CN109756135A - A kind of synchronous commutating control circuit - Google Patents
A kind of synchronous commutating control circuit Download PDFInfo
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- CN109756135A CN109756135A CN201910095474.1A CN201910095474A CN109756135A CN 109756135 A CN109756135 A CN 109756135A CN 201910095474 A CN201910095474 A CN 201910095474A CN 109756135 A CN109756135 A CN 109756135A
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Classifications
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- 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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- Dc-Dc Converters (AREA)
Abstract
The present invention is a kind of synchronous commutating control circuit based on inverse-excitation type switch power-supply, including power circuit, maximum frequency limiting circuit, voltage magnitude detection circuit, prevents from opening by mistake and open circuit, anti-leak-stopping unlatching circuit, shutdown threshold compensation circuitry, logic circuit, driving circuit and other control circuits, voltage magnitude detection circuit prevents from opening by mistake and opens the input terminal of circuit, shutdown threshold compensation circuitry and driving circuit and connect with the drain electrode of synchronous rectifier, and anti-leak-stopping opens the output end connection of the input terminal and logic circuit of circuit and maximum frequency limiting circuit.The present invention can guarantee the Precision switch of the synchronous rectifier under heavily loaded mode and light-load mode, avoids opening by mistake for synchronous rectifier and opens and leak unlatching, realizes the high efficiency conversion of Switching Power Supply, improve safety, the reliability of system.
Description
Technical field
The present invention relates to a kind of synchronous commutating control circuits to belong to rectification circuit neck for controlling inverse-excitation type switch power-supply
Domain.
Background technique
The demand of low-voltage high-current power source system is continuously increased, and inverse-excitation type switch power-supply is due to its efficient control and essence
Quasi- output, is widely used in the power-supply system.However, if continuing to use diode rectification in output end, such as Fig. 1 institute
Show, within the time of secondary coil conducting, the energy loss that diode generates accounts for the ratio of secondary coil gross energy are as follows:
Wherein Tons is the time of secondary side diode conducting, since diode drop is higher, the energy loss meeting of generation
Substantially reduce the transfer efficiency of inverse-excitation type switch power-supply.Using the MOSFET (Metal-Oxide- of low on-resistance
Semiconductor Field-Effect Transistor, metal-oxide semiconductor fieldeffect transistor) substitution it is whole
Stream diode then can preferably solve the above problems, as shown in Fig. 2, its conduction voltage drop can be down to 0.1V or less.However, metal-oxide-semiconductor
For gate controller part, synchronous commutating control circuit need to be cooperated just to be able to satisfy work requirements, therefore synchronous commutating control circuit energy
No accurate control synchronous rectifier directly decides the superiority and inferiority of Switching Power Supply.
Synchronous commutating control circuit can determine the switch of synchronous rectifier according to drain-source voltage or drain current, work as original
Side metal-oxide-semiconductor Q1 is closed, and secondary side synchronous commutating control circuit detects that synchronous rectifier drain-source voltage VS is reduced or occurred from source electrode
When flowing to the electric current of drain electrode, while detecting that VS voltage descending slope is met the requirements, the GATE of synchronous rectifier Q2 is opened in output
Driving signal；When the electric current that synchronous commutating control circuit detects synchronous rectifier drain-source voltage VS or drains from source electrode flow direction
Level off to 0 when, output close synchronous rectifier Q2 GATE signal.And in practical operation, although VS voltage slope detects
Can avoid voltage resonance bring synchronous rectifier to open by mistake and opens, but in the case that underloading, idle mode or other, synchronous rectification
Pipe drain-source voltage VS will appear the case where waveform slope mutation in decline, to influence reaction time and the detection knot of system
Easily there is the case where leakage is opened in fruit, synchronous rectifier, and continuity and the stability of system are affected.Shutdown is synchronized
Although the control of rectifying tube and being completed by detection drain-source voltage, with the change of synchronous rectifier grid voltage,
Its complexity turned off can also change, and such as when grid voltage reduces, the shutdown of synchronous rectifier can be become easier to, required
Turn-off time can also reduce, to bring the phenomenon that turning off in advance；When grid voltage increases, the shutdown of synchronous rectifier can become
It must be more difficult, the required turn-off time also will increase, to bring the phenomenon that being delayed to turn off.Synchronous rectifier, which is delayed to turn off, to be easy to make
At " common " phenomenon of the primary and secondary side coil of inverse-excitation type switch power-supply, the damage of circuit is brought, with the safety for reducing circuit
Property；And the reduction for be easy to causeing power supply conversion efficiency is turned off in advance.
