CN203326909U - Operation amplifier or comparator-controlled fly-back synchronous rectification circuit and fly-back power supply thereof - Google Patents
Operation amplifier or comparator-controlled fly-back synchronous rectification circuit and fly-back power supply thereof Download PDFInfo
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- CN203326909U CN203326909U CN2013203619546U CN201320361954U CN203326909U CN 203326909 U CN203326909 U CN 203326909U CN 2013203619546 U CN2013203619546 U CN 2013203619546U CN 201320361954 U CN201320361954 U CN 201320361954U CN 203326909 U CN203326909 U CN 203326909U
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- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The utility model relates to an operation amplifier or comparator-controlled fly-back synchronous rectification circuit and a fly-back power supply thereof, the fly-back power supply comprises an EMI filter circuit, a bridge rectifier circuit, a power frequency filtering electrolytic capacitor, a PWM controller, a fly-back transformer, an MOS transistor driving the fly-back transformer, a fly-back synchronous rectification circuit and an output filter circuit. An operation amplifier OP or a comparator OC is adopted for controlling outputting a synchronous rectifier MOS transistor so that the design cost of a switch power supply is reduced, the fly-back power supply is allowed to work in both a discontinuous mode DCM and a continuous mode CCM, the switch power supply is enabled to enter the continuous mode CCM when heavily loaded, and thus the overall conversion efficiency of the power supply is higher.
Description
Technical field
The utility model relates to inverse-excitation type switch power-supply output synchronous rectification field, particularly a kind of inverse-excitation type synchronous rectifying circuit and flyback power supply thereof of being controlled by amplifier or comparator.
Background technology
Synchronous rectification is to adopt the extremely low special power metal-oxide-semiconductor of on-state resistance, replaces rectifier diode to reduce a new technology of rectifier loss.It can improve the power supply conversion efficiency of supply convertor greatly.Power MOS pipe belongs to voltage-controlled device, while with power MOS pipe, making rectifier, requires grid voltage to synchronize and just can complete rectification function with the phase preserving that is rectified voltage, therefore be referred to as synchronous rectification.
Existing liquid shows the power supply changeover device of product AC-DC (AC-DC) list group output, and its output adopts by synchronous rectification control chip U2 control N-channel MOS pipe Q2 and does output synchronous rectification.For example, shown in Fig. 1, this power supply changeover device exists following problem:
1, the inverse-excitation type synchronous rectifying control chip is also widely applied at present in inverse-excitation type switch power-supply, so the price of this synchronous rectification control chip often more expensive (as: existing inverse-excitation type synchronous rectifying control chip price is usually in 0.2～0.3 U.S. dollar left and right).
The major part of the synchronous rectification control chip that 2, each producer develops at present only allows to be operated in discontinuous mode DCM, and can't be operated in preferably continuous mode CCM, and that Switching Power Supply is operated in continuous mode CCM is high than discontinuous mode DCM at the whole efficiency conversion aspect.
Summary of the invention
The purpose of this utility model is to provide a kind of inverse-excitation type synchronous rectifying circuit of being controlled by amplifier or comparator, alternative existing synchronous rectification control chip, and cost is low.
