CN102377357B - Secondary synchronous rectification controller and power switching circuit thereof - Google Patents
Secondary synchronous rectification controller and power switching circuit thereof Download PDFInfo
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- CN102377357B CN102377357B CN201010251257.6A CN201010251257A CN102377357B CN 102377357 B CN102377357 B CN 102377357B CN 201010251257 A CN201010251257 A CN 201010251257A CN 102377357 B CN102377357 B CN 102377357B
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Abstract
The invention relates to a prediction type secondary side synchronous rectification controller, which is used for controlling at least one synchronous rectification switch. The synchronous rectification controller is provided with a sawtooth wave generator, a peak sampling unit and an output control unit, wherein the sawtooth wave generator receives a synchronous signal so as to generate a sawtooth wave signal; the peak sampling unit captures peak voltage of the sawtooth wave signal so as to generate a prediction reference voltage signal; and the sawtooth wave signal is compared with the prediction reference voltage signal by the output control unit so as to generate a synchronous rectification control signal to control the conduction state of the switch.
Description
Technical field
The present invention relates to an a kind of synchronous rectifying controller and power-switching circuit thereof that is applied to exchange type power conversion circuit, especially a kind of prediction type secondary side synchronous rectifier controller and power-switching circuit thereof.
Background technology
In the technical field of power supply conversion, utilize transistor switch to replace diode to reduce power consumption, be a common technological means.
Fig. 1 is the power-switching circuit that a typical case has secondary side synchronous rectifier function.The primary side of power-switching circuit has a PDM keyer 11 and a main switch 12.PDM keyer 11 is according to the feedback signal of carrying out self-isolation feedback device 13, conducting or the cut-off of output pulse signal control main switch 12.The primary side of power-switching circuit has a synchronous rectification switch 15 and a primary side synchronous rectifying controller 20.Secondary side synchronous rectifier controller 20, according to the signal of the primary side winding 142 from transformer 14, is controlled conducting or the cut-off of synchronous rectification switch 15.
In the time of main switch 12 conducting, direct-flow input end VIN provides electrical power to the primary side winding 141 of transformer 14.At the same time, 15 of synchronous rectification switchs are to present cut-off.Therefore, can be stored in transformer 14 from the electric power of direct-flow input end VIN.Subsequently, in the time that main switch 12 transfers cut-off to, secondary side synchronous rectifier controller 20 detects the variation of the polarity of voltage of primary side winding 142, controls synchronous rectification switch 15 conductings.Now, transformer 14 starts to discharge the energy storing to output VO and filter capacitor 16.
It should be noted that the accurately work period of control synchronous rectification switch 15 of secondary side synchronous rectifier controller 20, with the running of simulating diode, avoid causing conversion efficiency loss or cause switch to burn.With regard to the power-switching circuit of Fig. 1, the main switch 12 of primary side must alternate conduction with the synchronous rectification switch 15 of primary side.Overlapping with the ON time of synchronous rectification switch 15 in order to prevent main switch 12, between the ON time of main switch 12 and the ON time of synchronous rectification switch 15, must a reserved Dead Time (dead time).That is in this Dead Time, main switch 12 is all to present cut-off with synchronous rectification switch 15.
Secondary side synchronous rectifier controller 20 in Fig. 1 adopts complicated digital control approach to calculate Dead Time.As shown in FIG., this primary side synchronous rectifying controller 20 has a clock pulse buffer cell (Clock Buffer) 22, a numeral cut-off controller (Digital Turn-off Controller) 24 and an output driver element 26.
Fig. 2 is the block schematic diagram of the numeral cut-off controller 24 in figure l.As shown in FIG., numeral cut-off controller 24 comprises an oscillating unit 242, one first counter 243, one second counter 244, a finite state control device (Finite States Machine) 246 and an output control unit (Output Control) 248.Wherein, the first counter 243 and the second counter 244 are the counter that can go up number and lower number.Oscillating unit 242 is in order to produce an inner counting clock signal CLK, counts for the first counter 243 and the second counter 244.Finite state control device 246 receives outer synchronous signal Sync, and control the counting of the first counter 243 and the second counter 244 according to this outer synchronous signal Sync during.The output signal of the primary side winding 142 of this outer synchronous signal Sync transformer 14.
