CN207732658U - A kind of synchronous rectification driving circuit for Switching Power Supply - Google Patents

Abstract

The utility model discloses a kind of synchronous rectification driving circuits for Switching Power Supply, are related to electronic technology field, and the T3 and T4 of the utility model are respectively two windings on transformer, wherein T3 is secondary side winding, is used for the transmission of energy, T4 is auxiliary winding.The voltage of voltage follow secondary side winding T3 on auxiliary winding T4 increases, to open synchronous rectification Mos pipes M1, armature winding CT1 and secondary windings CT2 is then two windings of Current Transmit, wherein, armature winding CT1 is gone here and there in main circuit, for detecting the electric current for flowing through Mos pipes, when the electric current in armature winding CT1 drops to zero, secondary windings CT2 will turn off M1, therefore, the synchronous rectification driving circuit of the utility model is with voltage signal control Mos pipes conducting, current signal controls the shutdown of Mos pipes, it is not only efficient, and the operation is stable, there is no open by mistake logical situation.

Description

A kind of synchronous rectification driving circuit for Switching Power Supply

Technical field

The utility model is related to electronic technology fields more particularly to a kind of synchronous rectification for Switching Power Supply to drive electricity Road.

Background technology

In general inverse-excitation type switch power-supply, the loss of the rectifier diode of secondary side be power-efficient great influence because One of element can alleviate this problem by selecting the Schottky diode of low conduction voltage drop.But on the one hand, this improvement pair The influence of performance is not very significant；On the other hand, if the voltage of output is higher, and the reversed pressure resistance of Schottky diode It is general relatively low, it is difficult to meet the requirements.

Utility model content

The purpose of this utility model is that：To solve to select the Xiao Te of low conduction voltage drop in existing inverse-excitation type switch power-supply Based diode is not fine come the effect for alleviating rectifier diode loss, and if the voltage of output is higher, and Schottky two The reversed pressure resistance of pole pipe is general relatively low, it is difficult to which the problem of meeting the requirements, the utility model provide a kind of for the same of Switching Power Supply Walk commutation driver circuit.

The technical solution of the utility model is as follows：

A kind of synchronous rectification driving circuit for Switching Power Supply, the circuit connecting mode are：The two of transformer one end A winding includes secondary side winding T3 and auxiliary winding T4, one end of secondary side winding T3 be separately connected diode D1 cathode and The anode of polar capacitor C3, one end of the armature winding CT1 of the other end connection current transformer of secondary side winding T3, it is primary around The drain electrode of the other end connection metal-oxide-semiconductor M1 of group CT1, the source electrode of the cathode connection metal-oxide-semiconductor M1 of polar capacitor C3, the sun of diode D2 Pole connects one end of the secondary windings CT2 of current transformer, one end of this one end connection resistance R2 of secondary windings CT2, resistance The other end of R2 is grounded, and the capacitance C2 and diode D4 that the other end connection of secondary windings CT2 is in parallel are grounded, diode D4's Plus earth；The resistance R1 and diode D2 of one end connection parallel connection of auxiliary winding T4, the cathode connected to the transistor of diode D2 The emitter of Q2, the base stage of the other end connecting triode Q2 of resistance R1, the one end of the emitter of triode Q2 also with capacitance C1 Connection, the other end of the collector connection capacitance C1 of triode Q2, the cathode and triode Q1 of diode D6 emitter, MOS The emitter of the cathode and triode Q1 of the grid connection diode D6 of pipe M1, the sun of the base stage connection diode D5 of triode Q1 Pole, earth-free one end cathode connection resistance R2 of diode D5, the grounded collector of triode Q1, auxiliary winding T4's is another End ground connection, the cathode of diode D2 are also associated with one end of diode D3, the other end ground connection of diode D3.

Specifically, the collector of the triode Q2, the grid of metal-oxide-semiconductor M1 connect capacitance C4 with the emitter of triode Q1 One end, capacitance C4 the other end ground connection.

