CN201839205U - Isolation conversion circuit - Google Patents
Isolation conversion circuit Download PDFInfo
- Publication number
- CN201839205U CN201839205U CN2010201316422U CN201020131642U CN201839205U CN 201839205 U CN201839205 U CN 201839205U CN 2010201316422 U CN2010201316422 U CN 2010201316422U CN 201020131642 U CN201020131642 U CN 201020131642U CN 201839205 U CN201839205 U CN 201839205U
- Authority
- CN
- China
- Prior art keywords
- input
- signal
- circuit
- output
- coupled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000002955 isolation Methods 0.000 title abstract description 7
- 238000006243 chemical reaction Methods 0.000 title abstract description 4
- 238000004804 winding Methods 0.000 claims abstract description 83
- 238000004146 energy storage Methods 0.000 claims abstract description 6
- 238000005070 sampling Methods 0.000 claims description 41
- 230000003321 amplification Effects 0.000 claims description 25
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 25
- 238000001514 detection method Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 abstract description 10
- 230000002093 peripheral effect Effects 0.000 abstract description 4
- 238000010168 coupling process Methods 0.000 description 7
- 238000005859 coupling reaction Methods 0.000 description 7
- 230000008878 coupling Effects 0.000 description 6
- TVZRAEYQIKYCPH-UHFFFAOYSA-N 3-(trimethylsilyl)propane-1-sulfonic acid Chemical compound C[Si](C)(C)CCCS(O)(=O)=O TVZRAEYQIKYCPH-UHFFFAOYSA-N 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000013507 mapping Methods 0.000 description 4
- 238000013519 translation Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 101100537098 Mus musculus Alyref gene Proteins 0.000 description 1
- 101150095908 apex1 gene Proteins 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007634 remodeling Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Landscapes
- Dc-Dc Converters (AREA)
Abstract
The utility model discloses an isolation converting circuit for carry out the isolation transform of former limit control. The method comprises the following steps: the circuit comprises an energy storage element of a primary winding and a secondary winding, wherein the primary winding receives an input signal; a switch having a first terminal, a second terminal, and a third terminal, wherein the first terminal is coupled to the primary winding; the feedback circuit is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are connected with the primary winding in parallel; the control unit is provided with a first input end, a second input end and an output end, wherein the first input end is directly or indirectly connected with the third end of the switch, and the second input end is connected with the output end of the feedback circuit; and the input end of the driving circuit is connected to the output end of the control unit, and the output end of the driving circuit is connected to the third end of the switch. The isolation conversion circuit does not need an auxiliary winding, and realizes the control of the output end through primary side feedback, thereby simplifying a peripheral circuit.
Description
Technical field
The utility model relates to the isolated variable circuit, and more particularly, the utility model relates to the isolated variable circuit of former limit control.
Background technology
Along with the raising of development of electronic technology and environmental requirement, efficient and stability become the vital design factor of voltage changer.
Isolated voltage changer can be used for adapter and the charger high to security requirement, and it comprises former limit circuit and secondary circuit, passes through transformer isolation.In application, the course of work comprises a constant current charge control procedure and a constant voltage control procedure, and output voltage and output current relation are seen Fig. 1.In the B interval, load is charged, work as output voltage V
OLess than output voltage threshold value V
ThThe time, converter keeps output current Io at output current higher limit I
ThNear constant and make output voltage V
OChange, make fast and stable output voltage V
OBe charged to voltage threshold V
Th, the control in B interval is constant current control.In the A interval, work as output voltage V
OArrive output voltage threshold value V
ThThe time, converter is in normal operating conditions, keeps output voltage V this moment
OConstant to provide stabilized power supply to load, simultaneously output current Io is regulated.For realizing the constant current regulating and controlling, need to detect output end current, according to the work of the former limit of the FEEDBACK CONTROL of output signal switching tube.Usually, adopt the secondary current testing circuit to be used for constant current control, obtain signal from secondary, but this mode complex structure, loss is big, efficient is low by optocoupler.
Therefore, in the isolated variable circuit, the control of former limit has obtained extensive use owing to do not need optocoupler and secondary control.Be illustrated in figure 2 as the isolated variable circuit 50 of existing former limit control, it is by the auxiliary winding T of transformer T
2With divider resistance R
1, R
2Come the output voltage V of feedback isolation translation circuit 50
OYet this isolated variable circuit 50 needs an auxiliary winding in order to the feedback output voltage, and this makes that the peripheral circuit of isolated variable circuit is still complicated.
Therefore having needs to propose a kind ofly to need not auxiliary winding and can realize the isolated variable circuit that feeds back, so that peripheral circuit becomes simple, and further reduces cost.
Summary of the invention
The purpose of this utility model is to solve prior art and need assists winding to realize feedback, thereby makes the complicated problem of circuit structure.
Based on above-mentioned purpose, the utility model proposes a kind of isolated variable circuit, it is characterized in that, comprising: comprise the energy-storage travelling wave tube of former limit winding and secondary winding, described former limit winding receiving inputted signal; Switch possesses first end, second end and the 3rd end, and wherein first end and described former limit winding couple; Feedback circuit possesses first input end and second input and output, and wherein the first input end and second input are in parallel with described former limit winding; Control unit possesses first input end, second input and output, and wherein first input end connects directly or indirectly and is connected with the 3rd end of described switch, and second input is connected with the output of described feedback circuit; Drive circuit, its input is connected to the output of described control unit, and its output is connected to the 3rd end of described switch.
According to embodiment of the present utility model, described isolated variable circuit also comprises: current sampling circuit is coupled between the first input end of second end of described switch and described control unit.
According to embodiment of the present utility model, described control unit comprises: the switching frequency control unit, and its input receives described feedback signal as second input of described control unit, and its output provides the switching frequency control signal; Peak current control unit, its input receive the electric current and the peak current reference signal of described detection as the first input end of described control unit, and its output provides the peak current control signal; Logical block, two input are connected respectively to the output of described switching frequency control unit and the output of described peak current control unit, and its output is connected to the input of described drive circuit.
According to embodiment of the present utility model, described feedback circuit comprises: input resistance, have two terminals, and its first terminal is coupled to described input, to receive the voltage signal of described former limit winding first end; Feedback resistance has two terminals, and its first terminal is coupled to described former limit winding, to receive the voltage signal of described former limit winding second end; Subtracter has two inputs, and its first input end is coupled to second terminal of described feedback resistance, and its second input is coupled to second terminal of described input resistance, so that described feedback signal to be provided.
According to embodiment of the present utility model, described feedback circuit comprises: input resistance, have two terminals, and its first terminal is coupled to described input, to receive the voltage signal of described former limit winding first end; Feedback resistance has two terminals, and its first terminal is coupled to described former limit winding, to receive the voltage signal of described former limit winding second end; First current sampling unit, input are coupled to second terminal of described feedback resistance, so that first sampled signal to be provided; Second current sampling unit, input are coupled to second terminal of described input resistance, so that second sampled signal to be provided; Subtracter according to described first sampled signal and described second sampled signal, provides described feedback signal.
According to embodiment of the present utility model, described feedback circuit also comprises selected cell, and its control end receives described switching signal, according to described switching signal, second end of described input resistance optionally is coupled to second input of described subtracter.
