CN208753975U - A kind of current foldback circuit and the Switching Power Supply comprising the circuit - Google Patents
A kind of current foldback circuit and the Switching Power Supply comprising the circuit Download PDFInfo
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- CN208753975U CN208753975U CN201821404377.3U CN201821404377U CN208753975U CN 208753975 U CN208753975 U CN 208753975U CN 201821404377 U CN201821404377 U CN 201821404377U CN 208753975 U CN208753975 U CN 208753975U
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Abstract
The utility model provides a kind of current foldback circuit and the Switching Power Supply comprising the circuit, and current foldback circuit includes overcurrent hiccup protections circuit, transient state current foldback circuit, compensation level input, current sense input, the first control terminal, the second control terminal and feeder ear；Switching Power Supply comprising the utility model current foldback circuit by overcurrent hiccup protections circuit can export electric current it is excessive when Switching Power Supply be turned off, and Switching Power Supply is made after certain time to resume work automatically state, that is, enters overcurrent hiccup protections state；It being capable of transient current peak value in real-time sampling circuit by transient state current foldback circuit; and down to several switch periods internal trigger overcurrent protections; prevent power device because transient current it is excessive caused by damage; overcurrent hiccup protections circuit is triggered simultaneously, Switching Power Supply is made to enter hiccup formula overcurrent protection state；Double-current ring protection can be realized using a dual operational amplifier in current foldback circuit, and circuit is simple, at low cost, high reliablity.
Description
Technical field:
The utility model relates to power circuit field, in particular to a kind of current foldback circuit and the switch comprising the circuit
Power supply.
Background technique:
Core component of the Switching Power Supply as modern transformation of electrical energy technology, has been widely used in electric power, communication, friendship
Fields, the relevant technologies of Switching Power Supply such as logical, Industry Control also obtain development highly visible.To keep switch converters effectively real
Existing various transformation of electrical energies, and can safely, smoothly run, it must just cooperate with other function module, form a control
System.The control mode of switch converters can be divided into two class of open loop and closed-loop control, and common opened loop control has feedforward control, closes
Ring control mainly includes voltage mode control, current-mode control etc..
Voltage mode control belongs to single-level NFB control, only samples to output voltage and realizes closed loop as feedback signal
Control, as Voltage loop negative feedback control can keep exporting even if input voltage or load current change in very large range
Voltage stabilization, but since in its work, the inductive current or switching current of power circuit have neither part nor lot in control, and loop gain is with defeated
Enter voltage change and change, so that compensation is become increasingly complex, while the variation of any input voltage or output loading is necessary first
Be converted into the variation of output voltage, then controlled to adjust again through feedback loop sampling feedback, thus the control method corresponding speed compared with
Slowly, it when input voltage or output loading jump, is easy to lead to power device transient current because control circuit responds not in time
Or voltage stress is excessive, and certain risk is caused to the reliability of power supply.
It can avoid the generation of the above problem using Controlled in Current Mode and Based, current-mode can be divided into Peak Current-Mode Controlled Circuit again
With average value current control mode, in peak value comparison method, directly sampling inductance or switch peak current participates in control, and puts down
In equal current control, inductance or switching current participate in controlling again after being then first averaged, due to the feature of the two respectively, average current
Control is applied primarily to PFC, and application of the Peak Current-Mode Controlled Circuit in Switching Power Supply is more extensive.
It is as shown in Figure 1 a kind of common peak current mode control switch converter circuit, by taking flyback converter as an example, E/A
For error amplifier, COMP is comparator, and Vo is output voltage, and Vr is reference voltage, and metal-oxide-semiconductor VT is main power switch tube,
The beginning in each period, driving conversion circuit export high level, and metal-oxide-semiconductor VT conducting, transformer T primary current ip is through detection electricity
It hinders Rs and generates Current feedback voltage Vs, output voltage Vo is controlled compared with reference voltage Vr, and after error amplifier amplifies
Voltage Ve processed.During switching tube VT conducting, Vs increases with the rising of primary side current of transformer ip, when Vs peak value reaches Ve
When level, comparator COMP state overturning, driving conversion circuit output becomes low level, switching tube VT cut-off, until next
Period arrives, and driving conversion circuit exports high level again, and converter work enters next cycle.
It is illustrated in figure 2 switching tube VT drive level V in the converter course of work shown in Fig. 1GIt is powered on sampling resistor
The relation schematic diagram for pressing Vs and Voltage loop feedback voltage V e, in fluid transducer, by taking inductor current continuous mode as an example, in t1
Moment, driving conversion circuit export high level, switching tube VT drive level VGBecome high level, switching tube conducting, transformer T original
Side electric current ip is linearly increasing, and corresponding voltage Vs is also linearly increasing on sampling resistor Rs, until the t2 moment, current sample voltage Vs
Ve is increased to, at this time comparator COMP output state flip, driving conversion circuit exports low level, switching tube VT drive level
VGFor low level, switching tube shutdown arrives until the t3 moment, and switching tube is connected again, i.e. t1 to t3 is a complete switch
The ratio of period, t1 to t2 time and t1 to t3 time are the conducting dutycycle of the switch periods switching tube, in fluid transducer
In, which can be 0, that is, assumes to be equal to or more than Ve in t1 moment Vs voltage, drive conversion circuit defeated at this time
Low level out, in the entire switch periods of t1 to t3, VGLevel is always low level.
