CN202363870U - Over-current protection circuit, power supply circuit and power supply - Google Patents
Over-current protection circuit, power supply circuit and power supply Download PDFInfo
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- CN202363870U CN202363870U CN2011204513696U CN201120451369U CN202363870U CN 202363870 U CN202363870 U CN 202363870U CN 2011204513696 U CN2011204513696 U CN 2011204513696U CN 201120451369 U CN201120451369 U CN 201120451369U CN 202363870 U CN202363870 U CN 202363870U
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Abstract
The utility model is suitable for the field of power supplies, and provides an over-current protection circuit, a power supply circuit and a power supply. The over-current protection circuit comprises an over-current delay unit, a protection maintaining unit and a reset unit, wherein an input end of the over-current delay unit is connected with an output end of a power supply output sampling circuit; a reference end of the over-current delay unit is connected with an external reference signal output end; an input end of the protection maintaining unit is connected with an output end of the over-current delay unit, and an output end of the protection maintaining unit is connected with a control end of a power supply pulse width control circuit; and an input end of the reset unit is connected with a turn-off control end of the protection maintaining unit, and an output end of the reset unit is connected with a reset end of the over-current delay unit. According to the embodiment of the utility model, through over-current detection, the power supply is under delay protection when the power supply is instantaneously over-current so as to avoid misoperation, the power supply is under turn-off protection during continuous over-current caused by abnormal load and the like, and the power supply is automatically turned on to work after the protection maintenance time, so that the power supply is comprehensively protected from being damaged.
Description
Technical field
The utility model belongs to field of power supplies, relates in particular to a kind of current foldback circuit, power circuit and power supply.
Background technology
Along with the develop rapidly of power electronic technology, power electronic equipment becomes more and more inseparable with people's work, life relation, and electronic equipment all be unable to do without reliable power supply; Especially at present Switching Power Supply has entered into various electronics, electric equipment field, and still, existing Switching Power Supply is in the process of using; Because the guard time of existing current foldback circuit is too short, perhaps Switching Power Supply is started shooting under capacitive load, produces impulse current sometimes; Cause power supply to produce misoperation, and, take place when unusual in output loading; Also can make power supply surpass rated power work; Cause power supply internal components and relevant device thereof to be damaged, reduce power supply useful life, also can cause security incidents such as fire, blast when serious.
The utility model content
The purpose of the utility model embodiment is to provide a kind of current foldback circuit, is intended to solve existing current foldback circuit can't carry out delay protection when the power supply overcurrent problem.
The utility model embodiment is achieved in that a kind of current foldback circuit, is connected between power supply output sampling circuit and the power supply pulse width control circuit, comprising:
Sampled signal to said power supply output sampling circuit output carries out over-current detection; When said sampled signal overcurrent; Carry out delay protection and handle, and when said sampled signal continues overcurrent, the overcurrent delay cell of output overcurrent protection control signal; The input of said overcurrent delay cell is connected with the output of said power supply output sampling circuit, and the reference edge of said overcurrent delay cell is connected with the external reference signal output;
After receiving said overcurrent protection control signal; In preset guard time, export cut-off signals; The unit is kept in protection with the protection power supply; The input that the unit is kept in said protection is connected with the output of said overcurrent delay cell, and the output that the unit is kept in said protection is connected with the control end of said power supply pulse width control circuit;
After receiving said shutoff control signal, power on; The reset unit that said overcurrent delay cell is resetted; The input of said reset unit is connected with the shutoff control end that the unit is kept in said protection, and the output of said reset unit is connected with the reset terminal of said overcurrent delay cell.
Further, said overcurrent delay cell comprises:
Said sampled signal is amplified, and the signal amplification module of sampled signal is amplified in output, and the input of said signal amplification module is the input of said overcurrent delay cell;
Said amplification sampled signal is carried out dividing potential drop, the division module of output dividing potential drop sampled signal, the input of said division module is connected with the output of said overcurrent delay cell;
Said dividing potential drop sampled signal and reference signal are compared; Carry out over-current detection; When said dividing potential drop sampled signal during greater than said reference signal, detecting said sampled signal is overcurrent, the comparison module of output overcurrent detection signal; The positive input of said comparison module is connected with the output of said division module, and the reverse input end of said comparison module is the reference edge of said overcurrent delay cell;
When receiving said over-current detection signal; Carrying out delay protection handles; And when continuing to receive said over-current detection signal, the delay protection module of output overcurrent protection control signal, the input of said delay protection module is connected with the output of said comparison module; The output of said delay protection module is the output of said overcurrent delay cell, and the reset terminal of said delay protection module is the reset terminal of said overcurrent delay cell.
