CN203813419U - Over-current protection circuit of switch power supply - Google Patents
Over-current protection circuit of switch power supply Download PDFInfo
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- CN203813419U CN203813419U CN201420120894.3U CN201420120894U CN203813419U CN 203813419 U CN203813419 U CN 203813419U CN 201420120894 U CN201420120894 U CN 201420120894U CN 203813419 U CN203813419 U CN 203813419U
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- 230000004224 protection Effects 0.000 title abstract description 13
- 238000007689 inspection Methods 0.000 claims description 17
- 230000003287 optical effect Effects 0.000 abstract 2
- 238000010586 diagram Methods 0.000 description 3
- 208000031361 Hiccup Diseases 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- IYRDVAUFQZOLSB-UHFFFAOYSA-N copper iron Chemical compound [Fe].[Cu] IYRDVAUFQZOLSB-UHFFFAOYSA-N 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
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Abstract
The utility model provides an over-current protection circuit of a switch power supply, the over-current protection circuit is arranged between an output terminal of the switch power supply and a switch control circuit, and over-current information is fed back to the switch control circuit via an optical coupler. The over-current protection circuit comprises a current-detecting resistor R31, a triode Q8, a voltage-dividing resistor R33, and a voltage-dividing resistor R32 connected in series in a switch power supply ground loop, a collector electrode of the triode Q8 is connected with an anode of the output terminal of the switch power supply via a light emitting diode U8A of the optical coupler U8, an emitter electrode of the triode Q8 is connected with a rear terminal of the current-detecting resistor R31, and a base electrode of the triode Q8 is respectively connected with the rear terminal and a front terminal of the current-detecting resistor R31 via the voltage-dividing resistor R32 and the voltage-dividing resistor R33. According to the over-current protection circuit, the structure is very simple, the quantity of employed components is small, and the cost is low.
Description
Technical field
The utility model relates to field of switch power, particularly a kind of current foldback circuit of Switching Power Supply.
Background technology
Along with the attention of the whole world to energy problem, the energy consumption issues of electronic product will be more and more outstanding, how reduce its stand-by power consumption, improve power supplying efficiency and become a problem anxious to be resolved.The shortcomings such as although traditional linear stabilized power supply circuit structure is simple, reliable operation, it exists efficiency low (only having 40%-50%), volume is large, copper iron consumption is large, and the high and adjusting range of working temperature is little.In order to raise the efficiency, people have developed switch-type stabilized power supply, and its efficiency can reach more than 85%, and voltage stabilized range is wide, in addition, also have the precision of voltage regulation high, do not use the features such as power transformer, be a kind of comparatively ideal stabilized voltage power supply.Just because of this, switch-type stabilized power supply has been widely used in various electronic equipments.
Be illustrated in figure 1 traditional reverse exciting switching voltage regulator basic circuit diagram, its structure comprises input rectifying filter circuit, transformer change-over circuit, ON-OFF control circuit, output rectifier and filter, voltage sample feedback circuit, current foldback circuit; Alternating current input power supplying passes through by after rectifier bridge DB1, again through by forming input direct voltage after capacitor C 3 filtering, then by limit, switching tube Q1 control transformer T1 source break-make, at the secondary output square wave of transformer T1, then produce VD by output rectifier and filter.The ON-OFF control circuit control that switching tube Q1 is made up of pwm signal generation chip U1 and peripheral circuit, steady in order to ensure output voltage, also need sampling to feed back to ON-OFF control circuit at DC output end.The control IC of ON-OFF control circuit is integrated circuit U1; integrated circuit U1 has 6 pins; it is respectively GND (ground connection) pin; FB (feedback) pin; OPP/Latch (protection is set) pin; CS (current detecting) pin, Vcc (power supply) pin, DRV (driving) pin.After utilizing the pressure reduction at inspection leakage resistance R31 two ends to be input to amplifier LM358 (U14A) 2 pin and 3 pin reference voltages to make comparisons, output low level plays overcurrent protection.Its operation principle: when in user side use procedure in product when output overloading; inspection leakage resistance R31 voltage raises; 2 pin that are connected to amplifier U14A by R33 are compared with 3 pin reference voltages; 2 pin voltages exceed 3 pin voltages; at this moment the 1 pin output low level of amplifier U14A, makes U6A conducting, makes the FB pin lower voltage of control chip U1 turn duty ratio down; make output voltage be reduced to zero and enter " having the hiccups " state, make circuit working in the time of overload and it is to protection.But this scheme complex circuit, cost is high, and product is lacked competitiveness, and is difficult to adapt to the demand in market.
