CN105429106B - A kind of output short circuit protection circuit of Switching Power Supply - Google Patents
A kind of output short circuit protection circuit of Switching Power Supply Download PDFInfo
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- CN105429106B CN105429106B CN201510897783.2A CN201510897783A CN105429106B CN 105429106 B CN105429106 B CN 105429106B CN 201510897783 A CN201510897783 A CN 201510897783A CN 105429106 B CN105429106 B CN 105429106B
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Abstract
The invention discloses a kind of output short-circuit protection method of Switching Power Supply and circuit, including start-up circuit, transformer assists winding power supply circuit, voltage sample and delay circuit, protect duration initialization circuit, start-up circuit breaking circuit, control IC operating voltage Vcc ports, the present general inventive concept is to judge whether Switching Power Supply output is short-circuit by detecting the voltage of transformer auxiliary power supply winding, when it is determined that during Switching Power Supply output short-circuit, again by controlling start-up circuit intermittent work, reduce Switching Power Supply output short-circuit power consumption and start-up circuit power consumption, greatly improve the reliability of Switching Power Supply output short circuit protection, the power density of Simultaneous Switching power supply can also greatly improve.
Description
Technical field
The present invention relates to the output short-circuit protection method and circuit of Switching Power Supply, more particularly to Switching Power Supply.
Background technology
With the progress of Power Electronic Technique, Switching Power Supply is constantly sent out to high power density, high efficiency, high reliability
Exhibition, the output short circuit protection of Switching Power Supply have become an important indicator of reliability.Realize that Switching Power Supply exports at present
The technology of short circuit, all it is by controlling IC to detect the electric current on main power circuit to realize, as shown in Figure 1.When Switching Power Supply is defeated
When going out short circuit, the inductance value of Transformer Winding will drastically decline, when main power circuit switching tube turns on, on main power circuit
Electric current will increased dramatically, and control IC will detect a very big electric current by main power circuit current detection circuit, then control
IC processed is judged and controlled by internal logic circuit.In general control method is that the PWM for making driving master power switch pipe drives
The dynamic intermittent output of level, industry is interior to be referred to as the protection of hiccup formula, reduces power consumption during Switching Power Supply output short-circuit.But opening
During powered-down source output short-circuit, assists winding power supply circuit can not again to control IC power supply, now control IC power supply will all by
Start-up circuit is powered.At the high input voltage application scenario such as railway, photovoltaic, the power consumption of start-up circuit will be very big.Assuming that input
Voltage is 1000VDC, and it be 20mA to control IC to consume total electric current during Switching Power Supply output short-circuit, and control IC, which works, to be suppressed as 10V,
So start-up circuit consumption power will be：(1000-10) × 0.02=19.8W.This means start-up circuit is very big by needs
The device of power, basic is difficult the requirement for meeting high power density, high reliability.Therefore prior art realizes that Switching Power Supply exports
Short-circuit protection is primarily present following shortcoming：
(1) at high input voltage application scenario, Switching Power Supply output short-circuit, start-up circuit power consumption is very big.
(2) at high input voltage application scenario, Switching Power Supply output short-circuit, it is difficult to compatible high power density and highly reliable
Property require.
The content of the invention
Have in view of that, one of the technical problem to be solved in the present invention is：Overcome in the prior art in high input voltage application
Occasion, during Switching Power Supply output short-circuit, start-up circuit power consumption is big, it is difficult to which compatible high power density and high reliability request etc. lack
Point, there is provided a kind of Switching Power Supply output short-circuit protection method, described Switching Power Supply output short-circuit protection method can both reduce
Short-circuit dissipation, the power consumption of start-up circuit when can reduce short circuit again, improve the power density and reliability of product.
Corresponding to this, the second technical problem to be solved by the present invention is：A kind of Switching Power Supply output short circuit protection electricity is provided
Road.
The present invention is solves one of above-mentioned technical problem, there is provided technical scheme be：
A kind of output short-circuit protection method of Switching Power Supply, comprises the following steps：
Starting step, start-up circuit make Switching Power Supply enter normal work to the power supply of control IC operating voltage Vcc ports；
After start completion, by transformer assists winding power supply circuit to the power supply of control IC operating voltage Vcc ports；
Start-up circuit turns off step, and voltage sample and delay circuit are to the control IC operating voltage Vcc ends in starting step
The voltage of mouth is detected, it is determined that after controlling the voltage of IC operating voltage Vcc ports normal and postponing a period of time, the letter of output one
Number control protection duration initialization circuit charging；Protection duration initialization circuit it is fully charged after will export a signal give start-up circuit pass
Deenergizing；Start-up circuit breaking circuit turns off start-up circuit after receiving the signal of protection duration initialization circuit；
Output short circuit protection step, during Switching Power Supply output short-circuit, the voltage of transformer assists winding power supply circuit output
Fall too low rapidly, can not continue to the power supply of control IC operating voltage Vcc ports, and now protect duration initialization circuit by opening
Dynamic circuit breaking circuit still continues to turn off start-up circuit, and control IC operating voltage Vcc port voltages will reduce rapidly, control IC
It is stopped, reduces working time during Switching Power Supply output short-circuit.If Switching Power Supply exports sustained short-circuit, Switching Power Supply will be followed
Ring above step, intermittent work is formed, play a part of reducing short-circuit dissipation and reduce start-up circuit power consumption.