Further, said signal amplification module comprises:
First operational amplifier, resistance R 1, resistance R 2, resistance R 3, resistance R 5 and capacitor C 1;
One end of said resistance R 1 is that the input of said signal amplification module is connected with an end of said resistance R 3; The other end ground connection of said resistance R 1; The other end of said resistance R 3 is connected with the reverse input end of said first operational amplifier; The positive input of said first operational amplifier is connected with an end of said resistance R 2; The other end ground connection of said resistance R 2, said capacitor C 1 and said resistance R 5 are parallel between the output of reverse input end and said first operational amplifier of said first operational amplifier, and the output of said first operational amplifier is the output of said signal amplification module.
Further, said division module comprises:
Resistance R 4, resistance R 6, resistance R 7, resistance R 8 and capacitor C 2;
One end of said resistance R 7 is the input of said division module; The other end of said resistance R 7 is connected with an end of said resistance R 8 and an end of said capacitor C 2 simultaneously; The other end ground connection of the other end of said resistance R 8 and said capacitor C 2; The other end of said resistance R 7 also is connected with an end of said resistance R 6; The other end of said resistance R 6 is connected with an end of said resistance R 4, the other end ground connection of said resistance R 4, and said resistance R 6 is the output of said division module with the common port of said resistance R 4.
Further, said comparison module comprises:
Resistance R 14, resistance R 15 and first comparator;
The positive input of said first comparator is that the positive input of said comparison module is connected with an end of said resistance R 15; The output of said first comparator be said comparison module output and said resistance R 15 the other end be connected; The reverse input end of said first comparator is connected with an end of said resistance R 14, and the other end of said resistance R 4 is the reverse input end of said comparison module.
Further, said delay protection module comprises:
Resistance R 16, resistance R 17, capacitor C 5, capacitor C 9 and voltage-stabiliser tube D1;
One end of said resistance R 16 is the input of said delay protection module; The other end of said resistance R 16 is that the reset terminal of said delay protection module is connected with an end of said capacitor C 9; The other end ground connection of said capacitor C 9; The other end of said resistance R 16 is connected with the negative electrode of said voltage-stabiliser tube D1 simultaneously; The anode of said voltage-stabiliser tube D1 is that the output of said delay protection module is connected the other end ground connection of the other end of said resistance R 17 and said capacitor C 5 with an end of said resistance R 17 and said capacitor C 5 simultaneously.
Further, said protection is kept the unit and is comprised:
First switching tube, capacitor C 3, capacitor C 4, capacitor C 6, capacitor C 7, resistance R 9, resistance R 10, resistance R 11, resistance R 12, resistance R 13, optocoupler and logic processor;
Said first control end of switching tube is the input that the unit is kept in said protection; The input of the said first output end of switching tube logic processor, the input of said first switching tube is connected with the output of said amplifier, and the trigger end of said logic processor is connected with an end of said resistance R 9 simultaneously; The other end of said resistance R 9 is connected with an end of said resistance R 10; Timing end said resistance R 10 and said logic processor is connected, and the timing end of said logic processor is simultaneously through said capacitor C 6 ground connection, and the power end of said logic processor is connected with said capacitor C 3 with supply voltage simultaneously; The other end ground connection of said capacitor C 3; The reset terminal of said logic processor is connected with an end of said resistance R 11 and an end of said capacitor C 4 simultaneously, and the other end of said resistance R 11 is connected with the power end of said logic processor, the other end ground connection of said capacitor C 4; The earth terminal ground connection of said logic processor; The counting end of said logic processor is through said capacitor C 7 ground connection, and the output of said logic processor is that the shutoff control end that the unit is kept in said protection is connected with an end of said resistance R 12, and the other end of said resistance R 12 is through said resistance R 13 ground connection; The other end of said resistance R 12 also is connected with the high potential input of said optocoupler; The electronegative potential input end grounding of said optocoupler, the high potential output of said optocoupler is the output that the unit is kept in said protection, the earth potential output head grounding of said optocoupler.