According to embodiment of the present utility model, described feedback circuit also comprises selected cell, and its control end receives described switching signal, according to described switching signal, second end of described input resistance optionally is coupled to the input of described second current sampling unit.
According to embodiment of the present utility model, described peak current control unit is a peak current comparator, its in-phase input end receives the sample rate current that flows through described switch, and its inverting input receives described peak current reference signal, and its output provides described peak current control signal.
According to embodiment of the present utility model, described peak current control unit comprises: peak current reference signal given circuit, the input of described selected cell receives described switching signal, optionally the input of described peak current reference signal given circuit is coupled to second end of described input resistance according to described switching signal, the output of described peak current reference signal given circuit provides the peak current reference signal; The peak current comparator, its input receives the electric current of described peak current reference signal and described detection, and described peak current control signal is provided.
According to embodiment of the present utility model, described peak current reference signal given circuit comprises: current source is coupled in another input of described peak current comparator and former limit with reference between the ground; The 3rd resistance is with described current source coupled in parallel; Current mirroring circuit is with described current source coupled in parallel; The input of described current mirroring circuit is second input of peak current control unit.
According to embodiment of the present utility model, described selected cell is a selector switch, and when described switching signal was low level, described selector switch was coupled to second end of input resistance the input of described peak current reference signal given circuit.
According to embodiment of the present utility model, described selected cell comprises: first connects switch, is coupled between second input of second terminal of described input resistance and described subtracter; Second connects switch, is coupled between the input of second terminal of described input resistance and described peak current reference signal given circuit; Described first connects switch is connected switch by described switching signal control conducting and disconnection with described second.
According to embodiment of the present utility model, the described first connection switch is the high level conducting; The described second connection switch is the low level conducting.
According to embodiment of the present utility model, described switching frequency control unit comprises oscillator, and its input receives described feedback signal, and its output provides described switching frequency control signal.
According to embodiment of the present utility model, described switching frequency control unit comprises: error amplifier, and its input receives described feedback signal and reference signal, and its output provides error amplification signal; Compensating circuit is coupled between the inverting input and output of described error amplifier; Oscillator, its input receives described error amplification signal, and its output provides described switching frequency control signal.
According to embodiment of the present utility model, described switching frequency control unit comprises: the threshold value comparator, and its input receives described feedback signal and reference signal, and its output provides the threshold value comparison signal; Error amplifier, its input receive described feedback signal and described reference signal, and its output provides error amplification signal; Compensating circuit is coupled between the inverting input and output of described error amplifier; First switch, its first termination is received described feedback signal, and its second end is coupled to the first input end of oscillator; Be switched on and disconnect according to described threshold value comparison signal; Second switch, its first termination is received described error amplification signal, and its second end is coupled to second input of described oscillator, is switched on and disconnects according to described threshold value comparison signal; Oscillator, its input receive described threshold value comparison signal, selectively receive described feedback signal or described error amplification signal according to described threshold value comparison signal; Its output provides described switching frequency control signal.
According to embodiment of the present utility model, when described threshold value comparison signal when being high, described first switch is closed conducting, and described second switch is disconnected; Described oscillator provides described switching frequency control signal according to described feedback signal; When described threshold value comparison signal when low, described first switch is disconnected, described second switch is closed conducting; Described oscillator provides described switching frequency control signal according to described error amplification signal.
According to embodiment of the present utility model, described switching frequency control unit further comprises: error amplifier, and its input receives described feedback signal and reference signal, and its output provides error amplification signal; Compensating circuit is coupled between the inverting input and output of described error amplifier; Minimum value selector, its first input end receives described feedback signal; Its second input receives described error amplification signal; Oscillator, its input receives the output signal of described minimum value selector, and its output provides the switching frequency control signal.
The foregoing circuit that the utility model proposes need not auxiliary winding, at the output voltage of the former limit of transformer feedback isolation translation circuit, realizes the control to output, thereby peripheral circuit is simplified the structure.
Description of drawings
Fig. 1 is isolated voltage changer working state schematic representation.
Fig. 2 is the isolated variable circuit 50 of existing former limit control.
Fig. 3 illustrates the isolated variable circuit 100 according to an embodiment of the utility model.
Fig. 4 illustrates the isolated variable circuit 200 according to another embodiment of the utility model.
Fig. 5 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 31 0.
Fig. 6 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 32 0.
Fig. 7 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 33 0.
Fig. 8 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 34 0.
Fig. 9 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 35 0.
Figure 10 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 36 0.
Figure 11 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 37 0.
Figure 12 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 38 0.
Figure 13 illustrates the main switch peak current and input relation of isolated variable circuit 200 shown in Figure 4.
Figure 14 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 41 0.
Figure 15 illustrates the control circuit IC of isolated variable circuit shown in Figure 4
1Inside physical circuit Figure 42 0.
Embodiment
To describe specific embodiment of the utility model in detail below.Should be noted that the embodiments described herein only is used to illustrate, be not limited to the utility model.
Based on the consideration of specification description and easy-to-read, it is as follows to define the term that occurs in the utility model patent application document one by one: the isolated variable circuit in the utility model comprises the converter of DC-to-DC inverse excitation type converter, AC-DC inverse excitation type converter or other type.Need to prove that above-mentioned term is only as censuring one of its title that means, therefore allly mean the title identical or approximate and all should be considered as its equivalent with it.
As Fig. 3, for according to isolated variable circuit 100 of the present utility model.This embodiment is used for the AC-DC translation circuit.But those skilled in the art should be appreciated that the isolated variable circuit and can be used for other circuit, as the DC-DC translation circuit.
Isolated variable circuit 100 comprises that one receives ac input signal V
INRectifier bridge, with the input capacitance C of described rectifier bridge coupled in parallel
IN, a transformer T(comprises former limit winding T
0With secondary winding T
1, those skilled in the art will appreciate that transformer T is energy-storage travelling wave tube that can storage power), main switch M, diode D
1, output capacitance C
O, switching frequency control unit 101, peak current control unit 102, feedback circuit 103, current sampling circuit 104, logical circuit 105 and drive circuit 106.
Rectifier bridge is with input signal V
INRectification is direct current signal V
DCThe former limit winding T of transformer T
0, main switch M, diode D
1, transformer T secondary winding T
1And output capacitance C
OCoupling mode constitute that the typical case is anti-to swash topology.Its coupling mode is those skilled in the art's a well-known way, no longer describes in detail here.Main switch M can be any controllable semiconductor switch device, for example mos field effect transistor (MOSFET), igbt (IGBT) etc.Output capacitance C
OThe voltage at two ends is the output voltage V of isolated variable circuit 100
OThose skilled in the art will appreciate that diode D among this embodiment
1Can replace by synchronous rectifier.Current sampling circuit 104 is coupled to main switch M, and sample streams is crossed the electric current of main switch M, and produces a current sampling signal I who represents this electric current
Sense, i.e. I
SenseFor flowing through the sample rate current of main switch M.Current sampling circuit 104 can be resistance sampling circuit, transformer sample circuit, current amplifier sample circuit etc.Feedback circuit 103 is coupled to former limit winding T
0With the output (if isolated variable circuit 100 does not contain rectifier bridge, then feedback circuit couples 103 inputs to isolated variable circuit 100) of rectifier bridge, in order to produce the feedback signal S of reflection isolated variable circuit 100 output signals
FBThe input of switching frequency control unit 101 is coupled to the output of feedback circuit 103, in order to receiving feedback signals S
FB, and according to feedback signal S
FBProduce switching frequency control signal f
CTRIn one embodiment, feedback signal S
FBAmplitude big more, switching frequency control signal f
CTRFrequency F
SBig more.An input of peak current control unit 102 is coupled to the output of current sampling circuit 104, in order to receive sample rate current I
SenseIts another input receives peak current reference signal V
LimitAnd according to sample rate current I
SenseWith peak current reference signal V
LimitOutput peak current control signal I
CTRAn input receiving key frequency control signal f of logical circuit 105
CTR, another input receives peak current control signal I
CTR, and according to switching frequency control signal f
CTRWith peak current control signal I
CTR, switching signal is provided.Drive circuit 106 receiving key signals provide drive signal, in order to the switching signal of control main switch M conducting and disconnection.In one embodiment, peak current control unit 102 is comparator or operational amplifier, and logical circuit 105 is rest-set flip-flop or gate circuit combination.