Fig. 3 is the oscillogram of each control signal in numeral cut-off controller 24.Referring to Fig. 2, when finite state control device 246 detects the leading edge of the first switch periods TSl of outer synchronous signal Sync, control the first counter 243 and start upper number, until finite state control device 246 detects the leading edge of the second switch cycle T S2 of outer synchronous signal Sync.Subsequently, finite state control device 246 is controlled the first counter 243 and is started lower number, until finite state control device 246 detects the leading edge of the 3rd switch periods TS3 of outer synchronous signal Sync.Suppose on the first counter 243 is in the first switch periods TSl and count to n, in the time that the first counter is counted to n-x 243 times, finite state control device 246 produces an output pick-off signal immediately, controls output control unit 248 and stops exporting Continuity signal (being the driving signal OUT of high potential).The numerical value of x is the count number of default Dead Time, and its large I is set end DTS by dead band and set.
In addition, when finite state control device 246 detects the leading edge of second switch cycle T S2 of outer synchronous signal Sync, together with time control the second counter 244 and start upper number, until finite state control device 246 detects the leading edge of the 3rd switch periods TS3 of outer synchronous signal Sync.The running of the second counter 244 and the first counter 243 is similar.In the 3rd switch periods TS3, finite state control device 246 is the count number according to the second counter 244, produces an output pick-off signal, controls output control unit 248 and stops exporting Continuity signal.
This primary side synchronous rectifying controller 20 utilizes upper number and lower several course of counter 243,244, can effectively predict the ON time of synchronous rectification switch in next switch periods, maintains roughly fixing Dead Time simultaneously.But, the circuit design of this primary side synchronous rectifying controller 20 is quite complicated, and cost of manufacture is difficult for reducing.
Summary of the invention
A main purpose of the present invention is for traditional prediction type secondary side synchronous rectifier controller, and the problem that circuit structure is too complicated, proposes the method solving.
Another main purpose of the present invention is to provide a kind of analogue type secondary side synchronous rectifier controller, can accurately control Dead Time, to avoid power supply conversion efficiency reduce or cause switch to burn.
In order to reach aforementioned object, one embodiment of the invention provide a kind of prediction type secondary side synchronous rectifier controller, in order to control at least one switch.This synchronous rectifying controller has a sawtooth generator, a peak sample unit, an output control unit.Wherein, sawtooth generator receives a synchronizing signal, to produce a sawtooth signal.One crest voltage of peak sample unit acquisition sawtooth signal, produces a reference voltage signal according to this.Output control unit is sawtooth signal and reference voltage signal relatively, to produce a synchronous rectification control signal, the conducting state of control switch, when the current potential of this sawtooth signal is during higher than the current potential of this prediction reference voltage signal, this output control unit turn-offs this synchronous rectification switch.This peak sample unit comprises that a reference bias source, keeps electric capacity and a releasing member.One high-pressure side of this maintenance electric capacity is connected to the output of this peak sample circuit, in order to receive this sawtooth signal; This releasing member is parallel to this maintenance electric capacity, in order to discharge the electric charge that is stored in this maintenance electric capacity; Wherein, this high-pressure side of this maintenance electric capacity is exported this prediction reference voltage signal, and this reference bias source, in order to drag down a stored voltage of this maintenance electric capacity, makes the maximum of this stored voltage be less than this crest voltage of this sawtooth signal.Output control unit has a comparator and a cutoff switch.Comparator compares the current potential of sawtooth signal and prediction reference voltage signal, to produce a Dead Time control signal with conducting cutoff switch.
