CN102823125A - AC-DC power supply converter and current modulation circuit therein - Google Patents
AC-DC power supply converter and current modulation circuit therein Download PDFInfo
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- CN102823125A CN102823125A CN2010800602222A CN201080060222A CN102823125A CN 102823125 A CN102823125 A CN 102823125A CN 2010800602222 A CN2010800602222 A CN 2010800602222A CN 201080060222 A CN201080060222 A CN 201080060222A CN 102823125 A CN102823125 A CN 102823125A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
- H03K17/082—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit
- H03K17/0822—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit in field-effect transistor switches
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/0018—Special modifications or use of the back gate voltage of a FET
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- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Amplifiers (AREA)
Abstract
An AC-DC power supply converter and a current modulation circuit therein. The current modulation circuit (300) includes an oscillator (310), a current limiting circuit (320) and a control circuit (330). The oscillator (310) generates a clock signal (CLK) of which the frequency is inversely proportional to a feedback voltage (VFB) indicating an output voltage (Vout) of the AC-DC power supply converter. The current limiting circuit (320) compares a sampling current (ISX) indicating a current that flows through an inductor at a primary side of the AC-DC power supply converter and a limiting current (Ilim) in proportion to the feedback voltage (VFB), and outputs a valid over-current protection signal (OCP) when the sampling current (ISX) exceeds the limiting current (Ilim). The control circuit (330) turns on a power switch at the primary side of the AC-DC power supply converter based on the clock signal (CLK) and turns off the power switch when the over-current protection signal (OCP) is valid. The current modulation circuit (300) enables the AC-DC power supply converter to operate in a constant current mode and prevents the operation frequency from decreasing to the audio frequency range.
Description
AC-DC power supply changeover devices and its interior current modulating circuit
Technical field
The present invention relates to field of circuit control, more particularly to a kind of AC-DC power supply changeover devices and its interior current modulating circuit.
Background technology
AC-DC power supply changeover devices are used for that AC power is transformed into dc source by transformer, and the transformer includes main lateral coil and secondary side coil, and wherein AC power inputs the primary side, and the primary side exports dc source.The AC-DC change-over circuits include power switch, and the power switch controls the turn-on and turn-off of primary side with a constant switching frequency.
Constant-current mode is worked in the AC-DC change-over circuits(Constant Current
When Mode), the primary side energy ^ stored when power switch is turned off " is:
1
Win lim ( 1 )
2
Wherein LMFor primary side inductance, IlimFor limitation electric current, when power switch is turned off, main I inductive currents are equal to or are proportional to the limitation electric current Ilim.The energy ^ ^ that the primary side is consumed in a switch periods of power switch are:
It is wherein the switching frequency or working frequency of power switch, it is the output voltage of primary side ,/, it is the output current of primary side.It can be obtained according to the conservation of energy:
Win * η=Wout (3) is by formula(1) and(2) formula is brought into(3), going forward side by side can obtain after line translation:
1 ? f
J =— Τ Τ2
2 lim ' γ (4)
Constant-current mode is worked in the AC-DC change-over circuits(Constant Current Mode) when, no matter how output voltage ^ changes, and is required for maintaining constant output current.According to formula(4), in order to keep system output current/., it is constant, limitation electric current IlimOn the premise of constant, it is desirable to working frequencyfWith the linear inverse ratio of output voltage.
Refer to shown in Fig. 1, it illustrates a kind of oscillating circuit 100 of the prior art.The oscillating circuit 100 can produce the oscillator signal OSC out of certain frequency, and the pulse-width signal of power switch can be generated based on the oscillator signal.So, the working frequency of power switch is equal to the frequency of the oscillator signal.The oscillator signal of the oscillating circuit output is 0 VrefSawtooth signal, its frequency is:
Wherein Rl is resistance Rl resistance value, and CI is electric capacity CI capacitance, VrefFor a reference voltage, VFBFor output voltage ^ feedback voltage, wherein V.ut =K1* VFB, Kl is constant.