Summary of the invention
The purpose of the present invention is to provide one kind can guarantee the synchronous rectifier under heavily loaded mode and underloading or idle mode
Precision switch, avoid synchronous rectifier opens by mistake open with leakage open synchronous commutating control circuit.
In order to achieve the above objectives, the invention provides the following technical scheme: a kind of synchronous commutating control circuit includes power supply electricity
Road, voltage magnitude detection circuit, prevents from opening by mistake and opens circuit, anti-leak-stopping unlatching circuit, shutdown threshold value maximum frequency limiting circuit
Compensation circuit, logic circuit, driving circuit and other control circuits, the output of the power circuit and inverse-excitation type switch power-supply
End connection, to the voltage and reference voltage of generation circuit work, voltage magnitude detection circuit prevents from opening by mistake and opens circuit, shutdown
The input terminal of threshold compensation circuitry and driving circuit is connect with the drain electrode of synchronous rectifier, turns off the defeated of threshold compensation circuitry
Enter end also to connect with the grid of synchronous rectifier, anti-leak-stopping opens the input terminal and logic of circuit and maximum frequency limiting circuit
The output end of circuit connects, and the input terminal that anti-leak-stopping opens circuit is also connect with the output end of voltage magnitude detection circuit, maximum
Frequency limit circuit, voltage magnitude detection circuit prevent from opening by mistake and open circuit, anti-leak-stopping unlatching circuit, shutdown threshold compensation electricity
The output end of road and other control circuits is both connected to the input terminal of logic circuit, and the logic circuit output control signal is made
For the input of driving circuit, the grid of the output end connection synchronous rectifier of the driving circuit is to control its switch.
Further, the logic circuit includes the first logic disjunction gate circuit, the first logic " with door " circuit, second
The input terminal of logic " with door " circuit and rest-set flip-flop circuit, the first logic disjunction gate circuit prevents from missing with described respectively
It opens circuit and is connected with the output end that the anti-leak-stopping opens circuit, the input terminal difference of the first logic " with door " circuit
With the maximum frequency limiting circuit, the voltage magnitude detection circuit, the first logic disjunction gate circuit and other open
Open control circuit output end connection, the input terminal of the second logic " with door " circuit respectively with the shutdown threshold compensation
Circuit, other output end to switch off control circuit connections, output end and the rest-set flip-flop of first logic " with door "
Set input connection, the output end of second logic " with door " is connect with described rest-set flip-flop the RESET input, described
The output end of rest-set flip-flop is connect with the input terminal of the driving circuit.
Further, described to prevent from opening by mistake that open circuit include first resistor, first capacitor and Schmidt trigger, it is described
One end of first resistor is connect with power circuit, the other end of the first resistor respectively with the first capacitor anode and
The input terminal of the Schmidt trigger connects, the cathode of the first capacitor and synchronous rectifier drain electrode connection.
Further, it includes the second logic disjunction gate circuit that the anti-leak-stopping, which opens circuit, first switch, the second capacitor,
First constant-current source and the second comparator, the input terminal of the logic disjunction gate circuit are defeated with voltage magnitude detection respectively
Outlet is connected with the output end of the rest-set flip-flop, the output end of the logic disjunction gate circuit and the control of the first switch
End connection processed, the input terminal of first constant-current source are connect with the power circuit, the output end connection of first constant-current source
In the anode of the second capacitor, first constant-current source is used for the second capacitor charging, and the first switch is used for described second
The anode of capacitor electric discharge, second capacitor is connect with the in-phase end of the second comparator, and the reverse side of second comparator connects
It connects on the power circuit for receiving the first reference voltage from the power circuit.
Further, the shutdown threshold compensation circuitry includes second resistance, 3rd resistor and the second comparator, institute
The input terminal for stating second resistance is connected to the drain electrode of the synchronous rectifier, and the input terminal of the 3rd resistor is connected to described
The grid of synchronous rectifier, the output end of the second resistance and the output end of 3rd resistor are connected to second ratio simultaneously
Compared with the in-phase end of device, the reverse side of second comparator is connected on power circuit for receiving from the power circuit
The second reference voltage.
Further, the driving circuit includes pulse delay circuit, logic " NOT gate " circuit, logic " XOR gate " electricity
Road, weak driving circuit and N-type metal-oxide-semiconductor, p-type metal-oxide-semiconductor, the pulse delay circuit, logic " NOT gate " circuit, logic " exclusive or
Door " the input terminal of circuit is connect with the output end of the logic circuit, the input terminal of logic " XOR gate " circuit also with
The output end of pulse delay circuit connects, and the output end of the pulse delay circuit also connects with the grid control terminal of p-type metal-oxide-semiconductor
It connects, the output end of logic " NOT gate " circuit is connect with the grid control terminal of the N-type metal-oxide-semiconductor, the source of the p-type metal-oxide-semiconductor
End is connect with power end, and drain terminal is connect with the drain terminal of the N-type metal-oxide-semiconductor, the source ground connection of the N-type metal-oxide-semiconductor, described to patrol
The drain electrode for collecting the output end, third reference voltage, the synchronous rectifier of " XOR gate " circuit is the defeated of weak driving circuit
Enter, the output end of the weak driving circuit is connect with the drain terminal of the p-type metal-oxide-semiconductor, N-type metal-oxide-semiconductor.
