CN1481066A - BUCK convertor containing synchronous rectitication drive circuit - Google Patents
BUCK convertor containing synchronous rectitication drive circuit Download PDFInfo
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- CN1481066A CN1481066A CNA03126977XA CN03126977A CN1481066A CN 1481066 A CN1481066 A CN 1481066A CN A03126977X A CNA03126977X A CN A03126977XA CN 03126977 A CN03126977 A CN 03126977A CN 1481066 A CN1481066 A CN 1481066A
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Abstract
The convertor includes input power source, rectifying tube, follow current tube, first drive circuit for driving the rectifying tube and second drive circuit for driving the follow current tube. The said second drive circuit includes second pulse width modulator, reverse isolation differential circuit, electrical level comparison and energy conversion circuit, auxiliary power supply and complement drive circuit connected in sequence. One end of complement drive circuit is connected to gate electrode of the follow current tube, and the other end is connected to ground. When shut-off signal comes, high electrical level output by isolation differential circuit is decreased quickly, and electrical level comparison and energy conversion circuit turns on quickly. The complement drive circuit makes electric charge on grid electrode of synchronous follow current MOS discharge quickly, and makes MOS transistor cut off. Thus, shutting down convertor does not generate negative voltage.
Description
Technical field:
The present invention relates to a kind of BUCK converter that contains synchronous rectification driving circuit.
Background technology:
Along with the development of information technology, the supply power voltage of digit chip requirement power supply is more and more lower, supply current is increasing.In order to adapt to digit chip this specification requirement to the low-voltage, high-current of power supply, the synchronous rectification that is used for the DC-DC converter is owing to having higher efficient than Schottky commutation technique and being widely adopted at DC-DC converter commutation technique.So-called synchronous rectification, but generally be the technology that replaces the rectification of Schottky (Schottky) diode realization DC-DC converter with the mosfet transistor of two-way admittance, the type of drive of synchronous rectification metal-oxide-semiconductor has self-powered driving, its driving and self-powered, and it drives three kinds of modes.
The self-powered type of drive is owing to simple and reliable with low cost being widely used in the DC-DC inverter main circuit topological structure of circuit.But, because normal shock DC-DC converter transformer magnetic core needs magnetic reset during Toff, the synchronous freewheeling metal-oxide-semiconductor during magnetic reset because of there not being driving voltage to end, inductive current will or add the Schottky diode circulation by diode in the afterflow metal-oxide-semiconductor body, and this advantage that makes synchronous rectification to raise the efficiency can't embody in low-voltage, high-current DC-DC converter.
The employed metal-oxide-semiconductor of synchronous rectification is the same with general MOSFET power tube, all have diode in the parasitic body, the on-state voltage drop of this body diode is up to 1.2V, and reverse recovery time is up to 60nS, its performance index are than Schottky diode difference, and are poorer than the switching characteristic of metal-oxide-semiconductor.The shortcoming of diode current flow in the body:, thereby reduce DC-DC converter overall efficiency 1. because the characteristic of the high on-state voltage drop of body diode makes that synchronous rectification metal-oxide-semiconductor operating efficiency is lower.2. since in the body diode losses big, temperature rise, fragile, thereby reduced the reliability of DC-DC converter complete machine.Owing to there is reverse recovery characteristic, make converter produce electromagnetic interference and loss when 3. body diode turn-offs.4. in order to reach international Electro Magnetic Compatibility EMI standard, need to increase EMI filtering components and parts, the cost of converter complete machine is strengthened.
Patent 99126693 has realized that preferably the self-powered of synchronous rectifier drives.In its circuit, rectifying tube is directly driven by transformer secondary in-phase end or auxiliary winding drives, and continued flow tube utilizes continued flow tube gate charge holding circuit to solve the problem that continued flow tube ends because of no driving voltage during the transformer magnetic reset preferably by the direct or auxiliary winding of transformer secondary end of oppisite phase.Simultaneously, by delay circuit, isolate the flexible that differential circuit, gate charge leadage circuit have been realized the drive waveforms trailing edge " dead band " of the drive waveforms rising edge of rectifying tube and continued flow tube preferably, can make " dead band " time be transferred to the best, conducting body diode ON time is very not little yet simultaneously for two pipes, and efficient and reliability are higher.