The utility model adopts following scheme to realize: a kind of inverse-excitation type synchronous rectifying circuit of being controlled by amplifier or comparator is characterized in that: comprise first input end, the second input and the 3rd input, the end that described first input end is resistance R 1 and R3, resistance R 1 other end and resistance R 2 one ends, the non-inverting input of amplifier OP2 is electrically connected, the source electrode of resistance R 2 other ends and synchronous rectification N-channel MOS Q2, manganin wire Rm mono-end is electrically connected, resistance R 3 other ends and resistance R 4 one ends, the inverting input of amplifier OP2 is electrically connected, the secondary ground of another termination flyback transformer T1 of resistance R 4 and manganin wire Rm, the grid of the output of amplifier OP2 and Q3N channel MOS is electrically connected, the drain electrode of the drain electrode of Q3N channel MOS and a Q4N channel MOS, resistance R 5 one ends, the grid of synchronous rectification N-channel MOS Q2 is electrically connected, the drain electrode of synchronous rectification N-channel MOS Q2 is as described the second input, resistance R 5 other ends and a diode D2 negative terminal are electrically connected, diode D2 anode and diode D1 anode, resistance R 6 one ends are electrically connected and as described the 3rd input, resistance R 6 other ends and resistance R 7 one ends, amplifier OP1 reverse input end are electrically connected, the feeder ear of one end, amplifier OP1 and the OP2 of diode D1 negative terminal and capacitor C 1 is electrically connected, the grid of the output of amplifier OP1 and Q4N channel MOS is electrically connected, and the source electrode of earth terminal, Q3 and the Q4N channel MOS tube of non-inverting input, amplifier OP1 and the OP2 of the other end of capacitor C 1, resistance R 7 other ends, amplifier OP1 connects the secondary ground of flyback transformer T1.
In the utility model one embodiment, replace described amplifier OP1 and OP2 with comparator OC1, OC2, and at output termination one pull-up resistor of described comparator OC1, OC2.
Another purpose of the present utility model is to provide a kind of flyback power supply of applying above-mentioned inverse-excitation type synchronous rectifying circuit, this power acquisition is controlled devices with amplifier OP or comparator OC and is reduced the Switching Power Supply design cost with synchronous rectification, allow flyback power supply can be operated in discontinuous pattern DCM, also can be operated in continuous mode CCM, make Switching Power Supply when heavy duty, enter continuous mode CCM, make the conversion efficiency of power source integral higher.
The utility model adopts following scheme to realize: a kind of flyback power supply is characterized in that: the metal-oxide-semiconductor and the output filter circuit that comprise inverse-excitation type synchronous rectifying circuit claimed in claim 1, EMI filter circuit, bridge rectifier, power frequency electrolytic capacitor filter, PWM controller, flyback transformer, driving flyback transformer; The output of EMI filter circuit is connected with the input of bridge rectifier, the output of described bridge rectifier is provided with a power frequency electrolytic capacitor filter Cb, and the non-dotted end of described flyback transformer primary side winding Np and the positive pole of described power frequency electrolytic capacitor filter Cb are electrically connected; The dotted end of primary side winding Np and the drain electrode of Q1N channel MOS are electrically connected, and the output pin of the grid of Q1N channel MOS and a PWM controller is electrically connected, and the source electrode of Q1N channel MOS connects primary side ground; The dotted end of the primary side winding Ns of described transformer and the input of described first input end and output filter circuit are electrically connected; The non-dotted end of primary side winding Ns and described the second input are electrically connected; The dotted end of the primary side winding Nd of described flyback transformer and described the 3rd input are electrically connected; The non-terminates secondary ground of getting ready of primary side winding Nd.
In the utility model one embodiment, described output filter circuit is comprised of inductance L 1, capacitor C 2, C3, and an end of described inductance L 1, an end of capacitor C 2 and described first input end are electrically connected; The other end of inductance L 1 is as the output of this flyback power supply and be connected with an end of capacitor C 3; Another terminates secondary ground of described capacitor C 2, C3.
Advantage of the present utility model:
1, adopt amplifier OP or comparator OC to control devices and reduce the Switching Power Supply design cost with synchronous rectification, as: adopt inner integrated 2 the amplifier OP of LM358, its single OP price is in 0.05 U.S. dollar.
2, allow flyback power supply can be operated in discontinuous pattern DCM, also can be operated in continuous mode CCM, make Switching Power Supply when heavy duty, enter continuous mode CCM, make the conversion efficiency of power source integral higher.
The accompanying drawing explanation
Fig. 1 is existing flyback power supply schematic block circuit diagram.
Fig. 2 is the circuit connection diagram by the inverse-excitation type synchronous rectifying circuit of amplifier OP control.