Further, it is described prevent from opening by mistake open circuit and use Schmidt trigger as voltage comparator circuit to improve sound
Speed is answered, the turnover voltage v1 of the Schmidt trigger is less than the one third of supply voltage, and turnover voltage v2 is greater than power supply
2/3rds of voltage.
Further, described to prevent the capacitance for opening by mistake the resistance value, first capacitor that open first resistor described in circuit basis
The variation of drain-source voltage slope and change, the magnitude of RC constant therefrom should reach nanosecond rank.
Further, it is described prevent from opening by mistake open circuit for avoid synchronous rectifier drain-source voltage occur oscillation or go out
Opening by mistake when existing wrong voltage is opened.
Further, described to prevent the capacitance for opening by mistake the resistance value, first capacitor that open first resistor described in circuit basis
The variation of drain-source voltage slope and change, RC time constant range is in 20 nanoseconds between 2000 nanoseconds.
Further, the anti-leak-stopping is opened the avoidable synchronous rectifier of circuit and is not examined correctly in drain-source voltage slope
Leakage when survey is opened.
Further, it is described shutdown threshold compensation circuitry in-phase end voltage can realize when driving circuit output voltage compared with
Drain voltage needed for reducing shutdown synchronous rectifier when high；Shutdown synchronous rectification is improved when driving circuit output voltage is lower
Drain voltage needed for managing.
Further, the shutdown threshold compensation circuitry can avoid the shutdown in advance of synchronous rectifier or be delayed to turn off, from
And play the role of protecting circuit.
Further, the driving circuit parallel controls synchronous rectifier using strong driving circuit, weak driving circuit
System, the strong driving circuit are controlled by the unlatching that the time is fixed in pulse delay circuit, and the weak driving circuit is then surplus
The remaining opening time controls synchronous rectifier, and the pulse width representative value of the pulse delay circuit was 500 nanoseconds.
Further, the weak driving circuit in the driving circuit is by synchronous rectifier drain voltage and third with reference to electricity
Pressure is compared, and keeps drain voltage lower than third reference voltage, and the driving voltage with the raising of drain voltage and
It reduces, the representative value of the third reference voltage is -80~-60 millivolts.
Further, the maximum frequency limiting circuit limits the minimum period of synchronous rectifier unlatching, in the period
Interior synchronous rectifier does not allow to open second.
Further, the maximum frequency limiting circuit can guarantee that circuit works under normal frequency, and interference-free
The influence of signal.
The beneficial effects of the present invention are: the present invention can guarantee the synchronous rectification under heavily loaded mode, underloading or idle mode
The Precision switch of pipe avoids opening by mistake for synchronous rectifier and opens and leak unlatching, and the high efficiency for realizing inverse-excitation type switch power-supply turns
It changes, improves safety, the reliability of system.
The above description is only an overview of the technical scheme of the present invention, in order to better understand the technical means of the present invention,
And can be implemented in accordance with the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention and the accompanying drawings.
Detailed description of the invention
Fig. 1 is the power circuit schematic diagram using diode.
Fig. 2 is the power circuit schematic diagram using metal-oxide-semiconductor.
Fig. 3 is synchronous commutating control circuit overall structure diagram of the present invention.
Fig. 4 is to prevent from opening by mistake opening circuit concrete structure schematic diagram.
Fig. 5 is that anti-leak-stopping opens circuit concrete structure schematic diagram.
Fig. 6 is off threshold compensation circuitry concrete structure schematic diagram.
Fig. 7 is driving circuit concrete structure schematic diagram
Fig. 8 is coherent signal waveform diagram inside driving circuit
Fig. 9 is the waveform diagram of the non-coherent signal at light load of inverse-excitation type switch power-supply.
Figure 10 is the waveform diagram of inverse-excitation type switch power-supply coherent signal at light load.
Specific embodiment
With reference to the accompanying drawings and examples, specific embodiments of the present invention will be described in further detail.Implement below
Example is not intended to limit the scope of the invention for illustrating the present invention.
