CN108258923A - A kind of synchronous rectification driving circuit of voltage decrease speed judgement - Google Patents
A kind of synchronous rectification driving circuit of voltage decrease speed judgement Download PDFInfo
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- CN108258923A CN108258923A CN201711319167.4A CN201711319167A CN108258923A CN 108258923 A CN108258923 A CN 108258923A CN 201711319167 A CN201711319167 A CN 201711319167A CN 108258923 A CN108258923 A CN 108258923A
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- synchronous rectification
- effect transistor
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- Rectifiers (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a kind of synchronous rectification driving circuits of voltage decrease speed judgement, which is applied to the switching power circuits such as flyback, normal shock type, and including a voltage clipping unit, a decrease speed detection unit, one opens comparator, and one and door.When the drain signal decrease speed of synchronous rectification power field effect transistor is faster than predetermined threshold value, and the drain signal of synchronous rectification power field effect transistor, less than when opening benchmark, synchronous rectification driving circuit output electric signal driving synchronous rectification power field effect transistor is connected.The differentiation of resonance conditions after realizing to switching power circuit primary side side switch closing situation and demagnetization, it is logical to avoid synchronous rectification power field effect transistor opening by mistake under resonance conditions after demagnetization, the transfer efficiency of switching power circuit is improved, simplifies the design of switching power circuit.
Description
[technical field]
It is synchronized the present embodiments relate to switch power technology field more particularly to a kind of driving circuit and Switching Power Supply whole
Current circuit.
[background technology]
Traditional Switching Power Supply outlet side rectification uses diode, but diode has forward voltage drop, therefore switchs electricity
Source efficiency can be restricted.Synchronous rectification substitutes diode using field-effect transistor, and designs suitable circuit drives
The conducting and shutdown of field-effect transistor, the working characteristics of simulating diode, but outstanding forward voltage drop is provided compared with diode,
So as to improve the efficiency index of Switching Power Supply.
Existing synchronous rectification control technology is sentenced by detecting the voltage between the drain electrode of field-effect transistor and source level
It is disconnected whether to need turn-on and turn-off field-effect transistor.When drain-source voltage is higher than predetermined threshold value, field-effect transistor is connected, when
When drain-source voltage is less than predetermined threshold value, field-effect transistor is turned off.
Under switching mode power supply transformer discontinuous conduct mode working condition, in each switch periods, when transformer energy storage
Release finishes, and resonance can occur for the parasitic capacitance of static exciter inductance and contactor node, synchronous rectification should be avoided to drive
Circuit opened by mistake in this resonant process it is logical, so as to influence power-efficient and normal work.
In the prior art, prevent opening by mistake for synchronous rectification driving circuit logical using the adjustable shielding time, i.e., same
After walking commutation driver circuit closing field-effect transistor, within some time, synchronous rectification driving circuit is forbidden to open field again
Effect transistor.
Shortcoming in the prior art is that the above-mentioned shielding time needs to be adjusted according to actual switch power circuit, increases
Add switching power circuit complexity and cost.
[invention content]
In view of this, to avoid circuit of synchronous rectification opening by mistake in circuit resonance logical, while simplify peripheral applications circuit
Design, the present invention provides a kind of circuit of synchronous rectification judged according to drain voltage decrease speed, provide a kind of novel
Synchronous rectifier field effect transistor opens decision logic.
In order to solve the above technical problems, the technical solution adopted by the present invention is, a kind of synchronization of voltage decrease speed judgement
Rectification circuit, applied to switching power circuit, the switching power circuit includes：One transformer winding, one synchronizes rectified power
Field-effect transistor, the synchronous rectification driving circuit include：
One voltage clipping unit, the input signal of the voltage clipping unit is the synchronous rectification power field effect crystal
The electric signal of pipe drain electrode, when the synchronous rectification power field effect transistor drain signal is higher, the voltage clipping unit
Export the voltage signal Jing Guo amplitude clamper；
One decrease speed detection unit, the input signal of the decrease speed detection unit is the voltage clipping unit
Output signal when the output signal decrease speed of the voltage clipping unit is more than predetermined threshold value, exports high RST；
One opens comparator, it is described open comparator input signal be respectively the voltage clipping unit output signal
Open benchmark with one, when the voltage clipping unit output signal less than it is described open reference voltage signal when, export high letter
Number；
One and door, the input signal with door is respectively the output signal of the decrease speed detection unit and described opens
The output signal of logical comparator；
When the drain signal decrease speed of the synchronous rectification power field effect transistor is faster than predetermined threshold value, and it is described
For the drain signal of synchronous rectification power field effect transistor less than when opening benchmark, the synchronous rectification driving circuit exports telecommunications
Number driving synchronous rectification power field effect transistor conducting.