Can see that isolated variable circuit 100 need not auxiliary winding feedback signal is provided, its feedback circuit 103 is coupled in the former limit winding T of transformer
0Its control circuit provides switching signal based on feedback signal and the current signal that flows through main switch M, in order to conducting and the disconnection of control main switch M, and then the output of control isolated variable circuit 100.
Figure 4 shows that isolated variable circuit 200 according to another embodiment of the utility model.Isolated variable circuit 200 adopts identical Reference numeral with the same section of isolated variable circuit 100 shown in Figure 3.Be that isolated variable circuit 200 comprises by rectifier bridge, coupled in parallel is at the input capacitance C at rectifier bridge two ends
IN, the direct current signal V after receiving ac input signal and exporting rectification
DCTransformer T(comprises former limit winding T
0With secondary winding T
1), main switch M(is set at control circuit IC
1Inner), transformer T stored energy when main switch M is switched on wherein, its energy is transferred into the output of isolated variable circuit when main switch M is disconnected; Be coupled in secondary winding T
1Diode D
1With output capacitance C
OAnd control circuit IC
1Control circuit IC
1Concrete internal structure will be shown in Fig. 5 ~ Figure 12.
Isolated variable circuit 200 also comprises and is coupled in rectification bridge output end and control circuit IC
1The 4th pin (input pin) V
SBetween input resistance R
DC, be coupled in control circuit IC
1Feedback resistance R between the three-prong D and second pin (feedback pin) FB
0, be coupled in the current sampling circuit 104 between control circuit the 5th pin S and the 6th pin GND, be coupled in control circuit first pin (power pin) V
CCAnd former limit is with reference to the self-powered capacitor C between the ground
1In the present embodiment, current sampling circuit 104 is a sampling resistor R
SFrom following description, can see, in the present embodiment, sampling resistor R
SWith main switch M coupled in series.
The former limit winding T of transformer T
0An end be coupled to the output of rectifier bridge, receive direct current signal V
DC, its other end is coupled to control circuit IC
1Three-prong D.The secondary winding T of transformer T
1With diode D
1After the coupled in series with output capacitance C
OCoupled in parallel, output capacitance C
OBoth end voltage is the output voltage V of isolated variable circuit 100
O
Figure 5 shows that control circuit IC according to the isolated variable circuit 200 of an embodiment of the utility model
1Inside physical circuit 210.
As shown in Figure 5, circuit 210 comprises:
(1) main switch M is coupled in control circuit IC
1Three-prong D and the 5th pin S between, and then the former limit winding T by transformer T
0Be coupled to input with rectifier bridge.When main switch M conducting, input signal V
INThrough rectifier bridge, former limit winding T
0, main switch M and sampling resistor R
STo ground, former limit winding T
0Stored energy, sampling resistor R
SThe both end voltage signal can reflect the sample rate current that flows through main switch M; When main switch M disconnects, input signal V
INAnd output voltage V
OAt former limit winding T
0Mapping signal n * V
OThrough former limit winding T
0, feedback resistance R
0Be sent to control circuit IC
1The second pin FB, be stored in former limit winding T simultaneously
0Energy be transferred into the output of isolated variable circuit 100, wherein n is the turn ratio of transformer T former limit winding and secondary winding.Those skilled in the art will appreciate that sampling resistor R here
SCan not adopt, and realize current sample by self conducting resistance of main switch M for example.
(2) subtracter U
3, its first input end is coupled to control circuit IC
1The second pin FB, with receiving inputted signal V
INWith mapping signal n * V
O, its second input is coupled to control circuit IC
1The 4th pin V
S, its output provides feedback signal S
FBCan see subtracter U from following description
3The difference signal of output is a feedback signal.Feedback circuit according to present embodiment comprises subtracter U
3, feedback resistance Ro, input resistance R
DC
(3) the switching frequency control unit 101, and its input receives the feedback signal S of feedback circuit output
FB, with according to feedback signal S
FBOutput switching frequency control signal f
CTRIn the present embodiment, switching frequency control unit 101 comprises oscillator OSC, according to subtracter U
3The feedback signal S of output
FB, output switching frequency control signal f
CTR
(4) the peak current control unit 102, its first input end (i.e. second comparator U
2In-phase input end) be coupled to the 5th pin S, flow through the sample rate current of main switch M with reception, its second input receives peak current reference signal V
LimitAnd according to sample rate current and peak current reference signal V
LimitThe peak current control signal I of main switch M peak current is crossed in output in order to control flows
CTRIn the present embodiment, peak current control unit 102 is comparator U
2
(5) logical circuit 105, receiving key frequency control signal f
CTRWith peak current control signal I
CTR, according to switching frequency control signal f
CTRWith peak current control signal I
CTROutput switching signal.In the present embodiment, logical circuit 105 is rest-set flip-flop U
0, its reset terminal R receives described peak current control signal I
CTR, set end S receiving key frequency control signal f
CTRIt is according to peak current control signal I
CTRBe reset, according to switching frequency control signal f
CTRBe set.
(6) drive circuit 106, the switching signal of receive logic circuit 105 outputs, and output drive signal is in order to the conducting of control main switch M and the switching signal of disconnection.
For avoiding output overvoltage, the self-powered deficiency, in the present embodiment, circuit 210 also comprises overvoltage crowbar OVP and self-powered comparator U
4, and with door U
1Overvoltage crowbar OVP receives subtracter U
3The feedback signal S of output
FB, the output over-voltage protection signal to door U
1Second input; Self-powered comparator U
4In-phase input end be received from the power supply capacitor C
1The voltage at two ends, inverting input receive the first reference signal V
Ref1, output comparison signal to door U
1The 3rd input.This first reference signal V
Ref1Than hysteresis loop comparator U
5Stagnant ring lower limit low.For example in one embodiment, hysteresis loop comparator U
5Stagnant ring lower limit get 8V, the first reference signal V
Ref1Get 7.8V.With door U
1The 3rd input be coupled to latch U
0Output is with door U
1Output be coupled to main switch M gate pole.
