CN105429106A - Output short circuit protection method of switch power supply and circuit - Google Patents
Output short circuit protection method of switch power supply and circuit Download PDFInfo
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- CN105429106A CN105429106A CN201510897783.2A CN201510897783A CN105429106A CN 105429106 A CN105429106 A CN 105429106A CN 201510897783 A CN201510897783 A CN 201510897783A CN 105429106 A CN105429106 A CN 105429106A
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Abstract
The invention discloses an output short circuit protection method of a switch power supply and a circuit. The circuit comprises a start circuit, a transformer auxiliary winding power supply circuit, a voltage sampling and delay circuit, a protection time duration setting circuit, a start circuit switch-off circuit and a control IC working voltage Vcc port. According to the general conception of the output short circuit protection method, the method comprises the following steps: judging whether the output of a switch power supply is in short circuit or not through detecting the voltage of a transformer auxiliary power supply winding; when confirming that the output of the switch power supply is in short circuit, controlling the start circuit to work in an intermittent mode to reduce the output short circuit power consumption of the switch power supply and the power consumption of the start circuit, thus greatly improving the reliability of the output short circuit protection and further improving the power density of the switch power supply greatly.
Description
Technical field
The present invention relates to Switching Power Supply, particularly the output short-circuit protection method of Switching Power Supply and circuit.
Background technology
Along with the progress of power electronic technology, Switching Power Supply is constantly to high power density, high efficiency, high reliability development, and the output short circuit protection of Switching Power Supply has become an important indicator of reliability.Realizing the technology of Switching Power Supply output short-circuit at present, is all that the electric current detected on main power circuit by control IC is realized, as shown in Figure 1.When Switching Power Supply output short-circuit, the inductance value of Transformer Winding will sharply decline, when the conducting of main power circuit switching tube, electric current on main power circuit will sharply increase, control IC will detect a very large electric current by main power circuit current detection circuit, then control IC is by internal logic circuit, carries out judging and controlling.General control method is that the PWM drive level intermittence of driving master power switch pipe is exported, and is called formula protection of having the hiccups, reduces power consumption during Switching Power Supply output short-circuit in industry.But when Switching Power Supply output short-circuit, auxiliary winding power circuitry cannot power to control IC again, and the now power supply of control IC will all be powered by start-up circuit.When the high input voltage such as railway, photovoltaic application scenario, the power consumption of start-up circuit will be very large.Suppose that input voltage is 1000VDC, during Switching Power Supply output short-circuit, control IC consumes total electric current is 20mA, and control IC work is suppressed as 10V, and the power of so start-up circuit consumption will be: (1000-10) × 0.02=19.8W.This means that start-up circuit will need very powerful device, be substantially difficult to the requirement meeting high power density, high reliability.Therefore mainly there is following shortcoming in existing techniques in realizing Switching Power Supply output short circuit protection:
(1), in high input voltage application scenario, during Switching Power Supply output short-circuit, start-up circuit power consumption is very large.
(2), in high input voltage application scenario, during Switching Power Supply output short-circuit, compatible high power density and high reliability request is difficult to.
Summary of the invention
Have in view of that; one of the technical problem to be solved in the present invention is: overcome in prior art in high input voltage application scenario; during Switching Power Supply output short-circuit; start-up circuit power consumption is large; be difficult to the shortcomings such as compatible high power density and high reliability request, provide a kind of Switching Power Supply output short-circuit protection method, described Switching Power Supply output short-circuit protection method both can reduce short-circuit dissipation; the power consumption of start-up circuit during short circuit can be reduced again, improve power density and the reliability of product.
Corresponding therewith, two of the technical problem to be solved in the present invention is: provide a kind of Switching Power Supply output short circuit protection circuit.
The present invention is for one of solving the problems of the technologies described above, and the technical scheme provided is:
An output short-circuit protection method for Switching Power Supply, comprises the steps:
Setting up procedure, start-up circuit powers to control IC operating voltage Vcc port, makes Switching Power Supply enter normal work; After having started, winding power circuitry is assisted to power to control IC operating voltage Vcc port by transformer;
Start-up circuit turns off step, voltage sample and the voltage of delay circuit to the control IC operating voltage Vcc port in setting up procedure detect, the voltage determining control IC operating voltage Vcc port normally and after postponing a period of time, export the charging of a signal controlling protection duration initialization circuit; Protection duration initialization circuit to be full of output one signal after electricity to start-up circuit breaking circuit; Start-up circuit turns off after receiving the signal of protection duration initialization circuit by start-up circuit breaking circuit;
Output short circuit protection step; during Switching Power Supply output short-circuit; the voltage that transformer assists winding power circuitry to export falls too low rapidly; cannot continue to power to control IC operating voltage Vcc port; and now protect duration initialization circuit still to continue start-up circuit to turn off by start-up circuit breaking circuit; control IC operating voltage Vcc port voltage will reduce rapidly, and control IC quits work, and reduce operating time during Switching Power Supply output short-circuit.If Switching Power Supply exports sustained short-circuit, Switching Power Supply will circulate above step, form intermittent work, play the effect reducing short-circuit dissipation and reduction start-up circuit power consumption.