Short-circuit self- recoverage step：When the elimination of Switching Power Supply output short-circuit, while protect duration initialization circuit guard time knot
Shu Hou, Switching Power Supply will enter normal condition from start-up course again.
The present invention for solve above-mentioned technical problem two, there is provided technical scheme be：
A kind of output short circuit protection circuit of Switching Power Supply：Including start-up circuit, transformer assists winding power supply circuit, electricity
Pressure sampling and delay circuit, protection duration initialization circuit, start-up circuit breaking circuit, control IC operating voltage Vcc ports, input
Voltage port Vin；Described start-up circuit includes an input, an output end, a control terminal；Described transformer assists winding
Power supply circuit includes a winding, an output end；Described voltage sample and delay circuit include an input, an output end；Institute
The protection duration initialization circuit stated includes an input, an output end；Described start-up circuit breaking circuit include an input,
One output end.Input voltage port Vin described in the input connection of described start-up circuit, the output of described start-up circuit
The described control IC operating voltage Vcc ports of end connection；The winding coupled main transformer of described transformer assists winding power supply circuit
The output winding of depressor, the control IC operating voltages described in the output end connection of described transformer assists winding power supply circuit
Vcc ports；Described voltage sample connects described control IC operating voltage Vcc ports with the input of delay circuit, described
Voltage sample the input of described protection duration initialization circuit is connected with the output end of delay circuit；Described protection duration
The input of start-up circuit breaking circuit described in the output end connection of initialization circuit；Described start-up circuit breaking circuit it is defeated
Go out the control terminal of the described start-up circuit of end connection.
Described start-up circuit is powered to described control IC operating voltage Vcc ports, Switching Power Supply is entered normal work
Make；After start completion, supplied by described transformer assists winding power supply circuit to described control IC operating voltage Vcc ports
Electricity；Described voltage sample and delay circuit are in described start-up circuit start-up course to described control IC operating voltages
The voltage of Vcc ports is detected, it is determined that the voltage of described control IC operating voltage Vcc ports is normal and postpones a period of time
Afterwards, the charging of the described protection duration initialization circuit of signal control is exported；After described protection duration initialization circuit is fully charged
A signal will be exported to described start-up circuit breaking circuit；When described start-up circuit breaking circuit receives described protection
Described start-up circuit is turned off after the signal of long initialization circuit；Control IC work electricity described in when Switching Power Supply output short-circuit
Pressure Vcc port voltages will reduce rapidly, and described control IC is stopped, if Switching Power Supply exports sustained short-circuit, Switching Power Supply
Above step will be circulated；When the elimination of Switching Power Supply output short-circuit, while described protection duration initialization circuit guard time terminates
Afterwards, Switching Power Supply will enter normal condition from start-up course again.
Preferably, described start-up circuit includes the first current-limiting resistance, and the second current-limiting resistance, the first triode, first is steady
Press diode, the first diode.One end connection power input and the second described current limliting electricity of the first described current-limiting resistance
One end of resistance, the colelctor electrode of the first triode described in the other end connection of the first described current-limiting resistance；The second described limit
The base stage of the first triode and the negative electrode of the first described voltage-regulator diode described in the other end connection of leakage resistance；Described
The anode of one voltage-regulator diode is connected to reference ground；The start-up circuit shut-off that the base stage connection of the first described triode is described is electric
The output end on road, the anode of the first diode described in the emitter stage connection of the first described triode；The one or three described pole
Manage as NPN type triode；Control IC operating voltage Vcc ports described in the negative electrode connection of the first described diode.
Preferably, described transformer assists winding power supply circuit includes the first winding, the 3rd current-limiting resistance, the two or two pole
Pipe, the first filter capacitor.The output winding voltage of the first described winding coupled main transformer, one end of the first described winding
Connect reference ground, the anode of the second diode described in the other end connection of the first described winding；The second described diode
Described the first filter capacitor of negative electrode connection one end and the described control IC operating voltage Vcc ports of connection；Described
The other end connection reference ground of first filter capacitor.