Utility model content
The utility model is for overcoming over current protection circuit arrangement complex circuit in current Switching Power Supply, and cost is high, and product is lacked competitiveness, and is difficult to the deficiency of the demand that adapts to market, and a kind of current foldback circuit of with low cost, the simple switching circuit of circuit is provided.
The technical solution of the utility model is: a kind of current foldback circuit of Switching Power Supply is arranged between the output and ON-OFF control circuit of Switching Power Supply, adopt optocoupler to feed back to described ON-OFF control circuit by crossing stream information, comprise the inspection leakage resistance R31 being connected on Switching Power Supply earth-return, triode Q8, divider resistance R33, divider resistance R32;
The collector electrode of described triode Q8 connects the output head anode of described Switching Power Supply by the light-emitting diode U8A of described optocoupler U8, the emitter of described triode Q8 connects the rear end of described inspection leakage resistance R31, and the base stage of described triode Q8 connects respectively rear end and the front end of described inspection leakage resistance R31 by described divider resistance R32 and divider resistance R33.
This current foldback circuit structure is very simple, and the component number of employing is few and cost is low.
Below in conjunction with specific embodiment, the utility model is described in more detail.
Brief description of the drawings
Fig. 1 is switching power circuit schematic diagram in prior art.
Fig. 2 is the utility model switching power circuit schematic diagram.
Embodiment
Embodiment 1; the present embodiment is a kind of current foldback circuit that is used for feeding back electric power outputting current situation in Switching Power Supply; when Switching Power Supply load hour; it does not exert an influence to ON-OFF control circuit; in the time that the load of power supply is greater than the electric current of regulation, for protection switch power supply is not destroyed, carry a signal to ON-OFF control circuit; allow ON-OFF control circuit produce the PWM switch controlling signal of less pulse width signal, reduce power output.As shown in Figure 2; the circuit of the present embodiment is arranged in switching power circuit; Switching Power Supply is a kind of conventional Switching Power Supply, adopts after the current foldback circuit of the present embodiment, forms a kind of switching power circuit of current foldback circuit of renewable type; switching power circuit comprises input rectifying filter circuit; transformer change-over circuit, ON-OFF control circuit, output rectifier and filter; voltage sample feedback circuit, current foldback circuit.The ac power input end of input rectifying filter circuit is connected with input and electromagnetic interference suppression circuit, alternating current input power supplying passes through by after rectifier bridge DB1, again through by forming input direct voltage after capacitor C 3 filtering, then by limit, switching tube Q1 control transformer T1 source break-make, at the secondary output square wave of transformer T1, then produce VD by output rectifier and filter.ON-OFF control circuit output pwm signal control switch pipe Q1, by controlling the duty ratio of PWM, controls output power of power supply, and in the normal situation of output, ON-OFF control circuit output pwm signal does not have the impact of feedback signal.In the primary coil of control transformer T1, electric current can break; the output of output filter circuit connection transformer change-over circuit; voltage sample feedback circuit connects output rectifier and filter, the elementary output rectifier and filter that connects of current foldback circuit, the elementary integrated circuit U1 that connects.The control IC of ON-OFF control circuit is integrated circuit U1; integrated circuit U1 has 6 pins; it is respectively GND (ground connection) pin; FB (feedback) pin; OPP/Latch (protection is set) pin; CS (current detecting) pin, Vcc (power supply) pin, DRV (driving) pin.In the present embodiment, shown in current protecting circuit dotted line frame as shown in Figure 2: comprise the inspection leakage resistance R31 being connected on Switching Power Supply earth-return, triode Q8, divider resistance R33, divider resistance R32; The collector electrode of triode Q8 connects the output head anode of Switching Power Supply by the light-emitting diode U8A of optocoupler U8, the emitter of triode Q8 connects the rear end of inspection leakage resistance R31, and the base stage of triode Q8 connects respectively rear end and the front end of inspection leakage resistance R31 by divider resistance R32 and divider resistance R33.
Current foldback circuit feature in the present embodiment: inspection leakage resistance R31 is connected on earth-return, 1 pin (base stage) of triode Q8 is connected to inspection leakage resistance R31 front end by divider resistance R33, and be connected to inspection leakage resistance R31 rear end by divider resistance R32, here triode Q8 is NPN triode, 1 pin is transistor base, 2 pin are triode, 3 pin are triode), 2 pin (emitter) of triode Q8 are received inspection leakage resistance rear end, 3 pin (collector electrode) of triode Q8 connect the namely negative electrode of 2 pin of the light-emitting diode U6A in optocoupler, 1 pin of light-emitting diode U6A namely anode connects the positive pole of Switching Power Supply.