The process described above further includes：One shutdown identifying unit, the input signal of the shutdown identifying unit is described
The output signal of voltage clipping unit.When the shutdown identifying unit is detected in the synchronous rectification power field effect transistor
During current over-zero, the synchronous rectification power field effect transistor is closed.
The process described above further includes：One control logic unit, the input signal of the control logic unit is described
Turn off the output signal of identifying unit and described and door output signal.The control logic unit controls the synchronous rectification work(
Rate field-effect transistor is turned on and off.
The process described above further includes：One driving unit；
The input terminal of the driving unit connects the output terminal of the control logic unit, the output terminal of the driving unit
Connect the grid of the synchronous rectification power field effect transistor.
The present invention also provides a kind of switching power circuits, include at least：One transformer winding rectified power synchronous with one
Field-effect transistor；
The synchronous rectification power field effect transistor of the switching power circuit uses drive described in any one of the above embodiments
Dynamic circuit is driven.
The present invention when the drain signal decrease speed of the synchronous rectification power field effect transistor is faster than predetermined threshold value,
And the drain signal of the synchronous rectification power field effect transistor, less than when opening benchmark, the synchronous rectification driving circuit is defeated
Go out electric signal and drive the synchronous rectification power field effect transistor conducting, realize to switch switching power circuit primary side side and close
The differentiation of resonance conditions, it is humorous after demagnetization to avoid synchronous rectification power field effect transistor after closing situation and demagnetizing
Opening by mistake in the case of shaking is logical, improves the transfer efficiency of switching power circuit, simplifies the design of switching power circuit.
[description of the drawings]
Fig. 1 is a kind of structural representation of the circuit of synchronous rectification of voltage decrease speed judgement provided in an embodiment of the present invention
Figure；
Wherein, 10 be driving circuit, and 11 be voltage clipping unit, and 12 be decrease speed detection unit, and 13 be shutdown judgement
Unit, 14 is open comparator, and 15 is open benchmark, 16 be with door, 17 logic units in order to control, 18 be driving unit.
Fig. 2 is a kind of work schedule of the circuit of synchronous rectification of voltage decrease speed judgement provided in an embodiment of the present invention
Figure.
[specific embodiment]
The present invention is described in further detail with reference to the accompanying drawings and examples.It is understood that this place is retouched
The specific embodiment stated is used only for explaining the present invention rather than limitation of the invention.It also should be noted that in order to just
Part related to the present invention rather than entire infrastructure are illustrated only in description, attached drawing.In the absence of conflict, the present invention is real
Applying the feature in example and embodiment can be combined with each other.
Core spirit of the present invention is, by the drain voltage decrease speed for detecting synchronous rectification power field effect transistor
To distinguish following state：
1, primary side power switch turn-off transient, under the drain voltage of synchronous rectification power field effect transistor is quick at this time
Drop, the body diode of synchronous rectification power field effect transistor are connected, and the electric current in synchronous rectification power field effect transistor is fast
Speed reaches peak value, at this point, synchronous rectification power field effect transistor should be driven to be connected.
2, after transformer demagnetizes, resonance occurs for all parasitic capacitances on static exciter inductance and switching node, this
When synchronous rectification power field effect transistor drain voltage change speed and 1 in situation difference a number of orders of magnitude, if resonance
The body diode of synchronous rectification power field effect transistor is connected, at this point, driving circuit does not answer output drive signal to synchronization
Rectified power field-effect transistor.