Short circuit self-recoverage step: when Switching Power Supply output short-circuit is eliminated, after protecting duration initialization circuit guard time to terminate, Switching Power Supply will enter normal condition from start-up course again simultaneously.
The present invention for solve the problems of the technologies described above two, the technical scheme provided is:
A kind of output short circuit protection circuit of Switching Power Supply: comprise start-up circuit, winding power circuitry assisted by transformer, voltage sample and delay circuit, protection duration initialization circuit, start-up circuit breaking circuit, control IC operating voltage Vcc port, input voltage port Vin; Described start-up circuit comprises an input, an output, a control end; Described transformer assists winding power circuitry to comprise a winding, an output; Described voltage sample and delay circuit comprise an input, an output; Described protection duration initialization circuit comprises an input, an output; Described start-up circuit breaking circuit comprises an input, an output.The input voltage port Vin described in input connection of described start-up circuit, the control IC operating voltage Vcc port described in output connection of described start-up circuit; The output winding of the winding coupled main transformer of winding power circuitry assisted by described transformer, and the control IC operating voltage Vcc port described in output connection of winding power circuitry assisted by described transformer; Control IC operating voltage Vcc port described in described voltage sample is connected with the input of delay circuit, the input of the protection duration initialization circuit described in described voltage sample is connected with the output of delay circuit; The input of the start-up circuit breaking circuit described in output connection of described protection duration initialization circuit; The control end of the start-up circuit described in output connection of described start-up circuit breaking circuit;
Described start-up circuit powers to described control IC operating voltage Vcc port, makes Switching Power Supply enter normal work; After having started, winding power circuitry is assisted to power to described control IC operating voltage Vcc port by described transformer; Described voltage sample and delay circuit detect the voltage of described control IC operating voltage Vcc port in described start-up circuit start-up course, the voltage determining described control IC operating voltage Vcc port normally and after postponing a period of time, export the charging of the protection duration initialization circuit described in a signal controlling; Described protection duration initialization circuit to be full of output one signal after electricity to described start-up circuit breaking circuit; Described start-up circuit turns off after receiving the signal of described protection duration initialization circuit by described start-up circuit breaking circuit; Control IC operating voltage Vcc port voltage described in when Switching Power Supply output short-circuit will reduce rapidly, and described control IC quits work, if Switching Power Supply exports sustained short-circuit, Switching Power Supply will circulate above step; When Switching Power Supply output short-circuit is eliminated, after the protection duration initialization circuit guard time simultaneously terminates, Switching Power Supply will enter normal condition from start-up course again.
Preferably, described start-up circuit comprises the first current-limiting resistance, the second current-limiting resistance, the first triode, the first voltage stabilizing didoe, the first diode.One end of the first described current-limiting resistance connects one end of power input and the second described current-limiting resistance, the collector electrode of first triode described in other end connection of the first described current-limiting resistance; The base stage of the first triode described in other end connection of the second described current-limiting resistance and the negative electrode of the first described voltage stabilizing didoe; The anode of the first described voltage stabilizing didoe is connected to reference to ground; The output of the start-up circuit breaking circuit described in base stage connection of the first described triode, the anode of first diode described in emitter connection of the first described triode; The first described triode is NPN type triode; The control IC operating voltage Vcc port described in negative electrode connection of the first described diode;
Preferably, described transformer assists winding power circuitry to comprise the first winding, the 3rd current-limiting resistance, the second diode, the first filter capacitor.The output winding voltage of the first described winding coupled main transformer, one end of the first described winding connects with reference to ground, the anode of second diode described in other end connection of the first described winding; The one end of the first filter capacitor described in the negative electrode of the second described diode connects be connected described in control IC operating voltage Vcc port; The other end of the first described filter capacitor connects with reference to ground;
Preferably, described voltage sample and delay circuit comprise the first divider resistance, the second divider resistance, and first postpones electric capacity, the 3rd divider resistance, the 4th divider resistance, the first operational amplifier, the 3rd diode.Control IC operating voltage Vcc port described in one end of the first described branch pressure voltage connects, one end of the one end of the second divider resistance described in the other end of the first described divider resistance connects and the first delay electric capacity described in being connected; Described first other end postponing electric capacity is connected to reference to ground; The other end of the second described divider resistance is to reference ground; The series connection node of the first described divider resistance and the second described divider resistance is connected to the in-phase input end of the first described operational amplifier; The control IC operating voltage Vcc port described in the connection of one end of the 3rd described branch pressure voltage, one end of the 4th divider resistance described in other end connection of the 3rd described divider resistance; The other end of the 4th described divider resistance is connected to reference to ground; The series connection node of the 3rd described divider resistance and the 4th described divider resistance is connected to the inverting input of the first described operational amplifier; The control IC operating voltage Vcc port described in power positive end connection of the first described operational amplifier, the power supply negative terminal of the first described operational amplifier is connected to reference to ground, the anode of the 3rd diode described in output connection of the first described operational amplifier; The negative electrode of the 3rd described diode as the output of described voltage sample and delay circuit, the input of the protection duration initialization circuit described in connection.