One embodiment of the invention also provide a power-switching circuit with prediction type synchronous rectification.This power-switching circuit has a transformer, a synchronous rectification switch and a prediction type secondary side synchronous rectifier controller.Wherein, transformer comprises a primary side winding and a primary side winding.Synchronous rectification switch is connected to primary side winding.Prediction type secondary side synchronous rectifier controller is in order to control synchronous rectification switch.This primary side synchronous rectifying controller has a sawtooth generator, a peak sample unit and an output control unit.Wherein, sawtooth generator receives a synchronizing signal, to produce a sawtooth signal.One crest voltage of peak sample unit acquisition sawtooth signal, produces a reference voltage signal according to this.Output control unit is sawtooth signal and reference voltage signal relatively, to produce a synchronous rectification control signal, control the conducting state of synchronous rectification switch, when the current potential of this sawtooth signal is during higher than the current potential of this prediction reference voltage signal, this output control unit turn-offs this synchronous rectification switch.This peak sample unit comprises that a reference bias source, keeps electric capacity and a releasing member.One high-pressure side of this maintenance electric capacity is connected to the output of this peak sample circuit, in order to receive this sawtooth signal; This releasing member is parallel to this maintenance electric capacity, in order to discharge the electric charge that is stored in this maintenance electric capacity; Wherein, this high-pressure side of this maintenance electric capacity is exported this prediction reference voltage signal, and this reference bias source, in order to drag down a stored voltage of this maintenance electric capacity, makes the maximum of this stored voltage be less than this crest voltage of this sawtooth signal.Output control unit has a comparator and a cutoff switch.Comparator compares the current potential of sawtooth signal and prediction reference voltage signal, to produce a Dead Time control signal with conducting cutoff switch.
Can be further understood by means of the following detailed description and accompanying drawings about the advantages and spirit of the present invention.
Accompanying drawing explanation
Fig. 1 is the power-switching circuit that a typical case has secondary side synchronous rectifier function;
Fig. 2 is the block schematic diagram of the numeral cut-off controller in Fig. 1;
Fig. 3 is the oscillogram of the control signal of numeral cut-off controller;
Fig. 4 is the circuit diagram of synchronous rectified power change-over circuit one first embodiment of the present invention;
Fig. 5 is the circuit diagram of synchronous rectified power change-over circuit one second embodiment of the present invention;
Fig. 6 is the circuit diagram of secondary side synchronous rectifier controller one first embodiment of Fig. 4;
Fig. 7 is the control waveform figure of the secondary side synchronous rectifier controller of Fig. 6;
Fig. 8 is the circuit diagram of secondary side synchronous rectifier controller one second embodiment of the present invention;
Fig. 9 is the oscillogram of control signal one preferred embodiment of the secondary side synchronous rectifier controller of Fig. 8;
Figure 10 is the circuit diagram of secondary side synchronous rectifier power-switching circuit 1 the 3rd embodiment of the present invention;
Figure 11 is the oscillogram of control signal one preferred embodiment of the secondary side synchronous rectifier controller of Figure 10.
[main element description of reference numerals]
Secondary side synchronous rectifier controller 20
Primary side winding 141
Primary side winding 142
Input VIN
Output VO
Clock pulse buffer cell 22
Numeral cut-off controller 24
Oscillating unit 242
The first counter 243
The second counter 244
Finite state control device 246
Counting clock signal CLK
Synchronizing signal Sync, Sync0, Sync1
The first switch periods TS1
Second switch cycle T S2
The 3rd switch periods TS3
End DTS is set in dead band
Secondary side synchronous rectifier controller 40
Transformer 34
Primary side winding 341
Primary side winding 342
Primary side is assisted winding 344
Sawtooth generator 42
Sawtooth signal Ramp
Prediction reference voltage signal PS
Synchronous rectification control signal SRC
Drive signal OUT
Dead Time control signal Comp
Trailing edge trigger impulse FTP
Leading edge trigger impulse RTP
Sawtooth waveforms produces electric capacity 422
Resetting Switching 426
Keep electric capacity 442
Releasing member 444
Trailing edge trigger element 427
Primary side winding 541
Primary side winding 542
Secondary side synchronous rectifier controller 60
Reference bias Vr
Power input VCC
The first primary side turn-on cycle ta1
Second subprime side turn-on cycle ta2
Level side turn-on cycle ta3 for the third time
The first primary side turn-on cycle tb1
The second primary side turn-on cycle tb2
Dead Time td
Embodiment
The present invention is a kind of prediction type secondary side synchronous rectifier controller and method.This control circuit and control method can be applicable to flyback, forward type, semibridge system or full-bridge type topology in the control of continuous current mode (Current Continuous Mode, CCM).In addition, prediction type secondary side synchronous rectifier controller of the present invention adopts the turn-on cycle of easy analog circuit control synchronous rectification switch, is suitable for the secondary side synchronous rectifier control of various fixed switched power suppliers frequently.