These patent circuit existing problems:
1. only some dead band is adjustable for this patent, and the drive waveforms rising edge dead band of the drive waveforms trailing edge of circuit rectifying tube and continued flow tube is non-adjustable, and " dead band " time is bigger, and 20～200nS is arranged, and efficient is low.See Fig. 1 a for details, Fig. 1 c.
Should " dead band " time during by transformer excitation inductance, former limit leakage inductance and resonant capacitance, main power MOS pipe junction capacitance, rectifying tube junction capacitance resonance the grid cut-in voltage of capacitance voltage and continued flow tube determine that jointly computing formula is as follows:
As: turn ratio n=10, cut-in voltage=2.5V, " dead band " time is 72nS, loss in efficiency 1.7%.
The rate of climb that voltage is set up on the resonant capacitance during resonance is fast more, and " dead band " time is more little, and the ON time of continued flow tube body diode is short more, and DC-DC transducer effciency and reliability are higher more.
The continued flow tube reverse-conducting makes output voltage produce negative pressure when 2. adopting the DC-DC inverter off of this patent circuit, sees Fig. 1 a for details, Fig. 1 b.
It drives type of drive owing to cost height, less employing in the actual use of DC-DC converter.
Self-powered it drive mode because have self-powered concurrently, it drives the advantage of mode and extensively adopts in low-voltage, high-current DC-DC converter.Its self-powered of driving mode of so-called self-powered generally is the driving of rectifying tube, self-powered it drive mode it to drive generally be the driving of continued flow tube.Patent US6304463 has realized its driving of self-powered of synchronous rectifier preferably, and drive waveforms is a quasi-square wave.In this patent circuit, rectifying tube is directly driven by transformer secondary in-phase end or auxiliary winding drives, and continued flow tube realizes that by P channel MOS tube, diode and voltage source continued flow tube drives and charge discharging resisting.These patent circuit existing problems:
1. adopt the continued flow tube or the rectifying tube of the DC-DC converter of this patent circuit to make output voltage produce negative pressure reverse-conducting, see Fig. 2.
Output end voltage Vout is as greater than rectification metal-oxide-semiconductor SR1 grid source electrode cut-in voltage during the DC-DC inverter off, rectification metal-oxide-semiconductor SR1 is with conducting, then the electric charge on the output capacitance Cout will pass through inductance L, transformer, rectification metal-oxide-semiconductor SR1 releases, continued flow tube SR2 gate charge is released by diode D, electric current flows through source electrode by the drain electrode of rectification metal-oxide-semiconductor SR1, opposite with normal freewheel current direction, because inductance L, transformer, impedance on the rectification metal-oxide-semiconductor SR1 loop is often less, vent discharge fails to be convened for lack of a quorum very big, SR1 causes very big current stress to the rectification metal-oxide-semiconductor, inductance L and capacitor C out also can form vibration simultaneously, form negative voltage at output, have polar capacitor and load to output cause damage, when output zero load or underloading, because load impedance is relatively large, flows through inductance L, the electric current of rectification metal-oxide-semiconductor SR1 is also relatively large, and this problem can be more serious.By the same token, adopt the DC-DC converter of this synchronous rectification driving circuit also can't be applied in the occasion that requires the output energy directly in parallel.
DC-DC converter output voltage V o is as less than afterflow MOS transistor Q grid source electrode cut-in voltage poor greater than its grid source electrode cut-in voltage and diode D conduction voltage drop, gate charge owing to afterflow MOS transistor SR2 when shutting down can't be released, afterflow metal-oxide-semiconductor SR2 is with reverse-conducting, then the electric charge on the output capacitance Cout will pass through inductance L, afterflow metal-oxide-semiconductor SR2 releases, electric current flows through source electrode by the drain electrode of afterflow metal-oxide-semiconductor SR2, opposite with normal freewheel current direction, because inductance L, impedance on the afterflow metal-oxide-semiconductor SR2 loop is often less, vent discharge fails to be convened for lack of a quorum very big, SR2 causes very big current stress to the afterflow metal-oxide-semiconductor, inductance L and capacitor C out also can form vibration simultaneously, form negative voltage at output, have polar capacitor and load to output cause damage, when output zero load or underloading, because load impedance is relatively large, flows through inductance L, the electric current of afterflow metal-oxide-semiconductor SR2 is also relatively large, and this problem can be more serious.By the same token, adopt the DC-DC converter of this synchronous rectification driving circuit also can't be applied in the occasion that requires the output energy directly in parallel.