Fig. 3 is the flyback power supply schematic block circuit diagram of application drawing 2.
Fig. 4 is the sequential chart of inverse-excitation type switch power-supply while being operated in continuous mode (CCM).
Fig. 5 is the sequential chart of inverse-excitation type switch power-supply while being operated in discontinuous mode (DCM).
Fig. 6 is the examples of implementation theory diagram that the flyback power supply circuit adopts comparator OC.
Embodiment
Below in conjunction with drawings and Examples, the utility model is described further.
As shown in Figure 2, it is a kind of by amplifier OP(operational amplifier that the utility model provides) or the inverse-excitation type synchronous rectifying circuit controlled of comparator OC (comparator), it is characterized in that: comprise first input end, the second input and the 3rd input, the end that described first input end is resistance R 1 and R3, resistance R 1 other end and resistance R 2 one ends, the non-inverting input of amplifier OP2 is electrically connected, the source electrode of resistance R 2 other ends and synchronous rectification N-channel MOS Q2, manganin wire Rm mono-end is electrically connected, resistance R 3 other ends and resistance R 4 one ends, the inverting input of amplifier OP2 is electrically connected, another terminates secondary ground (flyback transformer primary side ground is referred to as secondary ground) of resistance R 4 and manganin wire Rm, the grid of the output of amplifier OP2 and Q3N channel MOS is electrically connected, the drain electrode of the drain electrode of Q3N channel MOS and a Q4N channel MOS, resistance R 5 one ends, the grid of synchronous rectification N-channel MOS Q2 is electrically connected, the drain electrode of synchronous rectification N-channel MOS Q2 is as described the second input, resistance R 5 other ends and a diode D2 negative terminal are electrically connected, diode D2 anode and diode D1 anode, resistance R 6 one ends are electrically connected and as described the 3rd input, resistance R 6 other ends and resistance R 7 one ends, amplifier OP1 reverse input end are electrically connected, the feeder ear of one end, amplifier OP1 and the OP2 of diode D1 negative terminal and capacitor C 1 is electrically connected, the grid of the output of amplifier OP1 and Q4N channel MOS is electrically connected, and the source electrode of earth terminal, Q3 and the Q4N channel MOS tube of non-inverting input, amplifier OP1 and the OP2 of the other end of capacitor C 1, resistance R 7 other ends, amplifier OP1 connects secondary ground.
In addition, the present embodiment provides a kind of flyback power supply, this power supply comprises above-mentioned inverse-excitation type synchronous rectifying circuit, please refer to Fig. 3, in figure, AC mains (90Vrms～264Vrms) offers bridge rectifier 2 and carries out full-wave rectification after EMI filter circuit 1 carries out EMI filtering, generate again a direct current with certain voltage ripple and provide the input electric energy for flyback transformer T1 after power frequency electrolytic capacitor filter Cb carries out power frequency filtering, the negative pole of power frequency electrolytic capacitor filter Cb connects elementary ground (flyback transformer primary side ground is referred to as elementary ground), the anodal non-dotted end with flyback transformer T1 primary side winding Np of power frequency electrolytic capacitor filter Cb is electrically connected, the drain electrode of the dotted end of Np and Q1N channel MOS is electrically connected, the output pin of the grid of Q1N channel MOS and a PWM controller U1 is electrically connected, the source electrode of Q1N channel MOS connects elementary ground, when this Switching Power Supply normal operation, the output pin of PWM controller U1 will be exported a PWM pulse-width signal, control this Q1N channel MOS tube by this PWM pulse-width signal and do the Push And Release action, thereby control this flyback transformer T1, from primary side Np winding, the electric energy power frequency electrolytic capacitor filter Cb is transferred to output filter circuit 4 by primary side winding Ns, the dotted end of the primary side winding Ns of transformer T1 and the end of resistance R 1 and R3, the anode of capacitor C 2, one end of inductance L 1 is electrically connected, the anode of the other end of inductance L 1 and capacitor C 3 is electrically connected, the output that this C3 anode is this inverse-excitation type switch power-supply, export the direct current that a voltage is Vout, resistance R 1 other end and