Prediction type secondary side synchronous rectifier controller of the present invention, produce a sawtooth signal according to a primary side synchronizing signal, and capture the crest voltage of sawtooth signal, produce corresponding reference voltage, and this reference voltage is compared with the sawtooth signal of next work period, to produce a dead zone signals, cutoff synchronization rectifier switch.
Fig. 4 is the circuit diagram of synchronous rectified power change-over circuit one first embodiment of the present invention.The present embodiment one flyback power-switching circuit.As shown in FIG., the primary side of this power-switching circuit has a PDM keyer 31 and a main switch 32.PDM keyer 31 is according to the feedback signal of carrying out self-isolation feedback device 33, conducting or the cut-off of output pulse signal control main switch 32.The primary side of this power-switching circuit has a synchronous rectification switch 35 and a primary side synchronous rectifying controller 40.This primary side synchronous rectifying controller 40, according to the synchronizing signal Sync0 of a pulse signal corresponding to primary side, is controlled the conducting state of synchronous rectification switch 35.In the present embodiment, secondary side synchronous rectifier controller 40 is assisted a synchronizing signal Sync0 of winding 344 according to the primary side that comes from transformer 34, controls conducting or the cut-off of synchronous rectification switch 35.The height potential change of this synchronizing signal Sync0 is contrary with the pulse signal of primary side.
In the time of 32 conducting of pulse signal control main switch, direct-flow input end VIN provides electrical power to the primary side winding 341 of transformer 34.At the same time, secondary side synchronous rectifier controller 40 is controlled synchronous rectification switch 35 and is ended.Therefore, can be stored in transformer 34 from the electric power of direct-flow input end VIN.Subsequently, in the time that pulse signal control main switch 32 transfers cut-off to, the current potential of synchronizing signal Sync0 changes.After the current potential that secondary side synchronous rectifier controller 40 detects synchronizing signal Sync0 changes, control synchronous rectification switch 35 conductings.Now, transformer 34 starts to discharge the energy storing to output VO and filter capacitor 36.
Fig. 6 is the circuit diagram of secondary side synchronous rectifier controller the 40 one the first embodiment of Fig. 4.As shown in FIG., this primary side synchronous rectifying controller 40 has a sawtooth generator 42, a peak sample unit 44, an output control unit 46 and an output driver element 48.Wherein, sawtooth generator 42 receives a synchronizing signal Sync0, to produce a sawtooth signal Ramp.Peak sample unit 44 captures a crest voltage of sawtooth signal Ramp, produces according to this prediction reference voltage signal PS.Relatively sawtooth signal Ramp and prediction reference voltage signal PS of output control unit 46, to produce a synchronous rectification control signal SRC.Output driver element 48, according to this synchronous rectification control signal SRC, produces one and drives signal OUT, controls the conducting state of synchronous rectification switch 35.
Secondly, the secondary side synchronous rectifier controller 40 of the present embodiment has a power input VCC.External power source supplies power to sawtooth generator 42 and output driver element 48 by this power input VCC.Shown in Fig. 4, in the present embodiment, this power input VCC is connected to the auxiliary winding 344 of a primary side.But, the present invention is not limited to this.This power input VCC also can be connected to other DC power supply.
Fig. 7 is the control waveform figure of the secondary side synchronous rectifier controller of Fig. 6.As shown in FIG., in the first primary side turn-on cycle ta1, synchronizing signal Sync0 is in high potential, and Resetting Switching 426 is in cut-off state.Now, charge power supply 424 produces electric capacity 422 to sawtooth waveforms and charges, and the current potential that makes sawtooth waveforms produce the high-pressure side of electric capacity 422 progressively improves (that is current potential of sawtooth signal Ramp).Subsequently, while entering the first primary side turn-on cycle tb1, synchronizing signal Sync0 changes electronegative potential into.Now, Resetting Switching 426 conductings, sawtooth waveforms produces electric capacity 422 and discharges rapidly, to form sawtooth signal Ramp.Subsequently, while entering second subprime side turn-on cycle ta2, synchronizing signal Sync0 overline changes high potential into, and Resetting Switching 426 ends once again, makes sawtooth waveforms produce electric capacity 422 and again charges.