Preferably, described voltage sample and delay circuit include the first divider resistance, the second divider resistance, the first delay
Electric capacity, the 3rd divider resistance, the 4th divider resistance, the first operational amplifier, the 3rd diode.The one of the first described sub-resistance
The described control IC operating voltage Vcc ports of end connection, second point described in the other end connection of the first described divider resistance
One end of the first delay electric capacity described in one end of piezoresistance and connection；The other end of the first described delay electric capacity is connected to ginseng
Examine ground；The other end of the second described divider resistance is to reference ground；The first described divider resistance and the second described partial pressure electricity
The series connection node of resistance is connected to the in-phase input end of the first described operational amplifier；One end of the 3rd described divider resistance connects
Described control IC operating voltage Vcc ports are connect, the 4th partial pressure that the other end connection of the 3rd described divider resistance is described is electric
One end of resistance；The other end of the 4th described divider resistance is connected to reference ground；The 3rd described divider resistance and described
The series connection node of four divider resistances is connected to the inverting input of the first described operational amplifier；The first described operation amplifier
Control IC operating voltage Vcc ports described in the power positive end connection of device, the power supply negative terminal of the first described operational amplifier connect
It is connected to reference ground, the anode of the 3rd diode described in the output end connection of the first described operational amplifier；Described the 3rd
Output end of the negative electrode of diode as described voltage sample and delay circuit, connect described protection duration initialization circuit
Input.
Preferably, described voltage sample and delay circuit include the first divider resistance, the second divider resistance, the first delay
Electric capacity, the 3rd divider resistance, the second voltage-regulator diode, the first operational amplifier, the 3rd diode.The first described divider resistance
The described control IC operating voltage Vcc ports of one end connection, the other end connection of the first described divider resistance it is described the
One end of the first delay electric capacity described in one end of two divider resistances and connection；The other end connection of the first described delay electric capacity
To reference ground；The other end of the second described divider resistance is to reference ground；The first described divider resistance and described second point
The series connection node of piezoresistance is connected to the in-phase input end of the first described operational amplifier；The one of the 3rd described divider resistance
The described control IC operating voltage Vcc ports of end connection, second that the other end connection of the 3rd described divider resistance is described are steady
Press the negative electrode of diode；The anode of the second described voltage-regulator diode is connected to reference ground；The 3rd described divider resistance and institute
The series connection node for the second voltage-regulator diode stated is connected to the inverting input of the first described operational amplifier；Described first
Control IC operating voltage Vcc ports described in the power positive end connection of operational amplifier, the electricity of the first described operational amplifier
Source negative terminal is connected to reference ground, the anode of the 3rd diode described in the output end connection of the first described operational amplifier；Institute
Output end of the negative electrode for the 3rd diode stated as described voltage sample and delay circuit, connects described protection duration and sets
Determine the input of circuit.
Preferably, described protection duration initialization circuit includes the first storage capacitor, the first discharge resistance, the first biased electrical
Resistance.One end of the first described storage capacitor connects one end of the first described discharge resistance and is connected to described voltage sample
With the output end of delay circuit；The other end of the first described storage capacitor is connected to reference ground；The first described discharge resistance
The other end be connected to one end of the first described biasing resistor；The other end of the first described biasing resistor is connected to reference
Ground；The first described discharge resistance and the series connection node of the first described biasing resistor are as described protection duration initialization circuit
Output end, be connected to the input of described start-up circuit breaking circuit.
Preferably, described start-up circuit breaking circuit includes the second triode.The base stage of the second described triode is made
For the input of start-up circuit breaking circuit, the described output end for protecting duration initialization circuit is connected；The two or three described pole
Output end of the colelctor electrode of pipe as start-up circuit breaking circuit, connect the control terminal of described start-up circuit；Described second
The emitter stage of triode is connected to reference ground.The second described triode is NPN type triode.
Preferably, described start-up circuit breaking circuit includes the first metal-oxide-semiconductor.The grid conduct of the first described metal-oxide-semiconductor
The input of start-up circuit breaking circuit, connect the output end of described protection duration initialization circuit；The first described metal-oxide-semiconductor
The output end to drain as start-up circuit breaking circuit, connect the control terminal of described start-up circuit；The first described metal-oxide-semiconductor
Source electrode is connected to reference ground.The first described metal-oxide-semiconductor is N-channel FET.
Preferably, described voltage sample and delay circuit and described protection duration initialization circuit work independently, and extend
Time and guard time can independent settings.
The present invention operation principle embodiment part will labor, will not be described here.