As can be seen from Figure 5, circuit 210 also comprises controlled current source DSS and hysteresis loop comparator U
5Wherein controlled current source DSS is coupled in power pin V
CCWith former limit winding T
0Between, its control end is coupled to hysteresis loop comparator U
5Output.Hysteresis loop comparator U
5In-phase input end be coupled to the self-powered capacitor C
1, inverting input receives the second reference signal V
Ref2One skilled in the art would recognize that when controlled current source DSS is used to provide isolated variable circuit 100 to start being coupled to control circuit IC
1The first pin V
CCThe self-powered capacitor C
1Charging.When the self-powered capacitor C
1When being charged to required voltage (100 startups of isolated variable circuit are finished), hysteresis loop comparator U
5Turn-off current source DSS is to its charging; When its both end voltage less than control circuit IC
1During inner required supply power voltage, hysteresis loop comparator U
5Again firing current source DSS.
In one embodiment, circuit 210 also comprises two pulse front edge blanking L.E.B(Lead Edge Blanking) module.One of them L.E.B module is coupled to the second pin FB, and another L.E.B module is coupled to the 5th pin S, and the effect of two L.E.B modules is and suppresses the rub-out signal that secondary diode reverse recovery and parasitic parameter vibration cause.Those skilled in the art will appreciate that in the utility model, two L.E.B modules all can be omitted.Control circuit IC
1The 6th pin meet former limit winding T
0Reference ground.
In the present embodiment, main switch M is set at control circuit IC
1Inside, control circuit IC
1Flow through sample rate current and the feedback signal of main switch M by reception, produce switching signal, via behind the drive circuit in order to conducting and the disconnection of control main switch M, and then the output of control isolated variable circuit 200.
During isolated variable circuit 200 normal operations, when oscillator OSC exports high level signal to rest-set flip-flop U
0Set end S, rest-set flip-flop U
0Output signal Q uprise, via with door U
1After, main switch M is switched on, former limit winding T
0The beginning stored energy.This moment input signal V
INVia rectifier bridge, former limit winding T
0, main switch M, sampling resistor R
STo ground.The electric current that flows through main switch M increases gradually, makes sampling resistor R when it increases to
SThe voltage at two ends is greater than peak current reference signal V
LimitThe time, peak current comparator U
2Output uprises, and then the rest-set flip-flop U that resets
0Output Q, via with door U
1After, main switch M is disconnected.Be stored in former limit winding T this moment
0Energy be transferred into secondary winding T
1Isolated variable circuit 200 is normally in service, at switching frequency control unit 101 places, subtracter U
3First input end by feedback resistance R
0Receiving inputted signal V
INWith output voltage V
OAt former limit winding T
0Mapping voltage sum, that is:
Wherein n is former limit winding T
0With secondary winding T
1Turn ratio; Subtracter U
3Second input by rectifier bridge and input resistance R
DCReceiving inputted signal V
IN, that is:
If feedback resistance R
0With input resistance R
DCGet identical resistance value, i.e. R
DC=R
0=R, then subtracter is output as
It is the output voltage V that the output of subtracter is proportional to isolated variable circuit 100
O, feedback resistance R
0, input resistance R
DCAnd subtracter U
3This coupling mode feedback signal S is provided
FBIsolated variable circuit 200 need not auxiliary winding and has promptly realized the control of former limit.More particularly, the feedback circuit of isolated variable circuit 200 is positioned at the former limit winding T of energy-storage travelling wave tube (transformer T)
0, the output voltage V of the isolated variable circuit 200 of sampling
O, output feedback signal is to control circuit IC
1
If feedback resistance R
0With input resistance R
DCGet different resistance values, also can be at subtracter U
3Two inputs before the first current sampling unit U is set
6With the second current sampling unit U
7, control circuit IC as shown in Figure 6
1Inside physical circuit Figure 32 0.
Control circuit IC shown in Figure 6
1Other parts of inside physical circuit Figure 32 0 identical with circuit shown in Figure 5 210, adopt identical Reference numeral, simple and clear for narrating, the circuit coupling mode of both same sections no longer is described in detail in detail here.The coefficient of two current sampling units is k, and two current sampling units transfer voltage signal to current signal.Subtracter U
3First input end by feedback resistance R
0And the first current sampling unit U
6Receiving inputted signal V
INWith output voltage V
OAt former limit winding T
0Mapping voltage n * V
OSum; Second input is by input resistance R
DCAnd the second current sampling unit U
7Receiving inputted signal V
IN, then
Therefore, subtracter U
3The difference signal of output
Be the output S of subtracter
FBBe proportional to the output voltage V of isolated variable circuit 100
OFeedback resistance R
0, input resistance R
DC, the first current sampling unit U
6, the second current sampling unit U
7With subtracter U
3This coupling mode feedback signal is provided.Isolated variable circuit 200 need not auxiliary winding and has promptly realized the winding control of former limit.More particularly, the feedback circuit of isolated variable circuit 200 is positioned at the former limit winding T of energy-storage travelling wave tube (transformer T)
0, the output voltage V of the isolated variable circuit 200 of sampling
O, output feedback signal is to control circuit IC
1
Output voltage V when isolated variable circuit 200
ODo not reach output threshold voltage V
ThThe time, promptly isolated variable circuit 200 need be operated in the constant current charge control procedure.If output voltage V
OIncrease subtracter U
3Output S
FBCorresponding increase, then the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SAlso corresponding increase.
At this moment, if the isolated variable circuit working is under discontinuous mode, according to law of conservation of energy, the former limit of transformer winding T
0With secondary winding T
1The both sides energy is equal, that is:
Wherein η is the conversion efficiency of isolated variable circuit 100, and L is the former limit of transformer winding T
0The inductance value of magnetizing inductance, i
PeakCurrent peak for the main switch M that flows through.
For a definite system, η, L and i
PeakAll fixing.Owing to output voltage V this moment
OIncrease the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SAlso corresponding increase, so output current I
OKeep constant.Otherwise, work as output voltage V
ODuring step-down, the switching frequency control signal f of oscillator OSC output then
CTRFrequency F
SAlso corresponding reducing, so output current I
OStill keep constant.
If isolated variable circuit 200 is operated under the continuous mode, according to law of conservation of energy, then:
Wherein η is the conversion efficiency of isolated variable circuit 200, and L is the former limit of transformer winding T
0The inductance value of magnetizing inductance, i
PeakBe the current peak of the main switch M that flows through, i
InitialFlow through when just having been opened initial current on it for main switch M in one-period.
For a definite system, η, L and i
Peak, i
InitialAll fixing.Work as output voltage V
OIncrease, then the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SAlso corresponding increase, so output current I
OKeep constant.Otherwise, work as output voltage V
OWhen reducing, the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SAlso corresponding reducing, so output current I
OKeep constant.Therefore, inner physical circuit figure is that the isolated variable circuit 200 of circuit 210 and circuit 220 need not auxiliary winding, has realized the constant current control of output by former limit feedback.
If the inside physical circuit figure of isolated variable circuit 200 is made further modification, as shown in Figure 7, with the feedback signal S of feedback circuit output in the switching frequency control unit 101
FBDirectly be not delivered to oscillator OSC, and its output is coupled to the input of error amplifying stage, the output of error amplifying stage is coupled to oscillator OSC.Specifically, the output of feedback circuit is coupled to operational amplifier U
AInverting input.Operational amplifier U
AIn-phase input end receive reference signal R
Ef, the error amplification signal CMP of operational amplifier output is transported to the input of oscillator OSC.And at operational amplifier U
AOutput and inverting input between be coupled with compensating circuit Z
CBe that the error amplifying stage comprises error amplifier U
AWith compensating circuit Z
COther parts of circuit 230 shown in Figure 7 are identical with circuit 210 shown in Figure 5.Easy for narrating, its circuit structure no longer is described in detail in detail here.