Further, said reset unit comprises:
Resistance R 18, resistance R 19, capacitor C 8 and second switch pipe;
One end of said resistance R 18 is the input of said reset unit; The other end of said resistance R 18 is connected with the control end of said second switch pipe; The control end of said second switch pipe is connected with an end of said capacitor C 8, an end of said resistance R 19 simultaneously; The other end ground connection of the other end of said capacitor C 8 and said resistance R 19, the input of said second switch pipe are that the output of said reset unit connects the output head grounding of said second switch pipe.
Another purpose of the utility model embodiment is to provide a kind of power circuit that comprises above-mentioned current foldback circuit.
Another purpose of the utility model embodiment is to provide a kind of power supply that comprises above-mentioned power circuit.
The utility model embodiment passes through over-current detection; When the power supply instantaneous overcurrent, carry out delay protection avoiding misoperation, strengthen power source life, when the lasting overcurrent that load abnormal etc. causes; Power supply is carried out turn-off protection; And after protection is held time, start power work automatically, and protect power supply not to be damaged all sidedly, reduced the spoilage of power supply.
Description of drawings
The structure chart of the current foldback circuit that Fig. 1 provides for the utility model one embodiment;
The exemplary circuit structure chart of the current foldback circuit that Fig. 2 provides for the utility model one embodiment;
Embodiment
For the purpose, technical scheme and the advantage that make the utility model is clearer,, the utility model is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the utility model, and be not used in qualification the utility model.
The utility model embodiment is through over-current detection, when the power supply instantaneous overcurrent, carries out delay protection avoiding misoperation, when the lasting overcurrent that load abnormal etc. causes, power supply carried out turn-off protection, and holds time in protection and to start power supply later automatically.
Fig. 1 shows the structure chart of the current foldback circuit that the utility model one embodiment provides, and for the ease of explanation, only shows the part relevant with the utility model embodiment.
The current foldback circuit that provides as the utility model one embodiment can be applicable to the power circuit of any kind, and in the power supply, this current foldback circuit is connected between power supply output sampling circuit 2 and the power supply pulse width control circuit 3, comprising:
Sampled signal to the output of power supply output sampling circuit carries out over-current detection; When the sampled signal overcurrent; Carry out delay protection and handle, and when sampled signal continues overcurrent, the overcurrent delay cell 11 of output overcurrent protection control signal; The input of this overcurrent delay cell 11 is connected with the output of power supply output sampling circuit, and the reference edge of overcurrent delay cell 11 is connected with the external reference signal output;
After receiving the overcurrent protection control signal; In preset guard time, export cut-off signals; Unit 12 is kept in protection with the protection power supply; The input that unit 12 is kept in this protection is connected with the output of overcurrent delay cell 11, and the output that unit 12 is kept in protection is connected with the control end of power supply pulse width control circuit;
After receiving the shutoff control signal, power on; The reset unit 13 that overcurrent delay cell 11 is resetted; The input of this reset unit 13 is connected with the shutoff control end that unit 12 is kept in protection, and the output of reset unit 13 is connected with the reset terminal of overcurrent delay cell 11.
Embodiment passes through over-current detection at the utility model; When the power supply instantaneous overcurrent, carry out delay protection avoiding misoperation, strengthen power source life, when the lasting overcurrent that load abnormal etc. causes; Power supply is carried out turn-off protection; And after protection is held time, start power work automatically, and protect power supply not to be damaged all sidedly, reduced the spoilage of power supply.
Be elaborated below in conjunction with the realization of specific embodiment to the utility model.
Fig. 2 shows the exemplary circuit structure of the current foldback circuit that the utility model one embodiment provides, and for the ease of explanation, only shows the part relevant with the utility model embodiment.