In actual circuit, due to the presence of parasitic capacitance, switching tube can be generated in conducting moment on sampling resistor Rs
Biggish high-frequency noise interference, if electric current loop reaction speed is too fast, switchs false triggering caused by will lead to because of switching noise, makes
Converter can not work normally, therefore is usually added into blanking circuit to comparator COMP input terminal in sampling resistor Rs and is made an uproar with filtering out
Acoustic jamming, but the addition of blanking circuit will lead to current sampling signal can not real-time transmission to comparator COMP, in actual circuit
In, the state conversion of comparator, driving conversion circuit and MOS pipe can all have certain delay, therefore switching tube conducting accounts for
Sky is than being centainly greater than 0.As shown in dotted line in Fig. 2, at the t1 moment, switching tube VT conducting, when VS ' reaches Ve, due to electric current loop
Delay, until t2 ' moment switching tube VT is just turned off.When converter output overcurrent, short circuit, drop angle under inductive current
Rate reduces, and at t3 the or t5 moment, current sample voltage Vs has reached or more than Ve, but due to the presence of electric current loop delay, accounts for
Empty ratio can not be reduced to 0, therefore inductive current has increase in each switch periods, if the inductive current in the switch periods
It is dropped by less than value added, then inductive current persistent accumulation in each switch periods, causes converter transient current out of control, to change
Parallel operation reliability brings great risk.
To reduce current run-away bring risk, circuit goes the response for reducing electric current loop to prolong as far as possible in design
When, for example adjust blanking circuit, using low delay driving IC etc., but these measures still can not be eliminated thoroughly in many cases
Current run-away phenomenon.
Utility model content
In view of this, the utility model overcomes the above deficiency, a kind of current foldback circuit and opening comprising the circuit are provided
Powered-down source, in switch power source output overcurrent or short circuit, when power circuit transient current is excessive, it can be achieved that in several switch periods
Switching Power Supply is turned off rapidly, and each component is not damaged in protection power source.
Current foldback circuit technical solution provided by the utility model is as follows:
A kind of current foldback circuit, comprising: overcurrent hiccup protections circuit, transient state current foldback circuit, compensation level input
End, current sense input, the first control terminal, the second control terminal and feeder ear；
Feeder ear connects the feeder ear and transient state current foldback circuit of overcurrent hiccup protections circuit simultaneously；Overcurrent hiccup protections
The input terminal of circuit is to compensate level input, and the output end of overcurrent hiccup protections circuit is the second control terminal；Transient state mistake
The input terminal of stream protection circuit is current sense input, and the output end of transient state current foldback circuit is the first control terminal；
Transient state current foldback circuit is connected by its triggering end with the end that is triggered of overcurrent hiccup protections circuit, transient state overcurrent protection electricity
Road also passes through it and is pulled down end to be connected with the lower pull end of overcurrent hiccup protections circuit；
When compensate level input level raise to above or be equal to the first setting value when, overcurrent hiccup protections circuit it is defeated
Outlet exports low level, until when compensation level input level decreases below the second setting value, overcurrent hiccup protections circuit
Output end high-impedance state or hanging is presented, complete an overcurrent hiccup protections；
When current sense input peak raises to above or is equal to third setting value, transient state current foldback circuit
Output end export low level, while overcurrent hiccup protections circuit is triggered by the triggering end of transient state current foldback circuit so that
The level of the output end of overcurrent hiccup protections circuit is low level by high level overturning, and overcurrent hiccup protections circuit passes through it at this time
Lower pull end resets transient state current foldback circuit, i.e. the output end of transient state current foldback circuit becomes high-impedance state or hanging, and mistake
The output end of stream hiccup protections circuit just exits guard mode after maintaining low level setting duration, i.e., overcurrent hiccup protections are electric at this time
High-impedance state or hanging is presented in the output end on road, completes a subtransient overcurrent protection.
Preferably, transient state current foldback circuit includes: first resistor, second resistance, 3rd resistor, the 4th resistance, the 5th
Resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, first diode, the second diode, third diode,
One operational amplifier, first capacitor, the first NPN triode；The anode connection current sense input of first diode, the one or two
The cathode of pole pipe is connected to the ground line end through first resistor, and the cathode of first diode also successively connects through second resistance, the 5th resistance
It is connected to the non-inverting input terminal of the first operational amplifier, first capacitor one end connects the tie point of second resistance and the 5th resistance, the
The one capacitor other end connects ground terminal, and the first operational amplifier power end connects feeder ear, and the first operational amplifier power ground connects
Grounding terminal, feeder ear, which also passes through 3rd resistor and is connected to the 4th resistance, to be followed by ground terminal, and the first operational amplifier is reversely defeated
Enter the tie point of end connection 3rd resistor and the 4th resistance, the first operational amplifier output terminal is by the 7th resistance connection the one or three
The base stage of pole pipe, the first transistor base connect the emitter of the first NPN triode through the 8th resistance, the first NPN triode
Emitter connects ground terminal, and the first NPN triode collector connects the first control terminal, the non-inverting input terminal of the first operational amplifier
The output end of the first operational amplifier is connected through the 6th resistance, the output end of the first operational amplifier is also connected with the second diode sun
Pole, the second diode cathode connect one end of the 9th resistance, and the other end of the 9th resistance is the triggering of transient state current foldback circuit
End, third diode anode connect the tie point of second resistance and the 5th resistance, and third diode cathode is transient state overcurrent protection
Circuit is pulled down end.