The voltage of sawtooth signal Ramp can be stored to maintenance electric capacity 442 by reference to bias generator 446 and peak sample circuit 448.The reference bias Vr that reference bias source 446 provides can make to keep the stored maximum voltage of electric capacity 442 to be less than the crest voltage of sawtooth signal Ramp.In the time entering the first primary side turn-on cycle tb1, the current potential of sawtooth signal Ramp can fast reducing.Under comparing, be slowly to discharge by a releasing member 444 with high impedance owing to keeping the electric charge in electric capacity 442, therefore, can be progressively slowly reduced by the current potential of the prediction reference voltage signal PS that keeps the high-pressure side of electric capacity 442 to export.
Enter after second subprime side turn-on cycle ta2, the current potential of sawtooth signal Ramp rises once again.But, the current potential of prediction reference voltage signal PS still slowly reduces.Originally, the current potential of sawtooth signal Ramp remains the current potential lower than prediction reference voltage signal PS.Along with the current potential of sawtooth signal Ramp progressively rises, at a specific time point, when the current potential of sawtooth signal Ramp rises to after the current potential that exceedes prediction reference voltage signal PS, comparator 462 produces a dead band (dead time) control signal Comp immediately.Dead Time control signal Comp is in order to adjust the time span of second subprime side turn-on cycle ta2 of synchronizing signal Sync0, to produce synchronous rectification control signal SRC.
The Dead Time control signal Comp of this high potential can last till that the second primary side turn-on cycle tb2 starts.As shown in FIG., the time point of the ascent stage of synchronous rectification control signal SRC is identical with synchronizing signal Sync0, and but, the time point of the descending branch of synchronous rectification control signal SRC is to be determined by Dead Time control signal Comp.
Dead Time control signal Comp is at primary side turn-on cycle ta1, and ta2, defines Dead Time td in ta3.As shown in FIG., be prediction reference voltage signal PS by the second turn-on cycle relatively and determine corresponding to the sawtooth signal Ramp of second subprime side turn-on cycle ta2 corresponding to the Dead Time td of the second turn-on cycle (comprising the second primary side turn-on cycle tb2 and second subprime side turn-on cycle ta2).The maximum voltage of the prediction reference voltage signal PS of the second turn-on cycle is determined by the crest voltage of the sawtooth signal Ramp corresponding to the first primary side turn-on cycle ta1.
In each turn-on cycle, the descending slope of the rate of rise of sawtooth signal Ramp and prediction reference voltage signal PS is all to remain certain.Therefore, the duration of the high potential synchronous rectification control signal SRC of each turn-on cycle is determined by the crest voltage of the sawtooth signal Ramp of previous turn-on cycle, is namely determined by the time span of previous primary side turn-on cycle.
The rate of rise of sawtooth signal Ramp can produce by changing sawtooth waveforms the capacitance of electric capacity 422 and be adjusted, and the descending slope of prediction reference voltage signal PS can be adjusted with keeping electric capacity 442 by releasing member 444.The length of Dead Time td can be adjusted by changing the rate of rise of sawtooth signal Ramp and the descending slope of prediction reference voltage signal PS.The capacitance that sawtooth waveforms produces electric capacity 422 is larger, and the impedance of releasing member 444 is larger, keeps the capacitance of electric capacity 442 larger, and Dead Time td is shorter.
Fig. 5 is the circuit diagram of synchronous rectification flyback power-switching circuit of the present invention one second embodiment.In the embodiment of Fig. 4, synchronous rectification switch 35 is arranged between primary side winding 342 and earth terminal, and 35 of the synchronous rectification switchs of the present embodiment are to be arranged between primary side winding 342 and output VO.In addition, in the embodiment of Fig. 4, secondary side synchronous rectifier controller 40 is to be connected to the auxiliary winding 344 of primary side to capture required electric energy, 40 of the secondary side synchronous rectifier controllers of the present embodiment are to be connected to primary side winding 342, and the auxiliary winding 344 of primary side also changes the output being connected in series to primary side winding 342 into.Although it is different that circuit connects, but the operation principles of secondary side synchronous rectifier controller 40 and the embodiment of Fig. 4 of the present embodiment are roughly the same, are not repeated at this.
