitor CS41 through the capacitor CS43B and the capacitor CS43A connected in series.
The backflow prevention protection module comprises an NPN triode QS42B and an NPN triode QS 42A.
The collector of the transistor QS42A is connected to the base of the transistor QS42A, the base of the transistor QS42A is grounded, and the emitter of the transistor QS42A is connected to the collector of the transistor QS 43. The collector of the transistor QS42B is connected to the base of the transistor QS42B, the base of the transistor QS42B is connected to the protection trigger terminal of the driver chip U1, and the emitter of the transistor QS42B is connected to the collector of the transistor QS 43.
The transistor QS42A protects the circuit, and the transistor QS42B is used as a backflow prevention element to protect the normal operation of the driving chip.
When a load exists, the secondary side of the transformer provides a stable small current to the base of the transistor QS43 through the voltage stabilizing module and the mirror image input source, in this embodiment, the input voltage is 3.3V, the resistance of the RS40 is 120K Ω, the voltage at the resistance RS42 is greater than 1V, the voltage on the pull-down resistor is a negative value, the current on the secondary side L41C winding of the transformer is a negative current, at this time, the transistor QS43 is cut off, a constant current flows to the protection trigger end of the driving chip U1, and the output full load voltage is about 95V.
When the circuit is in no-load state, the output voltage of the driving output module rises, the voltage and the negative current on the secondary side L41C winding coupled to the transformer rise, the voltage at the connection position of the pull-up resistor and the pull-down resistor drops to 0V, the triode QS43 is conducted, at the moment, the current on the protection trigger end of the driving chip U1 is reduced, the voltage drops, and meanwhile, the frequency is controlled to rise, so that the circuit enters a protection state.
The circuit is used as a peripheral circuit of the driving chip, has a simple circuit structure, detects the change of the output voltage to control the starting protection function of the driving chip, and does not influence the working condition of the power supply. Can be adapted to different driving chips.
It should be understood that the examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Claims (6)
1. A no-load protection circuit comprises a driving chip U1 with a protection function and a voltage stabilizing module, and is characterized in that the no-load protection circuit further comprises a pull-up resistor, a pull-down resistor, a transformer and an NPN triode QS 43; the output end of the driving chip U1 is connected with a driving output module, and the driving output module comprises a primary side L41A of a transformer; the secondary side L41C of the transformer is connected with a voltage stabilizing module, the output end of the voltage stabilizing module is connected with the base electrode of a triode QS43 through a mirror image input source, the collector electrode of the triode QS43 is connected with the protection trigger end of a driving chip U1, the emitter electrode of the triode QS43 is connected with the first end of a pull-down resistor, and the second end of the pull-down resistor is connected with the secondary side L41C of the transformer; a first end of the pull-up resistor is connected to the base of the transistor QS43, and a second end of the pull-up resistor is connected to a first end of the pull-down resistor.
2. The no-load protection circuit of claim 1, wherein said mirror input sources comprise an NPN transistor QS41A and an NPN transistor QS 41B; the collector of the transistor QS41A is connected with the output end of the voltage stabilizing module, and the collector of the transistor QS41B is connected with the collector of the transistor QS 43; the base of the transistor QS41A is connected to the base of the transistor QS41B, the emitter of the transistor QS41A is connected to the emitter of the transistor QS41B, and the emitter of the transistor QS41A is connected to the emitter of the transistor QS 43.
3. The no-load protection circuit according to claim 1 or 2, further comprising a backflow prevention protection module, wherein the backflow prevention protection module is disposed between the transistor QS43 and the protection trigger terminal of the driver chip U1.
4. The no-load protection circuit of claim 3, wherein the anti-backflow protection module comprises an NPN transistor QS42B, a collector of the transistor QS42B is connected to a base of the transistor QS42B, a base of the transistor QS42B is connected to the protection trigger terminal of the driver chip U1, and an emitter of the transistor QS42B is connected to a collector of the transistor QS 43.
5. An empty load protection circuit according to claim 3 or 4, wherein said anti-backflow protection module comprises an NPN transistor QS42A, the collector of transistor QS42A is connected to the base of transistor QS42A, the base of transistor QS42A is grounded, and the emitter of transistor QS42A is connected to the collector of transistor QS 43.
6. The no-load protection circuit of claim 1, wherein the pull-up resistor comprises a resistor RS45A and a resistor RS45B connected in series, the pull-down resistor comprises a resistor RS46A and a resistor RS46B connected in parallel, a diode DS42 is arranged between the pull-down resistor and the secondary side L41C of the transformer, an anode of the diode DS42 is connected to the second end of the pull-down resistor, and a cathode of the diode DS42 is connected to the secondary side L41C of the transformer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011399644.4A CN112566343B (en) | 2020-12-02 | 2020-12-02 | No-load protection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011399644.4A CN112566343B (en) | 2020-12-02 | 2020-12-02 | No-load protection circuit |
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| CN112566343A true CN112566343A (en) | 2021-03-26 |
| CN112566343B CN112566343B (en) | 2023-02-17 |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203787935U (en) * | 2014-04-09 | 2014-08-20 | 太原科技大学 | Over-current protection circuit based on high side current detection |
| CN206452321U (en) * | 2017-01-17 | 2017-08-29 | 深圳市瑞必达科技有限公司 | A kind of low voltage start circuit |
| CN109287025A (en) * | 2018-05-14 | 2019-01-29 | 惠州市西顿工业发展有限公司 | It is a kind of to can inhibit the excessively high LED drive circuit of floating voltage |
| CN110879627A (en) * | 2019-12-23 | 2020-03-13 | 中国电子科技集团公司第四十九研究所 | Topological structure of band-gap reference voltage with current output capability |
| CN210867178U (en) * | 2019-10-12 | 2020-06-26 | 浙江凯耀照明有限责任公司 | Driver short-circuit protection circuit |
| CN214506546U (en) * | 2020-12-02 | 2021-10-26 | 浙江凯耀照明有限责任公司 | No-load protection circuit |
-
2020
- 2020-12-02 CN CN202011399644.4A patent/CN112566343B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203787935U (en) * | 2014-04-09 | 2014-08-20 | 太原科技大学 | Over-current protection circuit based on high side current detection |
| CN206452321U (en) * | 2017-01-17 | 2017-08-29 | 深圳市瑞必达科技有限公司 | A kind of low voltage start circuit |
| CN109287025A (en) * | 2018-05-14 | 2019-01-29 | 惠州市西顿工业发展有限公司 | It is a kind of to can inhibit the excessively high LED drive circuit of floating voltage |
| CN210867178U (en) * | 2019-10-12 | 2020-06-26 | 浙江凯耀照明有限责任公司 | Driver short-circuit protection circuit |
| CN110879627A (en) * | 2019-12-23 | 2020-03-13 | 中国电子科技集团公司第四十九研究所 | Topological structure of band-gap reference voltage with current output capability |
| CN214506546U (en) * | 2020-12-02 | 2021-10-26 | 浙江凯耀照明有限责任公司 | No-load protection circuit |
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| CN112566343B (en) | 2023-02-17 |
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