resistance R 2 one ends, the non-inverting input of amplifier OP2 is electrically connected, the source electrode of resistance R 2 other ends and synchronous rectification N-channel MOS Q2, manganin wire Rm mono-end is electrically connected, resistance R 3 other ends and resistance R 4 one ends, the inverting input of amplifier OP2 is electrically connected, resistance R 4 other ends, capacitor C 2 and C3 negative terminal connect secondary ground, the grid of the output of amplifier OP2 and Q3N channel MOS is electrically connected, the drain electrode of the drain electrode of Q3N channel MOS and a Q4N channel MOS, resistance R 5 one ends, the grid of synchronous rectification N-channel MOS Q2 is electrically connected, the non-dotted end of the primary side winding Ns of the drain electrode of synchronous rectification N-channel MOS Q2 and flyback transformer T1 is electrically connected, resistance R 5 other ends and a diode D2 negative terminal are electrically connected, diode D2 anode and diode D1 anode, the dotted end of the detecting winding Nd of resistance R 6 one ends and flyback transformer is electrically connected, resistance R 6 other ends and resistance R 7 one ends, amplifier OP1 reverse input end is electrically connected, one end of diode D1 negative terminal and capacitor C 1, the feeder ear of amplifier OP1 and OP2 is electrically connected, the grid of the output of amplifier OP1 and Q4N channel MOS is electrically connected, the other end of capacitor C 1, the non-dotted end of detecting winding Nd, resistance R 7 other ends, the non-inverting input of amplifier OP1, the earth terminal of amplifier OP1 and OP2, the source electrode of Q3 and Q4N channel MOS tube connects secondary ground, wherein the Q3/Q4 available rates cheap as model electronic components such as RK7002 or 2N7002.
When this inverse-excitation type switch power-supply is operated in continuous mode (CCM), can be with reference to figure 4 sequential charts;
During Ton: the output of PWM controller U1 is exported the grid of a high level High signal to the Q1N channel MOS, obtaining a voltage between the grid of Q1N channel MOS and source electrode is that Vgs (Q1)=VH[VH is high level on signal], make the conducting of Q1N channel MOS, make to produce a voltage V between the non-dotted end of primary side winding Np of transformer T1 and dotted end
Np=V
Cb=Lp*di/dt=Lp* (Ip-Ip0)/Ton, [wherein: V
Cbfor the voltage of power frequency electrolytic capacitor filter Cb anode to elementary ground, the inductance value that Lp is flyback transformer T1Np winding, di/dt flows into from the non-dotted end of Np winding, the electric current flowed out from Np winding dotted end is in the recruitment of unit interval, Ip is last primary side winding Np electric current during Ton, initial current when Ip0 is Ton], and flyback transformer T1 starts energy storage, the polarities of potentials of the non-dotted end of flyback transformer T1 primary side winding Np is "+", the dotted end polarities of potentials of Np is "-", according to transformer Same Name of Ends principle, at the primary side winding Ns of flyback transformer T1 and the polarities of potentials that non-dotted end induces of detecting winding Nd, be now also "+", at the primary side winding Ns of transformer T1 and the polarities of potentials that dotted end induces of detecting winding Nd, be also "-", the non-terminates secondary ground of getting ready due to detecting winding Nd, therefore the dotted end at detecting winding Nd produces a voltage V
Nd=-V
Cb* Nd/Np, [number of turns of the detecting winding Nd that wherein Nd is flyback transformer T1, the number of turns of the primary side winding Np that Np is flyback transformer T1], the reverse input end at amplifier OP1 produces a voltage V-(OP1)=V simultaneously
Nd* R7/ (R6+R7)<V+ (OP1)=0V, [wherein V+ (OP1) is amplifier OP1 non-inverting input voltage], make amplifier OP1 output export the grid of a high level signal to the Q4N channel MOS tube, that is: obtain the voltage of a voltage Vgs (Q4)=VH between the grid of Q4N channel MOS tube and source electrode, make Q4MOS manage conducting fast, make the gate charge of devices be released fast, that is: when the conducting of Q1N channel MOS, the Q2N channel MOS is ended fast, to guarantee that electric energy in output filter circuit 4 can not pour in down a chimney again to causing in flyback transformer T1 the Q2N channel MOS tube when the cut-off, producing higher peak voltage between the drain electrode of this MOS and source electrode makes this Q2MOS pipe because of the breakdown problem of withstand voltage deficiency.