As the utility model one embodiment, overcurrent delay cell 11 comprises:
Sampled signal is amplified, and the signal amplification module 111 of sampled signal is amplified in output, and the input of this signal amplification module 111 is the input of overcurrent delay cell 11;
Carry out dividing potential drop to amplifying sampled signal, the division module 112 of output dividing potential drop sampled signal, the input of this division module 112 is connected with the output of overcurrent delay cell 11;
Dividing potential drop sampled signal and reference signal Vref are compared; Carry out over-current detection; When dividing potential drop sampled signal during greater than reference signal Vref, the detection sampled signal is an overcurrent, the comparison module 113 of output overcurrent detection signal; The positive input of this comparison module 113 is connected with the output of division module 112, and the reverse input end of comparison module 113 is the reference edge of overcurrent delay cell 11;
When receiving the over-current detection signal; Carrying out delay protection handles; And when continuing to receive the over-current detection signal, the delay protection module 114 of output overcurrent protection control signal, the input of this delay protection module 114 is connected with the output of comparison module 113; The output of delay protection module 114 is the output of overcurrent delay cell 11, and the reset terminal of delay protection module 114 is the reset terminal of overcurrent delay cell 11.
Preferably, signal amplification module 111 comprises:
The first operational amplifier U1A, resistance R 1, resistance R 2, resistance R 3, resistance R 5 and capacitor C 1;
One end of resistance R 1 is that the input of signal amplification module 111 is connected with an end of resistance R 3; The other end ground connection of resistance R 1; The other end of resistance R 3 is connected with the reverse input end of the first operational amplifier U1A; The positive input of the first operational amplifier U1A is connected with an end of resistance R 2; The other end ground connection of resistance R 2, capacitor C 1 and resistance R 5 are parallel between the output of reverse input end and the first operational amplifier U1A of the first operational amplifier U1A, and the output of the first operational amplifier U1A is the output of signal amplification module 111.
Preferably, division module 112 comprises:
Resistance R 4, resistance R 6, resistance R 7, resistance R 8 and capacitor C 2;
One end of resistance R 7 is the input of division module 112; The other end of resistance R 7 is connected with an end of resistance R 8 and an end of capacitor C 2 simultaneously; The other end ground connection of the other end of resistance R 8 and capacitor C 2, the other end of resistance R 7 also are connected with an end of resistance R 6, and the other end of resistance R 6 is connected with an end of resistance R 4; The other end ground connection of resistance R 4, resistance R 6 is the output of division module 112 with the common port of resistance R 4.
Preferably, comparison module 113 comprises:
Resistance R 14, resistance R 15 and the first comparator U1B;
The positive input of the first comparator U1B is that the positive input of comparison module 113 is connected with an end of resistance R 15; The output of the first comparator U1B be comparison module 113 output and resistance R 15 the other end be connected; The reverse input end of the first comparator U1B is connected with an end of resistance R 14, and the other end of resistance R 4 is the reverse input end of comparison module 113.
Preferably, delay protection module 114 comprises:
Resistance R 16, resistance R 17, capacitor C 5, capacitor C 9 and voltage-stabiliser tube D1;
One end of resistance R 16 is the input of delay protection module 114; The other end of resistance R 16 is that the reset terminal of delay protection module 114 is connected with an end of capacitor C 9; The other end ground connection of capacitor C 9; The other end of resistance R 16 is connected with the negative electrode of voltage-stabiliser tube D1 simultaneously, and the anode of voltage-stabiliser tube D1 is that the output of delay protection module 114 is connected the other end ground connection of the other end of resistance R 17 and capacitor C 5 with an end of resistance R 17 and capacitor C 5 simultaneously.
