CN105577001A - Hybrid synchronous rectification circuit - Google Patents
Hybrid synchronous rectification circuit Download PDFInfo
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- CN105577001A CN105577001A CN201410544409.XA CN201410544409A CN105577001A CN 105577001 A CN105577001 A CN 105577001A CN 201410544409 A CN201410544409 A CN 201410544409A CN 105577001 A CN105577001 A CN 105577001A
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Abstract
The invention relates to a hybrid synchronous rectification circuit comprising a transformer, a current transformer, a synchronous rectifier tube and a synchronous rectifier tube control circuit. The transformer is formed by a secondary side winding and an auxiliary winding; the starting point and the end point of the secondary side winding are connected with a primary winding starting point and a secondary winding end point of the current transformer respectively; the end point of the primary winding of the current transformer is connected with a drain electrode of the synchronous rectifier tube; and a source electrode of the synchronous rectifier tube and a substrate are grounded. The synchronous rectifier tube control circuit consists of a first driving triode and a second driving triode; a first capacitor is connected in parallel between an emitter and a collector of the second driving triode. According to the invention, the hybrid synchronous rectification circuit has the following characteristics: (1), the circuit can be widely applied to various output voltages; (2), the circuit structure and principle are simple; (2), the driving loss is low and the efficiency is high; and (4), the circuit certainty is good.
Description
Technical field
The present invention relates to electronic circuit field, particularly, relate to a kind of mixed type circuit of synchronous rectification.
Background technology
Along with the development of large power white light LED technology, Lighting Industry starts to face new opportunities and challenges.LED is applied to general illumination field more and more, and road lighting is then the important applied field of one of them great potential.Due to the feature of LED specific long-life itself, potential specular removal, design a high-efficiency constant-current driving power that can give full play to this feature and then seem particularly important.
In general inverse-excitation type switch power-supply, the rectifier diode loss of secondary side is also one of important factor in order of power-efficient, can alleviate this problem by selecting the Schottky diode of low conduction voltage drop.But on the one hand, the impact of this improvement on performance is not show very much; On the other hand, in this application, output voltage is higher, and Schottky diode is reverse withstand voltage general lower, is difficult to meet the demands.
Reasonable method adopts synchronous rectification exactly, and the Mos pipe low by conducting resistance substitutes traditional rectifier diode.Synchronous rectification drives type and self-powered type outside can being divided into according to working method, divides by operation principle, can be divided into again voltage-type driving, current mode drive and mode of resonance driving etc.These synchronous rectification modes differ from one another, but also respectively have deficiency.But due to by the gate drive voltage clamper of Mos pipe at output voltage, and gate pole puncture voltage is lower, is therefore only applicable to the situation compared with low output voltage.
Summary of the invention
Being only applicable to the technological deficiency of the lower applicable cases of output voltage for overcoming existing synchronous rectification when driven MOS pipe, the invention discloses a kind of mixed type circuit of synchronous rectification.
Mixed type circuit of synchronous rectification of the present invention, be made up of transformer, current transformer, synchronous rectifier and synchronous rectifier control circuit, described transformer is made up of secondary side winding and auxiliary winding, described secondary side winding starting point is connected with current transformer armature winding starting point and secondary winding terminal respectively with terminal, the terminal of described current transformer armature winding drains with synchronous rectifier and is connected, the source electrode of synchronous rectifier and Substrate ground;
Described synchronous rectifier control circuit comprises the first driving triode and second and drives triode, described first drives transistor emitter to connect synchronous rectification tube grid, grounded collector, base stage connects secondary transformer winding terminal, described second drives the collector electrode of triode to connect synchronous rectification tube grid, base stage connection transformer assists winding starting point, second drives the emitter of triode to assist winding starting point by rectifier diode connection transformer, described rectifier diode negative pole connects second and drives transistor emitter, the first electric capacity is also parallel with between the emitter and collector of described second driving triode.