Preferably, described voltage sample and delay circuit comprise the first divider resistance, the second divider resistance, and first postpones electric capacity, the 3rd divider resistance, the second voltage stabilizing didoe, the first operational amplifier, the 3rd diode.Control IC operating voltage Vcc port described in one end of the first described branch pressure voltage connects, one end of the one end of the second divider resistance described in the other end of the first described divider resistance connects and the first delay electric capacity described in being connected; Described first other end postponing electric capacity is connected to reference to ground; The other end of the second described divider resistance is to reference ground; The series connection node of the first described divider resistance and the second described divider resistance is connected to the in-phase input end of the first described operational amplifier; The control IC operating voltage Vcc port described in the connection of one end of the 3rd described branch pressure voltage, the negative electrode of second voltage stabilizing didoe described in other end connection of the 3rd described divider resistance; The anode of the second described voltage stabilizing didoe is connected to reference to ground; The 3rd described divider resistance and the series connection node of the second described voltage stabilizing didoe are connected to the inverting input of the first described operational amplifier; The control IC operating voltage Vcc port described in power positive end connection of the first described operational amplifier, the power supply negative terminal of the first described operational amplifier is connected to reference to ground, the anode of the 3rd diode described in output connection of the first described operational amplifier; The negative electrode of the 3rd described diode as the output of described voltage sample and delay circuit, the input of the protection duration initialization circuit described in connection.
Preferably, described protection duration initialization circuit comprises the first storage capacitor, the first discharge resistance, the first biasing resistor.The one end of the first discharge resistance described in one end of the first described storage capacitor connects and be connected to described voltage sample and the output of delay circuit; The other end of the first described storage capacitor is connected to reference to ground; The other end of the first described discharge resistance is connected to one end of the first described biasing resistor; The other end of the first described biasing resistor is connected to reference to ground; The series connection node of the first described discharge resistance and the first described biasing resistor, as the output of described protection duration initialization circuit, is connected to the input of described start-up circuit breaking circuit.
Preferably, described start-up circuit breaking circuit comprises the second triode.The base stage of the second described triode as the input of start-up circuit breaking circuit, the output of the protection duration initialization circuit described in connection; The collector electrode of the second described triode as the output of start-up circuit breaking circuit, the control end of the start-up circuit described in connection; The emitter of the second described triode is connected to reference to ground.The second described triode is NPN type triode;
Preferably, described start-up circuit breaking circuit comprises the first metal-oxide-semiconductor.The grid of the first described metal-oxide-semiconductor as the input of start-up circuit breaking circuit, the output of the protection duration initialization circuit described in connection; The drain electrode of the first described metal-oxide-semiconductor as the output of start-up circuit breaking circuit, the control end of the start-up circuit described in connection; The source electrode of the first described metal-oxide-semiconductor is connected to reference to ground.The first described metal-oxide-semiconductor is N channel field-effect pipe;
Preferably, described voltage sample and delay circuit and described protection duration initialization circuit work alone, and time expand and guard time can independently set.
Operation principle of the present invention will labor in embodiment part, is not repeated herein.
Compared with prior art, the present invention has following outstanding advantage:
(1), during Switching Power Supply output short-circuit, can enter intermittent work pattern, short-circuit dissipation is little.Operating time when carrying out configuration switch power supply short circuit by regulating circuit parameter.
(2), during Switching Power Supply output short-circuit, start-up circuit intermittent work, start-up circuit power consumption is very little.Under high input voltage occasion, the advantage that start-up circuit power consumption is little is more obvious, ensures the reliability of Switching Power Supply, greatly improves the power density of product simultaneously.
Accompanying drawing explanation
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;
The PWM drive waveforms that when Fig. 7 is Switching Power Supply output short-circuit, control IC operating voltage Vcc and control IC exports.