It include power circuit, most in one of a preferred embodiment of the present invention synchronous commutating control circuit referring to Fig. 3
Big frequency limit circuit, voltage magnitude detection circuit prevent from opening by mistake and open circuit, anti-leak-stopping unlatching circuit, shutdown threshold compensation electricity
The output end of road, logic circuit, driving circuit and other control circuits, the power circuit and inverse-excitation type switch power-supply connects,
To the voltage and reference voltage of generation circuit work, voltage magnitude detection circuit prevents from opening by mistake and opens circuit, shutdown threshold value benefit
The input terminal for repaying circuit and driving circuit is connect with the drain electrode of synchronous rectifier, turns off the input terminal of threshold compensation circuitry also
It is connect with the grid of synchronous rectifier, the input terminal and logic circuit of anti-leak-stopping unlatching circuit and maximum frequency limiting circuit
Output end connection, the input terminal that anti-leak-stopping opens circuit are also connect with the output end of voltage magnitude detection circuit, maximum frequency limit
Circuit processed, voltage magnitude detection circuit, prevent from opening by mistake open circuit, anti-leak-stopping opens circuit, shutdown threshold compensation circuitry and its
The output end of his control circuit is both connected to the input terminal of logic circuit, and the logic circuit output control signal is as driving
The input of circuit, the grid of the output end connection synchronous rectifier of the driving circuit is to control its switch.
In the above-described embodiments, with reference to Fig. 7, logic circuit includes the first logic disjunction gate circuit, the first logic " with door "
Circuit, the second logic " with door " circuit and rest-set flip-flop circuit, the input terminal of the first logic disjunction gate circuit respectively with prevent from missing
Open circuit and anti-leak-stopping and open the output end of circuit and connect, the input terminal of the first logic " with door " circuit respectively with it is maximum frequently
Rate limiting circuit, voltage magnitude detection circuit, the first logic disjunction gate circuit and other open control circuits output end connect
Connect, the input terminal of the second logic " with door " circuit respectively with shutdown threshold compensation circuitry, other output ends to switch off control circuit
Connection, the output end of the first logic " with door " and the set input of rest-set flip-flop are connect, the output of the second logic " with door "
End is connect with rest-set flip-flop the RESET input, and the output end of rest-set flip-flop and the input terminal of driving circuit connect.
In the above-described embodiments, it prevents from opening by mistake opening circuit and preventing from opening by mistake and opens circuit for avoiding synchronous rectifier in drain-source
Oscillation occurs for voltage or opening by mistake when there is wrong voltage is opened, it includes first resistor, first capacitor and Schmidt trigger,
One end of first resistor is connect with power circuit, and the other end of first resistor is touched with the anode of first capacitor and Schmidt respectively
The input terminal connection of device is sent out, the cathode and synchronous rectifier of first capacitor, which drain, to be connected.It prevents from opening by mistake and opens circuit using Schmidt
Trigger improves response speed as voltage comparator circuit, and the turnover voltage v1 of Schmidt trigger is less than supply voltage
One third, turnover voltage v2 are greater than 2/3rds of supply voltage, prevent from opening by mistake and open the resistance value of first resistor in circuit, the
The capacitance of one capacitor can be changed according to the variation of drain-source voltage slope, and RC time constant range is received in 20 nanoseconds to 2000
Between second, representative value was 200 nanoseconds in actual application.
In the above-described embodiments, it includes the second logic disjunction gate circuit, first switch, the second electricity that anti-leak-stopping, which opens circuit,
Hold, the first constant-current source and the second comparator, the input terminal of logic disjunction gate circuit respectively with the output end of voltage magnitude detection and
The output end of rest-set flip-flop connects, and the output end of logic disjunction gate circuit and the control terminal of first switch connect, the first constant-current source
Input terminal connect with power circuit, the output end of the first constant-current source is connected to the anode of the second capacitor, and the first constant-current source is used for
To the second capacitor charging, first switch is used to discharge to the second capacitor, the in-phase end of the anode and the second comparator of the second capacitor
Connection, the reverse side of the second comparator are connected on power circuit for receiving the first reference voltage from power circuit, prevent
Leak-stopping is opened circuit and be can be realized when synchronous rectifier is closed to the second capacitor charging, and the weight when drain-source voltage is lower than 0V
It newly starts to charge, the time representative value that charging voltage reaches the first reference voltage is 5 microseconds, and anti-leak-stopping is opened circuit and be can avoid
Leakage of the synchronous rectifier when drain-source voltage slope is not correctly detected is opened.
In the above-described embodiments, shutdown threshold compensation circuitry includes second resistance, 3rd resistor and the second comparator,
The input terminal of second resistance is connected to the drain electrode of synchronous rectifier, and the input terminal of 3rd resistor is connected to the grid of synchronous rectifier
Pole, the output end of second resistance and the output end of 3rd resistor are connected to the in-phase end of the second comparator, the second comparator simultaneously
Reverse side be connected on power circuit for receiving the second reference voltage from power circuit.