By formula(5) formula is brought into(4) it can obtain:
1 1 1
I = LMI (6)
Kl - Cl - Vref - Rl V0lK1 R1 C1-V, shown in Fig. 2, it illustrates a kind of current limit circuit 200 of the prior art(The current limit circuit 200 is used for comparing the sample rate current of the inductive current of primary side
Limit electric current Ilim, and in the sample rate current IsxMore than or equal to limitation electric current IlimWhen, the power switch is turned off by output end OCP.The limitation electric current IlimIt is that reference current is provided, the reference current ^ " is
Wherein Δ is poor for MOS transistor MN1 and MN2 gate source voltage.Reference current ^ is mirrored after 2 times of Κ of duplication as limitation electric current Ilim, K2 is constant:
By formula(7) formula is substituted into(6), it can obtain:
2 M K1 - R22 - Rl - Cl - VrefAccording to formula(8) understand, output current I.utWith output voltage V.utIt is unrelated, therefore with output voltage V.utDecline, system output current I.utDo not change, can keep constant.However, according to formula(5) understand, working frequency and output voltage V.utIt is directly proportional, with output voltage Vout decline, working frequency can also decline, once working frequency ^ drops in audiorange, audio disturbances, the normal application of influence occurs in some audio areas.Therefore, it is necessary to propose a kind of improved current modulating circuit to overcome above mentioned problem.
The content of the invention
The purpose of this part is some aspects for summarizing embodiments of the invention and briefly introduces some preferred embodiments.Obscured in this part and the description of the present application summary with the purpose that a little simplified or omission may be done in denomination of invention to avoid making this part, specification digest and denomination of invention, and this simplification or omission cannot be used for limiting the scope of the present invention.
An object of the present invention is to provide a kind of AC-DC power supply changeover devices, in constant-current mode, the decline with system output voltage can be realized, working frequency rises on the contrary, so as to avoid audio disturbances.The second object of the present invention is to provide the current modulating circuit in a kind of AC-DC power supply changeover devices, in constant-current mode, the decline with system output voltage can be realized, working frequency rises on the contrary, so as to avoid audio disturbances.To achieve the above object, according to an aspect of the present invention, the invention provides a kind of current modulating circuit of AC-DC power supply changeover devices.The current modulating circuit includes:Oscillator, current limit circuit and control circuit.The oscillator produces the clock signal that frequency is inversely proportional with feedback voltage, and the feedback voltage characterizes the output voltage of AC-DC power supply changeover devices.
The current limit circuit; compare sample rate current and limitation electric current; when the sample rate current is less than the limitation electric current; the invalid overcurrent protection signal of output; when the sample rate current is more than the limitation electric current; effective overcurrent protection signal is exported, the sample rate current characterizes the inductive current of the primary side of AC-DC power supply changeover devices, and the limitation electric current is directly proportional to feedback voltage.The control circuit opens the power switch of the primary side of AC-DC power supply changeover devices based on the clock signal, goes to turn off the power switch when the overcurrent protection signal is effective.
According to another aspect of the present invention, the present invention provides a kind of AC-DC power supply changeover devices.The AC-DC power supply changeover devices include:Power switch, voltage sampling circuit, current sampling circuit and the current modulating circuit of primary side.The voltage sampling circuit sampling characterizes the feedback voltage of the output voltage of AC-DC power supply changeover devices.The current sampling circuit sampling characterizes the sample rate current of the inductive current of primary side.The current modulating circuit includes:Oscillator, produces the clock signal that frequency is inversely proportional with feedback voltage;Current limit circuit; compare sample rate current and limitation electric current; the limitation electric current is directly proportional to feedback voltage; when the sample rate current is less than the limitation electric current; the invalid overcurrent protection signal of output; when the sample rate current is more than the limitation electric current, effective overcurrent protection signal is exported;Circuit is controlled, the power switch is opened based on the clock signal, goes to turn off the power switch when the overcurrent protection signal is effective.