Preferably, overcurrent hiccup protections circuit includes: the tenth resistance, eleventh resistor, twelfth resistor, the 13rd electricity
Resistance, the 14th resistance, the 4th diode, the 5th diode, the 6th diode, second operational amplifier, the second capacitor；Tenth electricity
One end connection compensation level input is hindered, the tenth resistance other end connects the anode of the 6th diode, and the 6th diode cathode connects
Connecing second operational amplifier inverting input terminal, eleventh resistor one end connects second operational amplifier inverting input terminal, and the 11st
The resistance other end connects ground terminal, and second capacitor one end connects second operational amplifier inverting input terminal, the second capacitor other end
Ground terminal is connected, second operational amplifier power end connects feeder ear, and second operational amplifier power end also passes through the 13rd electricity
Resistance is connected to twelfth resistor and is followed by ground terminal, and second operational amplifier non-inverting input terminal connects thirteenth resistor and the 12nd
The tie point of resistance, second operational amplifier non-inverting input terminal connect the 4th diode anode, the four or two pole through the 14th resistance
Tube cathode connects the output end of second operational amplifier, and second operational amplifier output end connects the cathode of the 5th diode, the
The anode of five diodes connects the second control terminal, and second operational amplifier power ground connects ground terminal, and second operational amplifier is anti-
It is the end that is triggered of overcurrent hiccup protections circuit to input terminal, second operational amplifier output end is overcurrent hiccup protections circuit
Lower pull end.
Preferably, transient state current foldback circuit includes: first resistor, second resistance, 3rd resistor, the 4th resistance, the 5th
Resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, first diode, the second diode, third diode,
One operational amplifier, first capacitor, the first N-channel MOS pipe；The anode connection current sense input of first diode, first
The cathode of diode is connected to the ground line end through first resistor, and the cathode of first diode successively connects through second resistance, the 5th resistance
It is connected to the non-inverting input terminal of the first operational amplifier, first capacitor one end connects the tie point of second resistance and the 5th resistance, the
The one capacitor other end connects ground terminal, and the 6th resistance one end connects the non-inverting input terminal of the first operational amplifier, the 6th resistance
The other end connects the output end of the first operational amplifier, and the first operational amplifier power end connects feeder ear, the first operation amplifier
Device power ground connects ground terminal, and 3rd resistor one end connects feeder ear, and the 3rd resistor other end is connected to the 4th resistance and passes through
4th resistance is connected to ground terminal, and the first operational amplifier reverse input end connects the tie point of 3rd resistor and the 4th resistance, the
One operational amplifier output terminal connects the grid of the first N-channel MOS pipe by the 7th resistance, and the first N-channel MOS tube grid is through the
Eight resistance connect the source electrode of the first N-channel MOS pipe, and the source electrode of the first N-channel MOS pipe connects ground terminal, the first N-channel MOS pipe
Drain electrode the first control terminal of connection, the first operational amplifier output terminal connect the second diode anode, the connection of the second diode cathode
One end of 9th resistance, the other end of the 9th resistance are the triggering end of transient state current foldback circuit, the connection of third diode anode
First operational amplifier noninverting input, what third diode cathode was linked as transient state current foldback circuit is pulled down end.
Accordingly, the Switching Power Supply provided by the present application comprising above-mentioned current foldback circuit, it is characterised in that:
It compensates level input level in Switching Power Supply output short-circuit or overcurrent to increase, the level when exporting electric current and reducing
It reduces；
Switching Power Supply stops working when first control terminal is low level, and Switching Power Supply is resumed work when being high level；
Switching Power Supply stops working when second control terminal is low level, and Switching Power Supply is resumed work when being high level；
The voltage waveform of current sense input voltage waveform corresponding with power supply main power circuit electric current is identical.
Illustrate using the Switching Power Supply working principle of the utility model current foldback circuit:
In common peak current mode control switch converter circuit, it is defeated to there is compensation level relevant to Voltage loop
Enter to hold Comp (or being expressed as FB), feature are as follows: at steady state, compensation level input level is a stable DC electricity
Pressure, when electric power outputting current increases, compensation level input Comp (or FB) end level increases accordingly, is exporting on the contrary
When electric current reduces, compensation level input Comp (or FB) end level is accordingly reduced.
In common peak current mode control switch converter circuit, an electric current relevant to electric current loop is existed simultaneously
Detection input can detect the transient current waveform in power circuit in real time, and be converted into corresponding voltage waveform, lead to
Often show as triangular wave.
In common peak current mode control switch converter circuit, at least there is a control terminal, in control terminal electricity
When pressure is low level, power supply stops working, and when control terminal voltage is high level or vacant state, power supply is started to work on the contrary.
In the present invention, overcurrent hiccup protections circuit is by the voltage of detection compensation level input, and inside it
Reference voltage (i.e. the first setting value) be compared, when export electric current it is excessive when, compensation level input level be higher than overcurrent
Second control terminal of the internal reference voltage in hiccup protections circuit, overcurrent hiccup protections circuit exports low level, Switching Power Supply
Stop output；Overcurrent hiccup protections circuit has clocking capability, after overcurrent hiccup protections circuit enters guard mode, passes through
After a certain period of time, the second control terminal output of overcurrent hiccup protections circuit shows as vacant state or high-impedance state, Switching Power Supply weight
Newly enter working condition.
In the present invention, transient state current foldback circuit passes through the voltage of detection current sense input, by its peak value
It is compared with therein reference voltage (i.e. third setting value), when transient current is excessive in circuit, current sense input
Crest voltage is greater than transient state current foldback circuit internal reference voltage, and the first control terminal of transient state current foldback circuit exports low electricity
Flat, Switching Power Supply stops working, while transient state over-current control circuit triggering end exports high level, by overcurrent hiccup protections circuit quilt
Triggering end level is drawn high, overcurrent hiccup protections circuit output low level, i.e., the lower pull end of overcurrent hiccup protections circuit exports low electricity
It is flat, it will be pulled down end level in transient state current foldback circuit and drag down, transient state current foldback circuit exits guard mode, overcurrent hiccup
Protection circuit remains guard mode, until hiccup end cycle (i.e. maintenance low level sets duration) backed off after random guard mode.