As the utility model one embodiment, protection is kept unit 12 and is comprised:
First switching tube 121, capacitor C 3, capacitor C 4, capacitor C 6, capacitor C 7, resistance R 9, resistance R 10, resistance R 11, resistance R 12, resistance R 13, optocoupler OT1 and logic processor U3;
The control end of first switching tube 121 is for protecting the input of keeping unit 12, and the output head grounding of first switching tube 121, the input of first switching tube 121 are connected with the trigger end TRIG of logic processor U3; The trigger end TRIG of logic processor U3 is connected with an end of resistance R 9 simultaneously, and the other end of resistance R 9 is connected with an end of resistance R 10, and timing end DISCH resistance R 10 and logic processor U3 is connected; The timing end DIS of logic processor U3 is simultaneously through capacitor C 6 ground connection; The power end VDD of logic processor U3 is connected with capacitor C 3 with supply voltage simultaneously, the other end ground connection of capacitor C 3, and the reset terminal RES of logic processor U3 is connected with an end of resistance R 11 and an end of capacitor C 4 simultaneously; The other end of resistance R 11 is connected with the power end VDD of logic processor U3; The other end ground connection of capacitor C 4, the earth terminal GND ground connection of logic processor U3, the counting end CONT of logic processor U3 is through capacitor C 7 ground connection; The shutoff control end that the output OUT of logic processor U3 keeps unit 12 for protection is connected with an end of resistance R 12; The other end of resistance R 12 is through resistance R 13 ground connection, and the other end of resistance R 12 also is connected with the high potential input of optocoupler OT1, the electronegative potential input end grounding of optocoupler OT1; The high potential output of optocoupler OT1 is for protecting the output of keeping unit 12, the earth potential output head grounding of optocoupler OT1.
As the utility model one preferred embodiment; First switching tube 121 can adopt N type metal-oxide-semiconductor Q1; The drain electrode of this N type metal-oxide-semiconductor Q1 is the input of first switching tube 121; The source class of N type metal-oxide-semiconductor Q1 is the output of first switching tube 121, and the grid of N type metal-oxide-semiconductor Q1 is the control end of first switching tube 121.This first switching tube 121 can also adopt NPN type triode; The current collection of this NPN type triode is the input of first switching tube 121 very; The emission of NPN type triode is the output of first switching tube 121 very, and the base stage of NPN type triode is the control end of first switching tube 121.
As the utility model one embodiment, reset unit 13 comprises:.
Resistance R 18, resistance R 19, capacitor C 8 and second switch pipe 131;
One end of resistance R 18 is the input of reset unit 13; The other end of resistance R 18 is connected with the control end of second switch pipe 131; The control end of second switch pipe 131 is connected with an end of capacitor C 8, an end of resistance R 19 simultaneously; The other end ground connection of the other end of capacitor C 8 and resistance R 19, the input of second switch pipe 131 are that the output of reset unit 13 connects the output head grounding of second switch pipe 131.
As the utility model one preferred embodiment; Second switch pipe 131 can adopt NPN type triode Q2; The current collection of this NPN type triode Q2 is the input of second switch pipe 131 very; The emission of NPN type triode Q2 is the output of second switch pipe 131 very, and NPN type triode Q2 base stage is the control end of second switch pipe 131.This second switch pipe 131 can also adopt N type metal-oxide-semiconductor, and the drain electrode of this N type metal-oxide-semiconductor is the input of second switch pipe 131, and the source class of N type metal-oxide-semiconductor is the output of second switch pipe 131, and the grid of N type metal-oxide-semiconductor is the control end of second switch pipe 131.
In the utility model embodiment, to export just often when the electric current of power supply, signal amplification module 111 obtains sampled signal through the voltage that detects on the resistance R 1; Resistance R 1 is converted into the sampling voltage signal with the sampling current signal and carries out the signal amplification for the first operational amplifier U1A, and multiplication factor can be chosen as 50 times, wherein can regulate multiplication factor through regulating resistance R 5 with the ratio of resistance R 3; Direct proportion of first operational amplifier U1A output is in the amplification sampled signal of input voltage; And, export to dividing potential drop sampled signal of the first comparator U1B through resistance R 7, resistance R 6, resistance R 4 dividing potential drops, resistance R 8 can be carried out filtering with capacitor C 2; The first comparator U1B compares this dividing potential drop sampled signal with preset reference signal Vref; When the voltage of dividing potential drop sampled signal during less than the voltage of reference signal Vref, i.e. source current output just often, the first comparator U1B exports a low-voltage; The unit to the back does not trigger the power supply operate as normal.