Compared with prior art, the present invention has advantages below:
In current modulating circuit in AC-DC power supply changeover devices proposed by the present invention, the frequency and the output voltage of AC-DC power supply changeover devices for the clock signal that oscillator is produced are inversely proportional, and current limit circuit produces the limitation electric current I being directly proportional to the output voltage of AC-DC power supply changeover devicesUm.So, it is in constant-current mode in AC-DC power supply changeover devices(Constant Current Mode) when, the output current and output voltage of AC-DC power supply changeover devices are not related.It is thereby achieved that as output voltage declines, constant output current, the working frequency of AC-DC converters rises, it is to avoid audio disturbances.After the detailed description of refer to the attached drawing and ensuing embodiment is combined, other objects, features and advantages of the invention would is that obviously.
Illustrate after refer to the attached drawing and ensuing detailed description, the present invention will be better understood, wherein:Fig. 1 is the circuit diagram of oscillator of the prior art;Fig. 2 is the circuit diagram of current limit circuit of the prior art;Fig. 3 is the block diagram for the current modulating circuit in AC-DC power supply changeover devices in one embodiment of the present of invention;Fig. 4 A are the circuit diagrams of the oscillator in one embodiment of the present of invention;Fig. 4 B are the waveform diagrams of each signal of the oscillator shown in Fig. 4 A;Fig. 5 is the circuit diagram of the current limit circuit in one embodiment of the present of invention;Fig. 6 is the circuit diagram of the current limit circuit in an alternative embodiment of the invention;It is the waveform diagram of each signal of the AC-DC current modulating circuits shown in Fig. 3 with Fig. 7.
Embodiment
The detailed description of the present invention is main to be presented by program, step, logical block, process or other symbolistic descriptions, the running of the technical scheme in its direct or indirect simulation present invention.Technical staff in art is using these descriptions herein and states that the others skilled in the art into art effectively introduce their work essence.
" one embodiment " or " embodiment " referred to herein refers to that the special characteristic related to the embodiment, structure or characteristic at least may be included at least one implementation of the invention." in one embodiment " that different places occur in this manual not necessarily all refers to same embodiment, is also necessarily the independent or selection example mutually exclusive with other embodiment.This sunset is foretold, and represents the sequence of modules in method, flow chart or the functional block diagram of one or more embodiments
And revocable any particular order of reference, also it is not construed as limiting the invention.
For AC-DC power supply changeover devices, when it works in constant-current mode, in order to avoid making working frequency drop in audiorange, working frequency can be made to be inversely proportional with output voltage ^ ^ in the present invention, so in the output voltage Vout of AC-DC power supply changeover devices decline, working frequency goes up not down.In addition, in order that the output current of AC-DC power supply changeover devices/.ΜίKeep constant and meet the formula(4) limitation electric current I can, be made in the present inventionlimWith output voltageV." ' be directly proportional.
Refer to shown in Fig. 3, it is the block diagram for the current modulating circuit 300 in AC-DC power supply changeover devices in one embodiment of the present of invention.The current modulating circuit 300 includes oscillator 310, current limit circuit 320 and control circuit 330.
The oscillator 310 produces frequency and feedback voltage VFBThe clock signal being inversely proportional
CLK, the feedback voltage VFBCharacterize the output voltage of the AC-DC power supply changeover devices
Vout。
The current limit circuit 320 compares sample rate current IsxWith limitation electric current Ilim, the sample rate current IsxCharacterize the inductive current of primary side, the limitation electric current IlimWith feedback voltage VFBIt is directly proportional, in the sample rate current IsxLess than the limitation electric current IlimWhen, invalid overcurrent protection signal OCP (Over Current Protection) is exported, in the sample rate current IsxMore than the limitation electric current IlimWhen, export effective overcurrent protection signal OCP.
The control circuit 330 opens the power switch of the AC-DC power supply changeover devices based on the clock signal clk, goes to turn off the power switch when the overcurrent protection signal OCP is effective.So can using the frequency of clock signal clk as the power switch working frequency or switching frequency, while can also be in the sample rate current IsxMore than the limitation electric current IlimWhen go to turn off the power switch.