Compared with prior art, the present invention has the advantages of following prominent：
(1) during Switching Power Supply output short-circuit, intermittent work pattern can be entered, short-circuit dissipation is small.Can be by adjusting circuit
Parameter carrys out working time during configuration switch power supply short circuit.
(2) during Switching Power Supply output short-circuit, start-up circuit intermittent work, start-up circuit power consumption very little.In height input electricity
Have a meeting, an audience, etc. well under one's control under conjunction, the advantage of start-up circuit small power consumption is more obvious, ensures the reliability of Switching Power Supply, while greatly improves product
Power density.
Brief description of the drawings
Fig. 1 is the schematic diagram of prior art Switching Power Supply output short circuit protection circuit；
Fig. 2 is principle of the invention block diagram；
Fig. 3 is the circuit diagram of the embodiment of the present invention one；
Fig. 4 is the circuit diagram of the embodiment of the present invention two；
Fig. 5 is the circuit diagram of the embodiment of the present invention three；
Fig. 6 is the circuit diagram of the embodiment of the present invention four；
IC operating voltages Vcc is controlled when Fig. 7 is Switching Power Supply output short-circuit and controls the PWM drive waveforms of IC outputs.
Embodiment
The design of the technology of the present invention is to judge that Switching Power Supply exports by detecting the voltage of transformer auxiliary power supply winding
Whether short circuit, when it is determined that during Switching Power Supply output short-circuit, then by controlling start-up circuit intermittent work, it is defeated to reduce Switching Power Supply
Go out short-circuit dissipation and start-up circuit power consumption, greatly improve the reliability of Switching Power Supply output short circuit protection, Simultaneous Switching power supply
Power density can also greatly improve.
In order to be better understood from technical scheme, the present invention is entered below in conjunction with the drawings and specific embodiments
One step is described in detail.
Referring to Fig. 2, for the functional block diagram of the present invention, including start-up circuit 1, transformer assists winding power supply circuit 2, voltage
Sampling and delay circuit 3, protection duration initialization circuit 4, start-up circuit breaking circuit 5, control IC operating voltage Vcc ports.
Further illustrated with reference to specific implementation circuit.
Embodiment one
Fig. 3 is the circuit diagram of the embodiment of the present invention one, and it includes：Start-up circuit 1, transformer assists winding power supply circuit 2,
Voltage sample and delay circuit 3, protection duration initialization circuit 4, start-up circuit breaking circuit 5, control IC operating voltage Vcc ends
Mouth, input voltage port Vin；Start-up circuit 1 includes an input, an output end, a control terminal；Transformer assists winding is powered
Circuit 2 includes a winding, an output end；Voltage sample and delay circuit 3 include an input, an output end；Protection duration is set
Determining circuit 4 includes an input, an output end；Start-up circuit breaking circuit 5 includes an input, an output end.Start-up circuit 1
Input connection input voltage port Vin, the output end connection control IC operating voltage Vcc ports of start-up circuit 1；Transformer
The output winding of the winding coupled main transformer of assists winding power supply circuit 2, the output end of transformer assists winding power supply circuit 2
Connection control IC operating voltage Vcc ports；Voltage sample connects control IC operating voltage Vcc ends with the input of delay circuit 3
Mouthful, voltage sample connects the input of protection duration initialization circuit 4 with the output end of delay circuit 3；Protect duration initialization circuit 4
Output end connection start-up circuit breaking circuit 5 input；The output end connection start-up circuit 1 of start-up circuit breaking circuit 5
Control terminal.