The circuit of synchronous rectification of voltage decrease speed judgement provided in an embodiment of the present invention can be applied to switching power circuit,
The break-make of synchronous rectifier field effect transistor in switching power circuit can be controlled.Fig. 1 is that the embodiment of the present invention provides
A kind of driving circuit structure diagram.As shown in Figure 1, the driving circuit 10 is applied to switching power circuit, switch electricity
Source circuit includes：One transformer winding T (secondary that transformer winding is illustrated that in Fig. 1), one synchronize rectified power field-effect
It connects the secondary side of transistor M1, M1 and transformer winding.
Driving circuit 10 includes：Voltage clipping unit 11, the input signal of voltage clipping unit 11 is synchronous rectification power
The drain electrode of field effect transistor M 1, it is (reachable when synchronous rectification power field effect transistor M1 closings and its higher drain voltage
To the 100V orders of magnitude), its voltage signal is clamped to safe voltage (the 10V orders of magnitude) by voltage clipping unit 11, for internal low
Logic circuit is pressed to use.
Decrease speed detection unit 12, the input signal of decrease speed detection unit 12 are the output of voltage clipping unit 11
Signal (such as drops to 0V) within 100 nanoseconds when the output signal rapid decrease of voltage clipping unit 11 from 10V, declines
Speed detection unit 12 exports a pulse signal, (such as declines when the output signal of voltage clipping unit 11 slowly declines from 10V
It was more than 100 nanoseconds to 0V), the not output signal of decrease speed detection unit 12.
Comparator 14 is opened, two input terminals for opening comparator are respectively the output signal and one of voltage clipping unit 11
Benchmark 15 is opened, when the body diode conducting of synchronous rectification power field effect transistor M1, synchronous rectification power field effect is brilliant
The drain voltage DRAIN voltages of body pipe M1 are negative body diode pressure drop (about 600mV), and it is about 200mV- to open 15 voltage of benchmark
Therefore the 300mV orders of magnitude, in the body diode conducting of M1, open comparator 14 and export high level signal.
It is respectively the output signal of decrease speed detection unit 12 with two input signals of door 16 and opens comparator 14
Output signal.In decrease speed detection unit 12 and open (the i.e. drain electrode electricity of M1 when comparator 14 exports high level signal
Drops speed is met the requirements, and during the body diode conducting of M1), the output signal with door 16 is high level.
Identifying unit 13 is turned off, the input signal of the shutdown identifying unit 13 is the output signal of voltage clipping unit 11,
When the electric current of synchronous rectification power field effect pipe M1 declines, the drain voltage signal of synchronous rectification power field effect transistor M1
Also reduce, the output signal of voltage clipping unit 11 also reduces, when the output signal of voltage clipping unit 11 is decreased to default threshold
During value, shutdown identifying unit 13 outputs signal to control logic unit 17.
Control logic unit 17 controls leading for synchronous rectification power field effect transistor M1 according to the output signal of door 16
It is logical；According to the closing of the output signal control synchronous rectification power field effect transistor M1 of shutdown identifying unit 13.
The output signal of the input signal of driving unit 18 logic unit 17 in order to control, the output signal of driving unit 18 connect
Connect the grid of synchronous rectification power field effect transistor M1.The function of driving unit 18 is to amplify the output of control logic unit 17
Signal and effective and quickly driving synchronous rectification power field effect transistor M1 grid, synchronous rectification power field to be controlled to imitate
Answer being turned on and off for transistor M1.
Fig. 2 is a kind of drive circuit works sequence diagram provided in an embodiment of the present invention.With reference to reference to figure 1 and Fig. 2 institutes
Show, drive circuit works process is specifically described in mode according to embodiments of the present invention.
Driving circuit 10 applies the work(in the secondary side of switching power circuit transformer winding and transformer winding primary side side
Rate switch driver is connected without direct signal, it is therefore desirable to control synchronization according to transformer winding secondary side voltage and current signal
Rectified power field effect transistor M 1 being opened and closing.When in primary side side, power switch is connected, synchronous rectification power field effect
Transistor M1 should be closed, and the drain voltage Vd of synchronous rectification power field effect transistor M1 is height.In primary side side, power switch closes
When closing, transformer winding secondary effluent is through electric current Isec, and synchronous rectification power field effect transistor M1 should be connected, as electric current Isec
When dropping to predetermined threshold value or primary side side power switch is connected again, synchronous rectification power field effect transistor M1 should be closed
It closes.