The Switching Power Supply of the utility model can will switch electricity by overcurrent hiccup protections circuit when output electric current is excessive
Source shutdown, and Switching Power Supply is made after certain time to resume work automatically state, that is, enter overcurrent hiccup protections state；It is logical
Cross transient state current foldback circuit can transient current peak value in real-time sampling switching power circuit, and down to several switch periods
Internal trigger overcurrent protection, prevent power device because transient current it is excessive caused by damage, while triggering overcurrent hiccup protections circuit,
Switching Power Supply is set to enter hiccup formula overcurrent protection state.The beneficial effects of the utility model are summarized as follows:
(1) under switch power source output overcurrent or short-circuit condition, the hiccup time of overcurrent protection can easy adjustment；
(2) excessive in power circuit transient current, it can be achieved that several under switch power source output overcurrent or short-circuit conditions
Switch periods interior power turns off rapidly, and each component does not damage in protection power source；
(3) double-current ring overcurrent protection can be realized using a common dual operational amplifier in specific implementing circuit, electricity
Road is simple, at low cost, high reliablity.
Detailed description of the invention
Fig. 1 is a kind of common peak current mode control switch converter circuit；
Fig. 2 is switching tube drive level in the converter course of work shown in Fig. 1, sampling resistor voltage and Voltage loop feedback electricity
The relationship of pressure is illustrated；
Fig. 3 is the Switching Power Supply functional block diagram comprising the utility model current foldback circuit；
Fig. 4 is the schematic diagram of the utility model first embodiment；
Fig. 5 is the schematic diagram of the utility model second embodiment.
Specific embodiment
The utility model of the application is contemplated that using two overcurrent protection loops, realizes that main power circuit transient current is excessive
Or power supply overcurrent hiccup protections can be achieved in the duplicate protection that average current is excessive, two ways, to prevent the whole electricity of product
It flows through under big or specific condition that transient current stress is excessive to cause component damage, fundamentally realizes the overcurrent guarantor to power supply
Shield.
It is with reference to the accompanying drawings and embodiments, further detailed to the utility model for the utility model is more clearly understood
It describes in detail bright.It should be pointed out that specific embodiment described herein is only used to explain the utility model, it is not used to limit this reality
With novel.
First embodiment
It is illustrated in figure 4 the schematic diagram of the utility model first embodiment, a kind of Switching Power Supply current foldback circuit is special
Sign is: including first resistor R1, second resistance R2,3rd resistor R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6,
7th resistance R7, the 8th resistance R8, the 9th resistance R9, the tenth resistance R10, eleventh resistor R11, twelfth resistor R12,
13 resistance R13, the 14th resistance R14, first diode D1, the second diode D2, third diode D3, the 4th diode
D4, the 5th diode D5, the 6th diode D6, the first operational amplifier AR1, second operational amplifier AR2, first capacitor C1,
Second capacitor C2, the first NPN triode Q1.
The component that transient state current foldback circuit in the present embodiment includes are as follows: first resistor R1, second resistance R2,
Three resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9,
One diode D1, the second diode D2, third diode D3, the first operational amplifier AR1, first capacitor C1, tri- pole the first NPN
Pipe Q1；The component that overcurrent hiccup protections circuit includes are as follows: the tenth resistance R10, eleventh resistor R11, twelfth resistor R12,
Thirteenth resistor R13, the 14th resistance R14, the 4th diode D4, the 5th diode D5, the 6th diode D6, the second operation are put
Big device AR2, the second capacitor C2.
The connection relationship of the present embodiment are as follows: the anode of current sense input CS connection first diode D1, the one or two pole
The cathode of pipe D1 is connected to the ground line end through first resistor R1, and the cathode of first diode D1 is successively through second resistance R2, the 5th electricity
Resistance R5 is connected to the non-inverting input terminal of the first operational amplifier AR1, and the one end first capacitor C1 connects the electricity of second resistance R2 and the 5th
The tie point of R5 is hindered, the first capacitor C1 other end connects ground terminal, and the 6th one end resistance R6 connects the first operational amplifier AR1's
Non-inverting input terminal, the other end of the 6th resistance R6 connect the reverse input end of the first operational amplifier AR1, the first operation amplifier
Device AR1 power end connects feeder ear, and the first operational amplifier AR1 power ground connects ground terminal, the third electricity that feeder ear also passes through
It hinders the 4th resistance R4 that R3 is connected to and ground terminal, the first operational amplifier AR1 reverse input end is connected to by the 4th resistance R4
The tie point of 3rd resistor R3 and the 4th resistance R4 are connected, the first operational amplifier AR1 output end passes through the 7th resistance R7 connection
The base stage of first triode Q1, the base stage of the first triode Q1 through the emitter of the 8th resistance R8 the first NPN triode Q1 of connection,
The emitter of first NPN triode Q1 connects ground terminal, and the first NPN triode Q1 collector connects the first control terminal Ctrl1, the
One operational amplifier AR1 output end connects the anode of the second diode D2, and the second diode D2 cathode is through the 9th resistance R9 connection
Second operational amplifier AR2 inverting input terminal, third diode D3 anode connect the connection of second resistance R2 and the 5th resistance R5
Point, third diode D3 cathode connect second operational amplifier AR2 output end, compensate level input Comp through the tenth resistance
The anode of the 6th diode D6 of R10 connection, the 6th diode D6 cathode connect second operational amplifier AR2 inverting input terminal, the
11 one end resistance R11 connect second operational amplifier AR2 inverting input terminal, and the eleventh resistor R11 other end connects ground wire
End, second one end capacitor C2 connect second operational amplifier AR2 inverting input terminal, and the second capacitor C2 other end connects ground terminal,
Feeder ear Vcc also passes through thirteenth resistor R13 and is connected to twelfth resistor R12 and is connected to ground wire by twelfth resistor R12
End, second operational amplifier AR2 non-inverting input terminal connect the tie point of thirteenth resistor R13 and twelfth resistor R12, the second fortune
Calculate anode of the amplifier AR2 non-inverting input terminal through the 4th diode D4 of the 14th resistance R14 connection, the 4th diode D4 cathode
The output end of second operational amplifier AR2 is connected, second operational amplifier AR2 output end connects the cathode of the 5th diode D5,
The anode of 5th diode D5 connects the second control terminal Ctrl2, and second operational amplifier AR2 power end connects feeder ear Vcc, the
Two operational amplifier AR2 power grounds connect ground terminal.