After adopting the above scheme, the beneficial effects of the utility model are：

T3 and T4 is respectively two windings on transformer, wherein T3 is secondary side winding, is used for the transmission of energy, T4 For auxiliary winding.The voltage of voltage follow T3 on T4 increases, and is electricity to open synchronous rectification Mos pipes M1, CT1 and CT2 then Two windings of current transformer CT, wherein armature winding CT1 is gone here and there in main circuit, for detecting the electric current for flowing through Mos pipes, When the electric current in CT1 drops to zero, CT2 will turn off M1, and therefore, the synchronous rectification driving circuit of the utility model is with electricity Signal control Mos pipes conducting is pressed, current signal controls the shutdown of Mos pipes, not only efficient, but also the operation is stable, and there is no open by mistake Logical situation.

Description of the drawings

Fig. 1 is the circuit diagram of the utility model；

Fig. 2 is that the no-voltage in the embodiments of the present invention opens circuit.

Specific implementation mode

The following will be combined with the drawings in the embodiments of the present invention, the technical solution in the present embodiment is carried out it is clear, complete Site preparation describes, it is clear that described embodiment is only a part of the embodiment of the utility model, rather than whole implementation Example.Based on the embodiments of the present invention, those of ordinary skill in the art are obtained without making creative work The every other embodiment obtained, shall fall within the protection scope of the present invention.

A kind of synchronous rectification driving circuit for Switching Power Supply in the present embodiment, circuit connecting mode are：Transformer Two windings of one end include secondary side winding T3 and auxiliary winding T4, and one end of secondary side winding T3 is separately connected diode D1 Cathode and polar capacitor C3 anode, secondary side winding T3 the other end connection current transformer armature winding CT1 one End, the drain electrode of the other end connection metal-oxide-semiconductor M1 of armature winding CT1, the source electrode of the cathode connection metal-oxide-semiconductor M1 of polar capacitor C3, two One end of the secondary windings CT2 of the anode connection current transformer of pole pipe D2, this one end connection resistance R2's of secondary windings CT2 One end, the other end ground connection of resistance R2, the capacitance C2 and diode D4 that the other end connection of secondary windings CT2 is in parallel are grounded, and two The plus earth of pole pipe D4；The cathode of one end connection resistance R1 and diode D2, diode D2 in parallel of auxiliary winding T4 connects Connect the emitter of triode Q2, the base stage of the other end connecting triode Q2 of resistance R1, the emitter of triode Q2 also with capacitance One end of C1 connects, the other end of the collector connection capacitance C1 of triode Q2, the cathode and triode Q1 of diode D6 hair Emitter-base bandgap grading, the emitter of the cathode and triode Q1 of the grid connection diode D6 of metal-oxide-semiconductor M1, the base stage of triode Q1 connect two poles The anode of pipe D5, earth-free one end cathode connection resistance R2 of diode D5, the grounded collector of triode Q1, auxiliary winding The other end of T4 is grounded, and the cathode of diode D2 is also associated with one end of diode D3, the other end ground connection of diode D3.It is described The collector of triode Q2, the grid of metal-oxide-semiconductor M1 connect one end of capacitance C4 with the emitter of triode Q1, and capacitance C4's is another End ground connection.

Specifically, during use, the circuit of the utility model is to open circuit by transformer and no-voltage Connection, specific no-voltage open circuit as shown in Fig. 2, no-voltage open circuit the working process of the utility model is as follows：The In one stage, the shutdown of transformer primary side Mos pipes, electric current is from the primary side change of current of transformer to secondary side.Secondary side winding T3 is logical CT1 is crossed, M1 is output capacitor C3 chargings.The output voltage of secondary side winding T3 is clamped in C3 both end voltages (in this application In about 52V).

Since T4 windings are an auxiliary winding of transformer, the voltage ratio of Same Name of Ends B points rises to a height Voltage.Then B point voltages are capacitor C1, C4 charging by diode D2.Wherein, the gate pole that capacitor C4 is Mos pipes M1 inputs Capacitance, usually less than 1nF, it is shown in dotted line.Capacitor C1 is additional capacitance, takes 10 times of C4 capacitances or more.Since C4 is remote Less than C1, and capacitance very little, according to the series connection voltage divider principle of capacitor, C point voltages are charged to nearly 10V, M1 conductings quickly. Meanwhile the energy in Current Transmit from winding CT2 by diode D1 feed-in output capacitor C3, reduce switch and drive Dynamic loss, D point voltages are also clamped at about 52V.