In the above-described embodiments, driving circuit includes pulse delay circuit, logic " NOT gate " circuit, logic " XOR gate "
Circuit, weak driving circuit and N-type metal-oxide-semiconductor, p-type metal-oxide-semiconductor, pulse delay circuit, logic " NOT gate " circuit, logic " XOR gate "
The input terminal of circuit is connect with the output end of logic circuit, and the input terminal of logic " XOR gate " circuit is also electric with pulse delay
The output end on road connects, and the output end of pulse delay circuit is also connect with the grid control terminal of p-type metal-oxide-semiconductor, logic " NOT gate " electricity
The output end on road is connect with the grid control terminal of N type metal-oxide-semiconductor, and the source of p-type metal-oxide-semiconductor is connect with power end, drain terminal and N-type
The drain terminal of metal-oxide-semiconductor connects, the source ground connection of N-type metal-oxide-semiconductor, the output end of logic " XOR gate " circuit, third reference voltage, same
The drain electrode of step rectifying tube is the input of weak driving circuit, the leakage of the output end and p-type metal-oxide-semiconductor, N-type metal-oxide-semiconductor of weak driving circuit
End connection.
In the above-described embodiments, the in-phase end voltage for turning off threshold compensation circuitry can be realized when driving circuit output voltage
Drain voltage needed for reducing shutdown synchronous rectifier when higher；When driving circuit output voltage is lower, raising shutdown is synchronized whole
Drain voltage needed for flow tube.Shutdown threshold compensation circuitry can avoid the shutdown in advance of synchronous rectifier or be delayed to turn off, to rise
To the effect of protection circuit.
In the above-described embodiments, driving circuit controls synchronous rectifier using strong driving circuit, weak driving circuit
System, strong driving circuit are controlled by the unlatching that the time is fixed in pulse delay circuit, and weak driving circuit is then when residue is opened
Between synchronous rectifier is controlled, the pulse width representative value of the pulse delay circuit was 500 nanoseconds.In driving circuit
Weak driving circuit synchronous rectifier drain voltage is compared with third reference voltage, and keep drain voltage lower than the
Three reference voltages, and the driving voltage reduces, the representative value of the third reference voltage with the raising of drain voltage
It is -80~-60 millivolts.
In the above-described embodiments, maximum frequency limiting circuit limits the minimum period of synchronous rectifier unlatching, in this week
Synchronous rectifier does not allow to open second in phase.Maximum frequency limiting circuit can guarantee that circuit works under normal frequency,
Without the influence of interfered signal.
In specific work process, as shown in figure 3, after side switching tube is closed, the drain voltage VS of synchronous rectifier
Decline rapidly since positive voltage, the waveform of drain voltage VS waveform and rest-set flip-flop output signal SW are as shown in Figure 7.At this point,
The voltage of voltage magnitude detection circuit real-time tracking synchronous rectifier drain voltage VS, while circuit inspection is opened by preventing from opening by mistake
The decrease speed for surveying VS, when VS voltage decrease speed is very fast and VS voltage is lower than 0V, voltage magnitude detection circuit S1 output end
High level signal is exported, prevents from opening by mistake and opens circuit S2 output end and also export high level signal, other open control circuits and maximum
Frequency limit circuit exports high level signal, the first logic " with door " circuit output trigger signal to rest-set flip-flop, RS touching simultaneously
It sends out device and exports SW signal to driving circuit, driving circuit exports GATE signal to open synchronous rectifier.When other unlatchings control
When circuit does not issue high level signal or maximum frequency limiting circuit detects that frequency is more than setpoint frequency, rest-set flip-flop will not
It is triggered, synchronous rectifier can not be turned on.
It prevents from opening by mistake and opens circuit diagram as shown in figure 4, including first resistor, first capacitor and Schmidt trigger, the
One end of one resistance is connect with power circuit, the other end of first resistor respectively with the anode of first capacitor and schmidt trigger
The input terminal of device connects, and the cathode and synchronous rectifier of first capacitor, which drain, to be connected, and the turnover voltage v1 of Schmidt trigger is small
In a quarter of supply voltage, turnover voltage v2 is greater than 3/4ths of supply voltage, by Schmitt trigger to pulse
Signal carries out shaping, and opening by mistake for synchronous rectifier can be effectively prevented and open.