Embodiment
The design of the technology of the present invention is; judge that Switching Power Supply exports whether short circuit by the voltage detecting transformer auxiliary power supply winding; when determining 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; the reliability of Switching Power Supply output short circuit protection is improved greatly, and the power density of Simultaneous Switching power supply also can improve greatly.
Technical scheme for a better understanding of the present invention, below in conjunction with the drawings and specific embodiments, the present invention is described in more detail.
See Fig. 2, be functional block diagram of the present invention, comprise start-up circuit 1, winding power circuitry 2, voltage sample and delay circuit 3 assisted by transformer, protect duration initialization circuit 4, start-up circuit breaking circuit 5, control IC operating voltage Vcc port.
Further illustrate below in conjunction with specific implementation circuit.
Embodiment one
Fig. 3 is the circuit diagram of the embodiment of the present invention one, and it comprises: start-up circuit 1, transformer assist winding power circuitry 2, voltage sample and delay circuit 3, protection duration initialization circuit 4, start-up circuit breaking circuit 5, control IC operating voltage Vcc port, input voltage port Vin; Start-up circuit 1 comprises an input, an output, a control end; Transformer assists winding power circuitry 2 to comprise a winding, an output; Voltage sample and delay circuit 3 comprise an input, an output; Protection duration initialization circuit 4 comprises an input, an output; Start-up circuit breaking circuit 5 comprises an input, an output.The input of start-up circuit 1 connects input voltage port Vin, the output connection control IC operating voltage Vcc port of start-up circuit 1; The output winding of the winding coupled main transformer of winding power circuitry 2 assisted by transformer, and the output connection control IC operating voltage Vcc port of winding power circuitry 2 assisted by transformer; The input connection control IC operating voltage Vcc port of voltage sample and delay circuit 3, voltage sample is connected the input of protection duration initialization circuit 4 with the output of delay circuit 3; The output of protection duration initialization circuit 4 connects the input of start-up circuit breaking circuit 5; The output of start-up circuit breaking circuit 5 connects the control end of start-up circuit 1.
Start-up circuit 1 comprises the first current-limiting resistance R8, the second current-limiting resistance R9, the first triode Q2, the first voltage stabilizing didoe Z1, the first diode D3.One end of first current-limiting resistance R8 connects one end of power input and the second current-limiting resistance R9, and the other end of the first current-limiting resistance R8 connects the collector electrode of the first triode Q2; The other end of the second current-limiting resistance R9 connects the base stage of the first triode Q2 and the negative electrode of the first voltage stabilizing didoe Z1; The anode of the first voltage stabilizing didoe Z1 is connected to reference to ground; The base stage of the first triode Q2 connects the output of start-up circuit breaking circuit 5, and the emitter of the first triode Q2 connects the anode of the first diode D3; First triode Q2 is NPN type triode; The negative electrode connection control IC operating voltage Vcc port of the first diode D3;
Transformer assists winding power circuitry 2 to comprise the first winding Nf, the 3rd current-limiting resistance R1, the second diode D1, the first filter capacitor C1.Voltage on the output winding Ns of the first winding Nf coupling main transformer, one end of the first winding Nf connects with reference to ground, and the other end of the first winding Nf connects the anode of the second diode D1; The negative electrode of the second diode D1 connects one end and the connection control IC operating voltage Vcc port of the first filter capacitor C1; The other end of the first filter capacitor C1 connects with reference to ground;
Voltage sample and delay circuit 3 comprise the first divider resistance R2, the second divider resistance R3, and first postpones electric capacity C2, the 3rd divider resistance R4, the 4th divider resistance R5, the first operational amplifier A R1, the 3rd diode D2.One end connection control IC operating voltage Vcc port of the first branch pressure voltage R2, the other end of the first divider resistance R2 connects one end of the second divider resistance R3 and the one end being connected the first delay electric capacity C2; First other end postponing electric capacity C2 is connected to reference to ground; The other end of the second divider resistance R3 is to reference ground; The series connection node of the first divider resistance R2 and the second divider resistance R3 is connected to the in-phase input end of the first operational amplifier A R1; One end connection control IC operating voltage Vcc port of the 3rd branch pressure voltage R4, the other end of the 3rd divider resistance R4 connects one end of the 4th divider resistance R5; The other end of the 4th divider resistance R5 is connected to reference to ground; The series connection node of the 3rd divider resistance R4 and the 4th divider resistance R5 is connected to the inverting input of the first operational amplifier A R1; The power positive end connection control IC operating voltage Vcc port of the first operational amplifier A R1, the power supply negative terminal of the first operational amplifier A R1 is connected to reference to ground, and the output of the first operational amplifier A R1 connects the anode of the 3rd diode D2; The negative electrode of the 3rd diode D2, as the output of voltage sample and delay circuit 3, connects the input of protection duration initialization circuit 4.