Preferably, described current transformer terminal is connected by the first diode with between Circuit Fault on Secondary Transformer winding, described first diode cathode connection transformer, and positive pole connects secondary transformer winding terminal.
Concrete, described first drives transistor base to connect current transformer by driving rectifier diode, and described driving rectifier diode positive pole connects secondary transformer winding terminal.
Concrete, described power tube is power NMOS tube.
Mixed type circuit of synchronous rectification of the present invention has following features: 1) can be widely used in various output voltage.2) circuit structure and principle are comparatively simple.3) drive loss little, efficiency is high.4) circuit certainty is good, error-free motion.
Accompanying drawing explanation
Fig. 1 is a kind of embodiment schematic diagram of the present invention.
Embodiment
Below in conjunction with embodiment and accompanying drawing, to the detailed description further of the present invention's do, but embodiments of the present invention are not limited thereto.
Mixed type circuit of synchronous rectification of the present invention, be made up of transformer, current transformer, synchronous rectifier M1 and synchronous rectifier control circuit, described transformer is made up of secondary side winding and auxiliary winding, described secondary side winding starting point is connected with current transformer armature winding starting point and secondary winding terminal respectively with terminal, the terminal of described current transformer armature winding drains with synchronous rectifier and is connected, the source electrode of synchronous rectifier and Substrate ground;
Described synchronous rectifier control circuit comprises the first driving triode Q1 and second and drives triode Q2, described first drives transistor emitter to connect synchronous rectification tube grid, grounded collector, base stage connects secondary transformer winding terminal, described second drives the collector electrode of triode to connect synchronous rectification tube grid, base stage connection transformer assists winding starting point, second drives the emitter of triode to assist winding starting point by rectifier diode connection transformer, described rectifier diode negative pole connects second and drives triode Q2 emitter, the first electric capacity is also parallel with between the emitter and collector of described second driving triode.
Preferably, described current transformer terminal is connected by the first diode D1 with between Circuit Fault on Secondary Transformer winding, described first diode cathode connection transformer, and positive pole connects secondary transformer winding terminal.
Concrete, described first drives transistor base to connect current transformer by driving rectifier diode D5, and described driving rectifier diode positive pole connects secondary transformer winding terminal
As shown in Figure 1, T3 and T4 is respectively two windings on transformer: wherein, and T3 is secondary side winding, and for the transmission of energy, T4 is auxiliary winding.The voltage of the voltage follow T3 on T4 raises, in order to open synchronous rectification Mos pipe M1.CT1 and CT2 is then two windings of Current Transmit, and wherein, armature winding CT1 is gone here and there in main circuit, for detecting the electric current flowing through Mos pipe.When the electric current in CT1 drops to zero, CT2 will turn off M1.Therefore, this scheme is with the conducting of voltage signal control Mos pipe, and current signal control Mos pipe turns off, and not only efficiency is high, and working stability, does not exist and opens by mistake logical situation.Labor is done below by the course of work of this drive scheme.
1) first stage, transformer primary side Mos pipe turns off, and electric current is from the primary side change of current of transformer to secondary side.T3 winding is that output capacitor C3 charges by CT1, M1.The output voltage of T3 winding by clamper in C3 both end voltage (being about 52V in this application).
Due to the auxiliary winding that T4 winding is transformer, therefore, the voltage ratio of Same Name of Ends B point rises to a high voltage (being about 10V in this application).Then B point voltage is capacitor C1, C4 charging by diode D2.Wherein, capacitor C4 is the gate pole input capacitance of Mos pipe M1, is usually less than 1nF, shown in broken lines.Capacitor C1 is additional electric capacity, more than 10 times that get C4 capacitance.Because C4 is much smaller than C1, and capacitance is very little, and according to the series connection voltage divider principle of capacitor, C point voltage is charged to nearly 10V, M1 conducting very soon.Meanwhile, the energy in Current Transmit is from winding CT2 by diode D1 feed-in output capacitor C3, and reduce switch drive loss, D point voltage is also clamped at about 52V.