2. can not realize the rising edge and the flexible of trailing edge " dead band " time of rectifying tube and continued flow tube drive waveforms, see Fig. 2.
Summary of the invention:
Purpose of the present invention be exactly for solve synchronous rectification BUCK converter in the prior art produce when the shutdown between the problem of negative pressure and synchronous rectifier exist " dead band " non-adjustable or can only the adjustable problem of part, a kind of BUCK converter that contains synchronous rectification driving circuit is provided.
The BUCK converter that contains synchronous rectification driving circuit that the present invention proposes for achieving the above object includes input power supply, rectifying tube, continued flow tube, drive first drive circuit of rectifying tube, second drive circuit of driving continued flow tube, it is characterized in that: described second drive circuit comprises that second pulse width modulator, reverse isolation differential circuit, the level ratio that link to each other successively reach power conversion circuits, accessory power supply, complementary drive circuit; One end of complementary drive circuit links to each other with the gate pole of above-mentioned continued flow tube, other end ground connection.
According to the embodiment of the invention:
Also comprise first resistance in the converter, this resistance is connected between second pulse width modulator and the reverse isolation differential circuit.
Described first drive circuit comprises: first pulse width modulator and driver for isolating, and the grid of described rectifying tube connects the output of driver for isolating, and the input of driver for isolating links to each other with the output of first pulse width modulator.A kind of BUCK converter that contains synchronous rectification driving circuit as claimed in claim 1, it is characterized in that described first drive circuit comprises: first pulse width modulator, transformer and power MOS pipe, the grid of described power MOS pipe connects the output of first pulse width modulator, source ground, drain electrode connects primary winding negative terminal, the positive termination input of primary winding power supply, the grid of secondary positive termination rectifying tube and continued flow tube drain electrode, secondary negative terminal connects the rectifying tube drain electrode.
Described level ratio reaches power conversion circuits and comprises: reference level and MOS transistor, and the grid of this MOS transistor connects reference level, and its source electrode links to each other with the output of reverse isolation differential circuit, the input of complementary drive circuit respectively with drain electrode.
Described level ratio reaches power conversion circuits and comprises: reference level, second, three, four resistance, operational amplifier and MOS transistor, second, three resistance string are associated between reference level and the operational amplifier output terminal, the 4th resistance one end ground connection, the mid point of the other end and above-mentioned series circuit is connected in the positive input terminal of operational amplifier jointly, the negative input end of operational amplifier links to each other with the output of reverse isolation differential circuit, the output of operational amplifier links to each other with the grid of MOS transistor, the source electrode of MOS transistor and the drain electrode respectively with ground, the input of complementary drive circuit links to each other
Above-mentioned complementary drive circuit comprises transistor, following transistor and the 5th resistance, described upper and lower transistor common base or grid and common emitter or source electrode, go up transistorized emitter and connect accessory power supply, following transistorized collector electrode or grounded drain, the 5th resistance is connected between accessory power supply and upper and lower transistor base or the grid.
Also comprise the 6th resistance, this resistance is connected between complementary drive circuit and the continued flow tube.
Described first pulse width modulator and second pulse width modulator are an adjustable pulse width modulator with two-way output.
Owing to adopted above scheme, signalling GT1 and GT2 can utilize the inner integrated crossover time-delay logic control circuit of pwm chip to regulate, thereby it is adjustable to make rectifying tube turn-off " dead band " time td of continued flow tube complete conduction period; In like manner, it is adjustable to turn-off rectifying tube conduction period " dead band " time td from continued flow tube.And, when off signal arrives, isolate differential circuit output this moment by the very fast reduction of high level, isolate differential circuit output by the very fast reduction of high level, level ratio reaches the quick conducting of power conversion circuits, complementary drive circuit is released the continued flow tube gate charge fast, and continued flow tube is ended, thereby output does not produce negative pressure when making therebetween inverter off.