Protection duration initialization circuit 4 comprises the first storage capacitor C3, the first discharge resistance R6, the first biasing resistor R7.One end of first storage capacitor C3 connects one end of the first discharge resistance R6 and is connected to the output of voltage sample and delay circuit 3; The other end of the first storage capacitor C3 is connected to reference to ground; The other end of the first discharge resistance R6 is connected to one end of the first biasing resistor R7; The other end of the first biasing resistor R7 is connected to reference to ground; The series connection node of the first discharge resistance R6 and the first biasing resistor R7, as the output of protection duration initialization circuit 4, is connected to the input of start-up circuit breaking circuit 5.
Start-up circuit breaking circuit 5 comprises the second triode Q1.The base stage of the second triode Q1, as the input of start-up circuit breaking circuit 5, connects the output of protection duration initialization circuit 4; The collector electrode of the second triode Q1, as the output of start-up circuit breaking circuit 5, connects the control end of start-up circuit 1; The emitter of the second triode Q1 is connected to reference to ground.Second triode Q1 is NPN type triode;
Its operation principle is as follows:
Start-up course: start-up circuit 1 powers to control IC operating voltage Vcc port, makes Switching Power Supply enter normal work, and switch power source output voltage is set up normal.Transformer assists the voltage on winding power circuitry 2 coupling output winding to power to control IC operating voltage Vcc port;
Start-up circuit turn off process: in start-up course, R4, R5 form a reference voltage by dividing potential drop, R2, R3 are sampled to Vcc voltage by dividing potential drop, C2 carries out a period of time time delay to sampled signal, when ensureing that Switching Power Supply exports not short circuit, start-up circuit 1 has time enough to complete start-up course.Sampling confirms that Vcc power supply reaches normal voltage; after C2 has postponed sampled signal simultaneously; operational amplifier A R1 exports the electric capacity C3 of a high level to protection duration initialization circuit 4 and charges; because operational amplifier A R1 exports internal resistance; much smaller than R6; therefore, before can ensureing that start-up circuit is turned off, the voltage on electric capacity C3 is filled the voltage approximating Vcc.After protection duration initialization circuit 4 is full of electricity, the triode Q1 of start-up circuit breaking circuit 5 is by saturation conduction.The base stage of the triode Q2 of start-up circuit 1 will be dragged down, cannot conducting, and start-up circuit turns off.
Output short circuit protection process: during Switching Power Supply output short-circuit; output voltage falls too low; the voltage that transformer exports on winding Ns also becomes very low; the voltage that transformer auxiliary power supply winding Nf is coupled to also falls too low; cannot continue to power to control IC operating voltage Vcc port; and start-up circuit has also been turned off before this, control IC operating voltage Vcc port voltage will reduce rapidly, and control IC quits work.But the electric capacity C3 of protection duration initialization circuit 4 is filled electricity; the triode Q1 of start-up circuit breaking circuit 5 will continue saturation conduction, and start-up circuit is still turned off, and control IC is not owing to having operating voltage; still quit work, the out-of-work time is determined by electric capacity C3, R6.Thus operating time when reducing Switching Power Supply output short-circuit, play the effect reducing short-circuit dissipation and reduce start-up circuit power consumption.
Short circuit self-recoverage process: after the capacitor discharge time of protection duration initialization circuit 4 completes, start-up circuit will restart powers to control IC.If Switching Power Supply output short-circuit is not eliminated, by the course of work above for circulation; If after Switching Power Supply output short-circuit is eliminated, transformer auxiliary power supply winding power circuitry can be powered by bio-occlusion control IC, and product can enter normal operating state.
Embodiment two
Fig. 4 is the circuit diagram of the embodiment of the present invention two, its operation principle and embodiment one just the same, unique difference is, the benchmark setting means in voltage sample and delay circuit 3 is different.Embodiment one adopts two resistance R4, R5 dividing potential drops to form reference voltage, embodiment two adopts R4 series voltage stabilizing pipe Z2 to form reference voltage, the negative electrode of the second voltage stabilizing didoe Z2 is connected to the tie point of the input in the same way of the 3rd divider resistance R4 and the first operational amplifier A R1, and the anode of the second voltage stabilizing didoe Z2 is connected to reference to ground.Other all working process and embodiment one just the same, do not repeat them here.