The t1 moment in primary side side power switch turn-off transient, i.e. Fig. 2, at this point, primary side pwm pulse signal is declines
Edge, transformer winding secondary side electric current Isec rise very rapidly up to peak value, the drain electrode electricity of synchronous rectification power field effect transistor M1
Pressure DRAIN is dropped rapidly to about -600mV, and decrease speed detection unit 12 detects that the decrease speed of DRAIN voltages is more than at this time
Predetermined threshold value (such as 100ns/10V) exports a high level pulse signal, makes synchronous rectification power when DRAIN voltages drop to
During the body diode conducting of field effect transistor M 1, DRAIN voltages are negative M1 body diode pressure drops, at this point, opening comparator
14 output high level signals, then be high level with two input signals of door 16, high level, control logic also exported with door 16
Synchronous rectification power field effect transistor M1 is connected in 17 output signal of unit.
When electric current drops to zero in synchronous rectification power field effect transistor M1, i.e. the t2 moment in Fig. 2, shutdown judgement
Unit 13 detects that DRAIN voltages drop to zero, then outputs signal to control logic unit 17, and control logic unit 17 exports
Signal closes synchronous rectification power field effect transistor M1.
From the t2 moment, the magnetizing inductance and circuit parasitic capacitance of transformer start resonance, and make synchronization at the t3 moment
The body diode conducting of rectified power field effect transistor M 1, high level output may be occurred by opening comparator 14 at this time, but
It is, since the decrease speed of DRAIN voltages is less than the predetermined threshold value of decrease speed detection unit 12, decrease speed detection unit 12
Output is maintained low level, thus is also maintained low level with the output signal of door 16, and then control logic unit 17 will not be again
It is secondary to open synchronous rectification power field effect transistor M1.
Driving circuit provided in an embodiment of the present invention, applied to switching power circuit.And pass through synchronous rectification power field
The detection of the decrease speed of the drain voltage DRAIN of effect transistor M1 is realized to switch switching power circuit primary side side and be closed
The differentiation of resonance conditions, avoids synchronous rectification power field effect transistor M1 after demagnetization after closing situation and demagnetizing
Opening by mistake under resonance conditions is logical, improves the transfer efficiency of switching power circuit, simplifies the design of switching power circuit.
Note that it above are only presently preferred embodiments of the present invention and institute's application technology principle.It will be appreciated by those skilled in the art that
The present invention is not limited to specific embodiment described here, can carry out for a person skilled in the art various apparent variations,
It readjusts and substitutes without departing from protection scope of the present invention.Therefore, although being carried out by above example to the present invention
It is described in further detail, but the present invention is not limited only to above example, without departing from the inventive concept, also
It can include other more equivalent embodiments, and the scope of the present invention is determined by scope of the appended claims.
Claims (5)
1. a kind of circuit of synchronous rectification of voltage decrease speed judgement, applied to switching power circuit, which is characterized in that described to open
Powered-down source circuit includes：One transformer winding, one synchronizes rectified power field-effect transistor, the synchronous rectification driving circuit packet
It includes：
One voltage clipping unit, the input signal of the voltage clipping unit are leaked for the synchronous rectification power field effect transistor
The electric signal of pole, when the synchronous rectification power field effect transistor drain signal is higher, the voltage clipping unit output
By the voltage signal of amplitude clamper；
One decrease speed detection unit, the input signal of the decrease speed detection unit are the output of the voltage clipping unit
Signal when the output signal decrease speed of the voltage clipping unit is more than predetermined threshold value, exports high RST；
One opens comparator, it is described open comparator input signal be respectively the voltage clipping unit output signal and one
Open benchmark, when the voltage clipping unit output signal less than it is described open reference voltage signal when, export high RST；
One and door, it is described to be respectively the output signal of the decrease speed detection unit with door input signal and described open ratio
Compared with the output signal of device；
It is characterized in that, when the drain signal decrease speed of the synchronous rectification power field effect transistor is faster than predetermined threshold value
When, and the drain signal of the synchronous rectification power field effect transistor, less than when opening benchmark, the synchronous rectification driving is electric
Road output electric signal drives the synchronous rectification power field effect transistor conducting.