When electric power outputting current during, detect sampled signal through resistance R 1, after amplifying through the first operational amplifier U1A greater than preset electric current; Through division module 112 dividing potential drops, input to the first comparator U1B relatively, this moment, this dividing potential drop sampled signal was greater than preset reference signal Vref; Therefore high voltage of first comparator U1B output through 9 chargings of 16 pairs of capacitor C of resistance R, carries out delay protection; And; When the voltage of capacitor C 9 before not surpassing the voltage stabilizing value of voltage-stabiliser tube D1, (mean the instantaneous overcurrent signal that this over-current signal possibly bring for impulse current) when the over-current signal of power supply has been removed, promptly sampled signal is also corresponding to becoming less than reference signal greater than reference signal; Then not conducting of voltage-stabiliser tube D1; Overcurrent delay cell 11 is output overcurrent protection control signal control power remove not, and the power supply operate as normal has prevented misoperation effectively.
When the voltage of capacitor C 9 when surpassing the voltage stabilizing value of voltage-stabiliser tube D1; (do not mean that this over-current signal possibly cause the non-instantaneous overcurrent signal of power supply output for load abnormal) when the over-current signal of power supply still is disengaged, promptly said sampled signal continues overcurrent, control first switching tube 121 conductings after the voltage-stabiliser tube D1 conducting; And then after triggering logic processor U3 and being triggered; Export a high-tension shutoff control signal and make the input stage OT1A conducting of optocoupler OT1, the output stage OT1B conducting of control optocoupler, the output that unit 12 is kept in protection is dragged down; The pulse width signal of power supply pulse width control circuit 3 is output not; Switching tube is closed, and power supply is output not, gets into guard mode.Do not have between period of output at power supply; Power source voltage Vcc is charged through 10 pairs of capacitor C 6 of resistance R; When the voltage of capacitor C 6 surpassed 2/3Vcc, logic processor U3 resetted, and exports a low-voltage again; Power supply has output again, and the protection that power supply restarted after wherein this section resetted from power-off to logic processor U3 is held time can be through setting the parameter setting of resistance R 10 and capacitor C 6.Reset circuit 13 discharges to capacitor C 9 after the high-tension shutoff control signal of receiving logic processor U3 output, and discharge back overcurrent delay cell 11 resets, to carry out next protection period.
When output overcurrent disappeared, the first comparator U1B exported a low-voltage again, and the voltage of capacitor C 9 is lower than D1 voltage stabilizing value, and logic processor U3 is not triggered, the power up operate as normal.
As the utility model one embodiment, can be through the value of control capacittance C9, the control lag guard time can also be regulated protection through the value of control capacittance C6 and hold time.
The utility model embodiment carries out delay protection to avoid misoperation through over-current detection when the power supply instantaneous overcurrent, strengthen power source life; When the lasting overcurrent that load abnormal etc. causes, power supply is carried out turn-off protection, and hold time in protection and to start power work later automatically; Its delay protection time and protection are held time and all can be provided with voluntarily, and flexibility is strong, protect power supply not to be damaged all sidedly; Reduced the occurrence probability of the spoilage and the security incident of power supply.
More than be merely the preferred embodiment of the utility model,, any modification of being done within all spirit at the utility model and the principle, be equal to and replace and improvement etc., all should be included within the protection range of the utility model not in order to restriction the utility model.
Claims (10)
1. a current foldback circuit is connected between power supply output sampling circuit and the power supply pulse width control circuit, it is characterized in that said current foldback circuit comprises:
Sampled signal to said power supply output sampling circuit output carries out over-current detection; When said sampled signal overcurrent; Carry out delay protection and handle, and when said sampled signal continues overcurrent, the overcurrent delay cell of output overcurrent protection control signal; The input of said overcurrent delay cell is connected with the output of said power supply output sampling circuit, and the reference edge of said overcurrent delay cell is connected with the external reference signal output;
After receiving said overcurrent protection control signal; In preset guard time, export cut-off signals; The unit is kept in protection with the protection power supply; The input that the unit is kept in said protection is connected with the output of said overcurrent delay cell, and the output that the unit is kept in said protection is connected with the control end of said power supply pulse width control circuit;
After receiving said shutoff control signal, power on; The reset unit that said overcurrent delay cell is resetted; The input of said reset unit is connected with the shutoff control end that the unit is kept in said protection, and the output of said reset unit is connected with the reset terminal of said overcurrent delay cell.