Its working principle is that:
When electric power outputting current is excessive, compensation level input Comp voltage is increased, and passes through resistance R10, diode
D6 charges to capacitor C2, when the both ends capacitor C2 are higher than the voltage between resistance R12 and R13, operational amplifier AR2 output end electricity
Pressure becomes low level from high level, and the second control terminal Ctrl2 level becomes low level, and power supply stops working；At this time because of resistance R14
And the effect of diode D4, operational amplifier AR2 non-inverting input terminal end level are pulled to lower level, due to resistance R11 with
Capacitor C2 is in parallel, under the charge at the both ends capacitor C2 can be fallen by resistance R11 slow consumption, therefore capacitor C2 both end voltage is slow
Drop, when its voltage is decreased below operational amplifier AR2 non-inverting input terminal voltage, operational amplifier AR2 exports high level, electricity
Source restarting, completes an overcurrent hiccup protections.
When transient current is excessive in power circuit, the crest voltage of current sense input CS is larger, passes through two poles
Pipe D1 and resistance R2 charges to capacitor C1, and forward conduction voltage drop difference is larger when due to having electric current and no current in diode D1,
Therefore certain bias current is added to diode using resistance R1, to reduce caused by diode D1 forward voltage drop deviation accidentally
Difference, resistance R2 and capacitor C1 composition low-pass filter cause caused interference, therefore the voltage at the both ends capacitor C1 to filter out high frequency
Remain DC voltage corresponding with CS voltage peak；Resistance R5, R6 and operational amplifier AR1 form hysteresis loop comparator, electricity
It hinders the partial pressure of R3 and R4 and provides reference voltage for operational amplifier AR1 composition, put operation when capacitor C1 both end voltage rises to
When big device AR1 non-inverting input terminal voltage is higher than reverse input end voltage, operational amplifier AR1 exports high level, passes through resistance
The partial pressure of R7, R8, NPN triode Q1 enter saturation state by off state, and the first control terminal Ctrl1 becomes low level, switch
Power supply stops working；Simultaneously because operational amplifier AR1 output end is high level, the electric current of AR1 output end outflow passes through diode
D2, resistance R9 flow into capacitor C2, and capacitor C2 both end voltage gradually rises, when capacitor C2 both end voltage is higher than operational amplifier AR2
Non-inverting input terminal voltage when, operational amplifier AR2 output becomes low level, and the second control terminal Ctrl2 is low level state, electricity
Source continuous exhibition is stop working state, while the charge in capacitor C1 flows into second operational amplifier AR2's through diode D3
Output end, capacitor C1 both end voltage reduce, while through resistance R5 by the non-inverting input terminal voltage pull-down of operational amplifier AR1, when
The non-inverting input terminal voltage drop of operational amplifier AR1 down to less-than operation amplifier AR1 inverting input terminal voltage when, operation is put
The output end of big device AR1 becomes low level from high level, i.e. transient state current foldback circuit exits guard mode；Therefore transient state overcurrent
The working principle of protection circuit can be summarized are as follows: when transient current is excessive, transient state current foldback circuit quickly enters guard mode, makes
First control terminal Ctrl1 exports rapidly low level, while triggering overcurrent hiccup protections circuit, makes overcurrent hiccup protections circuit output
Low level maintains guard mode, and overcurrent hiccup protections circuit resets transient state current foldback circuit, i.e. transient state current foldback circuit
Guard mode is exited, overcurrent hiccup protections circuit continues to guard mode and the overcurrent hiccup protections circuit after setting time
Guard mode is exited, i.e. the second control terminal Ctrl2 becomes high-impedance state or hanging again, and Switching Power Supply restarting completes one
The transient state overcurrent protection period.
Second embodiment
It is illustrated in figure 5 the schematic diagram of the utility model second embodiment, a kind of Switching Power Supply current foldback circuit is special
Sign is: including first resistor R1, second resistance R2,3rd resistor R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6,
7th resistance R7, the 8th resistance R8, the 9th resistance R9, the tenth resistance R10, eleventh resistor R11, twelfth resistor R12,
13 resistance R13, the 14th resistance R14, first diode D1, the second diode D2, third diode D3, the 4th diode
D4, the 5th diode D5, the 6th diode D6, the first operational amplifier AR1, second operational amplifier AR2, first capacitor C1,
Second capacitor C2, the first N-channel field-effect tube Q1.