End during Ton, it is Ip that the electric current that the primary side winding Np of transformer T1 flows through reaches maximum, the energy that transformer is stored is W
Ton=1/2*L
p* I
P 2-1/2*L
p* I
P0 2.
During Toff: the output of PWM controller U1 is exported the grid of a low level Low signal to the Q1N channel MOS, between the grid of Q1N channel MOS and source electrode voltage to become Vgs (Q1)=VL=0V[VL be low level Low signal], make the cut-off of Q1N channel MOS tube, when the Q1N channel MOS tube ends, the polarity inversion of all winding current potentials of flyback transformer, that is: flyback transformer T1Np winding, the Ns winding, the non-dotted end polarities of potentials of Nd winding becomes "-" by "+", flyback transformer T1Np winding, the Ns winding, the dotted end polarities of potentials of Nd winding becomes "+" by "-", Q2N channel MOS tube parasitic diode D now
Q2first forward conduction, the electromagnetic energy that makes transformer T1 primary side winding Ns start flyback transformer T1 is stored during Ton discharges, and produces an electric current I s path: secondary ground → Rm manganin wire → D
Q2anode → D
Q2dotted end → capacitor C 2 anodes and the inductance L 1 of the non-dotted end of negative terminal → flyback transformer T1Ns winding → flyback transformer T1Ns winding, electric current flows through manganin wire Rm and produces a negative pressure Vs=-Is*Rm at the source electrode of Q2N channel MOS, and [resistance that wherein Rm is manganin wire], and produce a voltage at the non-inverting input of amplifier OP2 and be:
V+ (OP2)=V
C2* R2/ (Rl+R2)-Is*Rm*R1/ (R1+R2), and produce a voltage at the reverse input end of amplifier OP2 and be: V-(OP2)=V
C2* R4/ (R3+R4), owing to examining filter while to transformer T1, being operated in discontinuous mode DCM, Toff when between the Q1N channel MOS off period, flyback transformer T1 can just all discharge complete by energy that in this flyback transformer T1, air gap is stored in the time being less than Toff, in during Toff, the Is electric current can become 0A, in order to prevent that transformer T1 from may make electric energy in output filter circuit 4 again pour in down a chimney to causing in flyback transformer T1 the Q2N channel MOS tube when the cut-off after energy releases, producing higher peak voltage between the drain electrode of this MOS and source electrode makes this Q2N channel MOS tube because of the breakdown problem of withstand voltage deficiency, therefore need to be after the Is electric current approaches 0A, amplifier OP2 output need to be exported a high level signal is ended the Q2N channel MOS fast, so when Is=0A, need to meet V+(OP2)-V-(OP2) the Vio[input offset voltage that wherein Vio is amplifier OP (Input offset voltage)], as: the Vio=2mV that LM358A is transported into, therefore can pass through parameters, as: Rm=24m Ω, R1=R3=15K Ω, R2=27 Ω, R4=22 Ω, if V
C2=16V, at V+(OP2)=V-(OP2)+5.3mV,
That is: V
C2* R2/ (R1+R2)=V
C2* R4/ (R3+R4)+5.3mV,
Therefore when the Q1N channel MOS ends,
V+(OP2)＝V
C2*R2/(R1+R2)-Is*Rm*R1/(R1+R2)
＝V
C2*R4/(R3+R4)+5.3mV-Is*Rm*R1/(R1+R2)
＝V-(OP2)+5.3mV-Is*Rm*R1/(R1+R2)
If during Is=5A, V+(OP2)=V-(OP2)-114.48mV is: amplifier OP2 reverse input end voltage is greater than non-inverting input voltage, makes amplifier OP2 output export a low level signal and makes the cut-off of Q3N channel MOS.The dotted end of the detecting winding Nd of flyback transformer T1 will be responded to a voltage V simultaneously
Nd=V
C2* Nd/Ns, [V wherein
C2For the voltage of capacitor C 2 anodes to secondary ground, the number of turns that Nd is flyback transformer T1 detecting winding, the number of turns that Ns is flyback transformer T1 primary side winding Ns], and produce a voltage V-(OPl)=V at the reverse input end of amplifier OP1