Description of drawings:
Fig. 1 a is first kind of existing BUCK converter that contains synchronous rectification driving circuit;
Fig. 1 b is the exemplary operation oscillogram of foregoing circuit;
Fig. 1 c is the full load synchronous freewheeling pipe drive waveforms of foregoing circuit;
Fig. 2 is second kind of existing BUCK converter that contains synchronous rectification driving circuit;
Fig. 3 a is first kind of BUCK converter that contains synchronous rectification driving circuit of the present invention;
Fig. 3 b is second kind of BUCK converter that contains synchronous rectification driving circuit of the present invention;
Fig. 3 c is that of the present invention the third contains the BUCK converter of synchronous rectification driving circuit;
Fig. 4 a is the first kind of common circuit of PWM drive circuit dead band regulating circuit described in the synchronous rectification driving circuit of the present invention;
Fig. 4 b is the second kind of common circuit of PWM drive circuit dead band regulating circuit described in the synchronous rectification driving circuit of the present invention;
Fig. 5 a is the first kind of common circuit of auxiliary power circuit described in the synchronous rectification driving circuit of the present invention;
Fig. 5 b is the second kind of common circuit of auxiliary power circuit described in the synchronous rectification driving circuit of the present invention;
Fig. 6 applies example for synchronous rectification driving circuit of the present invention in the two normal shock BUCK converters of resonance clamp;
Fig. 7 adopts the example of applying in the normal shock BUCK converter that winding drives for synchronous rectification driving circuit of the present invention at secondary synchronous rectification MOS transistor SR1, SR2;
The exemplary operation waveform of Fig. 8 converter when adopting synchronous rectification driving circuit of the present invention.
Embodiment:
Also the present invention is described in further detail in conjunction with the accompanying drawings below by specific embodiment.
The drive circuit of DC-DC converter of the present invention, the main circuit of its converter comprises power MOS pipe part, transformer portion, synchronous rectification part (SR1, SR2), filtering part, and described drive circuit is made up of with power conversion circuits MOS transistor Sa, complementary drive circuit, resistance R a, Rb, Rc, accessory power supply Vcc1 and a reference level the drive pulse signal GT2 of a turnable pulse width, an isolation differential circuit, a level ratio.The output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion circuits MOS transistor Sa with described level ratio, described level ratio is connected with reference level with the grid of power conversion circuits MOS transistor Sa, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, and the emitter of complementary drive circuit is connected with the gate pole of synchronous rectification afterflow MOS transistor SR2.
Wherein, the drive pulse signal GT2 of described turnable pulse width is generally exported to simplify circuit by general integrated PWM controlling and driving chip, and two examples wherein are respectively shown in Fig. 4 a, Fig. 4 b.
Fig. 4 a represents that a kind of drive pulse signal GT2 of turnable pulse width is made up of integrated pwm chip and chip for driving and exports, pwm chip OUT1, OUT2 are connected with IN1, the IN2 of chip for driving respectively, pwm chip Vref, Td_set are connected with pulse-width regulated resistance R td two ends respectively, regulate resistance R td and can reduce synchronous freewheeling MOS transistor body diode ON time, can avoid SR1, SR2 conducting simultaneously simultaneously again reliably to obtain greater efficiency.Integrated PWM controller and chip for driving also can integrate output drive signal GT, are divided into GT1, GT2 two-way drive pulse signal again, and this moment, GT2 transferred wide non-adjustable.
Fig. 4 b represents that a kind of drive pulse signal GT2 integrates output drive signal GT by integrated PWM controller and chip for driving, is divided into GT1, GT2 two-way drive pulse signal again, and it is non-adjustable that this moment, GT2 transferred arteries and veins.
Described isolation differential circuit can be made up of Transformer Winding Npa and Nsa, two electric capacity, a resistance, a diode, described winding Npa is connected with a described electric capacity, and described winding Nsa is connected with diode by the described resistance of a described electric capacity with parallel connection.
Described complementary drive circuit can be made up of NPN and PNP triode, and described NPN triode is in parallel with the base stage of PNP triode, and described NPN triode is in parallel with the emitter of PNP triode.
Perhaps: described complementary drive circuit is made up of P channel MOS transistor, N-channel MOS transistor, and the grid of described N-channel MOS transistor AND gate P channel MOS transistor and source electrode are in parallel respectively.
Described accessory power supply Vcc1 adopts multiple auxiliary power circuit, and two examples wherein are respectively as Fig. 5 a, Fig. 5 b.
Fig. 5 a represents that a kind of auxiliary power circuit is made up of the auxiliary winding of inductance L, diode, electric capacity, resistance, and inductance L assists the winding in-phase end to be connected with diode, and diode is connected with electric capacity, resistance, and electric capacity and inductance L are assisted the winding end of oppisite phase.