Operation principle: when in user side use procedure in product when output overloading, inspection leakage resistance R31 voltage raises, be delivered to triode Q8 base stage by divider resistance R33, at this moment the base voltage of triode Q8 raises and then makes triode Q8 conducting, then make light-emitting diode U8A conducting, 4 pin of the photosensitive end U8B of optocoupler and 3 pin conductings like this, make namely to feed back pin lower voltage as the FB pin of the integrated circuit U1 of the control IC of ON-OFF control circuit and close PWM, output voltage reduces to zero, at this moment examine leakage resistance R31 lower voltage, triode Q8 cut-off, light-emitting diode U8A cut-off in optocoupler, not luminous, 4 pin of the photosensitive end U8B of optocoupler and 3 not conductings of pin, the FB pin of integrated circuit U1 namely feeds back pin voltage not to be reduced, DRV produces pwm signal, product can restart, finally make the pattern that under overload condition, output enters hiccup protections, thereby arrive the function of overvoltage protection.Owing to needing only an inspection leakage resistance of 2 0805 Chip-Rs and a paster triode in the scheme of the present embodiment, cost is very low.
Claims (1)
1. the current foldback circuit of a Switching Power Supply, this current foldback circuit is arranged between the output and ON-OFF control circuit of Switching Power Supply, adopt optocoupler to feed back to described ON-OFF control circuit by crossing stream information, comprise the inspection leakage resistance R31 being connected on Switching Power Supply earth-return, it is characterized in that: also comprise triode Q8, divider resistance R33, divider resistance R32;
The collector electrode of described triode Q8 connects the output head anode of described Switching Power Supply by the light-emitting diode U8A of described optocoupler U8, the emitter of described triode Q8 connects the rear end of described inspection leakage resistance R31, and the base stage of described triode Q8 connects respectively rear end and the front end of described inspection leakage resistance R31 by described divider resistance R32 and divider resistance R33.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420120894.3U CN203813419U (en) | 2014-03-17 | 2014-03-17 | Over-current protection circuit of switch power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420120894.3U CN203813419U (en) | 2014-03-17 | 2014-03-17 | Over-current protection circuit of switch power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203813419U true CN203813419U (en) | 2014-09-03 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420120894.3U Expired - Fee Related CN203813419U (en) | 2014-03-17 | 2014-03-17 | Over-current protection circuit of switch power supply |
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| CN (1) | CN203813419U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108258656A (en) * | 2018-02-28 | 2018-07-06 | 厦门讯亨电子科技有限公司 | Switching Power Supply overloads delay protection circuit |
| CN110224611A (en) * | 2019-05-31 | 2019-09-10 | 深圳市奋勇光电有限公司 | A kind of completely isolated circuit |
| CN112014621A (en) * | 2020-08-03 | 2020-12-01 | 深圳创维－Rgb电子有限公司 | A current detection circuit, switching power supply and TV set |
| CN116169885A (en) * | 2023-03-20 | 2023-05-26 | 深圳市华杰电气技术有限公司 | A Wide Input Range Multi-coil Winding Switching Power Supply |
-
2014
- 2014-03-17 CN CN201420120894.3U patent/CN203813419U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108258656A (en) * | 2018-02-28 | 2018-07-06 | 厦门讯亨电子科技有限公司 | Switching Power Supply overloads delay protection circuit |
| CN110224611A (en) * | 2019-05-31 | 2019-09-10 | 深圳市奋勇光电有限公司 | A kind of completely isolated circuit |
| CN112014621A (en) * | 2020-08-03 | 2020-12-01 | 深圳创维－Rgb电子有限公司 | A current detection circuit, switching power supply and TV set |
| CN116169885A (en) * | 2023-03-20 | 2023-05-26 | 深圳市华杰电气技术有限公司 | A Wide Input Range Multi-coil Winding Switching Power Supply |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address |
Address after: 518000 Nanshan medical equipment Industrial Park, No. 1019, Nanshan Road, Nanshan District, Shenzhen, Guangdong Province, A211-A213 Patentee after: Shenzhen Hai Yun new energy Co.,Ltd. Address before: 518000 Nanshan District, Guangdong, South China Sea Road, No. 1019 Nanshan medical equipment Industrial Park, A408, B401-403, Patentee before: SHENZHEN LANDING TECHNOLOGY Co.,Ltd. |
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| CP03 | Change of name, title or address | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140903 |
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| CF01 | Termination of patent right due to non-payment of annual fee |