CN202737448U - Short-circuit protection circuit - Google Patents
Short-circuit protection circuit Download PDFInfo
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- CN202737448U CN202737448U CN 201220377259 CN201220377259U CN202737448U CN 202737448 U CN202737448 U CN 202737448U CN 201220377259 CN201220377259 CN 201220377259 CN 201220377259 U CN201220377259 U CN 201220377259U CN 202737448 U CN202737448 U CN 202737448U
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Abstract
The utility model relates to a short-circuit protection circuit which comprises a PWM control module, a sampling feedback module and a short circuit protection module. A first base pin of a first control pin of the PWM control module is connected with the output positive end of an optoelectronic coupler of the sampling feedback module and the negative input end of a comparator of the short circuit protection module respectively. The output end of the comparator is connected with the first control pin, and a closed loop feedback circuit is formed. Output signals of an error amplifier of the PWM control module are not influenced by an input voltage and a capacitive load; the value of a first capacitor can be freely set and the delay time of the circuit is adjusted, and thus the capacitive load capability of a power supply is controlled and the capacitive load capability within all input voltage ranges is improved. At the same time, the short-circuit protection circuit has a simple structure and only uses one way of the comparator in circuit connection to form the closed loop feedback circuit and the other way for power input undervoltage protection, with the above design, the level of integration is high and the size of the circuit is small; and the short-circuit protection circuit has a wide application prospect.
Description
Technical field
The utility model relates to a kind of switching power circuit, particularly a kind of short circuit overcurrent protective circuit of Switching Power Supply.
Background technology
Along with Switching Power Supply being widely used of each field, every profession and trade, the user is also more and more higher to its reliability requirement.This just requires Switching Power Supply under various abnormal conditions, can protect the safety of self and load equipment.In the various protections of Switching Power Supply, short-circuit protection conduct wherein most important protection is paid close attention to by people more.Switching Power Supply is when short circuit, and the electric current that flows through on main switch, the output rectifying tube constant power device can be very large, and the power device heating seriously even because temperature rise is too high damages; Output end voltage is very little, voltage or current feedback loop cisco unity malfunction.Therefore, the design of the short-circuit protection of Switching Power Supply is very important.
At present Switching Power Supply short-circuit protection circuit operation principle commonly used is: failing to be convened for lack of a quorum according to the peak electricity of input side power switch when the output short circuit becomes large this phenomenon; the peak current of direct-detection power switch; when peak current surpasses a certain thresholding; duty ratio is reduced; output voltage reduces, and supply power voltage is also along with reduction, when being lower than the cut-in voltage of control chip; whole circuit is closed, and realizes short-circuit protection.But this short-circuit protection has some obvious shortcomings: if when input voltage or load variations, the power during the protection action changes thereupon, can't accurately set its protection point, and the protection action is unreliable; When normal shock is used, larger with the relation of input voltage although boost voltage is also followed exporting change, also be difficult to parameter adjustment to a desirable numerical value, make it reach the over-current protection point of wanting.
The utility model content
The purpose of this utility model is to provide a kind of short circuit protecting circuit for switch power that output short-circuit is responded fast, guarantees at different input voltages, can both make reliable protection to Switching Power Supply under the different loads.
The technical scheme that its technical problem that solves the utility model adopts is:
A kind of short-circuit protection circuit; it is characterized in that comprising PWM control module, sampling feedback module, short circuit protection module; the first control chip first pin of described PWM control module is connected the comparator negative-phase input with the photoelectrical coupler output plus terminal of sampling feedback module respectively and is connected with short circuit protection module; the output of comparator is communicated with the first control chip, forms the closed loop feedback control circuit.
The negative-phase input of described comparator is connected with the negative electrode of the 3rd diode, the anode of the 3rd diode is connected with the 3rd resistance, the 4th resistance in parallel and the first electric capacity between the negative-phase input of comparator and the ground, the 3rd diode cathode and the 4th resistance in parallel be connected an end of electric capacity and be connected; Connect a forward the first diode between the normal phase input end of comparator and the output, the normal phase input end of comparator also is connected with the common point of the first resistance with the second resistance, the other end ground connection of the first resistance, the 8th pin of another termination the first control chip of the second resistance; Comparator output terminal is connected with the first pin of the first control chip by the second diode.
The output signal of PWM control module error amplifier of the present utility model is not subjected to input voltage and with the impact of capacitive load, the value of the first electric capacity can free setting, the delay time of regulating circuit, thereby the size of control power supply with capacitance load capability, not only improve the band capacitance load capability in the full input voltage range, but also had the little characteristics of short-circuit dissipation.The utility model line construction is simple simultaneously, and a road of a usage comparison device is used for circuit and is connected to form the closed loop feedback control circuit, and other one the tunnel is used for the protection of power supply input undervoltage, and the integrated design degree is high like this, and the circuit volume is little; Application prospect is extensive.
Description of drawings
Fig. 1 is circuit connection diagram of the present utility model.
Embodiment
The selection of the utility model circuit element: the first control chip U1 is UCC3800 among Fig. 1, and the model of photoelectrical coupler U3 is PS2703, and comparator U2 is LM393.The first diode D1, the second diode D2 and the 3rd diode D3 model are LL4148.