Embodiment three
Fig. 5 is the circuit diagram of the embodiment of the present invention three, its operation principle and embodiment one just the same, unique difference is, start-up circuit breaking circuit 5 adopts metal-oxide-semiconductor TR1 to substitute triode Q1, the grid of metal-oxide-semiconductor TR1, as the input of start-up circuit breaking circuit 5, connects the output of protection duration initialization circuit 4; The drain electrode of metal-oxide-semiconductor TR1, as the output of start-up circuit breaking circuit 5, connects the control end of start-up circuit 1; The source electrode of metal-oxide-semiconductor TR1 is connected to reference to ground.Other all working process and embodiment one just the same, do not repeat them here.
Embodiment four
Fig. 6 is the circuit diagram of the embodiment of the present invention four, its operation principle and embodiment two just the same, unique difference is, start-up circuit breaking circuit 5 adopts metal-oxide-semiconductor TR1 to substitute triode Q1, the grid of metal-oxide-semiconductor TR1, as the input of start-up circuit breaking circuit 5, connects the output of protection duration initialization circuit 4; The drain electrode of metal-oxide-semiconductor TR1, as the output of start-up circuit breaking circuit 5, connects the control end of start-up circuit 1; The source electrode of metal-oxide-semiconductor TR1 is connected to reference to ground.Other all working process and embodiment two just the same, do not repeat them here.
In above four embodiments, during Switching Power Supply output short-circuit, the PWM drive waveforms that control IC operating voltage Vcc and control IC exports as shown in Figure 7.The beneficial effect of the present embodiment is further illustrated below by way of concrete experimental data:
Operating current I1=20mA total when getting control IC short circuit, Switching Power Supply input voltage vin=1000V, control IC operating voltage Vcc=15V, short circuiting work time ton=20ms, short circuit is had the hiccups cycle T=1000ms.
When adopting prior art, during Switching Power Supply output short-circuit, the power consumption of start-up circuit is:
P＝(Vin-Vcc)*I
1＝(1000-15)×20×10
-3＝19.7(W)
When adopting 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 large; When adopting the present embodiment, the lower power consumption of start-up circuit is original
Embodiments of the present invention are not limited thereto; according to foregoing of the present invention; utilize ordinary technical knowledge and the customary means of this area; do not departing under the present invention's above-mentioned basic fundamental thought prerequisite; the present invention can also make amendment, the change of replacement goods of other various ways, all drops within rights protection scope of the present invention.
Claims (12)
1. an output short-circuit protection method for Switching Power Supply, comprises the steps:
Setting up procedure, start-up circuit powers to control IC operating voltage Vcc port, makes Switching Power Supply enter normal work, after having started, assists winding power circuitry to power to described control IC operating voltage Vcc port by transformer;
Start-up circuit turns off step, voltage sample and the voltage of delay circuit to the control IC operating voltage Vcc port in described setting up procedure detect, the voltage determining described control IC operating voltage Vcc port is normally and after postponing a period of time, export the charging of a signal controlling protection duration initialization circuit, described protection duration initialization circuit to be full of after electricity by output one signal to start-up circuit breaking circuit, and described start-up circuit turns off after receiving the signal of described protection duration initialization circuit by described start-up circuit breaking circuit;
Output short circuit protection step, during Switching Power Supply output short-circuit, described control IC operating voltage Vcc port voltage will reduce rapidly, and described control IC quits work, if Switching Power Supply exports sustained short-circuit, Switching Power Supply will circulate above step.
Short circuit self-recoverage step, when Switching Power Supply output short-circuit is eliminated, after the protection duration initialization circuit guard time simultaneously terminates, Switching Power Supply will enter normal condition from start-up course again.
2. an output short circuit protection circuit for Switching Power Supply, is characterized in that: comprise start-up circuit, winding power circuitry assisted by transformer, voltage sample and delay circuit, protection duration initialization circuit, start-up circuit breaking circuit, control IC operating voltage Vcc port, input voltage port Vin; Described start-up circuit comprises an input, an output, a control end; Described transformer assists winding power circuitry to comprise a winding, an output; Described voltage sample and delay circuit comprise an input, an output; Described protection duration initialization circuit comprises an input, an output; Described start-up circuit breaking circuit comprises an input, an output; The input voltage port Vin described in input connection of described start-up circuit, the control IC operating voltage Vcc port described in output connection of described start-up circuit; The output winding of the winding coupled main transformer of winding power circuitry assisted by described transformer, and the control IC operating voltage Vcc port described in output connection of winding power circuitry assisted by described transformer; Control IC operating voltage Vcc port described in described voltage sample is connected with the input of delay circuit, the input of the protection duration initialization circuit described in described voltage sample is connected with the output of delay circuit; The input of the start-up circuit breaking circuit described in output connection of described protection duration initialization circuit; The control end of the start-up circuit described in output connection of described start-up circuit breaking circuit; Described start-up circuit powers to described control IC operating voltage Vcc port, makes Switching Power Supply enter normal work; After having started, winding power circuitry is assisted to power to described control IC operating voltage Vcc port by described transformer; Described voltage sample and delay circuit detect the voltage of described control IC operating voltage Vcc port in described start-up circuit start-up course, the voltage determining described control IC operating voltage Vcc port normally and after postponing a period of time, export the charging of the protection duration initialization circuit described in a signal controlling; Described protection duration initialization circuit to be full of output one signal after electricity to described start-up circuit breaking circuit; Described start-up circuit turns off after receiving the signal of described protection duration initialization circuit by described start-up circuit breaking circuit; Control IC operating voltage Vcc port voltage described in when Switching Power Supply output short-circuit will reduce rapidly, and described control IC quits work, if Switching Power Supply exports sustained short-circuit, Switching Power Supply will circulate above step; When Switching Power Supply output short-circuit is eliminated, after the protection duration initialization circuit guard time simultaneously terminates, Switching Power Supply will enter normal condition from start-up course again.