Output voltage V when isolated variable circuit 200
OReach its output threshold voltage V
Th, isolated variable circuit 200 need be operated in the constant voltage control procedure.Because operational amplifier U
AEffect, feedback signal S
FBClamped at operational amplifier U
AIn-phase input end reference signal R
EfPotential value.Those skilled in the art will appreciate that reference signal R
EfPotential value and output threshold voltage V
ThCorresponding.Therefore, the output voltage V of isolated variable circuit 200
OBe maintained at output threshold voltage V
ThConstant.If output voltage V
OInstantaneous increase is because of error amplifier U
AEffect, output voltage V
OTo be maintained at output threshold voltage V
ThConstant.And because of error amplifier U
AThe negative feedback coupling mode, along with output voltage V
OInstantaneous increase, error amplification signal CMP reduces.Correspondingly, the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SReduce.According to law of conservation of energy, that is:
By by-pass cock frequency control signal f
CTRFrequency F
S, output voltage V then
OReduce.Thereby output voltage V
OBe Controlled is stabilized in output threshold voltage V
ThThe place realizes the constant control to output.Otherwise, if output voltage V
OInstantaneous reducing, then switching frequency control signal f
CTRFrequency F
SIncrease.According to law of conservation of energy, that is:
By by-pass cock frequency control signal f
CTRFrequency F
S, output voltage V then
OIncrease.Thereby output voltage V
OBe Controlled is stabilized in output threshold voltage V
ThThe place realizes the constant control to output.Therefore, the isolated variable circuit 200 that inner physical circuit figure is a circuit 230 need not auxiliary winding, has realized the constant voltage control of output by former limit feedback.
Figure 8 shows that the another cut-away view 340 of isolated variable circuit 200.Circuit 240 is similar with circuit 230.Different with circuit 230 is that the feedback circuit of circuit 240 comprises the first current sampling unit U of circuit 220 shown in Figure 6
6With the second current sampling unit U
7Be that circuit 240 is at the error amplifier U that has added circuit 230
AWith compensating circuit Z
CThe circuit structure basis on, also added the first current sampling unit U of circuit 220 at feedback circuit
6With the second current sampling unit U
7Its circuit working principle is identical with circuit 210, all makes isolated variable circuit 200 need not auxiliary winding, realizes the constant voltage control of output by former limit feedback.Easy for narrating, its work no longer is described in detail in detail here.
If with circuit 210 shown in Figure 5 and circuit shown in Figure 7 230 in conjunction with and make suitable modification, can obtain isolated variable circuit 200 concrete cut-away views circuit 250 as shown in Figure 9.Specifically, circuit 250 is at switching frequency control unit 101 places, and the output of feedback circuit is via first switch S
1Be coupled to the first input end of oscillator OSC.Be subtracter U
3Output be coupled to first switch S
1An end, first switch S
1The other end be coupled to the first input end of oscillator OSC.Simultaneously, the feedback signal S of feedback circuit output
FBBe delivered to threshold value comparator U respectively
CWith operational amplifier U
AInverting input.Threshold value comparator U
CIn-phase input end and operational amplifier U
AIn-phase input end receive reference signal R
EfOperational amplifier U
AOutput be coupled to second switch S
2An end, second switch S
2The other end be coupled to second input of oscillator OSC.Threshold value comparator U
COutput be coupled to first switch S
1With second switch S
2Control end.And as threshold value comparator U
CWhen the threshold value comparison signal of output is high, first switch S
1Closed conducting, second switch S
2Disconnect; As threshold value comparator U
CWhen the threshold value comparison signal of output is low, first switch S
1Disconnect second switch S
2Closed conducting.Further, operational amplifier U
AOutput and inverting input between also be coupled with compensating circuit Z
C
As previously mentioned, when the output voltage V of isolated variable circuit 200
ODo not reach its output threshold voltage V
Th, isolated variable circuit 200 need be operated in the constant current charge control procedure.This moment threshold value comparator U
CBe output as height, this high level signal is with first switch S
1Closed conducting is with second switch S
2Disconnect, then operational amplifier U
AOutput signal inoperative to oscillator OSC, the feedback signal S of feedback circuit output
FBBe transported to oscillator OSC.At this moment, the operating state of circuit 250 is identical with circuit 210.That is, if output voltage V
OIncrease subtracter U
3Output I
CCorresponding increase, then the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SAlso corresponding increase.Therefore, isolated variable circuit 100 is satisfying law of conservation of energy, promptly satisfies equation
Or
Prerequisite under, its output current I
OKeep constant.Otherwise, if the output voltage V of isolated variable circuit 200
OReduce the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SAlso corresponding reducing, so its output current I
OKeep constant.
Output voltage V when isolated variable circuit 200
OReach output threshold voltage V
Th, promptly isolated variable circuit 200 need be operated in the constant voltage control procedure.Threshold value comparator U
CBe output as lowly, this low level signal is with first switch S
1Disconnect, with second switch S
2Closed conducting.Then this moment operational amplifier U
AThe error amplification signal CMP of output also is delivered to oscillator OSC.Because error amplifier U
AEffect, output voltage V
OBe maintained at its output threshold voltage V
ThThe place.If output voltage V
OInstantaneous increase, feedback signal S
FBCorresponding increase.Because operational amplifier U
AThe negative feedback coupling mode, operational amplifier U
AThe error amplification signal CMP of output reduces, correspondingly, and the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SReduce.
According to law of conservation of energy, that is:
By by-pass cock frequency control signal f
CTRFrequency F
S, output voltage V then
OReduce.Thereby output voltage V
OBe Controlled is stabilized in output threshold voltage V
ThThe place realizes the constant control to output.Otherwise, if output voltage V
OInstantaneous reducing, then switching frequency control signal f
CTRFrequency F
SIncrease.
According to law of conservation of energy, that is:
By by-pass cock frequency control signal f
CTRFrequency F
S, output voltage V then
OIncrease.Thereby output voltage V
OBe Controlled is stabilized in output threshold voltage V
ThThe place realizes the constant control to output.Therefore, the isolated variable circuit 200 that inner physical circuit figure is a circuit 250 need not auxiliary winding, has realized the constant current constant voltage control of output by former limit feedback.
Figure 10 shows that the another cut-away view 360 of isolated variable circuit 200.Circuit 260 is that with circuit 250 differences its feedback circuit comprises the first current sampling unit U of circuit 220 shown in Figure 6
6With the second current sampling unit U
7Be the combination of circuit 260 for circuit 250 and circuit 220.Its circuit working principle is identical with circuit 250, all makes isolated variable circuit 200 need not auxiliary winding, realizes the constant current constant voltage control of output by former limit feedback.Easy for narrating, its work no longer is described in detail in detail here.
If with circuit 210 shown in Figure 6 and circuit shown in Figure 8 230 in conjunction with and make suitable modification, can also obtain isolated variable circuit 200 concrete cut-away views circuit 270 as shown in figure 11.Specifically, at switching frequency control unit 101 places, subtracter U
3The feedback signal S of output
FBVia minimum value selector U
SELBe transported to the input of oscillator OSC, error amplifier U
AThe error amplification signal CMP of output also is transported to the input of oscillator OSC via minimum value selector.The output that is feedback circuit is coupled to minimum value selector U
SELFirst input end; The output of feedback circuit is coupled to the input of error amplifying stage simultaneously, and the output of error amplifying stage is coupled to second input of minimum value selector; Minimum value selector U
SELOutput be coupled to the input of oscillator OSC.