As shown in Figure 1; a kind of short-circuit protection circuit; comprise PWM control module, sampling feedback module, short circuit protection module; the first control chip U1 first pin of described PWM control module is connected comparator U2 negative-phase input with the photoelectrical coupler U3 output plus terminal of sampling feedback module respectively and is connected with short circuit protection module; the output of comparator U2 is communicated with the first control chip U1, forms the closed loop feedback control circuit.The negative-phase input of described comparator U2 is connected with the negative electrode of the 3rd diode D3, the anode of the 3rd diode D3 is connected with the 3rd resistance R 3, between the negative-phase input of comparator U2 and the ground the 4th resistance R 4 in parallel and the first capacitor C 1, the three diode D3 negative electrode and the 4th resistance R 4 in parallel be connected an end of capacitor C 1 and be connected; Meet a forward the first diode D1 between the normal phase input end of comparator U2 and the output, the normal phase input end of comparator U2 also is connected with the common point of the first resistance R 1 and the second resistance R 2, the other end ground connection of the first resistance R 1, the 8th pin of another termination first control chip U1 of the second resistance R 2; Comparator U2 output is connected with the first pin of the first control chip U1 by the second diode D2.
In the use when the Switching Power Supply short circuit, the output voltage of the error amplifier of pwm chip uprises, by the 3rd resistance R 3, make the 3rd diode D3 conducting, give the first capacitor C 1 charging, the reference voltage Vref 1(that charging voltage on the first capacitor C 1 is higher than positive input passes through the first resistance R 1 and the second resistance R 2 dividing potential drop gained by the reference voltage Vref of control chip U1), the output of comparator U2 becomes low level, this low level drags down the output voltage of the error amplifier of control chip U1 by reverse second a diode D2, and then the first control chip U1 quits work.Owing to the existence of the first diode D1, make the normal phase input end voltage step-down of comparator U2, to lock this state; When having no progeny in the Switching Power Supply pass, the first capacitor C 1 is by 4 discharges of the 4th resistance R, when the voltage on the first capacitor C 1 is lower than reference voltage Vref 1, the output of comparator U2 becomes high level, the second diode D2 turn-offs, thereby the rising of the output voltage of the error amplifier of control chip U1, pwm circuit is started working, and Switching Power Supply is recovered output.If this moment, output also was in short-circuit condition, the output voltage of the error amplifier of pwm chip uprises again, and behind comparator U2 and the second diode D2, the output voltage of the error amplifier of pwm chip drags down again, and Switching Power Supply is turn-offed again.As long as short-circuit conditions is not removed, Switching Power Supply just repeats the above-mentioned formula guard mode of having the hiccups.In addition, because the existence of the first electric capacity D1, after short trouble was eliminated, Switching Power Supply can from recovering, need not restart.
Claims (2)
1. short-circuit protection circuit; it is characterized in that comprising PWM control module, sampling feedback module, short circuit protection module; the first control chip (U1) first pin of described PWM control module is connected comparator (U2) negative-phase input with photoelectrical coupler (U3) output plus terminal of sampling feedback module respectively and is connected with short circuit protection module; the output of comparator (U2) is communicated with the first control chip (U1), forms the closed loop feedback control circuit.
2. a kind of short-circuit protection circuit according to claim 1, the negative-phase input that it is characterized in that described comparator (U2) is connected with the negative electrode of the 3rd diode (D3), the anode of the 3rd diode (D3) is connected with the 3rd resistance (R3), the 4th resistance in parallel (R4) and the first electric capacity (C1) between the negative-phase input of comparator (U2) and the ground, the 3rd diode (D3) negative electrode and the 4th resistance (R4) in parallel be connected an end of electric capacity (C1) and be connected; Connect a forward the first diode (D1) between the normal phase input end of comparator (U2) and the output, the normal phase input end of comparator (U2) also is connected with the common point of the first resistance (R1) with the second resistance (R2), the other end ground connection of the first resistance (R1), the 8th pin of another termination the first control chip (U1) of the second resistance (R2); Comparator (U2) output is connected with the first pin of the first control chip (U1) by the second diode (D2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220377259 CN202737448U (en) | 2012-08-01 | 2012-08-01 | Short-circuit protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220377259 CN202737448U (en) | 2012-08-01 | 2012-08-01 | Short-circuit protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202737448U true CN202737448U (en) | 2013-02-13 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220377259 Expired - Fee Related CN202737448U (en) | 2012-08-01 | 2012-08-01 | Short-circuit protection circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN202737448U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016090547A1 (en) * | 2014-12-09 | 2016-06-16 | 深圳市聚作照明股份有限公司 | Switch-mode power supply and short-circuit protection circuit thereof |
| CN107579554A (en) * | 2017-08-15 | 2018-01-12 | 张家港市华为电子有限公司 | A kind of circuit of charger charging |
| CN108809069A (en) * | 2018-07-30 | 2018-11-13 | 广州金升阳科技有限公司 | A kind of monocycle peak current limit circuit |
| CN108963964A (en) * | 2018-08-28 | 2018-12-07 | 浙江正泰电器股份有限公司 | The heat memory protection circuit of breaker controller |
-
2012
- 2012-08-01 CN CN 201220377259 patent/CN202737448U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016090547A1 (en) * | 2014-12-09 | 2016-06-16 | 深圳市聚作照明股份有限公司 | Switch-mode power supply and short-circuit protection circuit thereof |
| CN107579554A (en) * | 2017-08-15 | 2018-01-12 | 张家港市华为电子有限公司 | A kind of circuit of charger charging |
| CN108809069A (en) * | 2018-07-30 | 2018-11-13 | 广州金升阳科技有限公司 | A kind of monocycle peak current limit circuit |
| CN108809069B (en) * | 2018-07-30 | 2023-09-08 | 广州金升阳科技有限公司 | Single-period peak current limiting circuit |
| CN108963964A (en) * | 2018-08-28 | 2018-12-07 | 浙江正泰电器股份有限公司 | The heat memory protection circuit of breaker controller |
| CN108963964B (en) * | 2018-08-28 | 2024-05-14 | 浙江正泰电器股份有限公司 | Thermal memory protection circuit of circuit breaker controller |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130213 Termination date: 20170801 |
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| CF01 | Termination of patent right due to non-payment of annual fee |