CN100388609C - Driving device of synchronous rectifier transistor - Google Patents
Driving device of synchronous rectifier transistor Download PDFInfo
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- CN100388609C CN100388609C CNB2003101016723A CN200310101672A CN100388609C CN 100388609 C CN100388609 C CN 100388609C CN B2003101016723 A CNB2003101016723 A CN B2003101016723A CN 200310101672 A CN200310101672 A CN 200310101672A CN 100388609 C CN100388609 C CN 100388609C
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Abstract
The present invention discloses a driving device of a synchronous rectifier tube, which comprises a drive winding, diodes VD1, VD2, VD3, a controllable switch VT1 and a resistor R1, wherein the drive winding is coupled with a main transformer; the positive homonymous terminal of the drive winding and the positive homonymous terminal of a primary side winding of the main transformer have identical astringent performance without a central tap; the positive homonymous terminal of the drive winding is connected with the control terminal of the controllable switch VT1, a negative electrode of the diode VD2 and a gate electrode of an output synchronous rectification MOS tube; the negative homonymous terminal of the drive winding is connected with a positive electrode of the diode VD3, a negative electrode of the diode VD1 and one end of the controllable switch VT1; the other end of the controllable switch VT1 is connected with a negative electrode of the diode VD3 and is connected with a gate electrode of an output synchronous follow current MOS tube and one end of the resistor R1; the other end of the resistor R1 is connected with the positive electrodes of the diodes VD1, VD2 and the source electrodes of the output synchronous rectification MOS tube and the output simultaneous follow current MOS tube. The driving device of a synchronous rectifier tube of the present invention enables a follow current MOS tube in a main circuit to be sufficiently conducted when in follow current under the condition of any duty ratio, so the conduction of a parasitic diode of the follow current MOS tube is reduced, and the overall efficiency is increased; simultaneously, as the drive winding has no tap, the main transformer is convenient to manufacture.
Description
Technical field
The present invention relates to synchronous rectification, in particular to a kind of drive unit of synchronous rectifier.
Background technology
Synchronous rectification has been widely used in the direct current of low-voltage, high-current in the dc converter.Because the conduction voltage drop of low pressure MOSFET (being designated hereinafter simply as metal-oxide-semiconductor) far below the conduction voltage drop of diode, adopts synchronous rectification can improve the efficient of converter greatly.Because metal-oxide-semiconductor does not have reverse blocking capability, therefore must control its break-make at the gate pole increase control signal.Normally used forward DC to DC converter in, if output voltage is lower, transformer voltage ratio is bigger, for simplicity, general add one at secondary and be with the direct driven MOS pipe of centre tapped process auxiliary drive winding separately, Fig. 1 is the equivalent circuit theory figure of this synchronous rectificating device.As shown in Figure 1, first winding positive synonymous end of centre tapped driving winding of being with of main transformer coupling connects output synchronous rectification metal-oxide-semiconductor gate pole, reverse end of the same name connects output synchronous rectification metal-oxide-semiconductor source electrode and output synchronous freewheeling metal-oxide-semiconductor source electrode, and equivalence is attempted by between first winding for output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1.Drive second winding of winding end negative of the same name and connect output synchronous freewheeling metal-oxide-semiconductor gate pole, equivalence is attempted by between second winding for output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C 2.When conducting is responsible on the former limit of forward converter, main transformer transmits energy to secondary, drive winding positive synonymous end voltage and be higher than negative terminal voltage of the same name, output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1 is recharged, charging voltage is first winding both end voltage, this voltage is always greater than output synchronous rectification metal-oxide-semiconductor cut-in voltage, the conducting of output synchronous rectification metal-oxide-semiconductor, 2 discharges of output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C, final voltage is for negative, output synchronous freewheeling metal-oxide-semiconductor is closed, and realizes the transmission of former limit energy to secondary; When shutoff is responsible on the former limit of forward