2. the circuit of synchronous rectification of voltage decrease speed judgement according to claim 1, which is characterized in that further include：One
Identifying unit is turned off, the input signal of the shutdown identifying unit is the output signal of the voltage clipping unit.When the pass
When disconnected identifying unit detects current over-zero in the synchronous rectification power field effect transistor, the synchronous rectification power is closed
Field-effect transistor.
3. the circuit of synchronous rectification of voltage decrease speed judgement according to claim 2, which is characterized in that further include：One
Control logic unit, the input signal of the control logic unit is the output signal for turning off identifying unit and described and door
Output signal.The control logic unit controls being turned on and off for the synchronous rectification power field effect transistor.
4. the circuit of synchronous rectification of voltage decrease speed judgement according to claim 3, which is characterized in that further include：One
Driving unit；
The input terminal of the driving unit connects the output terminal of the control logic unit, the output terminal connection of the driving unit
The grid of the synchronous rectification power field effect transistor.
5. a kind of switching power circuit, which is characterized in that include at least：The rectified power field-effect synchronous with one of one transformer winding
Transistor；
The synchronous rectification power field effect transistor of the switching power circuit is used such as any one of Claims 1 to 4 institute
The driving circuit stated is driven.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711319167.4A CN108258923A (en) | 2017-12-12 | 2017-12-12 | A kind of synchronous rectification driving circuit of voltage decrease speed judgement |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711319167.4A CN108258923A (en) | 2017-12-12 | 2017-12-12 | A kind of synchronous rectification driving circuit of voltage decrease speed judgement |
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| CN108258923A true CN108258923A (en) | 2018-07-06 |
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| CN201711319167.4A Pending CN108258923A (en) | 2017-12-12 | 2017-12-12 | A kind of synchronous rectification driving circuit of voltage decrease speed judgement |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865541A (en) * | 2021-01-22 | 2021-05-28 | 成都启臣微电子股份有限公司 | Synchronous rectification controller, synchronous rectification system and synchronous rectification control method |
| CN113746358A (en) * | 2021-08-16 | 2021-12-03 | 西安鼎芯微电子有限公司 | Synchronous rectification switch control circuit |
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| CN102790542A (en) * | 2012-07-30 | 2012-11-21 | 华为技术有限公司 | Synchronous rectification control circuit, converter and synchronous rectification control method |
| WO2014138693A2 (en) * | 2013-03-08 | 2014-09-12 | Power Integrations, Inc. | Low threshold voltage comparator |
| CN105978341A (en) * | 2016-06-01 | 2016-09-28 | 西安矽力杰半导体技术有限公司 | Secondary side control circuit, secondary side control method, and fly-back converter adopting the same |
| CN107342691A (en) * | 2017-07-11 | 2017-11-10 | 成都芯源系统有限公司 | Control device and method for synchronous rectifier tube |
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2017
- 2017-12-12 CN CN201711319167.4A patent/CN108258923A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102790542A (en) * | 2012-07-30 | 2012-11-21 | 华为技术有限公司 | Synchronous rectification control circuit, converter and synchronous rectification control method |
| WO2014138693A2 (en) * | 2013-03-08 | 2014-09-12 | Power Integrations, Inc. | Low threshold voltage comparator |
| CN105978341A (en) * | 2016-06-01 | 2016-09-28 | 西安矽力杰半导体技术有限公司 | Secondary side control circuit, secondary side control method, and fly-back converter adopting the same |
| CN107342691A (en) * | 2017-07-11 | 2017-11-10 | 成都芯源系统有限公司 | Control device and method for synchronous rectifier tube |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865541A (en) * | 2021-01-22 | 2021-05-28 | 成都启臣微电子股份有限公司 | Synchronous rectification controller, synchronous rectification system and synchronous rectification control method |
| CN112865541B (en) * | 2021-01-22 | 2022-03-29 | 成都启臣微电子股份有限公司 | Synchronous rectification controller, synchronous rectification system and synchronous rectification control method |
| CN113746358A (en) * | 2021-08-16 | 2021-12-03 | 西安鼎芯微电子有限公司 | Synchronous rectification switch control circuit |
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Application publication date: 20180706 |