When Switching Power Supply work is in underloading or idle mode, the drain-source voltage VS waveform and RS of synchronous rectifier are triggered
Device output signal SW waveform is as shown in Figure 10.Since under underloading or idle mode, Switching Power Supply working frequency is lower, will lead to
The case where first siding ring energy fills influences so that the drain-source voltage VS decrease speed of secondary side synchronous rectifier be made to slow down
Prevent the judgement of error starting circuit.It works at this point, anti-leak-stopping opens circuit, starts in previous cycle SW signal failing edge
It waits and forces output high level after a certain period of time, if VS voltage magnitude meets simultaneously is lower than 0V, the touching of logic " with door " circuit output
It signals to rest-set flip-flop, rest-set flip-flop exports SW signal to driving circuit, and driving circuit exports GATE signal to open synchronization
Rectifying tube.Anti- leak-stopping opens circuit diagram as shown in figure 5, when rest-set flip-flop output signal SW exports high level, switch K1
Closure, capacitor C1 repid discharge, when SW exports low level, switch K1 is disconnected, and capacitor C1 is through constant current source charging, if through Td_eff
Time SW signal is still low level, and the voltage on the second capacitor C2 is greater than reference voltage VREF, the second comparator output terminal S3
Export high level signal.
Threshold compensation circuitry is turned off as shown in fig. 6, the relational expression of voltage VC and GATE can be acquired:
As VC=VREF, comparator is inverted, and when grid voltage GATE is reduced, then needs higher drain-source voltage
VS comparator could be overturn, to compensate for the phenomenon that grid voltage GATE reduction causes synchronous rectifier to turn off in advance.Together
Reason then needs lower drain-source voltage VS comparator that can overturn, to compensate for grid when grid voltage GATE is increased
The phenomenon that voltage GATE raising leads to synchronous rectifier time delayed turn-off.When in comparator output low level pulse, logic circuit
Rest-set flip-flop resets, synchronous rectifier shutdown, and waveform is as shown in Figure 8, Figure 9.
To sum up, the present invention can guarantee the Precision switch of the synchronous rectifier under heavily loaded mode, underloading or idle mode, keep away
Opening by mistake for synchronous rectifier is exempted to open and leak unlatching, has realized the high efficiency conversion of inverse-excitation type switch power-supply, improve the peace of system
Quan Xing, reliability.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
It cannot therefore be construed as limiting the scope of the patent.It should be pointed out that coming for those of ordinary skill in the art
It says, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to guarantor of the invention
Protect range.Therefore, the scope of protection of the patent of the invention shall be subject to the appended claims.
Claims (17)
1. a kind of synchronous commutating control circuit, for controlling inverse-excitation type switch power-supply, which is characterized in that the synchronous rectification control
Circuit includes power circuit, maximum frequency limiting circuit, voltage magnitude detection circuit, prevents from opening by mistake and open circuit, the unlatching of anti-leak-stopping
Circuit, shutdown threshold compensation circuitry, logic circuit, driving circuit and other control circuits, the power circuit are opened with inverse-excitation type
The output end in powered-down source connects, and to the voltage and reference voltage of generation circuit work, voltage magnitude detection circuit prevents from opening by mistake
The input terminal for opening circuit, shutdown threshold compensation circuitry and driving circuit is connect with the drain electrode of synchronous rectifier, and shutdown threshold value is mended
The input terminal for repaying circuit is also connect with the grid of synchronous rectifier, and anti-leak-stopping opens the input of circuit and maximum frequency limiting circuit
End is connect with the output end of logic circuit, and the input terminal that anti-leak-stopping opens circuit also connects with the output end of voltage magnitude detection circuit
It connects, maximum frequency limiting circuit, voltage magnitude detection circuit prevent from opening by mistake and open circuit, anti-leak-stopping unlatching circuit, shutdown threshold value benefit
The output end for repaying circuit and other control circuits is both connected to the input terminal of logic circuit, the logic circuit output control signal
As the input of driving circuit, the grid of the output end connection synchronous rectifier of the driving circuit is to control its switch.
2. synchronous commutating control circuit according to claim 1, it is characterised in that: the logic circuit includes the first logic
Disjunction gate circuit, the first logic " with door " circuit, the second logic " with door " circuit and rest-set flip-flop circuit, first logic
The input terminal of disjunction gate circuit respectively with it is described prevent from opening by mistake open the output end that circuit and the anti-leak-stopping open circuit and connect, institute
State the input terminal of the first logic " with door " circuit respectively with the maximum frequency limiting circuit, the voltage magnitude detection circuit,
The first logic disjunction gate circuit is connected with the output end of other open control circuits, the second logic " with door " circuit
Input terminal connect respectively with the shutdown threshold compensation circuitry, other output ends to switch off control circuit, first logic
The output end of " with door " is connect with the set input of the rest-set flip-flop, the output end of second logic " with door " with it is described
The connection of rest-set flip-flop the RESET input, the output end of the rest-set flip-flop are connect with the input terminal of the driving circuit.