Start-up circuit 1 includes the first current-limiting resistance R8, the second current-limiting resistance R9, the first triode Q2, the pole of the first voltage stabilizing two
Pipe Z1, the first diode D3.First current-limiting resistance R8 one end connection power input and the second current-limiting resistance R9 one end, the
The one current-limiting resistance R8 other end connects the first triode Q2 colelctor electrode；Second current-limiting resistance R9 other end connection the one or three
The negative electrode of pole pipe Q2 base stage and the first voltage-regulator diode Z1；First voltage-regulator diode Z1 anode is connected to reference ground；First
The output end of triode Q2 base stage connection start-up circuit breaking circuit 5, the first triode Q2 emitter stage connect the one or two pole
Pipe D3 anode；First triode Q2 is NPN type triode；First diode D3 negative electrode connection control IC operating voltages Vcc
Port；
Transformer assists winding power supply circuit 2 includes the first winding diode D1 of Nf, the 3rd current-limiting resistance R1, second, the
One filter capacitor C1.Voltage on the output winding Ns of first winding Nf coupling main transformers, the first winding Nf one end connection
Reference ground, the first winding Nf other end connect the second diode D1 anode；The second diode D1 filter of negative electrode connection first
Ripple electric capacity C1 one end and connection control IC operating voltage Vcc ports；First filter capacitor C1 other end connection reference ground；
Voltage sample and delay circuit 3 include the first divider resistance R2, the second divider resistance R3, the first delay electric capacity C2,
3rd divider resistance R4, the 4th divider resistance R5, the first operational amplifier A R1, the 3rd diode D2.First divider resistance R2's
One end connection control IC operating voltage Vcc ports, the first divider resistance R2 other end connect the second divider resistance R3 one end
With the first delay electric capacity C2 of connection one end；The first delay electric capacity C2 other end is connected to reference ground；Second divider resistance R3
The other end to reference ground；First divider resistance R2 and the second divider resistance R3 series connection node are connected to the first operational amplifier
AR1 in-phase input end；3rd divider resistance R4 one end connection control IC operating voltage Vcc ports, the 3rd divider resistance R4
The other end connect the 4th divider resistance R5 one end；The 4th divider resistance R5 other end is connected to reference ground；3rd partial pressure
Resistance R4 and the 4th divider resistance R5 series connection node is connected to the first operational amplifier A R1 inverting input；First computing
Amplifier AR1 power positive end connection control IC operating voltage Vcc ports, the first operational amplifier A R1 power supply negative terminal connection
To reference ground, the first operational amplifier A R1 output end connects the 3rd diode D2 anode；3rd diode D2 negative electrode is made
For the output end of voltage sample and delay circuit 3, the input of connection protection duration initialization circuit 4.
Protection duration initialization circuit 4 includes the first storage capacitor C3, the first discharge resistance R6, the first biasing resistor R7.The
One storage capacitor C3 one end connects the first discharge resistance R6 one end and is connected to the output of voltage sample and delay circuit 3
End；The first storage capacitor C3 other end is connected to reference ground；The first discharge resistance R6 other end is connected to the first biased electrical
Hinder R7 one end；The first biasing resistor R7 other end is connected to reference ground；First discharge resistance R6 and the first biasing resistor R7
Series connection node as the output end for protecting duration initialization circuit 4, be connected to the input of start-up circuit breaking circuit 5.
Start-up circuit breaking circuit 5 includes the second triode Q1.Second triode Q1 base stage turns off as start-up circuit
The input of circuit 5, the output end of connection protection duration initialization circuit 4；Second triode Q1 colelctor electrode is as start-up circuit
The output end of breaking circuit 5, connect the control terminal of start-up circuit 1；Second triode Q1 emitter stage is connected to reference ground.Second
Triode Q1 is NPN type triode；
Its operation principle is as follows：
Start-up course：Start-up circuit 1 is powered to control IC operating voltage Vcc ports, Switching Power Supply is entered normal work,
Switch power source output voltage is established normal.Transformer assists winding power supply circuit 2 couples the voltage exported on winding and gives control IC
Operating voltage Vcc ports power；
Start-up circuit turn off process：In start-up course, R4, R5 form a reference voltage by partial pressure, and R2, R3 are by dividing
Pressure samples to Vcc voltage, and C2 carries out a period of time delay to sampled signal, ensures that Switching Power Supply exports not short-circuit situation
Under, start-up circuit 1 has time enough to complete start-up course.Sampling confirms that Vcc power supplys have reached normal voltage, while C2 pairs
After the completion of sampled signal delay, operational amplifier A R1 exports a high level and the electric capacity C3 for protecting duration initialization circuit 4 is charged,
Because operational amplifier A R1 exports internal resistance, much smaller than R6, therefore before can ensureing that start-up circuit is turned off, the electricity on electric capacity C3
Pressure is filled the voltage for being approximately equal to Vcc.After protecting duration initialization circuit 4 fully charged, the triode of start-up circuit breaking circuit 5
Q1 is by saturation conduction.The triode Q2 of start-up circuit 1 base stage will be pulled low, and can not be turned on, start-up circuit shut-off.
Output short circuit protection process：During Switching Power Supply output short-circuit, output voltage is fallen too low, transformer output winding Ns
On voltage also become very low, the voltage that transformer auxiliary power supply winding Nf is coupled to also is fallen too low, and can not be continued to control
IC operating voltage Vcc ports are powered, and start-up circuit already also is switched off before this, control IC operating voltage Vcc ports electricity
Pressure will reduce rapidly, and control IC is stopped.But the electric capacity C3 of protection duration initialization circuit 4 is already filled with electricity, start-up circuit
The triode Q1 of breaking circuit 5 will continue saturation conduction, and start-up circuit is still turned off, and IC is due to no operating voltage for control, still
It is stopped, the time being stopped is determined by electric capacity C3, R6.So as to reduce working time during Switching Power Supply output short-circuit,
Play a part of reducing short-circuit dissipation and reduce start-up circuit power consumption.