Fig. 8 is the circuit diagram of secondary side synchronous rectifier controller one second embodiment of the present invention.Fig. 9 is the oscillogram of corresponding control signal.Compared to the embodiment of Fig. 6, the sawtooth generator 42 of the present embodiment has a trailing edge trigger element 427, the trailing edge (Falling Edge) of acquisition synchronizing signal Sync0, control Resetting Switching 426 conductings to produce trailing edge trigger impulse FTP, make sawtooth waveforms produce electric capacity 422 and discharge.In addition, the sawtooth generator 42 of Fig. 6 is to utilize synchronizing signal Sync0 to control Resetting Switching 426 to carry out periodic conducting, and produces the sawtooth signal Ramp of noncontinuity.In comparison, the present embodiment utilizes trailing edge trigger impulse FTP conducting Resetting Switching 426, significantly shortens the ON time of Resetting Switching 426, and produces the sawtooth signal Ramp of approximate continuity.The operation principles of other parts and the embodiment of Fig. 6 of this primary side synchronous rectifying controller 40 are roughly the same, are not repeated at this.
Figure 10 is the circuit diagram of synchronous rectified power change-over circuit 1 the 3rd embodiment of the present invention.The present embodiment one forward type power-switching circuit.The difference of the flyback power-switching circuit of itself and first embodiment of the invention is, the polarity of the primary side winding 542 of the present embodiment is different from the primary side winding 342 of the first embodiment, and the setting position of the synchronous rectification switch 55 of the present embodiment is different from the synchronous rectification switch 35 of the first embodiment.This synchronous rectification switch 55 forms a loop with primary side winding 542.And, between synchronous rectification switch 55 and filter capacitor 36, be connected with an inductance 56.In addition, the present embodiment has omitted the auxiliary winding 344 of primary side in the first embodiment.
Secondly, in the present embodiment, secondary side synchronous rectifier controller 60 is connected to the front end of primary side rectifier diode 57 with acquisition synchronizing signal Sync1.In the embodiment of Fig. 4 and Fig. 5, the height potential change of the pulse signal of synchronizing signal Sync0 and primary side is on the contrary.In the present embodiment, synchronizing signal Sync1 is consistent with the height potential change of the pulse signal of primary side.That is to say, in primary side turn-on cycle, synchronizing signal Sync1 can present high potential, but not electronegative potential.
Figure 11 demonstration utilizes secondary side synchronous rectifier controller of the present invention, and the synchronizing signal Sync1 in Figure 10 is converted to the oscillogram of Dead Time control signal Comp with the control signal of the conducting state of control synchronous rectification switch 55.The embodiment that is different from Fig. 9 is mode control Resetting Switching 426 conductings that adopt trailing edge to trigger, to form sawtooth signal Ramp.Because the height potential change of the synchronizing signal Sync1 of the present embodiment and the pulse signal of primary side is consistent, the present embodiment changes the mode triggering with leading edge (Rising Edge), produce leading edge trigger impulse RTP and control Resetting Switching 426 conductings, to form sawtooth signal Ramp.The generation principle of the Dead Time control signal Comp of the present embodiment and synchronous rectification control signal SRC, roughly the same with the embodiment of Fig. 6 and Fig. 9, do not repeated at this.
The present invention utilizes synchronizing signal Sync0, and the turn-on cycle that Sync1 defines produces sawtooth signal Ramp, the crest voltage of collocation peak sample technology acquisition sawtooth signal Ramp, and set a reference bias Vr, to produce Dead Time control signal Comp.Therefore, the present invention can replace the digital control circuit of known complexity.Secondly, because the present invention's crest voltage that peak sample technology captures of arranging in pairs or groups can change in response to the length in real work cycle, thereby can be in response to the change in real work cycle.Dead Time td length, can produce electric capacity 422 by sawtooth waveforms, keep the elements such as electric capacity 442 to be set.In sum, secondary side synchronous rectifier controller of the present invention is a kind of control mode of prediction type, captures the sawtooth signal Ramp in last cycle, to set Dead Time td.Therefore, can be applicable under operating frequency deviation is large, power supply voltage variation scope is large condition, to reach high efficiency power supply control.