3. synchronous commutating control circuit according to claim 1, it is characterised in that: described to prevent from opening by mistake that open circuit include the
One end of one resistance, first capacitor and Schmidt trigger, the first resistor is connect with power circuit, the first resistor
The other end is connect with the input terminal of the anode of the first capacitor and the Schmidt trigger respectively, and the first capacitor is born
Pole and synchronous rectifier drain electrode connection.
4. synchronous commutating control circuit according to claim 2, it is characterised in that: it includes that the anti-leak-stopping, which opens circuit,
Two logic disjunction gate circuits, first switch, the second capacitor, the first constant-current source and the second comparator, the logic disjunction gate circuit
Input terminal connect respectively with the output end of voltage magnitude detection and the output end of the rest-set flip-flop, the logic " or
The output end of door " circuit is connect with the control terminal of the first switch, the input terminal of first constant-current source and power supply electricity
Road connection, the output end of first constant-current source are connected to the anode of the second capacitor, and first constant-current source is used for the second electricity
Capacity charge, for the first switch for giving second capacitor electric discharge, the anode of second capacitor is same with the second comparator
The connection of phase end, the reverse side of second comparator are connected on the power circuit for receiving from the power circuit
First reference voltage.
5. synchronous commutating control circuit according to claim 1, it is characterised in that: the shutdown threshold compensation circuitry includes
Second resistance, 3rd resistor and the second comparator, the input terminal of the second resistance are connected to the leakage of the synchronous rectifier
Pole, the input terminal of the 3rd resistor are connected to the grid of the synchronous rectifier, the output end and third of the second resistance
The output end of resistance is connected to the in-phase end of second comparator simultaneously, and the reverse side of second comparator is connected to power supply
For receiving the second reference voltage from the power circuit on circuit.
6. synchronous commutating control circuit according to claim 1, it is characterised in that: the driving circuit includes pulse delay electricity
Road, logic " NOT gate " circuit, logic " XOR gate " circuit, weak driving circuit and N-type metal-oxide-semiconductor, p-type metal-oxide-semiconductor, the pulse delay
Circuit, logic " NOT gate " circuit, logic " XOR gate " circuit input terminal connect with the output end of the logic circuit, it is described
The input terminal of logic " XOR gate " circuit is also connect with the output end of pulse delay circuit, the output end of the pulse delay circuit
It is also connect with the grid control terminal of p-type metal-oxide-semiconductor, the grid control of the output end and the N-type metal-oxide-semiconductor of logic " NOT gate " circuit
End connection processed, the source of the p-type metal-oxide-semiconductor are connect with power end, and drain terminal is connect with the drain terminal of the N-type metal-oxide-semiconductor, the N
The source of type metal-oxide-semiconductor is grounded, the output end of logic " XOR gate " circuit, third reference voltage, the synchronous rectifier
Drain electrode is the input of weak driving circuit, the drain terminal of the output end of the weak driving circuit and the p-type metal-oxide-semiconductor, N-type metal-oxide-semiconductor
Connection.
7. synchronous commutating control circuit according to claim 3, it is characterised in that: it is described prevent from opening by mistake open circuit using applying
Schmitt trigger improves response speed as voltage comparator circuit, and the turnover voltage v1 of the Schmidt trigger is less than power supply
The one third of voltage, turnover voltage v2 are greater than 2/3rds of supply voltage.
8. synchronous commutating control circuit according to claim 3, it is characterised in that: it is described prevent from opening by mistake open described in circuit
Resistance value, the capacitance of first capacitor of first resistor can be changed, RC time constant range according to the variation of drain-source voltage slope
In 20 nanoseconds between 2000 nanoseconds.
9. synchronous commutating control circuit according to claim 3, it is characterised in that: it is described prevent from opening by mistake open circuit for keeping away
Exempt from synchronous rectifier opening by mistake when drain-source voltage occurs oscillation or wrong voltage occurs to open.
10. synchronous commutating control circuit according to claim 4, it is characterised in that: the anti-leak-stopping opens circuit can
It realizes when synchronous rectifier is closed to second capacitor charging, and restart to charge when drain-source voltage is lower than 0V, fills
The time representative value that piezoelectric voltage reaches first reference voltage is 5 microseconds.
11. synchronous commutating control circuit according to claim 4, it is characterised in that: the anti-leak-stopping is opened circuit and can be kept away
Exempt from leakage of the synchronous rectifier when drain-source voltage slope is not correctly detected to open.