Fig. 5 b represents that a kind of auxiliary power circuit is made up of the auxiliary winding of inductance L, diode, electric capacity, resistance, resistance, the auxiliary winding in-phase end of inductance L is connected with electric capacity, diode, diode is connected with resistance, and electric capacity is connected with resistance, and the auxiliary winding end of oppisite phase of inductance L is connected with resistance.
Fig. 6 represents that described DC/DC converter is the two forward converters of resonance clamp, the positive terminal of winding Np links to each other with the source electrode of main power MOS pipe S1, the negative pole end of winding Np links to each other with the drain electrode of main power MOS pipe S2, capacitor C c is in parallel with winding Np, the output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a connects and is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion small-power MOS transistor Sa with described level ratio, described level ratio is connected with reference level with the grid of power conversion small-power MOS transistor Sa, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, and the emitter of complementary drive circuit is connected with the gate pole of synchronous rectification afterflow MOS transistor SR2.
Fig. 7 represents the application of synchronous rectification driving circuit of the present invention in the resonance clamp forward converter that secondary synchronous rectification MOS transistor SR1 employing winding drives.Wherein, the source electrode of synchronous rectification MOS transistor SR1 is connected with the negative pole end of the positive terminal of winding Ns and driving winding N1, the gate pole of synchronous rectification MOS transistor SR1 is connected with the positive terminal that drives winding N1, the drain electrode of synchronous rectification MOS transistor SR1 is connected with the drain electrode of synchronous freewheeling MOS transistor SR2, the output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a connects and is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion small-power MOS transistor Sa with described level ratio, the grid of described level conversion small-power MOS transistor Sa is connected with reference level, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, and the emitter of complementary drive circuit is connected with the gate pole of synchronous rectification afterflow MOS transistor SR2.
Fig. 8 represents to adopt the converter exemplary operation oscillogram of circuit of the present invention.At t1 constantly, the PWM drive signal GT1 of main power MOS pipe S is low by hypermutation, the secondary winding Ns reversing of transformer, synchronous rectification MOS transistor SR1 turn-offs, the drive pulse signal GT2 of turnable pulse width brought and made SR2 to begin conducting this moment, to the t2 complete conducting of SR2 constantly, " dead band " time td is adjustable therebetween, this is because the inner integrated crossover time-delay logic control circuit of functional universal pwm chip, by similar 555, RC circuit control crossover time-delay, this R is the pulse-width regulated resistance R td of chip exterior.At t3 constantly, synchronous freewheeling MOS transistor SR2 begins to turn-off, and turn-offs fully to t4 moment SR2, and this moment, the PWM drive signal GT1 of main power MOS pipe S became high SR1 conducting by low, and " dead band " time td is adjustable therebetween; At t5 constantly, off signal arrives, the PWM drive signal GT1 of power MOS pipe S is a low level, synchronous rectification MOS transistor SR1 turn-offs, isolate differential circuit output this moment by the very fast reduction of high level, level conversion small-power MOS transistor Sa is because the conducting fast greater than cut-in voltage of gate-source voltage difference, base current will circulate by the small-power MOS transistor Sa drain-source utmost point and differential circuit fast, base stage partially directly is reduced to low level very soon, complementary drive circuit NPN triode ends fast, the quick conducting of PNP triode, synchronous freewheeling MOS transistor SR2 gate charge is released by complementary drive circuit PNP pipe fast, and synchronous freewheeling MOS transistor SR2 ends.By regulate isolating the differential circuit parameter, cooperate the parameter regulation of former secondary accessory power supply, complementary drive circuit PNP triode is to the releasing fast of synchronous freewheeling pipe SR2 gate charge in the time of can guaranteeing inverter off, and output does not produce negative pressure when making inverter off.
Therefore synchronous rectification driving circuit of the present invention can satisfy:
1. synchronous rectification MOS transistor SR1 conducting during rectification, SR2 turn-offs; SR2 conducting during afterflow, SR1 turn-offs;
2. synchronous rectification MOS transistor SR1 and SR2 can not be in conducting state simultaneously;
3. the drive waveforms of synchronous rectification MOS transistor SR1 and SR2 is a quasi-square wave;
4. " dead band " between the rising edge trailing edge of drive waveforms but the time flexible can reduce synchronous freewheeling MOS transistor body diode ON time and obtain greater efficiency, can avoid SR1, SR2 conducting simultaneously again reliably;
Can in time turn-off synchronous rectification MOS transistor SR2 when 4. converter is out-of-work, avoid reverse-conducting;
5. synchronous rectification driving circuit of the present invention has efficient height, circuit is simple, cost is low advantage.