The component that transient state current foldback circuit in the present embodiment includes are as follows: first resistor R1, second resistance R2,
Three resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9,
One diode D1, the second diode D2, third diode D3, the first operational amplifier AR1, first capacitor C1, the first N-channel field
Effect pipe Q1；The component that overcurrent hiccup protections circuit includes are as follows: the tenth resistance R10, eleventh resistor R11, twelfth resistor
R12, thirteenth resistor R13, the 14th resistance R14, the 4th diode D4, the 5th diode D5, the 6th diode D6, the second fortune
Calculate amplifier AR2, the second capacitor C2.
The connection relationship of the present embodiment are as follows: the anode of current sense input CS connection first diode D1, the one or two pole
The cathode of pipe D1 is connected to the ground line end through first resistor R1, and the cathode of first diode D1 is successively through second resistance R2, the 5th electricity
Resistance R5 is connected to the non-inverting input terminal of the first operational amplifier AR1, and the one end first capacitor C1 connects the electricity of second resistance R2 and the 5th
The tie point of R5 is hindered, the first capacitor C1 other end connects ground terminal, and the 6th one end resistance R6 connects the first operational amplifier AR1's
Non-inverting input terminal, the other end of the 6th resistance R6 connect the output end of the first operational amplifier AR1, the first operational amplifier AR1
Power end connects feeder ear, and the first operational amplifier AR1 power ground connects ground terminal, the 3rd resistor R3 that feeder ear also passes through
The 4th resistance R4 that is connected to simultaneously is connected to ground terminal, the connection of the first operational amplifier AR1 reverse input end by the 4th resistance R4
The tie point of 3rd resistor R3 and the 4th resistance R4, the first operational amplifier AR1 output end pass through the first N of the 7th resistance R7 connection
The grid of channel field-effect pipe Q1, the first N-channel field-effect tube Q1 grid is through the 8th resistance R8 connection the first N-channel field-effect
The source electrode of pipe Q1, the source electrode of the first N-channel field-effect tube Q1 connect ground terminal, the first N-channel field-effect tube Q1 drain electrode connection the
One control terminal Ctrl1, the first operational amplifier AR1 output end connect the anode of the second diode D2, the second diode D2 cathode
Through the 9th resistance R9 connection second operational amplifier AR2 inverting input terminal, third diode D3 anode connects the first operation amplifier
The non-inverting input terminal of device AR1, third diode D3 cathode connect second operational amplifier AR2 output end, compensate level input
Anode of the Comp through the 6th diode D6 of the tenth resistance R10 connection, the 6th diode D6 cathode connect second operational amplifier AR2
Inverting input terminal, the one end eleventh resistor R11 connect second operational amplifier AR2 inverting input terminal, and eleventh resistor R11 is another
End connection ground terminal, second one end capacitor C2 connect second operational amplifier AR2 inverting input terminal, and the second capacitor C2 other end connects
Grounding terminal, feeder ear Vcc also pass through thirteenth resistor R13 and are connected to twelfth resistor R12 and are connected by twelfth resistor R12
It is connected to ground terminal, second operational amplifier AR2 non-inverting input terminal connects the connection of thirteenth resistor R13 and twelfth resistor R12
Point, anode of the second operational amplifier AR2 non-inverting input terminal through the 4th diode D4 of the 14th resistance R14 connection, the four or two pole
Pipe D4 cathode connects the output end of second operational amplifier AR2, and second operational amplifier AR2 output end connects the 5th diode D5
Cathode, the anode of the 5th diode D5 connects the second control terminal Ctrl2, the connection power supply of second operational amplifier AR2 power end
Vcc is held, second operational amplifier AR2 power ground connects ground terminal, and the first control terminal Ctrl1 is connected with the second control terminal Ctrl2
It connects, the as same control terminal, referred to collectively below as control terminal.
Overcurrent hiccup protections circuit operation principle is identical as first embodiment principle, and which is not described herein again, implements with first
Example the difference is that, the first NPN triode is changed to N-channel field-effect tube, and third diode D3 anode is connected to the first fortune
Calculate the non-inverting input terminal of amplifier AR1, therefore the working principle of transient state current foldback circuit are as follows:
When transient current is excessive in power circuit, the crest voltage of current sense input CS is larger, passes through two poles
Pipe D1 and resistance R2 charges to capacitor C1, and forward conduction voltage drop difference is larger when due to having electric current and no current in diode D1,
Therefore certain bias current is added to diode using resistance R1, to reduce caused by diode D1 forward voltage drop deviation accidentally
Difference, resistance R2 and capacitor C1 composition low-pass filter cause caused interference, therefore the voltage at the both ends capacitor C1 to filter out high frequency
Remain DC voltage corresponding with CS voltage peak；Resistance R5, R6 and operational amplifier AR1 form hysteresis loop comparator, electricity
It hinders the partial pressure of R3 and R4 and provides reference voltage for operational amplifier AR1 composition, put operation when capacitor C1 both end voltage rises to
When big device AR1 non-inverting input terminal voltage is higher than inverting input terminal voltage, operational amplifier AR1 exports high level, passes through resistance
The partial pressure of R7, R8, N-channel field-effect tube Q1 enter on state by off state, and control terminal is low level, and power supply stops work
Make；Simultaneously because operational amplifier AR1 output end is high level, the electric current of AR1 output end outflow is flowed by diode D2, resistance R9
Enter capacitor C2, capacitor C2 both end voltage gradually rises, when capacitor C2 both end voltage is higher than the non-inverting input terminal of operational amplifier AR2
When voltage, operational amplifier AR2 output end becomes low level, and control terminal remains low level state at this time, and Switching Power Supply is still
Stop working state is remained, while the charge in capacitor C1 flows into the output end of second operational amplifier AR2 through diode D3,
Capacitor C1 both end voltage reduces, when capacitor C1 both end voltage decreases below the inverting input terminal voltage of operational amplifier AR1,
Operational amplifier AR1 output end becomes low level from high level, i.e. transient state current foldback circuit exits guard mode；Therefore transient state
The working principle of current foldback circuit can be summarized are as follows: when transient current is excessive, transient state current foldback circuit quickly enters protection shape
State makes control terminal export low level rapidly, while triggering overcurrent hiccup protections circuit, makes the low electricity of overcurrent hiccup protections circuit output
It is flat, guard mode is maintained, while overcurrent hiccup protections circuit resets transient state current foldback circuit, i.e. transient state current foldback circuit
Guard mode is exited, overcurrent hiccup protections circuit continues to guard mode and the overcurrent hiccup protections circuit after setting time
Guard mode is exited, i.e. control terminal becomes high-impedance state or hanging again, and Switching Power Supply restarting is completed a transient state overcurrent and protected
Protect the period.