Short-circuit self- recoverage process：After the completion of the capacitor discharge time of protection duration initialization circuit 4, start-up circuit will again
Start and give control IC power supplies.If Switching Power Supply output short-circuit does not eliminate, the course of work of the above will be circulated；If Switching Power Supply exports
After short circuit eliminates, transformer auxiliary power supply winding power circuitry can control IC power supplies with bio-occlusion, and product can enter normal work
Make state.
Embodiment two
Fig. 4 is the circuit diagram of the embodiment of the present invention two, and its operation principle and embodiment one are just the same, unique difference
It is that the benchmark setting means in voltage sample and delay circuit 3 is different.Embodiment one uses two resistance R4, R5 partial pressure shapes
Into reference voltage, embodiment two forms reference voltage, the second voltage-regulator diode Z2 negative electrode connection using R4 series voltage stabilizing pipes Z2
To the 3rd divider resistance R4 and the tie point of the first operational amplifier A R1 input in the same direction, the second voltage-regulator diode Z2 sun
Pole is connected to reference ground.Other all working processes and embodiment one are just the same, will not be repeated here.
Embodiment three
Fig. 5 is the circuit diagram of the embodiment of the present invention three, and its operation principle and embodiment one are just the same, unique difference
It is that start-up circuit breaking circuit 5 substitutes triode Q1 using metal-oxide-semiconductor TR1, metal-oxide-semiconductor TR1 grid turns off electricity as start-up circuit
The input on road 5, the output end of connection protection duration initialization circuit 4；Metal-oxide-semiconductor TR1 drain electrode is as start-up circuit breaking circuit 5
Output end, connect start-up circuit 1 control terminal；Metal-oxide-semiconductor TR1 source electrode is connected to reference ground.Other all working processes and
Embodiment one is just the same, will not be repeated here.
Example IV
Fig. 6 is the circuit diagram of the embodiment of the present invention four, and its operation principle and embodiment two are just the same, unique difference
It is that start-up circuit breaking circuit 5 substitutes triode Q1 using metal-oxide-semiconductor TR1, metal-oxide-semiconductor TR1 grid turns off electricity as start-up circuit
The input on road 5, the output end of connection protection duration initialization circuit 4；Metal-oxide-semiconductor TR1 drain electrode is as start-up circuit breaking circuit 5
Output end, connect start-up circuit 1 control terminal；Metal-oxide-semiconductor TR1 source electrode is connected to reference ground.Other all working processes and
Embodiment two is just the same, will not be repeated here.
In four embodiments of the above, during Switching Power Supply output short-circuit, control IC operating voltages Vcc and IC outputs are controlled
PWM drive waveforms are as shown in Figure 7.The beneficial effect of the present embodiment is further illustrated below by way of specific experimental data：
Operating current I1=20mA total when controlling IC short circuits is taken, Switching Power Supply input voltage vin=1000V, controls IC
Operating voltage Vcc=15V, short circuiting work time ton=20ms, short circuit hiccup cycle T=1000ms.
When using prior art, during Switching Power Supply output short-circuit, the power consumption of start-up circuit is：
P=(Vin-Vcc) * I1=(1000-15) × 20 × 10-3=19.7 (W)
When using the present embodiment technology, during Switching Power Supply output short-circuit, the power consumption of start-up circuit is：
By comparing calculation, under prior art conditions, during Switching Power Supply output short-circuit, the power consumption of start-up circuit is very big；
When using the present embodiment, the lower power consumption of start-up circuit is original
The implementation of the present invention is not limited to this, according to the above of the present invention, is known using the ordinary skill of this area
Knowledge and customary means, under the premise of the above-mentioned basic fundamental thought of the present invention is not departed from, the present invention can also make other a variety of shapes
The modification of formula, goods change is replaced, all fallen within rights protection scope of the present invention.