converter, main transformer resets, drive winding positive synonymous end voltage and be lower than negative terminal voltage of the same name, output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1 is discharged, output synchronous rectification metal-oxide-semiconductor is closed, 2 chargings of output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C, charging voltage is second winding both end voltage, during little duty ratio, it is long that the turn-off time is responsible on former limit, main transformer just resets, it is maximum that the transformer both end voltage reaches, begin afterwards to fall, respective drive winding coupled voltage is also along with falling, suppose that t1 constantly, driving winding coupled voltage just equals secondary and exports synchronous metal-oxide-semiconductor turning-on voltage, then t1 constantly before, output synchronous freewheeling metal-oxide-semiconductor is open-minded, is carved into former limit during from t1 and is responsible for the time period of next cycle between opening constantly, because the voltage that drives winding coupled is less than output synchronous freewheeling metal-oxide-semiconductor cut-in voltage, secondary output synchronous freewheeling metal-oxide-semiconductor turn-offs, because the outputting inductance electric current is continuous, causes exporting the conducting of synchronous freewheeling metal-oxide-semiconductor parasitic diode, the conduction loss of parasitic diode and switching loss are all very big, so overall efficiency is low, can cause the afterflow metal-oxide-semiconductor to damage when serious.So, adopt the direct driven MOS pipe of driving winding of band tap the problem that the synchronous freewheeling metal-oxide-semiconductor drives deficiency can occur exporting.In this case, load current can flow through the body diode of metal-oxide-semiconductor, causes than lossy.Adopt in addition and be with centre tapped driving winding technique trouble, especially pin too much causes difficulty to the flatness that guarantees transformer in flat surface transformer.For overcoming the above problems, the patent No. of the people such as Huang Guisong of Delta electronics application is that 00134742 patent is by driving series diode on the winding, keep the gate pole capacitance voltage constant, can keep the conducting always of afterflow metal-oxide-semiconductor, but the technical scheme of this patent still needs to use the driving winding of band tap, and transformer is made still very difficult.
Summary of the invention
Purpose of the present invention be exactly propose a kind of not with the synchronous rectification tube drive device of tap.
A kind of drive unit of synchronous rectifier comprises a driving winding that is coupled with main transformer, diode VD1, diode VD2, diode VD3, gate-controlled switch VT1 and resistance R 1; The positive synonymous end of described driving winding has identical adstringency with the former limit of main transformer winding positive synonymous end, and does not have centre cap; The positive synonymous end of described driving winding connects the control end of gate-controlled switch VT1, negative electrode and the output synchronous rectification metal-oxide-semiconductor gate pole of diode VD2; The end of the anode of the terminating diode VD3 negative of the same name of described driving winding, the negative electrode of diode VD1 and gate-controlled switch VT1; The other end of described gate-controlled switch VT1 links to each other with the negative electrode of diode VD3, and link to each other with an end of output synchronous freewheeling metal-oxide-semiconductor gate pole and resistance R 1, the other end of resistance R 1 connects anode and output synchronous rectification metal-oxide-semiconductor source electrode and the output synchronous freewheeling metal-oxide-semiconductor source electrode of diode VD1 to anode, diode VD2.
The present invention proposes a kind of drive electric charge that winding, diode, gate-controlled switch and resistance forms by no tap can self-sustaining synchronous rectification tube drive device, make under the situation of any duty ratio, output synchronous freewheeling metal-oxide-semiconductor fully conducting when afterflow in the main circuit, reduce the conducting of output synchronous freewheeling metal-oxide-semiconductor parasitic diode, improved overall efficiency.Do not have tap owing to drive winding simultaneously, be very easy to the making of main transformer.
Description of drawings
Fig. 1 is the equivalent circuit theory figure of synchronous rectificating device of the prior art.
Fig. 2 is the equivalent circuit theory figure that comprises the synchronous rectificating device of the synchronous rectification drive device that the present invention proposes.
Fig. 3 is the circuit theory diagrams of the concrete application of one embodiment of the present of invention.