Above are merely preferred embodiments of the utility model, it is noted that above-mentioned preferred embodiment should not regard
For limitations of the present invention, for those skilled in the art, in the essence for not departing from the utility model
In mind and range, several improvements and modifications can also be made, these improvements and modifications also should be regarded as the protection model of the utility model
It encloses, is no longer repeated here with example, the protection scope of the utility model should be defined by the scope defined by the claims..
Claims (5)
1. a kind of current foldback circuit, it is characterised in that: include: overcurrent hiccup protections circuit, transient state current foldback circuit, compensation
Level input, current sense input, the first control terminal, the second control terminal and feeder ear；
Feeder ear connects the feeder ear and transient state current foldback circuit of overcurrent hiccup protections circuit simultaneously；Overcurrent hiccup protections circuit
Input terminal be compensate level input, the output end of overcurrent hiccup protections circuit is the second control terminal；Transient state overcurrent is protected
The input terminal of protection circuit is current sense input, and the output end of transient state current foldback circuit is the first control terminal；Transient state
Current foldback circuit is connected by its triggering end with the end that is triggered of overcurrent hiccup protections circuit, and transient state current foldback circuit is also
End is pulled down by it to be connected with the lower pull end of overcurrent hiccup protections circuit；
When compensation level input level raises to above or is equal to the first setting value, the output end of overcurrent hiccup protections circuit
Export low level, until compensation level input level is when decreasing below the second setting value, overcurrent hiccup protections circuit it is defeated
High-impedance state or hanging is presented in outlet, completes an overcurrent hiccup protections；
When current sense input peak raise to above or be equal to third setting value when, transient state current foldback circuit it is defeated
Outlet exports low level, while triggering overcurrent hiccup protections circuit by the triggering end of transient state current foldback circuit, so that overcurrent
The level of the output end of hiccup protections circuit is low level by high level overturning, and overcurrent hiccup protections circuit is pulled down by it at this time
End resets transient state current foldback circuit, i.e. the output end of transient state current foldback circuit becomes high-impedance state or hanging, and overcurrent is beaten
The output end of belch protection circuit just exits guard mode after maintaining low level setting duration, i.e. overcurrent hiccup protections circuit at this time
High-impedance state or hanging is presented in output end, completes a subtransient overcurrent protection.
2. a kind of current foldback circuit according to claim 1, it is characterised in that: transient state current foldback circuit includes:
One resistance, second resistance, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th electricity
Resistance, first diode, the second diode, third diode, the first operational amplifier, first capacitor, the first NPN triode；The
The anode of one diode connects current sense input, and the cathode of first diode is connected to the ground line end through first resistor, and first
The cathode of diode is also successively connected to the non-inverting input terminal of the first operational amplifier, the first electricity through second resistance, the 5th resistance
Hold the tie point of one end connection second resistance and the 5th resistance, the first capacitor other end connects ground terminal, the first operational amplifier
Power end connects feeder ear, and the first operational amplifier power ground connects ground terminal, and feeder ear also passes through 3rd resistor and is connected to the
Four resistance are followed by ground terminal, and the first operational amplifier reverse input end connects the tie point of 3rd resistor and the 4th resistance, the
One operational amplifier output terminal connects the base stage of the first triode by the 7th resistance, and the first transistor base connects through the 8th resistance
The emitter of the first NPN triode is connect, the emitter of the first NPN triode connects ground terminal, and the first NPN triode collector connects
The first control terminal is connect, the non-inverting input terminal of the first operational amplifier connects the output end of the first operational amplifier through the 6th resistance,
The output end of first operational amplifier is also connected with the second diode anode, and the second diode cathode connects one end of the 9th resistance,
The other end of 9th resistance is the triggering end of transient state current foldback circuit, and third diode anode connects second resistance and the 5th electricity
The tie point of resistance, third diode cathode are pulled down end for transient state current foldback circuit.