Synchronous rectification driving circuit disclosed by the invention is confirmed by experiment, described circuit is used in the input of 36～75V direct current, 1.8V/20A in the DC-DC converter of direct current output, adopt the resonant reset forward main circuit, power stage efficient reaches more than 88%, can avoid the output of converter to produce negative pressure when converter is out-of-work.
Fig. 3 to Fig. 7 represents the application of described synchronous rectification driving circuit in various circuit
Fig. 3 a represents that described DC-DC converter is a resonance clamp single-end ortho-exciting BUCK converter, the positive terminal of winding Np links to each other with input capacitance, the negative pole end of winding Np links to each other with the drain electrode of main power MOS pipe S, the output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion small-power MOS transistor Sa with described level ratio, described level ratio is connected with reference level with the grid of power conversion small-power MOS transistor Sa, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, the emitter of complementary drive circuit be connected with the gate pole of synchronous rectification afterflow MOS transistor SR2 through resistance R c.
Fig. 3 b represents that described DC-DC converter is a resonance clamp single-end ortho-exciting BUCK converter, the positive terminal of winding Np links to each other with input capacitance, the negative pole end of winding Np links to each other with the drain electrode of main power MOS pipe S, the output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the end of oppisite phase of power conversion circuits (2) amplifier with described level ratio, and described level ratio is that MOS transistor (Sa) drain electrode is connected with described complementary drive circuit with the output of power conversion circuits amplifier, MOS transistor (Sa) source ground.Described level ratio is made up of amplifier, reference voltage and three resistance and MOS transistor (Sa) with power conversion circuits (2).The output of amplifier is connected with the grid and a resistance of MOS transistor (Sa), its in-phase end is connected with three resistance, its end of oppisite phase is connected with isolation differential circuit output, one resistance is connected with reference level, and MOS transistor (Sa) drain electrode is connected with the quick leadage circuit (3) of continued flow tube fast driving and gate charge thereof, its source ground.Described complementary drive circuit is made up of P channel MOS transistor, N-channel MOS transistor, the grid of described N-channel MOS transistor AND gate P channel MOS transistor and source electrode are in parallel respectively, and its source electrode is connected with the gate pole of synchronous rectification afterflow MOS transistor SR2 through resistance R c.
Fig. 4 c represents that described DC-DC converter is non-isolation BUCK converter.The output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion small-power MOS transistor Sa with described level ratio, described level ratio is connected with reference level with the grid of power conversion small-power MOS transistor Sa, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, the emitter of complementary drive circuit be connected with the gate pole of synchronous rectification afterflow MOS transistor SR2 through resistance R c.The output of described drive pulse signal GT1 is connected with the driver for isolating input, and the driver for isolating output is connected with the synchronous rectification tube grid.
Fig. 4 a represents that a kind of drive pulse signal GT2 of turnable pulse width is made up of integrated pwm chip and chip for driving and exports, pwm chip OUT1, OUT2 are connected with IN1, the IN2 of chip for driving respectively, pwm chip Vref, Td_set are connected with pulse-width regulated resistance R td two ends respectively, regulate resistance R td and can reduce synchronous freewheeling MOS transistor body diode ON time, can avoid SR1, SR2 conducting simultaneously simultaneously again reliably to obtain greater efficiency.
Fig. 4 b represents that a kind of drive pulse signal GT2 integrates output drive signal GT by integrated PWM controller and chip for driving, is divided into GT1, GT2 two-way drive pulse signal again, and this moment, GT2 transferred wide non-adjustable.
Fig. 5 a represents that a kind of auxiliary power circuit is made up of the auxiliary winding of inductance L, diode, electric capacity, resistance, and inductance L assists the winding in-phase end to be connected with diode, and diode is connected with electric capacity, resistance, and electric capacity and inductance L are assisted the winding end of oppisite phase.
Fig. 5 b represents that a kind of auxiliary power circuit is made up of the auxiliary winding of inductance L, diode, electric capacity, resistance, resistance, the auxiliary winding in-phase end of inductance L is connected with electric capacity, diode, diode is connected with resistance, and electric capacity is connected with resistance, and the auxiliary winding end of oppisite phase of inductance L is connected with resistance.