Due to limitation electric current IlimBe directly proportional to output voltage Vout, working frequency and the output voltage Vout of power switch are inversely proportional, thus still ensure that output current/.ΜίIt is unrelated with output voltage Vout, thus still ensured that when output voltage Vout changes constant output current/.Μί。
Fig. 4 Α are the circuit diagrams of the oscillator 400 in one embodiment of the present of invention.The oscillator 400 includes constant current source I, electric capacity C2, NMOS tube MN3, comparator comp and delay circuit DELAY.Current source I and electric capacity C2 are sequentially connected in series on power supply and ground
Between.Current source I connects with electric capacity C2 connecting node with comparator comp normal phase input end, and comparator comp output end connects via delay circuit with NMOS tube MN3 grid, and comparator comp inverting input connects feedback voltage VFB.NMOS tube MN3 drain electrode connects with comparator comp normal phase input end, and NMOS tube MN3 source class connects with ground.Current source I and electric capacity C2 connecting node can export triangular signal RAMP with an output end OSC out.The connecting node of delay circuit and NMOS tube MN3 grid can export clock signal clk with another output end.In other embodiments, the clock signal that control circuit 330 needs can also be generated according to triangular signal RAMP.
The current source I provides constant current and charged to electric capacity C2, the initial value of electric capacity C2 charging voltage is 0, now charging voltage is less than feedback voltage V FB, comparator comp exports low level, clock signal clk is low level, NMOS tube MN3 ends, and current source I is persistently charged to electric capacity C2.Lasting charging with current source I to electric capacity C2, electric capacity C2 charging voltage is greater than or equal to feedback voltage V FB, and comparator comp output saltus steps are high level, and clock signal clk is high level, NMOS tube MN3 is turned on, and repid discharge is carried out by NMOS tube MN3 to electric capacity C2.After discharging electric capacity C2, charging voltage is less than the feedback voltage V FB again, comparator comp exports low level again, just it is changed into low level after high level because the delay of delay circuit continues for some time clock signal clk, NMOS tube MN3 ends again, starts the charging to electric capacity C2 again.So go round and begin again, form triangular signal RAMP and clock signal clk.Fig. 4 B show the waveform of each signal of oscillator 400.
The output voltage amplitude of oscillator 400 is 0 VFBSawtooth waveforms.The triangular signal RAMP of the oscillator and the frequency of clock signal clk are: f = = ^ (9)
W C2 - VFB C2 - Vout
VFBFor output voltage, sampled voltage, wherein V.ut =Kl* VFB, K1 is constant, the constant current value that I provides for current source I.Oscillator difference with the prior art point is in the present embodiment:It is a constant current to the electric capacity C2 charging currents charged, and feedback voltage V is charged to electric capacity C2FBWhen stop.Therefore, the frequency ^ of the output signal of oscillator no longer with output voltage V.utInto
Direct ratio, but be inversely proportional with output voltage ^.So, in the output voltage Vout of AC-DC power supply changeover devices decline, working frequency goes up not down, so that avoiding makes working frequency/drop in audiorange.Constant current in the oscillator can also be obtained by the way of the duplication reference current shown in Fig. 2, and the reference current ^ is
Wherein Δ is poor for MOS transistor MN1 and MN2 gate source voltage.It is duplication ratio that the reference current, which is mirrored after K3 times of duplication and obtains constant current I, K3,
( 10)
R2
Fig. 5 is the circuit diagram of the current limit circuit 500 in one embodiment of the present of invention.The current limit circuit 500 includes limitation current generating circuit 510 and sample rate current generation circuit 520.The limitation current generating circuit 510 is produced and feedback voltage VFBThe limitation electric current I being directly proportionallim.The sample rate current generation circuit 520 produces the sample rate current being directly proportional to the inductive current of primary side.The limitation electric current IlimElectric current competition is carried out in competition node with sample rate current 1^, in limitation electric current IlimMore than sample rate current IsxWhen, competition node exports invalid overcurrent protection signal OCP, in limitation electric current IlimLess than sample rate current IsxWhen, competition node exports effective overcurrent protection signal OCP.