12. synchronous commutating control circuit according to claim 5, it is characterised in that: the shutdown threshold compensation circuitry
In-phase end voltage can realize drain voltage needed for reducing shutdown synchronous rectifier when driving circuit output voltage is higher；Work as driving
Drain voltage needed for improving shutdown synchronous rectifier when circuit output voltage is lower.
13. synchronous commutating control circuit according to claim 5, it is characterised in that: the shutdown threshold compensation circuitry can
It avoids the shutdown in advance of synchronous rectifier or is delayed to turn off, to play the role of protecting circuit.
14. synchronous commutating control circuit according to claim 6, it is characterised in that: the driving circuit is using strong driving
Circuit, weak driving circuit parallel control synchronous rectifier, and the strong driving circuit is consolidated by pulse delay circuit
The unlatching control fixed time, the weak driving circuit then control synchronous rectifier in the remaining opening time, the pulse
The pulse width representative value of delay circuit was 500 nanoseconds.
15. synchronous commutating control circuit according to claim 6, it is characterised in that: the weak driving in the driving circuit
Synchronous rectifier drain voltage is compared by circuit with third reference voltage, and keeps drain voltage lower than third with reference to electricity
Pressure, and the driving voltage is reduced with the raising of drain voltage, the representative value of the third reference voltage is -80~-60
Millivolt.
16. synchronous commutating control circuit according to claim 1, it is characterised in that: the maximum frequency limiting circuit limitation
The minimum period that synchronous rectifier is opened, synchronous rectifier does not allow to open second within the period.
17. synchronous commutating control circuit according to claim 1, it is characterised in that: the maximum frequency limiting circuit can
Guarantee that circuit works under normal frequency, without the influence of interfered signal.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910095474.1A CN109756135A (en) | 2019-01-31 | 2019-01-31 | A kind of synchronous commutating control circuit |
| PCT/CN2019/078497 WO2020155330A1 (en) | 2019-01-31 | 2019-03-18 | Synchronous rectification control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910095474.1A CN109756135A (en) | 2019-01-31 | 2019-01-31 | A kind of synchronous commutating control circuit |
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| CN109756135A true CN109756135A (en) | 2019-05-14 |
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| CN201910095474.1A Pending CN109756135A (en) | 2019-01-31 | 2019-01-31 | A kind of synchronous commutating control circuit |
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| CN (1) | CN109756135A (en) |
| WO (1) | WO2020155330A1 (en) |
Cited By (8)
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| CN110336461A (en) * | 2019-06-13 | 2019-10-15 | 无锡猎金半导体有限公司 | A kind of high efficiency BUCK synchronous commutating control circuit |
| CN110798071A (en) * | 2019-10-18 | 2020-02-14 | 杰华特微电子（杭州）有限公司 | Primary side conduction judgment method, control method, control circuit and flyback circuit |
| 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 |
| CN113162440A (en) * | 2021-04-25 | 2021-07-23 | 深圳市力生美半导体股份有限公司 | Switching power supply and synchronous rectification control circuit thereof |
| CN113346761A (en) * | 2019-12-10 | 2021-09-03 | 成都芯源系统有限公司 | Synchronous rectification switching power supply circuit, secondary side control circuit and method thereof |
| CN114123783A (en) * | 2020-08-27 | 2022-03-01 | 西安鼎芯微电子有限公司 | Synchronous rectification chip |
| CN114362483A (en) * | 2021-12-28 | 2022-04-15 | 成都芯源系统有限公司 | Switching power supply circuit, secondary side control circuit and method of synchronous rectification switch |
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| JP5601158B2 (en) * | 2010-11-02 | 2014-10-08 | 富士電機株式会社 | Semiconductor control device for switching power supply device and switching power supply device using the same |
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| CN107508473B (en) * | 2017-07-13 | 2019-08-23 | 苏州博创集成电路设计有限公司 | Synchronous rectifier converter |
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2019
- 2019-01-31 CN CN201910095474.1A patent/CN109756135A/en active Pending
- 2019-03-18 WO PCT/CN2019/078497 patent/WO2020155330A1/en active Application Filing
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| CN113346761A (en) * | 2019-12-10 | 2021-09-03 | 成都芯源系统有限公司 | Synchronous rectification switching power supply circuit, secondary side control circuit and method thereof |
| CN113346761B (en) * | 2019-12-10 | 2022-03-22 | 成都芯源系统有限公司 | Synchronous rectification switching power supply circuit, secondary side control circuit and method thereof |
| CN114123783A (en) * | 2020-08-27 | 2022-03-01 | 西安鼎芯微电子有限公司 | Synchronous rectification chip |
| 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 |
| CN113162440A (en) * | 2021-04-25 | 2021-07-23 | 深圳市力生美半导体股份有限公司 | Switching power supply and synchronous rectification control circuit thereof |
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