Output voltage V when isolated variable circuit 200
ODo not reach its output threshold voltage V
Th, isolated variable circuit 200 need be operated in the constant current charge process.Subtracter U then
3The feedback signal S of output
FBLess than reference signal R
EfThis moment feedback signal S
FBLess relatively, and error amplifier U
AThe error amplification signal CMP of output is relatively large.Therefore, minimum value selector U
SELBe output as feedback signal S
FBAs mentioned above, as if output voltage V this moment
OIncrease, then feedback signal S
FBIncrease the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SBecome big, make output current I
ORemain unchanged; If output voltage V
OReduce, then feedback signal S
FBReduce the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SReduce, make output current I
ORemain unchanged.Output voltage V when isolated variable circuit 200
OReach its output threshold voltage V
Th, isolated variable circuit 200 need be operated in the constant voltage control procedure.This moment feedback signal S
FBRelatively large, error amplification signal CMP is less relatively.Therefore, minimum value selector U
SELOutput signal be error amplification signal CMP.Because operational amplifier U
AEffect, feedback signal S
FBClamped at operational amplifier U
AIn-phase input end reference signal R
EfPotential value.Therefore, the output voltage V of isolated variable circuit 200
OBe maintained at output threshold voltage V
ThConstant.As mentioned above, if output voltage V
OInstantaneous increase, then error amplification signal CMP reduces, correspondingly, the switching frequency control signal f of oscillator OSC output
CTRFrequency F
SReduce.Otherwise, if output voltage V
OInstantaneous reducing, then switching frequency control signal f
CTRFrequency F
SIncrease.Thereby by by-pass cock frequency control signal f
CTRFrequency F
S, realized constant voltage control to output.Therefore, the isolated variable circuit 200 that inner physical circuit figure is a circuit 270 need not auxiliary winding, has realized the constant current constant voltage control of output by former limit feedback.
Figure 12 shows that another internal structure Figure 180 of isolated variable circuit 200.Circuit 280 is similar with circuit 270.Different with circuit 270 is that the feedback circuit of circuit 280 comprises the first current sampling unit U of circuit 220 shown in Figure 6
6With the second current sampling unit U
7Be the combination of circuit 180 for circuit 270 and circuit 220.Its circuit working principle is identical with circuit 270, all makes isolated variable circuit 200 need not auxiliary winding, realizes the constant current constant voltage control of output by former limit feedback.Easy for narrating, its work no longer is described in detail in detail here.
Feedback signal S
FBBe input to overvoltage crowbar OVP simultaneously, as the output V of isolated variable circuit 200
OWhen excessive, i.e. overvoltage condition, overvoltage crowbar OVP detects corresponding value of feedback I
CGreater than preset value.Therefore, overvoltage crowbar OVP output low level signal to door U
1Thereby, an invalid and door U
1Output, and then close main switch M, stop to secondary winding T
1Conveying capacity.Therefore, the second pin FB has realized the pin multiplexing function simultaneously.
Circuit is when operation, because a plurality of modules of signal demand process, this makes signal produce certain time-delay easily.For a given circuit, its delay time section is all fixed usually, uses T
DelayExpression.In isolated variable circuit 200, delayed time if be used to disconnect the switching signal of main switch M, then the ON time of main switch M is extended, and this may cause the overshoot of peak current.The magnitude of current of overshoot depends on current changing rate di/dt.According to:
V wherein
INBe input voltage, L
PBe former limit winding T
0Inductance value.
For given isolated variable circuit 200, because L
PValue is certain, input voltage V
INHigh more, then current changing rate di/dt is big more; Otherwise, input voltage V
INLow more, di/dt is more little for current changing rate.Therefore, for fixing delay time section T
Delay, as input voltage V
INWhen big more, current over pulse amount I is big more, as shown in figure 13: as input voltage V
INWhen big, V among corresponding Figure 13
IN_H, its current over pulse amount is I
HAs input voltage V
INHour, V among corresponding Figure 13
IN_L, its current over pulse amount is I
LCan see I
HI
LIn order to improve the influence that this because circuit internal delay time brings, the control circuit IC of another embodiment of the present utility model
1Cut-away view 400 as Fig. 6.The cut-away view 400 of control circuit IC1 shown in Figure 6 is that with the difference of aforementioned each structure chart it has added peak current reference signal given circuit to peak current reference signal V
LimitAdjust, and add a selected cell 106 at feedback circuit.
Specifically, in the present embodiment, peak current control unit 102 comprises: peak current comparator U
2, its first input end (in-phase input end) is coupled to the 5th pin S, flows through the sample rate current of main switch M with reception, and its second input (inverting input) receives peak current reference signal V
LimitPeak current reference signal given circuit, it comprises current source I
CS, the 3rd resistance R
3, by transistor Q
1And Q
2The current mirroring circuit of forming.Current source I wherein
CS, the 3rd resistance R
3, by transistor Q
1And Q
2The current mirroring circuit coupled in parallel of forming is at peak current comparator U
2Between inverting input and the ground.The input of peak current reference signal given circuit (being terminal 1) is coupled to selector switch S, in order to receive the input signal V of isolated variable circuit 100
INPromptly when selecting switch S to connect terminal 1, by rectifier bridge and input resistance R
DCReceiving inputted signal V
IN, and according to input signal V
INOutput peak current reference signal V
LimitTo peak current comparator U
2In the present embodiment, transistor Q
1And Q
2Be the pnp triode, wherein transistor Q
1Emitter be coupled to selector switch S, when selecting switch S to connect terminal 1, transistor Q
1Emitter by rectifier bridge and input resistance R
DCReceiving inputted signal V
INTransistor Q
2Emitter be coupled to peak current comparator U
2Inverting input; Transistor Q
1Collector electrode by first resistance R
1Be coupled to ground, transistor Q
2Collector electrode by second resistance R
2Be coupled to ground.The control end of selector switch S is by the output signal control of logical circuit 105.
In one embodiment, selected cell 106 is a selector switch S.The selection conducting situation of selector switch S is: the switching signal of exporting when logical circuit 105 is a high level, i.e. during main switch M conducting, selector switch S connects terminal 1, with input signal V
INBy rectifier bridge and input resistance R
DCBe delivered to peak current reference signal given circuit; When switching signal is a low level, when promptly main switch M disconnected, selector switch S connected terminal 2, with input signal V
INBy rectifier bridge and input resistance R
DCBe delivered to subtracter U
3Input.
When the switching signal of logical circuit 105 output when being high, main switch M is switched on, and selector switch S connects terminal 1, and then input signal is transferred into current mirroring circuit after by rectifier bridge, input capacitance, input resistance.As input signal V
INIncrease, current over pulse amount I increases, simultaneously direct current signal V
DCIncrease, correspondingly, flow through transistor Q
1Electric current:
Increase.Through the effect of current mirror, then flow through transistor Q
2Image current I
2Also increase, then flow through the 3rd resistance R
3Electric current I
3=I
CS-I
2Corresponding reducing.So, peak current reference signal V
Limit=I
3* R
3Also reduce, so V
Limit+ I remains unchanged.Otherwise, as input signal V
INWhen reducing, behind peak current reference signal given circuit, peak current reference signal V
LimitIncrease, then V
Limit+ I is constant.That is, the peak current reference signal given circuit of present embodiment has been eliminated circuit internal delay time and input voltage and has been changed main switch peak current I
PeakInfluence, new peak current reference signal V
Limit+ I is still steady state value.