Embodiment
The present invention is described in further detail below in conjunction with drawings and Examples.
Fig. 1 had carried out explanation in background technology.
Fig. 2 is the equivalent circuit theory figure that comprises the synchronous rectificating device of the synchronous rectification drive device that the present invention proposes.As shown in Figure 2, this synchronous rectificating device also comprises a main transformer and rectification metal-oxide-semiconductor except the drive unit that comprises the present invention's proposition.The synchronous rectification drive device that the present invention proposes comprises a driving winding that is coupled with main transformer, diode VD1, diode VD2, diode VD3, gate-controlled switch VT1 and resistance R 1; The positive synonymous end of described driving winding has identical adstringency with the former limit of main transformer winding positive synonymous end, and does not have centre cap; The positive synonymous end of described driving winding connects the control end of gate-controlled switch VT1, negative electrode and the output synchronous rectification metal-oxide-semiconductor gate pole of diode VD2; The end of the anode of the terminating diode VD3 negative of the same name of described driving winding, the negative electrode of diode VD1 and gate-controlled switch VT1; The other end of described gate-controlled switch VT1 links to each other with the negative electrode of diode VD3, and link to each other with an end of output synchronous freewheeling metal-oxide-semiconductor gate pole and resistance R 1, the other end of resistance R 1 connects anode and output synchronous rectification metal-oxide-semiconductor source electrode and the output synchronous freewheeling metal-oxide-semiconductor source electrode of diode VD1 to anode, diode VD2.Between positive synonymous end that equivalent electric circuit drives winding for output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1 is attempted by and the anode of diode VD2; Output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C 2 is attempted by between the negative electrode of the anode of diode VD2 and diode VD3.Operation principle of the present invention is as follows:
When conducting was responsible on the former limit of forward converter, main transformer transmitted energy to secondary, drove winding positive synonymous end voltage and was higher than negative terminal voltage of the same name.Before positive synonymous end voltage does not rise to gate-controlled switch VT1 turning-on voltage (about the general 3V of control conducting voltage of gate-controlled switch VT1), the close passage that drives winding, main power output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1, diode VD1 makes diode VD1 prior to gate-controlled switch VT1 conducting, and diode VD2 closes anti-Pianguan County simultaneously.After gate-controlled switch VT1 conducting, output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C 2 is equivalent to by short circuit, discharge rapidly, and output synchronous freewheeling metal-oxide-semiconductor turn-offs.Simultaneously, drive winding and by output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1, diode VD1 loop rectification metal-oxide-semiconductor gate pole capacitor C 1 is charged, the conducting of output synchronous rectification metal-oxide-semiconductor realizes the transmission of former limit energy to secondary.When shutoff is responsible on the former limit of forward converter, main transformer resets, drive winding positive synonymous end voltage and be lower than negative end of the same name, output synchronous rectification metal-oxide-semiconductor gate pole capacitor C 1 is by driving winding, diode VD3, the discharge of resistance R 1 loop, after voltage on the capacitor C 1 is lower than output synchronous rectification metal-oxide-semiconductor cut-in voltage, output synchronous rectification metal-oxide-semiconductor is closed, after continuing to drop to 0, and diode VD2 conducting.The end negative of the same name that drives winding charges to afterflow metal-oxide-semiconductor gate pole capacitor C 2 by diode VD3, output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C 2, diode VD2 loop, diode VD1 ends, because this moment, gate-controlled switch VT1 control end voltage was low, not conducting, VD3 only has unilateral conduction, even descend so drive the winding both end voltage, the ceiling voltage that output synchronous freewheeling metal-oxide-semiconductor gate pole capacitor C 2 voltages remain on charging is constant, the conducting always of afterflow metal-oxide-semiconductor.