3. the output short circuit protection circuit of Switching Power Supply according to claim 2, is characterized in that: described start-up circuit comprises the first current-limiting resistance, the second current-limiting resistance, the first triode, the first voltage stabilizing didoe, the first diode; One end of the first described current-limiting resistance connects one end of power input and the second described current-limiting resistance, the collector electrode of first triode described in other end connection of the first described current-limiting resistance; The base stage of the first triode described in other end connection of the second described current-limiting resistance and the negative electrode of the first described voltage stabilizing didoe; The anode of the first described voltage stabilizing didoe is connected to reference to ground; The output of the start-up circuit breaking circuit described in base stage connection of the first described triode, the anode of first diode described in emitter connection of the first described triode; The first described triode is NPN type triode; The control IC operating voltage Vcc port described in negative electrode connection of the first described diode.
4. the output short circuit protection circuit of Switching Power Supply according to claim 2, is characterized in that: described transformer assists winding power circuitry to comprise the first winding, the 3rd current-limiting resistance, the second diode, the first filter capacitor; Voltage on the output winding of the first described winding coupled main transformer, one end of the first described winding connects with reference to ground, the anode of second diode described in other end connection of the first described winding; The one end of the first filter capacitor described in the negative electrode of the second described diode connects be connected described in control IC operating voltage Vcc port; The other end of the first described filter capacitor connects with reference to ground.
5. the output short circuit protection circuit of Switching Power Supply according to claim 2, it is characterized in that: described voltage sample and delay circuit comprise the first divider resistance, second divider resistance, first postpones electric capacity, 3rd divider resistance, 4th divider resistance, the first operational amplifier, the 3rd diode; Control IC operating voltage Vcc port described in one end of the first described branch pressure voltage connects, one end of the one end of the second divider resistance described in the other end of the first described divider resistance connects and the first delay electric capacity described in being connected; Described first other end postponing electric capacity is connected to reference to ground; The other end of the second described divider resistance is to reference ground; The series connection node of the first described divider resistance and the second described divider resistance is connected to the in-phase input end of the first described operational amplifier; The control IC operating voltage Vcc port described in the connection of one end of the 3rd described branch pressure voltage, one end of the 4th divider resistance described in other end connection of the 3rd described divider resistance; The other end of the 4th described divider resistance is connected to reference to ground; The series connection node of the 3rd described divider resistance and the 4th described divider resistance is connected to the inverting input of the first described operational amplifier; The control IC operating voltage Vcc port described in power positive end connection of the first described operational amplifier, the power supply negative terminal of the first described operational amplifier is connected to reference to ground, the anode of the 3rd diode described in output connection of the first described operational amplifier; The negative electrode of the 3rd described diode as the output of described voltage sample and delay circuit, the input of the protection duration initialization circuit described in connection.
6. the output short circuit protection circuit of Switching Power Supply according to claim 2, it is characterized in that: described voltage sample and delay circuit comprise the first divider resistance, second divider resistance, first postpones electric capacity, 3rd divider resistance, second voltage stabilizing didoe, the first operational amplifier, the 3rd diode; Control IC operating voltage Vcc port described in one end of the first described branch pressure voltage connects, one end of the one end of the second divider resistance described in the other end of the first described divider resistance connects and the first delay electric capacity described in being connected; Described first other end postponing electric capacity is connected to reference to ground; The other end of the second described divider resistance is to reference ground; The series connection node of the first described divider resistance and the second described divider resistance is connected to the in-phase input end of the first described operational amplifier; The control IC operating voltage Vcc port described in the connection of one end of the 3rd described branch pressure voltage, the negative electrode of second voltage stabilizing didoe described in other end connection of the 3rd described divider resistance; The anode of the second described voltage stabilizing didoe is connected to reference to ground; The 3rd described divider resistance and the series connection node of the second described voltage stabilizing didoe are connected to the inverting input of the first described operational amplifier; The control IC operating voltage Vcc port described in power positive end connection of the first described operational amplifier, the power supply negative terminal of the first described operational amplifier is connected to reference to ground, the anode of the 3rd diode described in output connection of the first described operational amplifier; The negative electrode of the 3rd described diode as the output of described voltage sample and delay circuit, the input of the protection duration initialization circuit described in connection.