3. a kind of current foldback circuit according to claim 1, it is characterised in that: overcurrent hiccup protections circuit includes:
Ten resistance, eleventh resistor, twelfth resistor, thirteenth resistor, the 14th resistance, the 4th diode, the 5th diode, the 6th
Diode, second operational amplifier, the second capacitor；Tenth resistance one end connection compensation level input, the tenth resistance other end
The anode of the 6th diode is connected, the 6th diode cathode connects second operational amplifier inverting input terminal, eleventh resistor one
End connection second operational amplifier inverting input terminal, the eleventh resistor other end connect ground terminal, second capacitor one end connection the
Two operational amplifier inverting input terminals, the second capacitor other end connect ground terminal, the connection power supply of second operational amplifier power end
End, second operational amplifier power end, which also passes through thirteenth resistor and is connected to twelfth resistor, to be followed by ground terminal, the second operation
Amplifier non-inverting input terminal connects the tie point of thirteenth resistor and twelfth resistor, second operational amplifier non-inverting input terminal warp
14th resistance connects the 4th diode anode, and the 4th diode cathode connects the output end of second operational amplifier, the second fortune
The cathode that amplifier out connects the 5th diode is calculated, the anode of the 5th diode connects the second control terminal, and the second operation is put
Big device power ground connects ground terminal, and second operational amplifier reverse input end is the end that is triggered of overcurrent hiccup protections circuit, the
Two operational amplifier output terminals are the lower pull end of overcurrent hiccup protections circuit.
4. a kind of current foldback circuit according to claim 1, it is characterised in that: transient state current foldback circuit includes:
One resistance, second resistance, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th electricity
Resistance, first diode, the second diode, third diode, the first operational amplifier, first capacitor, the first N-channel MOS pipe；The
The anode of one diode connects current sense input, and the cathode of first diode is connected to the ground line end through first resistor, and first
The cathode of diode is successively connected to the non-inverting input terminal of the first operational amplifier, first capacitor through second resistance, the 5th resistance
One end connects the tie point of second resistance and the 5th resistance, and the first capacitor other end connects ground terminal, the connection of the 6th resistance one end
The non-inverting input terminal of first operational amplifier, the other end of the 6th resistance connect the output end of the first operational amplifier, the first fortune
It calculates APS amplifier power supply end and connects feeder ear, the first operational amplifier power ground connects ground terminal, the connection power supply of 3rd resistor one end
End, the 3rd resistor other end are connected to the 4th resistance and are connected to ground terminal by the 4th resistance, and the first operational amplifier is reversely defeated
Enter the tie point of end connection 3rd resistor and the 4th resistance, the first operational amplifier output terminal connects the first N by the 7th resistance
The grid of channel MOS tube, the first N-channel MOS tube grid connect the source electrode of the first N-channel MOS pipe, the first N ditch through the 8th resistance
The source electrode of road metal-oxide-semiconductor connects ground terminal, the first N-channel MOS pipe drain electrode the first control terminal of connection, the first operational amplifier output terminal
The second diode anode is connected, the second diode cathode connects one end of the 9th resistance, and the other end of the 9th resistance is transient state mistake
The triggering end of stream protection circuit, third diode anode connect the first operational amplifier noninverting input, third diode cathode
Be linked as transient state current foldback circuit is pulled down end.
5. a kind of Switching Power Supply comprising any one of the claims 1 to 4 current foldback circuit, it is characterised in that:
It compensates level input level in Switching Power Supply output short-circuit or overcurrent to increase, when exporting electric current and reducing, level drops
It is low；
Switching Power Supply stops working when first control terminal is low level, and Switching Power Supply is resumed work when being high level；
Switching Power Supply stops working when second control terminal is low level, and Switching Power Supply is resumed work when being high level；
The voltage waveform of current sense input voltage waveform corresponding with power supply main power circuit electric current is identical.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821404377.3U CN208753975U (en) | 2018-08-29 | 2018-08-29 | A kind of current foldback circuit and the Switching Power Supply comprising the circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821404377.3U CN208753975U (en) | 2018-08-29 | 2018-08-29 | A kind of current foldback circuit and the Switching Power Supply comprising the circuit |
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| CN208753975U true CN208753975U (en) | 2019-04-16 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109088396A (en) * | 2018-08-29 | 2018-12-25 | 广州金升阳科技有限公司 | A kind of current foldback circuit and the Switching Power Supply comprising the circuit |
| CN110369160A (en) * | 2019-06-25 | 2019-10-25 | 深圳市四方电气技术有限公司 | Centrifuge driver protects circuit |
| CN112615548A (en) * | 2020-12-21 | 2021-04-06 | 四川升华电源科技有限公司 | DCM frequency conversion control method based on flyback DC-DC converter |
| CN112994430A (en) * | 2021-02-26 | 2021-06-18 | 西安微电子技术研究所 | Multi-mode combined short-circuit protection circuit and working method and application thereof |
| CN113489317A (en) * | 2021-05-26 | 2021-10-08 | 中国电子科技集团公司第四十一研究所 | Program-controlled output power control circuit |
-
2018
- 2018-08-29 CN CN201821404377.3U patent/CN208753975U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109088396A (en) * | 2018-08-29 | 2018-12-25 | 广州金升阳科技有限公司 | A kind of current foldback circuit and the Switching Power Supply comprising the circuit |
| CN110369160A (en) * | 2019-06-25 | 2019-10-25 | 深圳市四方电气技术有限公司 | Centrifuge driver protects circuit |
| CN110369160B (en) * | 2019-06-25 | 2021-07-30 | 深圳市四方电气技术有限公司 | Centrifuge driver protection circuit |
| CN112615548A (en) * | 2020-12-21 | 2021-04-06 | 四川升华电源科技有限公司 | DCM frequency conversion control method based on flyback DC-DC converter |
| CN112994430A (en) * | 2021-02-26 | 2021-06-18 | 西安微电子技术研究所 | Multi-mode combined short-circuit protection circuit and working method and application thereof |
| CN113489317A (en) * | 2021-05-26 | 2021-10-08 | 中国电子科技集团公司第四十一研究所 | Program-controlled output power control circuit |
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