In another embodiment, control circuit IC as shown in figure 15
1 Internal structure 320, selected cell 106 comprise the first selector switch M
1With the second selector switch M
2Wherein the first connection switch M1 is coupled in input resistance R
DCSecond terminal and subtracter U
3Second input between; Second connects switch M
2Be coupled in input resistance R
DCSecond terminal and the input of peak current reference signal given circuit between; First connects switch M
1Be connected switch M with described second
2Switching signal control conducting and disconnection by logical circuit 105 outputs.And when switching signal was high level, first connected switch M
1The Be Controlled conducting, second connects switch M
2Be Controlled disconnects; When switching signal was low level, second connected switch M
2The Be Controlled conducting, first connects switch M
1Be Controlled disconnects.
Control circuit IC shown in Figure 15
1 Internal structure 320 and control circuit IC shown in Figure 14
1Other parts of internal structure 310 are identical, and adopt identical Reference numeral.Simple and clear for narrating, no longer describe in detail here.
Can see, the isolated variable circuit that the utility model proposes has been realized need not to assist the former limit of winding to feed back the control that realizes output, and by increasing peak current reference signal given circuit in control circuit IC1 inside, the isolated variable circuit that the utility model provides has solved because the current over pulse problem that the circuit internal delay time causes.Simultaneously, can see that the isolated variable circuit that the utility model provides is realized functions such as overvoltage protection, self-powered detection by feedback pin, power pin, need not extra pin, has reached pin multiplexing, has further reduced cost.
Above disclosure only relates to preferred embodiment or embodiment, can produce many modifications and does not break away from the spirit and scope of the present utility model that claims propose, and should not be construed as the qualification to the utility model protection range.The described specific embodiment of this specification only is used for illustration purpose, and those skilled in the art can draw multiple modification, equivalent in spirit of the present utility model and principle.The protection range that the utility model is contained is as the criterion with appended claims.Therefore falling into whole variations in claim or its equivalent scope and remodeling all should be the claim of enclosing and contains.
Claims (18)
1. an isolated variable circuit is characterized in that, comprising:
The energy-storage travelling wave tube of former limit winding and secondary winding, described former limit winding receiving inputted signal;
Switch possesses first end, second end and the 3rd end, and wherein first end and described former limit winding couple;
Feedback circuit possesses first input end and second input and output, and wherein the first input end and second input are in parallel with described former limit winding;
Control unit possesses first input end, second input and output, and wherein first input end connects directly or indirectly and is connected with the 3rd end of described switch, and second input is connected with the output of described feedback circuit;
Drive circuit, its input is connected to the output of described control unit, and its output is connected to the 3rd end of described switch.
2. isolated variable circuit as claimed in claim 1 is characterized in that, described isolated variable circuit also comprises:
Current sampling circuit is coupled between the first input end of second end of described switch and described control unit.
3. isolated variable circuit as claimed in claim 1 is characterized in that, described control unit comprises:
The switching frequency control unit, its input receives described feedback signal as second input of described control unit, and its output provides the switching frequency control signal;
Peak current control unit, its input receive the electric current and the peak current reference signal of described detection as the first input end of described control unit, and its output provides the peak current control signal;
Logical block, two input are connected respectively to the output of described switching frequency control unit and the output of described peak current control unit, and its output is connected to the input of described drive circuit.
4. isolated variable circuit as claimed in claim 1 is characterized in that, described feedback circuit comprises:
Input resistance has two terminals, and its first terminal is coupled to described input, to receive the voltage signal of described former limit winding first end;
Feedback resistance has two terminals, and its first terminal is coupled to described former limit winding, to receive the voltage signal of described former limit winding second end;
Subtracter has two inputs, and its first input end is coupled to second terminal of described feedback resistance, and its second input is coupled to second terminal of described input resistance, so that described feedback signal to be provided.
5. isolated variable circuit as claimed in claim 1 is characterized in that, described feedback circuit comprises:
Input resistance has two terminals, and its first terminal is coupled to described input, to receive the voltage signal of described former limit winding first end;
Feedback resistance has two terminals, and its first terminal is coupled to described former limit winding, to receive the voltage signal of described former limit winding second end;
First current sampling unit, input are coupled to second terminal of described feedback resistance, so that first sampled signal to be provided;
Second current sampling unit, input are coupled to second terminal of described input resistance, so that second sampled signal to be provided;
Subtracter according to described first sampled signal and described second sampled signal, provides described feedback signal.
6. isolated variable circuit as claimed in claim 4, it is characterized in that described feedback circuit also comprises selected cell, its control end receives described switching signal, according to described switching signal, second end of described input resistance optionally is coupled to second input of described subtracter.
7. isolated variable circuit as claimed in claim 5, it is characterized in that described feedback circuit also comprises selected cell, its control end receives described switching signal, according to described switching signal, second end of described input resistance optionally is coupled to the input of described second current sampling unit.
8. isolated variable circuit as claimed in claim 3, it is characterized in that, described peak current control unit is a peak current comparator, its in-phase input end receives the sample rate current that flows through described switch, its inverting input receives described peak current reference signal, and its output provides described peak current control signal.
9. as claim 6 or 7 described isolated variable circuit, it is characterized in that described peak current control unit comprises:
Peak current reference signal given circuit, the input of described selected cell receives described switching signal, optionally the input of described peak current reference signal given circuit is coupled to second end of described input resistance according to described switching signal, the output of described peak current reference signal given circuit provides the peak current reference signal;
The peak current comparator, its input receives the electric current of described peak current reference signal and described detection, and described peak current control signal is provided.
10. isolated variable circuit as claimed in claim 9 is characterized in that, described peak current reference signal given circuit comprises:
Current source is coupled in another input of described peak current comparator and former limit with reference between the ground;
The 3rd resistance is with described current source coupled in parallel;
Current mirroring circuit is with described current source coupled in parallel; The input of described current mirroring circuit is second input of peak current control unit.
11. isolated variable circuit as claimed in claim 9, it is characterized in that, described selected cell is a selector switch, and when described switching signal was low level, described selector switch was coupled to second end of input resistance the input of described peak current reference signal given circuit.
12. isolated variable circuit as claimed in claim 9 is characterized in that, described selected cell comprises:
First connects switch, is coupled between second input of second terminal of described input resistance and described subtracter;
Second connects switch, is coupled between the input of second terminal of described input resistance and described peak current reference signal given circuit;
Described first connects switch is connected switch by described switching signal control conducting and disconnection with described second.
13. isolated variable circuit as claimed in claim 12 is characterized in that, the described first connection switch is the high level conducting; The described second connection switch is the low level conducting.
14. isolated variable circuit as claimed in claim 3 is characterized in that, described switching frequency control unit comprises:
Oscillator, its input receives described feedback signal, and its output provides described switching frequency control signal.