Claims (11)
- A kind of 1. output short circuit protection circuit of Switching Power Supply, it is characterised in that：Supplied including start-up circuit, transformer assists winding Circuit, voltage sample and delay circuit, protection duration initialization circuit, start-up circuit breaking circuit, control IC operating voltages Vcc Port, input voltage port Vin；Described start-up circuit includes an input, an output end, a control terminal；Described transformation Device assists winding power supply circuit includes a winding, an output end；Described voltage sample and delay circuit include an input, one Output end；Described protection duration initialization circuit includes an input, an output end；Described start-up circuit breaking circuit includes One input, an output end；Input voltage port Vin described in the input connection of described start-up circuit, described startup Control IC operating voltage Vcc ports described in the output end connection of circuit；Described transformer assists winding power supply circuit around The output winding of group coupling main transformer, the control IC described in the output end connection of described transformer assists winding power supply circuit Operating voltage Vcc ports；Described voltage sample connects described control IC operating voltage Vcc ends with the input of delay circuit Mouthful, described voltage sample connects the input of described protection duration initialization circuit with the output end of delay circuit；Described Protect the input of the described start-up circuit breaking circuit of the output end connection of duration initialization circuit；Described start-up circuit shut-off The control terminal of start-up circuit described in the output end connection of circuit；Described start-up circuit gives described control IC operating voltages Vcc ports power, and Switching Power Supply is entered normal work；After start completion, by described transformer assists winding power supply circuit Powered to described control IC operating voltage Vcc ports；Described voltage sample and delay circuit opens in described start-up circuit The voltage of described control IC operating voltage Vcc ports is detected during dynamic, it is determined that described control IC operating voltages The voltage of Vcc ports is normal and after postponing a period of time, the charging of the described protection duration initialization circuit of output one signal control； A signal will be exported after described protection duration initialization circuit is fully charged to described start-up circuit breaking circuit；Described startup Circuit breaking circuit turns off described start-up circuit after receiving the signal of described protection duration initialization circuit；When switch electricity Control IC operating voltage Vcc port voltages described in during the output short-circuit of source will reduce rapidly, and described control IC is stopped, if Switching Power Supply exports sustained short-circuit, and Switching Power Supply will circulate above step；It is while described when Switching Power Supply output short-circuit eliminates After protection duration initialization circuit guard time terminates, Switching Power Supply will enter normal condition from start-up course again.
- 2. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described start-up circuit Including the first current-limiting resistance, the second current-limiting resistance, the first triode, the first voltage-regulator diode, the first diode；Described first Current-limiting resistance one end connection power input and the second described current-limiting resistance one end, the first described current-limiting resistance it is another The colelctor electrode of the first described triode of one end connection；The one or three pole described in the other end connection of the second described current-limiting resistance The negative electrode of the base stage of pipe and the first described voltage-regulator diode；The anode of the first described voltage-regulator diode is connected to reference ground； The output end of start-up circuit breaking circuit described in the base stage connection of the first described triode, the hair of the first described triode The anode of the first described diode of emitter-base bandgap grading connection；The first described triode is NPN type triode；The first described diode The described control IC operating voltage Vcc ports of negative electrode connection.
- 3. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described transformer is auxiliary Winding power circuitry is helped to include the first winding, the 3rd current-limiting resistance, the second diode, the first filter capacitor；Described first around Group coupling main transformer output winding on voltage, the first described winding one end connection reference ground, described first around The anode of the second diode described in the other end connection of group；First that the negative electrode connection of the second described diode is described filters Control IC operating voltage Vcc ports described in one end of electric capacity and connection；The other end connection ginseng of the first described filter capacitor Examine ground.
- 4. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described voltage sample Include the first divider resistance, the second divider resistance, the first delay electric capacity, the 3rd divider resistance, the 4th partial pressure electricity with delay circuit Resistance, the first operational amplifier, the 3rd diode；Control IC operating voltages described in one end connection of the first described divider resistance Vcc ports, one end of the second described divider resistance of the other end connection of the first described divider resistance and connection it is described the One end of one delay electric capacity；The other end of the first described delay electric capacity is connected to reference ground；The second described divider resistance The other end is to reference ground；The series connection node of described the first divider resistance and the second described divider resistance is connected to described the The in-phase input end of one operational amplifier；Control IC operating voltages Vcc described in one end connection of the 3rd described divider resistance Port, one end of the 4th divider resistance described in the other end connection of the 3rd described divider resistance；Described the 4th partial pressure electricity The other end of resistance is connected to reference ground；The 3rd described divider resistance and the series connection node of the 4th described divider resistance are connected to The inverting input of the first described operational amplifier；Control described in the power positive end connection of the first described operational amplifier IC operating voltage Vcc ports, the power supply negative terminal of the first described operational amplifier are connected to reference ground, and the first described computing is put The anode of the 3rd diode described in the output end connection of big device；The negative electrode of the 3rd described diode is adopted as described voltage The output end of sample and delay circuit, connect the input of described protection duration initialization circuit.