Nd* R7/ (R6+R7)>V+ (OPl)=0V, that is: the reverse input end voltage of amplifier OP1 is greater than non-inverting input voltage, makes the OP1 output export a low level signal and makes the cut-off of Q4N channel MOS.With simultaneously now, the voltage V that the detecting winding Nd dotted end of transformer T1 is responded to
Nd=V
C2* Nd/Ns offers Q2N channel MOS tube grid through diode D2 and resistance R 5, make Q2N channel MOS tube fast conducting, and produce an electric current I s path and be: dotted end → capacitor C 2 anodes and the inductance L 1 of the non-dotted end of secondary ground → Rm manganin wire → Q2N channel MOS source electrode → Q2N channel MOS drain electrode → flyback transformer T1Ns winding → flyback transformer T1Ns winding.
During Toff, the electric current I s of the primary side winding Ns of transformer T1 flows through Q2N channel MOS parasitic diode D
Q2Time be the very of short duration Δ t time, and Toff-Δ t in the time Is electric current can between the source electrode of Q2N channel MOS tube and drain electrode, flow through, due to the conduction impedance R of this metal-oxide-semiconductor
DS(ON)Usually only have as: 10m Ω～40m Ω left and right, if: R
DS(ON)=20m Ω Rm=24m Ω, Is=5A, the loss P in this circuit of synchronous rectification
MOS=Is
2* (R
DS (ON)+ Rm)=1.1W, and if while adopting existing 20A/200V Schottky diode to do the output rectification, if this Schottky diode forward conduction voltage drop is V
FDuring=0.6V, the power of loss on this Schottky diode is at least up to P
Diode=V
F* I
SMore than=3W.
End during Toff, the electric current that the primary side winding Ns of flyback transformer T1 flows through is reduced to Is2 by Is1, and the energy that transformer discharges is W
Toff=l/2*L
s* I
S1 2-1/2*L
s* 1
S2 2, [sensibility reciprocal of the primary side winding Ns that Ls is transformer T1], and the energy W that equals to store during Ton
Ton.
When this inverse-excitation type switch power-supply is operated in discontinuous mode (DCM), can be with reference to lower Fig. 5 sequential chart.
Operating principle during Q1N channel MOS Ton is consistent with Fig. 4, but different from Fig. 4 when [Toff=t1+t2] during Q1N channel MOS Toff, when the Q1N channel MOS becomes cut-off by conducting, the polarity inversion of all winding current potentials of flyback transformer T1, that is: the Np winding of flyback transformer T1, the Ns winding, the non-dotted end polarities of potentials of Nd winding becomes "-" by "+", the Np winding of flyback transformer T1, the Ns winding, the dotted end polarities of potentials of Nd winding becomes "+" by "-", the energy that flyback transformer T1 stored in Q1N channel MOS conduction period discharges by the Ns winding, when at the t1 end, the Ns winding current Is that flows through flyback transformer T1 equals or while substantially approaching 0A, transformer T1 releases energy substantially, now the non-inverting input at amplifier OP2 produces a voltage V+(OP2) ratio inverse input terminal voltage V-(OP2) approximately be greater than about 5.3mV, that is: V+(OP2)=V-(OP2)+5.3mV, make amplifier OP2 output export a high level signal, make the conducting of Q3N channel MOS tube, make synchronous rectification N-channel MOS Q2 gate charge be released fast complete, that is: when the Is electric current becomes 0A by Isp [during Isp is Toff, the Ns winding initial current of flyback transformer T1], the Q2N channel MOS is ended fast, to prevent that this flyback transformer T1 from may make electric energy in output filter circuit 4 again pour in down a chimney to causing in transformer T1 the Q2MOS pipe when the cut-off after energy releases, producing higher peak voltage between the drain electrode of this MOS and source electrode makes this Q2MOS pipe because of the breakdown problem of withstand voltage deficiency.