2) second stage, the electric current flowing through D1 reduces to 0, and the electric current now flowing through CT1 reduces to Ioff.D1 turns off, and D point voltage starts to reduce, and finally make PNP type triode Q1 conducting, the electricity on C4 is let go, and C point becomes low-voltage, and M1 turns off, and synchronous rectification terminates.Due to now Ioff>0, the charging process of Circuit Fault on Secondary Transformer is not over yet, and diverted via the parasitic body diode afterflow of M1, and A point, B point are still high voltage.Because C4 is by Q1 short circuit, T4 is C1 charging by D2, Q1, until C1 is filled.It should be noted that why C1 selects electric capacity and do not use resistance, ensure that on the one hand the quick charge to C4 in the first stage, to make in second stage after Q1 conducting loss thereon be minimized on the other hand, improve the efficiency of driving.
3) phase III, transformer primary side Mos manages conducting again, and A point, B point are negative voltage, PNP triode Q2 conducting, and C1 is discharged, and ensure that next cycle can normally work again.C point voltage remains on low-voltage, and opening by mistake of M1 can not be caused logical.It should be noted that in each cycle, C1 can by impulse electricity repeatedly.Its loss can be obtained by formula P=1/2C*U2*f.Wherein, C is C1 capacitance, if C=10nF, U=10V, f=100kHz.Therefore P=50mW, the power of this i.e. loss on C1.Have no progeny when transformer primary side Mos manages again to close over time, new one-period starts.。
As mentioned above, the present invention can be realized preferably.
Claims (4)
1. mixed type circuit of synchronous rectification, it is characterized in that, be made up of transformer, current transformer, synchronous rectifier and synchronous rectifier control circuit, described transformer is made up of secondary side winding and auxiliary winding, described secondary side winding starting point is connected with current transformer armature winding starting point and secondary winding terminal respectively with terminal, the terminal of described current transformer armature winding drains with synchronous rectifier and is connected, the source electrode of synchronous rectifier and Substrate ground;
Described synchronous rectifier control circuit comprises the first driving triode and second and drives triode, described first drives transistor emitter to connect synchronous rectification tube grid, grounded collector, base stage connects secondary transformer winding terminal, described second drives the collector electrode of triode to connect synchronous rectification tube grid, base stage connection transformer assists winding starting point, second drives the emitter of triode to assist winding starting point by rectifier diode connection transformer, described rectifier diode negative pole connects second and drives transistor emitter, the first electric capacity is also parallel with between the emitter and collector of described second driving triode.
2. mixed type circuit of synchronous rectification according to claim 1, it is characterized in that, described current transformer terminal is connected by the first diode with between Circuit Fault on Secondary Transformer winding, described first diode cathode connection transformer, and positive pole connects secondary transformer winding terminal.
3. mixed type circuit of synchronous rectification according to claim 1, is characterized in that, described first drives transistor base to connect current transformer by driving rectifier diode, and described driving rectifier diode positive pole connects secondary transformer winding terminal.
4. mixed type circuit of synchronous rectification according to claim 1, is characterized in that, described power tube is power NMOS tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410544409.XA CN105577001A (en) | 2014-10-15 | 2014-10-15 | Hybrid synchronous rectification circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410544409.XA CN105577001A (en) | 2014-10-15 | 2014-10-15 | Hybrid synchronous rectification circuit |
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| CN105577001A true CN105577001A (en) | 2016-05-11 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107896068A (en) * | 2017-12-07 | 2018-04-10 | 绵阳伟成科技有限公司 | A kind of synchronous rectification driving circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107896068A (en) * | 2017-12-07 | 2018-04-10 | 绵阳伟成科技有限公司 | A kind of synchronous rectification driving circuit |
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Application publication date: 20160511 |