15. isolated variable circuit as claimed in claim 3 is characterized in that, described switching frequency control unit comprises:
Error amplifier, its input receives described feedback signal and reference signal, and its output provides error amplification signal;
Compensating circuit is coupled between the inverting input and output of described error amplifier;
Oscillator, its input receives described error amplification signal, and its output provides described switching frequency control signal.
16. isolated variable circuit as claimed in claim 3 is characterized in that, described switching frequency control unit comprises:
The threshold value comparator, its input receives described feedback signal and reference signal, and its output provides the threshold value comparison signal;
Error amplifier, its input receive described feedback signal and described reference signal, and its output provides error amplification signal;
Compensating circuit is coupled between the inverting input and output of described error amplifier;
First switch, its first termination is received described feedback signal, and its second end is coupled to the first input end of oscillator; Be switched on and disconnect according to described threshold value comparison signal;
Second switch, its first termination is received described error amplification signal, and its second end is coupled to second input of described oscillator, is switched on and disconnects according to described threshold value comparison signal;
Oscillator, its input receive described threshold value comparison signal, selectively receive described feedback signal or described error amplification signal according to described threshold value comparison signal; Its output provides described switching frequency control signal.
17. isolated variable circuit as claimed in claim 16 is characterized in that,
When described threshold value comparison signal when being high, described first switch is closed conducting, and described second switch is disconnected; Described oscillator provides described switching frequency control signal according to described feedback signal;
When described threshold value comparison signal when low, described first switch is disconnected, described second switch is closed conducting; Described oscillator provides described switching frequency control signal according to described error amplification signal.
18. isolated variable circuit as claimed in claim 3 is characterized in that, described switching frequency control unit further comprises:
Error amplifier, its input receives described feedback signal and reference signal, and its output provides error amplification signal;
Compensating circuit is coupled between the inverting input and output of described error amplifier;
Minimum value selector, its first input end receives described feedback signal; Its second input receives described error amplification signal;
Oscillator, its input receives the output signal of described minimum value selector, and its output provides the switching frequency control signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201316422U CN201839205U (en) | 2010-03-16 | 2010-03-16 | Isolation conversion circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201316422U CN201839205U (en) | 2010-03-16 | 2010-03-16 | Isolation conversion circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201839205U true CN201839205U (en) | 2011-05-18 |
Family
ID=44009305
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010201316422U Expired - Fee Related CN201839205U (en) | 2010-03-16 | 2010-03-16 | Isolation conversion circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201839205U (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101867295A (en) * | 2010-03-16 | 2010-10-20 | 成都芯源系统有限公司 | Circuit and control method |
| CN102437740A (en) * | 2011-12-22 | 2012-05-02 | 成都成电硅海科技股份有限公司 | Primary-side feedback flyback constant-current power supply with input voltage compensation function |
| CN102655378A (en) * | 2012-05-08 | 2012-09-05 | 成都芯源系统有限公司 | Isolated voltage converter circuit and control method thereof |
| CN102724799A (en) * | 2012-06-28 | 2012-10-10 | 上海晶丰明源半导体有限公司 | Light emitting diode (LED) drive circuit and method without auxiliary winding |
| CN106921296A (en) * | 2017-04-20 | 2017-07-04 | 中国电子科技集团公司第四十三研究所 | A kind of transmitted in both directions magnetic isolation feedback circuit and its implementation |
| CN107147082A (en) * | 2017-06-20 | 2017-09-08 | 矽力杰半导体技术(杭州)有限公司 | Overvoltage crowbar and apply its integrated circuit and switch converters |
-
2010
- 2010-03-16 CN CN2010201316422U patent/CN201839205U/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101867295A (en) * | 2010-03-16 | 2010-10-20 | 成都芯源系统有限公司 | Circuit and control method |
| CN101867295B (en) * | 2010-03-16 | 2014-07-16 | 成都芯源系统有限公司 | Circuit and control method |
| CN102437740A (en) * | 2011-12-22 | 2012-05-02 | 成都成电硅海科技股份有限公司 | Primary-side feedback flyback constant-current power supply with input voltage compensation function |
| CN102655378A (en) * | 2012-05-08 | 2012-09-05 | 成都芯源系统有限公司 | Isolated voltage converter circuit and control method thereof |
| CN102655378B (en) * | 2012-05-08 | 2014-06-04 | 成都芯源系统有限公司 | Isolated voltage converter circuit and control method thereof |
| CN102724799A (en) * | 2012-06-28 | 2012-10-10 | 上海晶丰明源半导体有限公司 | Light emitting diode (LED) drive circuit and method without auxiliary winding |
| CN106921296A (en) * | 2017-04-20 | 2017-07-04 | 中国电子科技集团公司第四十三研究所 | A kind of transmitted in both directions magnetic isolation feedback circuit and its implementation |
| CN106921296B (en) * | 2017-04-20 | 2023-11-07 | 中国电子科技集团公司第四十三研究所 | Bidirectional transmission magnetic isolation feedback circuit and implementation method thereof |
| CN107147082A (en) * | 2017-06-20 | 2017-09-08 | 矽力杰半导体技术(杭州)有限公司 | Overvoltage crowbar and apply its integrated circuit and switch converters |
| CN107147082B (en) * | 2017-06-20 | 2019-04-19 | 矽力杰半导体技术(杭州)有限公司 | Overvoltage crowbar and the integrated circuit and switch converters for applying it |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101867295B (en) | Circuit and control method | |
| CN209120065U (en) | Flyback power supply converter | |
| CN102497107B (en) | Switch power supply and controller of switch power supply | |
| CN101552560B (en) | Switch voltage stabilizing circuit and control method thereof | |
| CN101414764B (en) | Method and apparatus to reduce the volume required for bulk capacitance in a power supply | |
| CN102195492B (en) | Synchronous rectification switching power supply and control circuit and control method thereof | |
| CN103219878B (en) | A kind of capacitor discharging circuit and power inverter | |
| CN104734510B (en) | Switch power supply and control chip thereof | |
| CN103151924B (en) | High-precision constant-current and constant-power self-adaption compensating circuit | |
| CN201839205U (en) | Isolation conversion circuit | |
| CN104682745A (en) | Isolated voltage conversion circuit, control circuit and control method thereof | |
| CN102904448A (en) | Control chip of switch power supply and switch power supply | |
| CN104660022A (en) | System and method for providing overcurrent protection for power converter | |
| CN103023337B (en) | Power circuit of switching power converter | |
| CN101645655A (en) | Quasi-resonance controlled switch voltage stabilizing circuit and method | |
| CN103887984A (en) | Isolating converter and switching power supply comprising same | |
| CN111200364B (en) | AC-DC conversion device based on active clamping flyback converter | |
| CN102055341B (en) | Control circuit of switching power supply and switching power supply | |
| CN101841242A (en) | Switch power supply and method for adjusting output current thereof | |
| CN101594064A (en) | Switching power supply controller | |
| CN105515418A (en) | PFC shutdown circuit for light load | |
| CN101562397A (en) | Dual-mode constant current control method based on third winding detection and circuit thereof | |
| CN108631601A (en) | Multi input converter | |
| CN103683204A (en) | Switching power supply over-current protection circuit | |
| CN102545663B (en) | Overpower compensation circuit suitable for current mode switching power supply |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110518 Termination date: 20180316 |