2. circuit as claimed in claim 1 is characterized in that, said overcurrent delay cell comprises:
Said sampled signal is amplified, and the signal amplification module of sampled signal is amplified in output, and the input of said signal amplification module is the input of said overcurrent delay cell;
Said amplification sampled signal is carried out dividing potential drop, the division module of output dividing potential drop sampled signal, the input of said division module is connected with the output of said overcurrent delay cell;
Said dividing potential drop sampled signal and reference signal are compared; Carry out over-current detection; When said dividing potential drop sampled signal during greater than said reference signal, detecting said sampled signal is overcurrent, the comparison module of output overcurrent detection signal; The positive input of said comparison module is connected with the output of said division module, and the reverse input end of said comparison module is the reference edge of said overcurrent delay cell;
When receiving said over-current detection signal; Carrying out delay protection handles; And when continuing to receive said over-current detection signal, the delay protection module of output overcurrent protection control signal, the input of said delay protection module is connected with the output of said comparison module; The output of said delay protection module is the output of said overcurrent delay cell, and the reset terminal of said delay protection module is the reset terminal of said overcurrent delay cell.
3. circuit as claimed in claim 2 is characterized in that, said signal amplification module comprises:
First operational amplifier, resistance R 1, resistance R 2, resistance R 3, resistance R 5 and capacitor C 1;
One end of said resistance R 1 is that the input of said signal amplification module is connected with an end of said resistance R 3; The other end ground connection of said resistance R 1; The other end of said resistance R 3 is connected with the reverse input end of said first operational amplifier; The positive input of said first operational amplifier is connected with an end of said resistance R 2; The other end ground connection of said resistance R 2, said capacitor C 1 and said resistance R 5 are parallel between the output of reverse input end and said first operational amplifier of said first operational amplifier, and the output of said first operational amplifier is the output of said signal amplification module.
4. circuit as claimed in claim 2 is characterized in that, said division module comprises:
Resistance R 4, resistance R 6, resistance R 7, resistance R 8 and capacitor C 2;
One end of said resistance R 7 is the input of said division module; The other end of said resistance R 7 is connected with an end of said resistance R 8 and an end of said capacitor C 2 simultaneously; The other end ground connection of the other end of said resistance R 8 and said capacitor C 2; The other end of said resistance R 7 also is connected with an end of said resistance R 6; The other end of said resistance R 6 is connected with an end of said resistance R 4, the other end ground connection of said resistance R 4, and said resistance R 6 is the output of said division module with the common port of said resistance R 4.
5. circuit as claimed in claim 2 is characterized in that, said comparison module comprises:
Resistance R 14, resistance R 15 and first comparator;
The positive input of said first comparator is that the positive input of said comparison module is connected with an end of said resistance R 15; The output of said first comparator be said comparison module output and said resistance R 15 the other end be connected; The reverse input end of said first comparator is connected with an end of said resistance R 14, and the other end of said resistance R 4 is the reverse input end of said comparison module.
6. circuit as claimed in claim 2 is characterized in that, said delay protection module comprises:
Resistance R 16, resistance R 17, capacitor C 5, capacitor C 9 and voltage-stabiliser tube D1;
One end of said resistance R 16 is the input of said delay protection module; The other end of said resistance R 16 is that the reset terminal of said delay protection module is connected with an end of said capacitor C 9; The other end ground connection of said capacitor C 9; The other end of said resistance R 16 is connected with the negative electrode of said voltage-stabiliser tube D1 simultaneously; The anode of said voltage-stabiliser tube D1 is that the output of said delay protection module is connected the other end ground connection of the other end of said resistance R 17 and said capacitor C 5 with an end of said resistance R 17 and said capacitor C 5 simultaneously.