Fig. 3 is the circuit theory diagrams of the concrete application of one embodiment of the present of invention.As shown in Figure 3; in an embodiment of the present invention; gate-controlled switch VT1 is metal-oxide-semiconductor VT1 among Fig. 2; diode VD1 is fast recovery diode VD1, and diode VD2 is fast recovery diode VD2, and diode VD3 is the body diode of VT1; resistance is R1; be protection output synchronous freewheeling metal-oxide-semiconductor, shunt regulator tube VD4 on R1, its anode is connected with the VD2 anode.Above-mentioned device and driving winding are formed the electric charge of front the present invention proposition from the drive unit of keeping.Describe for convenient, Fig. 3 shows the forward converter circuit diagram that comprises synchronous rectificating device of the present invention.Transformer T is made of former limit winding TIN, secondary winding TOUT and driving winding TDROUT.Former limit winding TIN positive synonymous end is received positive source, and secondary winding TOUT has identical polarity with driving winding TDROUT positive synonymous end with former limit winding TIN positive synonymous end.S1, S2 are output synchronous rectification metal-oxide-semiconductors, the source electrode of rectification metal-oxide-semiconductor S1, S2 is connected with each other, and link to each other with VD2 anode in the drive circuit, the gate pole of rectification metal-oxide-semiconductor S1 is connected with driving winding TDROUT positive synonymous end, drain electrode is connected with the end negative of the same name of secondary winding TOUT, the drain electrode of rectification metal-oxide-semiconductor S2 is connected with the negative end of the same name of secondary winding TOUT, and rectification metal-oxide-semiconductor S2 gate pole is connected with VD3 negative electrode in the drive circuit.The course of work of this drive unit is as follows:
When the former limit person in charge of converter opens, driving winding coupled voltage is that forward end of the same name is higher than negative sense end of the same name, be made as V1, VD2 turn-offs, and VD1 is open-minded, after V1 rises to 2-3V, the VT1 conducting, afterflow metal-oxide-semiconductor gate pole electric capacity is by VT1, and VD1 is by short circuit, electric charge is bled off rapidly on the electric capacity, and the afterflow metal-oxide-semiconductor is closed.V1 continues to rise, after rectification metal-oxide-semiconductor gate voltage is higher than its cut-in voltage, and the conducting of rectification metal-oxide-semiconductor, along with V1 rises, its conducting resistance diminishes.After V1 rose to its maximum (VIN/N, VIN are input voltage, and N is the former limit of transformer winding and drives the winding turns ratio), the rectification metal-oxide-semiconductor was stablized conducting, realizes the transmission of the former limit of converter energy to secondary.
When shutoff was responsible on the former limit of converter, driving winding coupled voltage was that positive synonymous end is lower than negative sense end of the same name, is made as V2.VT1 turn-offs; VD1 turn-offs; rectification metal-oxide-semiconductor gate pole capacitor C 1 is by driving winding, VT1 body diode, the discharge of R1 loop; just begin the moment of discharging; afterflow metal-oxide-semiconductor gate voltage is rectification metal-oxide-semiconductor gate voltage and V2 sum; might surpass the afterflow metal-oxide-semiconductor gate voltage limit, damage the afterflow metal-oxide-semiconductor, so protect the afterflow metal-oxide-semiconductor with voltage-stabiliser tube VD4.When the C1 both end voltage put be 0 after, the rectification metal-oxide-semiconductor turn-offs, the VD2 conducting, afterflow metal-oxide-semiconductor gate pole capacitor C 2 two ends charging voltages are V2.When closing along with the converter person in charge, main transformer original edge voltage V resonance is finished after the maximum and is resetted, V resonance descends afterwards, and corresponding V2 also resonance descends, because VT1 closes, afterflow metal-oxide-semiconductor gate voltage can be along with V2 descends after reaching the maximum voltage V2MAX of coupling, but descend by R1 discharge, because R1 big (generally getting about 200 ohm), so that V2MAX descends is very slow, can guarantee to raise the efficiency in the former limit person in charge's blocking interval afterflow metal-oxide-semiconductor conducting always.