The limitation current generating circuit 510 includes operational amplifier OP (operational amplifier), resistance R3, NMOS tube MN4, PMOS MPb5 and MPb6.The normal phase input end of the operational amplifier OP connects the feedback voltage VFB, output termination NMOS pipes MN4 grid.NMOS tube MN4 source electrode connects with resistance R3.Operational amplifier OP inverting input is connected with NMOS tube MN4 and resistance R3 connecting node.Resistance R3 other end ground connection.PMOS MPb5 drain electrode is connected with NMOS tube MN4 drain electrode and PMOS MPb5 grid, and its source electrode meets power supply VDDIt is connected, its grid is connected with PMOS MPb6 grid.PMOS MPb6 source electrode meets power supply VDDIt is connected, the drain electrode output limitation electric current Ilim。
Electric current on leakage resistance R3 is that the electric current on ^, PMOS MPb5 is also ^.
R3 R3
PMOS MPb5 and PMOS MPb6 formation current mirroring circuits.The limitation electric current I of PMOS MPb6 outputslimFor: lYim=K4--^≡^ (11)
K1-R3
K4 is the current replication ratio between PMOS MPb5 and MPb6.So, limitation electric current IlimWith output voltage V.utIt is directly proportional.The sample rate current generation circuit 520 includes NMOS tube MN7 and MN8, NMOS pipe MN7 and MN8 formation current mirroring circuit.The electric current for flowing through NMOS tube MN8 is initial sample electric current Isx, it is replicated and the sample rate current I for flowing through NMOS tube MN7 is obtained after K5 timessx, the initial sample electric current Isx, it is directly proportional to the inductive current of primary side, K5 is current replication ratio.Formula (9), (10) and (11) is substituted into formula(4), it can obtain:
1 ? f
J =— Τ τ2 n.J sw
1 out » -^Af Jlim'/
1 , K3''AV.
-LM -K42 - (12) 2 M ' K1-R3J- C2-R2 is visible, output current and output voltage, unrelated, only related to the physical size and parameter of device, realizes the constant of output current, current-modulation is completed well.
In the present embodiment, the maximum distinctive points of current limit circuit and prior art are:Compare electric current IlimNo longer it is a constant current, but an electrograph 6 being directly proportional to output voltage Vout is the circuit diagram of the current limit circuit 600 in an alternative embodiment of the invention,
The current limit circuit 600 includes restricted current generating circuit 610 and sample rate current generation circuit 620.Current limit circuit 600 shown in Fig. 6 is only that with the current limit circuit 500 shown in Fig. 5:Limit the difference of the structure of current generating circuit 610 and limitation current generating circuit 510.
The limitation current generating circuit 610 includes the first limitation current generating circuit, the second limitation current generating circuit and mirror image circuit.
The first limitation current generating circuit includes NMOS tube MN13, PMOS MPbl7 and MPbl8, resistance R4.NMOS tube MN13 grid connects feedback voltage VFB, its source electrode is connected to the ground by resistance R4, and its drain electrode is connected with PMOS MPM7 drain electrode.PMOS MPbl7 drain electrode is connected with PMOS MPbl7 grid, and its grid is connected with PMOS MPbl8 grid, its source electrode and power supply VDDIt is connected.PMOS MPblS source electrode and power supply VDDIt is connected, drain electrode output first limits electric current Iliml.The electric current flowed through on resistance R4 isVfb R Z4Vgs13, ^ is NMOS tube MN13 grid
First limitation electric current I of MPbl8 outputslimlFor:
I liml" K6 '
R4
K6 is the current replication ratio between PMOS MPbl8 and MPbl7.The second limitation current generating circuit includes NMOS pipes MN15 and MN22, PMOS MPbl9, MPb20 and MPb21, resistance R5.NMOS tube MN22 source electrode is connected to the ground via resistance R5, and its grid is connected with NMOS tube MN15 drain electrode, and its drain electrode is connected with PMOS MPb21 drain electrode.NMOS tube MN15 source electrode is connected to the ground, and its grid is connected with NMOS tube MN22 source electrode, and its drain electrode is connected with PMOS MPb20 drain electrode.PMOS MPb20 grid is connected with PMOS MPb21 grid, and its source electrode connects power supply.PMOS MPb21 drain electrode is connected with its grid, and its source electrode connects power supply.PMOS MPbl9 source electrode connects power supply, and its grid connects PMOS MPb20 grid, and its output second that drains limits electric current Ilim2。