But; the above, be only preferred embodiment of the present invention, when not limiting scope of the invention process with this; be that all simple equivalences of doing according to the claims in the present invention protection range and invention description content change and revise, all remain within the scope of the patent.Arbitrary embodiment of the present invention or claim must not reach disclosed whole objects or advantage or feature in addition.In addition, summary part and title are only for the use of auxiliary patent document search, are not used for limiting claim protection range of the present invention.
Claims (12)
1. a secondary side synchronous rectifier controller, in order to control at least one synchronous rectification switch, is characterized in that, this secondary side synchronous rectifier controller comprises:
One sawtooth generator, receives a synchronizing signal, to produce a sawtooth signal;
One peak sample unit, capture a crest voltage of this sawtooth signal, produce according to this prediction reference voltage signal that a voltage progressively successively decreases, this peak sample unit comprises: one keeps electric capacity, a releasing member, a reference bias source and a peak sample circuit, wherein:
This reference bias source, is connected between the input of this sawtooth generator and this peak sample circuit;
One high-pressure side of this maintenance electric capacity is connected to the output of this peak sample circuit, in order to receive this sawtooth signal; And
This releasing member, is parallel to this maintenance electric capacity, in order to discharge the electric charge that is stored in this maintenance electric capacity;
Wherein, this high-pressure side of this maintenance electric capacity is exported this prediction reference voltage signal, and this reference bias source, in order to drag down a stored voltage of this maintenance electric capacity, makes the maximum of this stored voltage be less than this crest voltage of this sawtooth signal; And
One output control unit, there is a comparator and a cutoff switch, this comparator is the current potential of this sawtooth signal and this prediction reference voltage signal relatively, to produce a Dead Time control signal to control the conducting state of this cutoff switch, this output control unit is according to the conducting state of this synchronous rectification switch of conducting state control of this cutoff switch, when the current potential of this sawtooth signal is during higher than the current potential of this prediction reference voltage signal, this this cutoff switch of output control unit conducting also turn-offs this synchronous rectification switch accordingly.
2. secondary side synchronous rectifier controller as claimed in claim 1, is characterized in that, this sawtooth generator comprises:
One sawtooth waveforms produces electric capacity;
One charge power supply, produces capacitor charging to this sawtooth waveforms, to produce this sawtooth signal; And
One Resetting Switching, produces the stored electric charge of electric capacity to discharge this sawtooth waveforms, and this Resetting Switching is controlled by this synchronizing signal.
3. secondary side synchronous rectifier controller as claimed in claim 2, is characterized in that, this charge power supply is a constant current source or certain voltage source.
4. secondary side synchronous rectifier controller as claimed in claim 1, is characterized in that, this releasing member is a release impedance or a constant current source.
5. secondary side synchronous rectifier controller as claimed in claim 1, is characterized in that, this synchronizing signal is the output signal of a primary side winding.
6. secondary side synchronous rectifier controller as claimed in claim 1, is characterized in that, this output control unit, according to this dead band time control signal and this synchronizing signal, produces the conducting state of this synchronous rectification switch of synchronous rectification control signal control.
7. a power-switching circuit with secondary side synchronous rectifier function, is characterized in that, this power-switching circuit comprises:
One transformer, this transformer comprises a primary side winding and a primary side winding;
One synchronous rectification switch, is connected to this primary side winding;
One primary side synchronous rectifying controller, in order to control this synchronous rectification switch, this secondary side synchronous rectifier controller comprises:
One sawtooth generator, receives a synchronizing signal, to produce a sawtooth signal;
One peak sample unit, capture a crest voltage of this sawtooth signal, produce according to this prediction reference voltage signal that a voltage progressively successively decreases, this peak sample unit comprises: one keeps electric capacity, a releasing member, a reference bias source and a peak sample circuit, wherein:
This reference bias source, is connected between the input of this sawtooth generator and a peak sample circuit;
One high-pressure side of this maintenance electric capacity is connected to the output of this peak sample circuit, in order to receive this sawtooth signal; And
This releasing member, is parallel to this maintenance electric capacity, in order to discharge the electric charge that is stored in this maintenance electric capacity;
Wherein, this high-pressure side of this maintenance electric capacity is exported this prediction reference voltage signal, and this reference bias source, in order to drag down a stored voltage of this maintenance electric capacity, makes the maximum of this stored voltage be less than this crest voltage of this sawtooth signal; And
One output control unit, there is a comparator and a cutoff switch, this comparator is the current potential of this sawtooth signal and this prediction reference voltage signal relatively, to produce a Dead Time control signal to control the conducting state of this cutoff switch, this output control unit basis
The conducting state of this synchronous rectification switch of conducting state control of this cutoff switch, when this saw
The current potential of tooth ripple signal is during higher than the current potential of this prediction reference voltage signal, this output control
This cutoff switch of cell conduction also turn-offs this synchronous rectification switch accordingly.