Second stage, the electric current for flowing through D1 are reduced to 0, and the electric current for flowing through CT1 at this time is reduced to Ioff.D1 is turned off, D point voltages Start to reduce, be finally connected triode Q1, the electricity on C4 is let go, and C points become low-voltage, M1 shutdowns, synchronous rectification knot Beam.Due to Ioff at this time>0, the charging process of Circuit Fault on Secondary Transformer is not over yet, diverted via the parasitic body diode afterflow of M1, A Point, B points are still high voltage.Since C4 is by Q1 short circuits, T4 is charged by D2, Q1 for C1, until C1 is filled.It is noticeable It is why C1 selects capacitance without the use of resistance, on the one hand ensure that the quick charge to C4 in the first stage, on the other hand So that the loss in second stage after Q1 conductings on it is minimized, the efficiency of driving is improved.

Phase III, transformer primary side Mos pipes are connected again, and A points, B points are negative voltage, PNP triode Q2 conductings, C1 It is discharged, ensure that next period can work normally again.C point voltages are maintained at low-voltage, and opening by mistake for M1 will not be caused logical. It is worth noting that, in each period, C1 can be by impulse electricity repeatedly.Its loss can be obtained by formula P=1/2CU2f.Wherein, If C=10nF, U=10V, f=100kHz.Therefore P=50mW, this power being lost on C1.When transformer primary side After Mos pipes turn off again over time, new a cycle starts.

It will be seen that the utility model is with following excellent during the concrete operating principle that circuit above works Point：1) various output voltages can be widely used in.2) circuit structure and principle are relatively simple.3) drive loss is small, efficient. 4) circuit certainty is good, error-free motion.

It is obvious to a person skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and And without departing substantially from the spirit or essential attributes of the utility model, it can realize that this practicality is new in other specific forms Type.Therefore, in all respects, the present embodiments are to be considered as illustrative and not restrictive, this practicality is new The range of type is indicated by the appended claims rather than the foregoing description, it is intended that containing in the equivalent requirements of the claims will be fallen All changes in justice and range are embraced therein.Any reference numeral in claim should not be considered as limitation Involved claim.

In addition, it should be understood that although this specification is described in terms of embodiments, but not each embodiment is only wrapped Containing an independent technical solution, this description of the specification is merely for the sake of clarity, and those skilled in the art should It considers the specification as a whole, the technical solutions in the various embodiments may also be suitably combined, forms those skilled in the art The other embodiment being appreciated that.

Claims (2)

1. a kind of synchronous rectification driving circuit for Switching Power Supply, which is characterized in that the circuit connecting mode is：Transformer Two windings of one end include secondary side winding T3 and auxiliary winding T4, and one end of secondary side winding T3 is separately connected diode D1 Cathode and polar capacitor C3 anode, secondary side winding T3 the other end connection current transformer armature winding CT1 one End, the drain electrode of the other end connection metal-oxide-semiconductor M1 of armature winding CT1, the source electrode of the cathode connection metal-oxide-semiconductor M1 of polar capacitor C3, two One end of the secondary windings CT2 of the anode connection current transformer of pole pipe D2, this one end connection resistance R2's of secondary windings CT2 One end, the other end ground connection of resistance R2, the capacitance C2 and diode D4 that the other end connection of secondary windings CT2 is in parallel are grounded, and two The plus earth of pole pipe D4；The cathode of one end connection resistance R1 and diode D2, diode D2 in parallel of auxiliary winding T4 connects Connect the emitter of triode Q2, the base stage of the other end connecting triode Q2 of resistance R1, the emitter of triode Q2 also with capacitance One end of C1 connects, the other end of the collector connection capacitance C1 of triode Q2, the cathode and triode Q1 of diode D6 hair Emitter-base bandgap grading, the emitter of the cathode and triode Q1 of the grid connection diode D6 of metal-oxide-semiconductor M1, the base stage of triode Q1 connect two poles The anode of pipe D5, earth-free one end cathode connection resistance R2 of diode D5, the grounded collector of triode Q1, auxiliary winding The other end of T4 is grounded, and the cathode of diode D2 is also associated with one end of diode D3, the other end ground connection of diode D3.

2. a kind of synchronous rectification driving circuit for Switching Power Supply according to claim 1, which is characterized in that described three The collector of pole pipe Q2, the grid of metal-oxide-semiconductor M1 connect one end of capacitance C4, the other end of capacitance C4 with the emitter of triode Q1 Ground connection.