- 5. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described voltage sample Include the first divider resistance, the second divider resistance, the first delay electric capacity, the 3rd divider resistance, the second voltage stabilizing two with delay circuit Pole pipe, the first operational amplifier, the 3rd diode；The control IC work that one end connection of the first described divider resistance is described is electric Press Vcc ports, one end of the second described divider resistance of the other end connection of the first described divider resistance and connection are described One end of first delay electric capacity；The other end of the first described delay electric capacity is connected to reference ground；The second described divider resistance The other end to reference ground；The series connection node of described the first divider resistance and the second described divider resistance is connected to described The in-phase input end of first operational amplifier；Control IC operating voltages described in one end connection of the 3rd described divider resistance Vcc ports, the negative electrode of the second voltage-regulator diode described in the other end connection of the 3rd described divider resistance；Described second is steady The anode of pressure diode is connected to reference ground；The 3rd described divider resistance and the series connection node of the second described voltage-regulator diode It is connected to the inverting input of the first described operational amplifier；Described in the power positive end connection of the first described operational amplifier Control IC operating voltage Vcc ports, the power supply negative terminal of the first described operational amplifier is connected to reference ground, described first The anode of the 3rd diode described in the output end connection of operational amplifier；The negative electrode of the 3rd described diode is as described The output end of voltage sample and delay circuit, connect the input of described protection duration initialization circuit.
- 6. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described protection duration Initialization circuit includes the first storage capacitor, the first discharge resistance, the first biasing resistor；One end of the first described storage capacitor connects Connect one end of the first described discharge resistance and be connected to the output end of described voltage sample and delay circuit；Described first The other end of storage capacitor is connected to reference ground；The other end of the first described discharge resistance is connected to the first described biased electrical One end of resistance；The other end of the first described biasing resistor is connected to reference ground；The first described discharge resistance and described Output end of the series connection node of one biasing resistor as described protection duration initialization circuit, is connected to described start-up circuit and closes The input of deenergizing.
- 7. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described start-up circuit Breaking circuit includes the second triode；Input of the base stage of the second described triode as start-up circuit breaking circuit, even Connect the output end of described protection duration initialization circuit；The colelctor electrode of the second described triode is as start-up circuit breaking circuit Output end, connect the control terminal of described start-up circuit；The emitter stage of the second described triode is connected to reference ground.
- 8. the output short circuit protection circuit of Switching Power Supply according to claim 7, it is characterised in that：The two or three described pole Manage as NPN type triode.
- 9. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described start-up circuit Breaking circuit includes the first metal-oxide-semiconductor；Input of the grid of the first described metal-oxide-semiconductor as start-up circuit breaking circuit, connection The output end of described protection duration initialization circuit；The drain electrode of the first described metal-oxide-semiconductor is as the defeated of start-up circuit breaking circuit Go out end, connect the control terminal of described start-up circuit；The source electrode of the first described metal-oxide-semiconductor is connected to reference ground.
- 10. the output short circuit protection circuit of Switching Power Supply according to claim 9, it is characterised in that：The first described MOS Manage as N-channel FET.
- 11. the output short circuit protection circuit of Switching Power Supply according to claim 1, it is characterised in that：Described voltage is adopted Sample and delay circuit and described protection duration initialization circuit work independently, and extend the time and guard time can independent setting.
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| CN201510897783.2A CN105429106B (en) | 2015-12-08 | 2015-12-08 | A kind of output short circuit protection circuit of Switching Power Supply |
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| CN201510897783.2A CN105429106B (en) | 2015-12-08 | 2015-12-08 | A kind of output short circuit protection circuit of Switching Power Supply |
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| CN105429106B true CN105429106B (en) | 2018-01-23 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106100307B (en) * | 2016-06-30 | 2018-12-28 | 阳光电源股份有限公司 | A kind of Switching Power Supply and its short-circuit protection method |
| CN107070216B (en) * | 2017-02-15 | 2023-06-23 | 杰华特微电子股份有限公司 | Control method and control circuit of switching circuit and switching circuit |
| TWI688187B (en) * | 2019-01-10 | 2020-03-11 | 新唐科技股份有限公司 | Voltage monitoring system and method thereof |
| CN111181372B (en) * | 2020-03-02 | 2021-02-02 | 北京曙光航空电气有限责任公司 | Direct current bus current limiting circuit |
| CN111711170B (en) * | 2020-07-07 | 2023-06-13 | 成都芯源系统有限公司 | Switching power supply short-circuit protection circuit and method |
| CN112290512B (en) * | 2020-10-23 | 2023-03-14 | 广州金升阳科技有限公司 | Switch power supply overcurrent protection circuit capable of preventing false triggering |
| CN112564046B (en) * | 2020-12-02 | 2023-08-11 | 河南嘉晨智能控制股份有限公司 | Switching power supply short-circuit protection circuit |
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