8. power-switching circuit as claimed in claim 7, is characterized in that, this sawtooth generator comprises:
One sawtooth waveforms produces electric capacity;
One charge power supply, produces capacitor charging to this sawtooth waveforms, to produce this sawtooth signal; And
One Resetting Switching, produces the stored electric charge of electric capacity to discharge this sawtooth waveforms, and this Resetting Switching is controlled by this synchronizing signal.
9. power-switching circuit as claimed in claim 8, is characterized in that, this charge power supply is a constant current source or certain voltage source.
10. power-switching circuit as claimed in claim 7, is characterized in that, this releasing member is a release impedance or a constant current source.
11. power-switching circuits as claimed in claim 7, is characterized in that, this secondary side synchronous rectifier controller comprises a power input, and this power input is connected to the auxiliary winding of a primary side.
12. power-switching circuits as claimed in claim 7, is characterized in that, this synchronizing signal is an output signal of this primary side winding.
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| TWI569562B (en) * | 2015-11-16 | 2017-02-01 | 通嘉科技股份有限公司 | Method for controlling a dead time of a secondary side of a power converter |
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| CN102723856B (en) * | 2012-07-02 | 2014-06-25 | 矽力杰半导体技术(杭州)有限公司 | Synchronous rectifier control circuit and switch power supply employing same |
| CN105529799B (en) * | 2014-09-28 | 2018-12-21 | 比亚迪股份有限公司 | Charging system and its secondary control device based on secondary control |
| CN105529791B (en) * | 2014-09-28 | 2018-06-22 | 比亚迪股份有限公司 | Charging system and its secondary control device based on secondary control |
| US10008947B2 (en) * | 2015-07-31 | 2018-06-26 | Texas Instruments Incorporated | Flyback converter with secondary side regulation |
| CN106533207B (en) * | 2015-09-15 | 2019-02-05 | 通嘉科技股份有限公司 | Synchronous rectifier and its operating method applied to power adapter |
| CN106817017B (en) * | 2015-11-30 | 2019-10-18 | 通嘉科技股份有限公司 | The method for controlling the secondary side idle time of power adapter |
| CN105471286B (en) * | 2015-12-10 | 2017-09-29 | 无锡华润矽科微电子有限公司 | Circuit of synchronous rectification, wireless charging system and synchronous rectification method |
| CN108233450A (en) * | 2016-12-19 | 2018-06-29 | 中惠创智（深圳）无线供电技术有限公司 | A kind of resonance type wireless electric power system and its circuit of synchronous rectification |
| US10199919B2 (en) * | 2017-05-03 | 2019-02-05 | Microchip Technology Inc. | Zero dead time control circuit |
| CN112205078B (en) * | 2018-05-28 | 2024-01-26 | 侯经权 | Universal dimmer |
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| US4945292A (en) * | 1988-08-08 | 1990-07-31 | Unisys Corp. | Dynamic vertical height control circuit |
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| JP4438879B2 (en) * | 2008-03-19 | 2010-03-24 | Ｔｄｋ株式会社 | Synchronous rectification type DC / DC converter |
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| US4945292A (en) * | 1988-08-08 | 1990-07-31 | Unisys Corp. | Dynamic vertical height control circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI569562B (en) * | 2015-11-16 | 2017-02-01 | 通嘉科技股份有限公司 | Method for controlling a dead time of a secondary side of a power converter |
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