7. circuit as claimed in claim 1 is characterized in that, said protection is kept the unit and comprised:
First switching tube, capacitor C 3, capacitor C 4, capacitor C 6, capacitor C 7, resistance R 9, resistance R 10, resistance R 11, resistance R 12, resistance R 13, optocoupler and logic processor;
Said first control end of switching tube is the input that the unit is kept in said protection; The input of the said first output end of switching tube logic processor, the input of said first switching tube is connected with the output of said amplifier, and the trigger end of said logic processor is connected with an end of said resistance R 9 simultaneously; The other end of said resistance R 9 is connected with an end of said resistance R 10; Timing end said resistance R 10 and said logic processor is connected, and the timing end of said logic processor is simultaneously through said capacitor C 6 ground connection, and the power end of said logic processor is connected with said capacitor C 3 with supply voltage simultaneously; The other end ground connection of said capacitor C 3; The reset terminal of said logic processor is connected with an end of said resistance R 11 and an end of said capacitor C 4 simultaneously, and the other end of said resistance R 11 is connected with the power end of said logic processor, the other end ground connection of said capacitor C 4; The earth terminal ground connection of said logic processor; The counting end of said logic processor is through said capacitor C 7 ground connection, and the output of said logic processor is that the shutoff control end that the unit is kept in said protection is connected with an end of said resistance R 12, and the other end of said resistance R 12 is through said resistance R 13 ground connection; The other end of said resistance R 12 also is connected with the high potential input of said optocoupler; The electronegative potential input end grounding of said optocoupler, the high potential output of said optocoupler is the output that the unit is kept in said protection, the earth potential output head grounding of said optocoupler.
8. circuit as claimed in claim 1 is characterized in that, said reset unit comprises:
Resistance R 18, resistance R 19, capacitor C 8 and second switch pipe;
One end of said resistance R 18 is the input of said reset unit; The other end of said resistance R 18 is connected with the control end of said second switch pipe; The control end of said second switch pipe is connected with an end of said capacitor C 8, an end of said resistance R 19 simultaneously; The other end ground connection of the other end of said capacitor C 8 and said resistance R 19, the input of said second switch pipe are that the output of said reset unit connects the output head grounding of said second switch pipe.
9. a power circuit is characterized in that, the current foldback circuit of said power circuit is like each described current foldback circuit of claim 1 to 8.
10. a power supply is characterized in that, the power circuit of said power supply is a power circuit as claimed in claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204513696U CN202363870U (en) | 2011-11-15 | 2011-11-15 | Over-current protection circuit, power supply circuit and power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204513696U CN202363870U (en) | 2011-11-15 | 2011-11-15 | Over-current protection circuit, power supply circuit and power supply |
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| Publication Number | Publication Date |
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| CN202363870U true CN202363870U (en) | 2012-08-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2011204513696U Expired - Fee Related CN202363870U (en) | 2011-11-15 | 2011-11-15 | Over-current protection circuit, power supply circuit and power supply |
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| CN (1) | CN202363870U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102496903A (en) * | 2011-11-15 | 2012-06-13 | 深圳桑达国际电子器件有限公司 | Over-current protection circuit, power supply circuit and power supply |
| CN104037722A (en) * | 2014-06-18 | 2014-09-10 | 中国航天科技集团公司第九研究院第七七一研究所 | Safety circuit based on load over-current fault |
| CN104184101A (en) * | 2013-05-21 | 2014-12-03 | 海洋王（东莞）照明科技有限公司 | Accurate over current protection circuit |
-
2011
- 2011-11-15 CN CN2011204513696U patent/CN202363870U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102496903A (en) * | 2011-11-15 | 2012-06-13 | 深圳桑达国际电子器件有限公司 | Over-current protection circuit, power supply circuit and power supply |
| CN102496903B (en) * | 2011-11-15 | 2014-10-29 | 深圳桑达国际电子器件有限公司 | Over-current protection circuit, power supply circuit and power supply |
| CN104184101A (en) * | 2013-05-21 | 2014-12-03 | 海洋王（东莞）照明科技有限公司 | Accurate over current protection circuit |
| CN104037722A (en) * | 2014-06-18 | 2014-09-10 | 中国航天科技集团公司第九研究院第七七一研究所 | Safety circuit based on load over-current fault |
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