Fig. 6 represents that described DC-DC converter is the two normal shock BUCK converters of resonance clamp, the positive terminal of winding Np links to each other with the source electrode of main power MOS pipe S1, the negative pole end of winding Np links to each other with the drain electrode of main power MOS pipe S2, the output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a connects and is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion circuits small-power MOS transistor Sa with described level ratio, the grid of described level conversion small-power MOS transistor Sa is connected with reference level, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, and the emitter of complementary drive circuit is connected with the gate pole of synchronous rectification afterflow MOS transistor SR2 through resistance R c.
Fig. 7 represents the application of synchronous rectification driving circuit of the present invention in the resonance clamp normal shock BUCK converter that secondary synchronous rectification MOS transistor SR1 employing winding drives.Wherein, the source electrode of synchronous rectification MOS transistor SR1 is connected with the negative pole end of the positive terminal of winding Ns and driving winding N1, the gate pole of synchronous rectification MOS transistor SR1 is connected with the positive terminal that drives winding N1, the drain electrode of synchronous rectification MOS transistor SR1 is connected with the drain electrode of synchronous freewheeling MOS transistor SR2, the output of the drive pulse signal GT2 of described turnable pulse width is connected with resistance R a, resistance R a connects and is connected with the input of described isolation differential circuit, the output of described isolation differential circuit is connected with the source electrode of power conversion small-power MOS transistor Sa with described level ratio, described level level ratio is connected with reference level with the grid of power conversion small-power MOS transistor Sa, its drain electrode is connected with the base stage of resistance R b and complementary drive circuit, and the emitter of complementary drive circuit is connected with gate pole with synchronous rectification afterflow MOS transistor SR2 through resistance R c.
In the various application of Fig. 3～Fig. 7, the effect of synchronous rectification driving circuit of the present invention all is to avoid the output of BUCK converter to produce negative pressure and can improve conversion efficiency
More than describe the present invention by embodiment, but the present invention is not limited thereto, and is all in improvement or the replacement done without prejudice to spirit of the present invention and content, should be regarded as belonging to protection scope of the present invention.For example:
1, isolating differential circuit in the last example is anti-phase isolation differential circuit, is made up of driving transformer, positive clamping diode and differential circuit.Driving transformer act as former secondary electrical isolation and drive signal energy delivery; The effect of positive clamping diode is to guarantee that small-power metal-oxide-semiconductor Sa grid is zero level and following when low level; The effect of differential circuit is the small-power metal-oxide-semiconductor Sa gate charge of releasing, and can reach in the unification of charge discharging resisting between electric charge maintenance and low period between high period by regulating time constant.Wherein driving transformer just can be substituted by high speed photo coupling.
2, the fast driving that act as synchronous freewheeling pipe SR2 of complementary drive circuit and releasing fast of gate charge thereof can be substituted by N, P raceway groove small-power metal-oxide-semiconductor.
3, its of small-power metal-oxide-semiconductor Sa act as level ratio and drives power conversion with complementary drive circuit.Though small-power metal-oxide-semiconductor Sa is the simplest way of this function of realization, but still available amplifier etc. substitute (cost is higher).
4, the another kind of connection of the grid G of small-power metal-oxide-semiconductor Sa is to be connected to accessory power supply Vcc1, isolates the quick reduction of differential circuit output level during with the realization shutdown.
5, the another kind of connection between the grid of the quick leadage circuit (3) of continued flow tube fast driving and gate charge thereof and continued flow tube SR2 is that the quick leadage circuit (3) of continued flow tube fast driving and gate charge thereof is connected through the grid of resistance with continued flow tube SR2, and the effect of this resistance is to prevent the grid vibration and satisfy the EMC requirement.
Claims (9)
1, a kind of BUCK converter that contains synchronous rectification driving circuit, include the input power supply (+Vin), rectifying tube (SR1), continued flow tube (SR2), drive first drive circuit of rectifying tube (SR1), second drive circuit of driving continued flow tube (SR2), it is characterized in that: described second drive circuit comprises that second pulse width modulator (GT2), reverse isolation differential circuit (1), the level ratio that link to each other successively reach power conversion circuits (2), accessory power supply (Vcc1), complementary drive circuit (3); One end of complementary drive circuit (3) links to each other other end ground connection with the gate pole of above-mentioned continued flow tube (SR2).