7. the output short circuit protection circuit of Switching Power Supply according to claim 2, is characterized in that: described protection duration initialization circuit comprises the first storage capacitor, the first discharge resistance, the first biasing resistor; The one end of the first discharge resistance described in one end of the first described storage capacitor connects and be connected to described voltage sample and the output of delay circuit; The other end of the first described storage capacitor is connected to reference to ground; The other end of the first described discharge resistance is connected to one end of the first described biasing resistor; The other end of the first described biasing resistor is connected to reference to ground; The series connection node of the first described discharge resistance and the first described biasing resistor, as the output of described protection duration initialization circuit, is connected to the input of described start-up circuit breaking circuit.
8. the output short circuit protection circuit of Switching Power Supply according to claim 2, is characterized in that: described start-up circuit breaking circuit comprises the second triode; The base stage of the second described triode as the input of start-up circuit breaking circuit, the output of the protection duration initialization circuit described in connection; The collector electrode of the second described triode as the output of start-up circuit breaking circuit, the control end of the start-up circuit described in connection; The emitter of the second described triode is connected to reference to ground.
9. the output short circuit protection circuit of Switching Power Supply according to claim 8, is characterized in that: the second described triode is NPN type triode.
10. the output short circuit protection circuit of Switching Power Supply according to claim 2, is characterized in that: described start-up circuit breaking circuit comprises the first metal-oxide-semiconductor; The grid of the first described metal-oxide-semiconductor as the input of start-up circuit breaking circuit, the output of the protection duration initialization circuit described in connection; The drain electrode of the first described metal-oxide-semiconductor as the output of start-up circuit breaking circuit, the control end of the start-up circuit described in connection; The source electrode of the first described metal-oxide-semiconductor is connected to reference to ground.
The output short circuit protection circuit of 11. Switching Power Supplies according to claim 10, is characterized in that: the first described metal-oxide-semiconductor is N channel field-effect.
The output short circuit protection circuit of 12. Switching Power Supplies according to claim 2, is characterized in that: described voltage sample and delay circuit and described protection duration initialization circuit work alone, and time expand and guard time can independently set.
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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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| CN106100307A (en) * | 2016-06-30 | 2016-11-09 | 阳光电源股份有限公司 | A kind of Switching Power Supply and short-circuit protection method thereof |
| CN107123969A (en) * | 2017-02-15 | 2017-09-01 | 杰华特微电子（杭州）有限公司 | Output protection circuit and method |
| CN111181372A (en) * | 2020-03-02 | 2020-05-19 | 北京曙光航空电气有限责任公司 | Direct current bus current limiting circuit |
| CN111426866A (en) * | 2019-01-10 | 2020-07-17 | 新唐科技股份有限公司 | Voltage monitoring system and method thereof |
| CN111711170A (en) * | 2020-07-07 | 2020-09-25 | 成都芯源系统有限公司 | Short-circuit protection circuit and method for switching power supply |
| CN112290512A (en) * | 2020-10-23 | 2021-01-29 | 广州金升阳科技有限公司 | Switch power supply overcurrent protection circuit capable of preventing false triggering |
| CN112564046A (en) * | 2020-12-02 | 2021-03-26 | 郑州嘉晨电器有限公司 | Short-circuit protection circuit of switching power supply |
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| CN111181372A (en) * | 2020-03-02 | 2020-05-19 | 北京曙光航空电气有限责任公司 | Direct current bus current limiting circuit |
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| CN111711170A (en) * | 2020-07-07 | 2020-09-25 | 成都芯源系统有限公司 | Short-circuit protection circuit and method for switching power supply |
| CN112290512A (en) * | 2020-10-23 | 2021-01-29 | 广州金升阳科技有限公司 | Switch power supply overcurrent protection circuit capable of preventing false triggering |
| CN112564046A (en) * | 2020-12-02 | 2021-03-26 | 郑州嘉晨电器有限公司 | Short-circuit protection circuit of switching power supply |
| 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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