During t2: the electromagnetic energy in transformer T1 all is released complete, and due to this transformer T1 armature winding, there is leakage inductance L in Np
K, there is output capacitance C in the Q1N channel MOS
OSS, and there is stray capacitance Cp in transformer T1, makes the dotted end of flyback transformer T1 produce a ringing waveform caused by LC resonance.
And this inverse-excitation type switch power-supply is while being operated in discontinuous mode, the energy that flyback transformer T1 stores during Ton is: W
Ton=1/2*L
p* I
p 2[Ip is the electric current that the Ton later and decadent stage of a school of thought is crossed the Np winding of flyback transformer T1] and the energy that transformer T1 discharges during Toff is:
W
Toff=1/2*L
s* I
Sp 2And the energy storage of [T=Ton+Toff] transformer is the same with the size that releases energy in whole cycle T.By adopting this synchronous rectification, make the conversion efficiency of power supply obtain larger lifting, simultaneously because having adopted cheap amplifier OP or comparator OC to design, make designed power supply product in also concrete larger competitiveness in price.
In another embodiment of the utility model, the difference of Fig. 6 and Fig. 3 is that OP1 and the OP2 amplifier in former Fig. 3 is compared device OC replacement, because comparator output is generally the opener electrode or opens the drain electrode mode, therefore need to add connecting resistance R8 at comparator OC1 output, at comparator OC2 output, add connecting resistance R9 on.
The foregoing is only preferred embodiment of the present utility model, all equalizations of doing according to the utility model claim change and modify, and all should belong to covering scope of the present utility model.
Claims (5)
1. an inverse-excitation type synchronous rectifying circuit of being controlled by amplifier or comparator, is characterized in that: comprise first input end, the second input and the 3rd input, the end that described first input end is resistance R 1 and R3, resistance R 1 other end and resistance R 2 one ends, the non-inverting input of amplifier OP2 is electrically connected, the source electrode of resistance R 2 other ends and synchronous rectification N-channel MOS pipe Q2, manganin wire Rm mono-end is electrically connected, resistance R 3 other ends and resistance R 4 one ends, the inverting input of amplifier OP2 is electrically connected, another terminates secondary ground of resistance R 4 and manganin wire Rm, the grid of the output of amplifier OP2 and Q3 N-channel MOS is electrically connected, the drain electrode of the drain electrode of Q3 N-channel MOS and a N-channel MOS Q4, resistance R 5 one ends, the grid of synchronous rectification N-channel MOS Q2 is electrically connected, the drain electrode of synchronous rectification N-channel MOS Q2 is as described the second input, resistance R 5 other ends and a diode D2 negative terminal are electrically connected, diode D2 anode and diode D1 anode, resistance R 6 one ends are electrically connected and as described the 3rd input, resistance R 6 other ends and resistance R 7 one ends, amplifier OP1 reverse input end are electrically connected, the feeder ear of one end, amplifier OP1 and the OP2 of diode D1 negative terminal and capacitor C 1 is electrically connected, the grid of the output of amplifier OP1 and Q4 N-channel MOS is electrically connected, and the source electrode of the earth terminal of non-inverting input, amplifier OP1 and the OP2 of the other end of capacitor C 1, resistance R 7 other ends, amplifier OP1, Q3 and Q4 N-channel MOS pipe connects secondary ground.