2, a kind of BUCK converter that contains synchronous rectification driving circuit as claimed in claim 1 is characterized in that also comprising first resistance (Ra), and this resistance is connected between second pulse width modulator (GT2) and the reverse isolation differential circuit (1).
3, a kind of BUCK converter that contains synchronous rectification driving circuit as claimed in claim 1, it is characterized in that described first drive circuit comprises: first pulse width modulator (GT1) and driver for isolating, the grid of described rectifying tube (SR1) connects the output of driver for isolating, and the input of driver for isolating links to each other with the output of first pulse width modulator.
4, a kind of BUCK converter that contains synchronous rectification driving circuit as claimed in claim 1, it is characterized in that described first drive circuit comprises: first pulse width modulator (GT1), transformer (T) and power MOS pipe (S), the grid of described power MOS pipe (S) connects the output of first pulse width modulator (GT1), source ground, drain electrode connects the elementary winding negative terminal of transformer (T), the positive termination input of the elementary winding of transformer (T) power supply (+Vin), the grid of secondary positive termination rectifying tube (SR1) and continued flow tube (SR2) drain electrode, secondary negative terminal connects rectifying tube (SR1) drain electrode.
5, as claim 1 or 2 or 3 or 4 described a kind of BUCK converters that contain synchronous rectification driving circuit, it is characterized in that described level ratio reaches power conversion circuits (2) and comprising: reference level and MOS transistor (Sa), the grid of this MOS transistor (Sa) connects reference level, and its source electrode links to each other with the output of reverse isolation differential circuit (1), the input of complementary drive circuit (3) respectively with drain electrode.
6, as claim 1 or 2 or 3 or 4 described a kind of BUCK converters that contain synchronous rectification driving circuit, it is characterized in that described level ratio reaches power conversion circuits (2) and comprising: reference level, second, three, four resistance (R2, R3, R4), operational amplifier and MOS transistor (Sa), second, three resistance (R2, R3) be connected between reference level and the operational amplifier output terminal, the 4th resistance (R4) end ground connection, the mid point of the other end and above-mentioned series circuit is connected in the positive input terminal of operational amplifier jointly, the negative input end of operational amplifier links to each other with the output of reverse isolation differential circuit (1), the output of operational amplifier links to each other with the grid of MOS transistor (Sa), the source electrode of MOS transistor (Sa) and the drain electrode respectively with ground, the input of complementary drive circuit (3) links to each other
7, as claim 1 or 2 or 3 or 4 described a kind of BUCK converters that contain synchronous rectification driving circuit, it is characterized in that above-mentioned complementary drive circuit (3) comprises transistor, following transistor and the 5th resistance (Rb), described upper and lower transistor common base or grid and common emitter or source electrode, go up transistorized emitter and connect accessory power supply (Vcc1), following transistorized collector electrode or grounded drain, the 5th resistance (Rb) is connected between accessory power supply (Vcc1) and upper and lower transistor base or the grid.
8, a kind of BUCK converter that contains synchronous rectification driving circuit as claimed in claim 7 is characterized in that also comprising the 6th resistance (Rc), and this resistance is connected between complementary drive circuit (3) and the continued flow tube (SR2).
9,, it is characterized in that described first pulse width modulator and second pulse width modulator are an adjustable pulse width modulator with two-way output as claim 3 or 4 described a kind of BUCK converters that contain synchronous rectification driving circuit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB03126977XA CN1312835C (en) | 2003-06-19 | 2003-06-19 | BUCK convertor containing synchronous rectitication drive circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB03126977XA CN1312835C (en) | 2003-06-19 | 2003-06-19 | BUCK convertor containing synchronous rectitication drive circuit |
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| CN1481066A true CN1481066A (en) | 2004-03-10 |
| CN1312835C CN1312835C (en) | 2007-04-25 |
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| CNB03126977XA Expired - Lifetime CN1312835C (en) | 2003-06-19 | 2003-06-19 | BUCK convertor containing synchronous rectitication drive circuit |
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Address after: 518057 Nanshan District science and Technology Industrial Park, Guangdong, Shenzhen Branch Road, No. Patentee after: VERTIV TECH Co.,Ltd. Address before: 518057 Nanshan District science and Technology Industrial Park, Guangdong, Shenzhen Branch Road, No. Patentee before: EMERSON NETWORK POWER Co.,Ltd. |
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