Claims (5)
1. the drive unit of a synchronous rectifier is characterized in that, comprises a driving winding that is coupled with main transformer, diode VD1, diode VD2, diode VD3, gate-controlled switch VT1 and resistance R 1; The positive synonymous end of described driving winding has identical adstringency with the former limit of main transformer winding positive synonymous end, and does not have centre cap; The positive synonymous end of described driving winding connects the control end of gate-controlled switch VT1, negative electrode and the output synchronous rectification metal-oxide-semiconductor gate pole of diode VD2; The end of the anode of the terminating diode VD3 negative of the same name of described driving winding, the negative electrode of diode VD1 and gate-controlled switch VT1; The other end of described gate-controlled switch VT1 links to each other with the negative electrode of diode VD3, and link to each other with an end of output synchronous freewheeling metal-oxide-semiconductor gate pole and resistance R 1, the other end of resistance R 1 connects the anode of diode VD1, anode and output synchronous rectification metal-oxide-semiconductor source electrode and the output synchronous freewheeling metal-oxide-semiconductor source electrode of diode VD2.
2. the drive unit of a kind of synchronous rectifier according to claim 1, the control conducting voltage that it is characterized in that described gate-controlled switch VT1 is 3V.
3. the drive unit of a kind of synchronous rectifier according to claim 1 is characterized in that described diode VD1, VD2 are fast recovery diode.
4. the drive unit of a kind of synchronous rectifier according to claim 1 is characterized in that described gate-controlled switch VT1 is a metal-oxide-semiconductor, and described diode VD3 is the body diode of gate-controlled switch VT1.
5. the drive unit of a kind of synchronous rectifier according to claim 1, the resistance that it is characterized in that described resistance R 1 is 200 ohm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101016723A CN100388609C (en) | 2003-10-24 | 2003-10-24 | Driving device of synchronous rectifier transistor |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2003101016723A CN100388609C (en) | 2003-10-24 | 2003-10-24 | Driving device of synchronous rectifier transistor |
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| CN1538610A CN1538610A (en) | 2004-10-20 |
| CN100388609C true CN100388609C (en) | 2008-05-14 |
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| CNB2003101016723A Expired - Lifetime CN100388609C (en) | 2003-10-24 | 2003-10-24 | Driving device of synchronous rectifier transistor |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100440704C (en) * | 2004-11-26 | 2008-12-03 | 中兴通讯股份有限公司 | Synchronous commutating self-driving circuit for single-end conversion |
| CN104638994A (en) * | 2014-12-25 | 2015-05-20 | 延锋伟世通电子科技（上海）有限公司 | Active flow current circuit driven based on direct-current motor |
| CN104601016B (en) * | 2015-01-13 | 2017-02-08 | 西安工程大学 | Method for reducing loss of synchronous rectification drive circuit based on coupling coil |
| CN104953859B (en) * | 2015-07-06 | 2019-03-22 | 安徽省东科半导体有限公司 | A kind of synchronous diode |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10210740A (en) * | 1997-01-17 | 1998-08-07 | Murata Mfg Co Ltd | Synchronous rectifier |
| US6185114B1 (en) * | 1999-03-05 | 2001-02-06 | Murata Manufacturing Co., Ltd. | Isolating DC-DC converter |
| CN1381942A (en) * | 2001-02-09 | 2002-11-27 | 精电科技公司 | Supply transformer containing circuit for controlling synchronous rectifier |
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2003
- 2003-10-24 CN CNB2003101016723A patent/CN100388609C/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10210740A (en) * | 1997-01-17 | 1998-08-07 | Murata Mfg Co Ltd | Synchronous rectifier |
| US6185114B1 (en) * | 1999-03-05 | 2001-02-06 | Murata Manufacturing Co., Ltd. | Isolating DC-DC converter |
| CN1381942A (en) * | 2001-02-09 | 2002-11-27 | 精电科技公司 | Supply transformer containing circuit for controlling synchronous rectifier |
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| CN1538610A (en) | 2004-10-20 |
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