2. the inverse-excitation type synchronous rectifying circuit of being controlled by amplifier or comparator according to claim 1 is characterized in that: replace described amplifier OP1 and OP2 with comparator OC1, OC2, and at output termination one pull-up resistor of described comparator OC1, OC2.
3. a flyback power supply, is characterized in that: the metal-oxide-semiconductor and the output filter circuit that comprise inverse-excitation type synchronous rectifying circuit claimed in claim 1, EMI filter circuit, bridge rectifier, power frequency electrolytic capacitor filter, PWM controller, flyback transformer, driving flyback transformer; The output of EMI filter circuit and the input of bridge rectifier are electrically connected, the output of described bridge rectifier is provided with a power frequency electrolytic capacitor filter Cb, and the non-dotted end of described flyback transformer primary side winding Np and the positive pole of described power frequency electrolytic capacitor filter Cb are electrically connected; The dotted end of flyback transformer primary side winding Np and the drain electrode of Q1 N-channel MOS are electrically connected, and the output pin of the grid of Q1 N-channel MOS and a PWM controller is electrically connected, and the source electrode of Q1 N-channel MOS connects elementary ground; The dotted end of the primary side winding Ns of described flyback transformer and the input of described first input end and output filter circuit are electrically connected; The non-dotted end of the primary side winding Ns of flyback transformer and described the second input are electrically connected; The dotted end of the primary side winding Nd of described flyback transformer and described the 3rd input are electrically connected; The non-terminates secondary ground of getting ready of the primary side winding Nd of flyback transformer.
4. flyback power supply according to claim 3 is characterized in that: replace described amplifier OP1 and OP2 with comparator OC1, OC2, and at output termination one pull-up resistor of described comparator OC1, OC2.
5. flyback power supply according to claim 3, it is characterized in that: described output filter circuit is comprised of inductance L 1, capacitor C 2, C3, and an end of described inductance L 1, an end of capacitor C 2 and described first input end are electrically connected; The other end of inductance L 1 is as the output of this flyback power supply and be connected with an end of capacitor C 3; Another terminates secondary ground of described capacitor C 2, C3.
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| CN2013203619546U CN203326909U (en) | 2013-06-24 | 2013-06-24 | Operation amplifier or comparator-controlled fly-back synchronous rectification circuit and fly-back power supply thereof |
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| CN2013203619546U CN203326909U (en) | 2013-06-24 | 2013-06-24 | Operation amplifier or comparator-controlled fly-back synchronous rectification circuit and fly-back power supply thereof |
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|---|---|---|---|
| CN2013203619546U Withdrawn - After Issue CN203326909U (en) | 2013-06-24 | 2013-06-24 | Operation amplifier or comparator-controlled fly-back synchronous rectification circuit and fly-back power supply thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203326909U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103368423A (en) * | 2013-06-24 | 2013-10-23 | 冠捷显示科技（厦门）有限公司 | Flyback synchronous rectifying circuit controlled by operational amplifier or comparator and flyback power supply thereof |
| CN106936323A (en) * | 2015-12-29 | 2017-07-07 | 上海科特新材料股份有限公司 | AC-DC is without harmonic synchronous fairing |
-
2013
- 2013-06-24 CN CN2013203619546U patent/CN203326909U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103368423A (en) * | 2013-06-24 | 2013-10-23 | 冠捷显示科技（厦门）有限公司 | Flyback synchronous rectifying circuit controlled by operational amplifier or comparator and flyback power supply thereof |
| CN106936323A (en) * | 2015-12-29 | 2017-07-07 | 上海科特新材料股份有限公司 | AC-DC is without harmonic synchronous fairing |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20131204 Effective date of abandoning: 20150715 |
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| RGAV | Abandon patent right to avoid regrant |