V,
The electric current flowed through on resistance R5 is
R5
PMOS MPbl9, MPb20 and MPb21 formation current mirroring circuit, the second limitation electric current I of PMOS MPbl9 outputslim2For:
Ι η 2=7, Κ 7 answers for the electric current between PMOS MPbl9 and MPb21
R5
Mirror image circuit described in ratio processed includes NMOS tube MN14 and MN16, PMOS MPb23 and MPb24.The drain electrode of the NMOS tube MN14 is connected with PMOS MPbl9 and MPbl8 drain electrode and NMOS pipes MN14 grid, and its source ground, its grid connects NMOS tube MN16 grid.NMOS tube MN16 source ground, it, which drains, connects PMOS pipes MPb23 drain electrode.PMOS MPb23 drain electrode is connected with its grid, and its grid is connected with PMOS MPb24 grid, and its source electrode connects power supply.PMOS MPb24 source electrode connects power supply, its export-restriction electric current I that drainslim.It is the first limitation electric current I to flow through NMOS tube MN14 electric currentlimlWith the second limitation electric current Iiim2 sum.NMOS tube MN14 and MN16 formation current mirroring circuit, PMOS MPb24 and MPb23 formation current mirroring circuit.The limitation electric current of PMOS MPb24 outputs
Ilim is:
Ilim= K8 ( Ilimi+ Ilim2 ) = K8■ K6 -
Κ 8 is the current replication ratio between PMOS MPb24 and NMOS tube MN14, takes R4=R5, K6=K7, Vgsl3=Vgsl5, has:
Iiim= Κ8 · Κ6 · ^ = Κ8 · Κ6 - V〜
R4 K1 - R4
So, limitation electric current I can equally be realizedlimWith output voltage v.utIt is directly proportional.
Fig. 7 is each signal of the AC-DC current modulating circuits shown in Fig. 3 in one embodiment
Go to drive the power switch, it is turned in high level, be off in low level.The present invention can also provide a kind of AC-DC power supply changeover devices, and it includes current modulating circuit as shown in Figure 3.The description with certain particularity detailed enough has been carried out to the present invention above.Those of ordinary skill in art is it should be understood that what the description in embodiment was merely exemplary, and all changes are made on the premise of without departing from true spirit and scope of the present invention should all belong to protection scope of the present invention.Scope of the present invention is defined by described claims, rather than limited by the foregoing description in embodiment.
Claims (10)
- Claim1st, a kind of current modulating circuit of AC-DC power supply changeover devices, it includes:Oscillator, produces the clock signal that frequency is inversely proportional with feedback voltage, and the feedback voltage characterizes the output voltage of AC-DC power supply changeover devices;Current limit circuit, compares sample rate current and limitation electric current, and the sample rate current is characterizedThe inductive current of the primary side of AC-DC power supply changeover devices; the limitation electric current is directly proportional to feedback voltage; when the sample rate current is less than the limitation electric current; the invalid overcurrent protection signal of output; when the sample rate current is more than the limitation electric current, effective overcurrent protection signal is exported;WithCircuit is controlled, the power switch of the primary side of AC-DC power supply changeover devices is opened based on the clock signal, goes to turn off the power switch when the overcurrent protection signal is effective.2nd, circuit according to claim 1, it is characterised in that:The oscillator includes constant current source, charging capacitor, NMOS discharge tubes, comparator and delay circuit,The current source and charging capacitor are sequentially connected in series between power supply and ground, the current source connects with the connecting node of charging capacitor with the normal phase input end of the comparator, the output end of the comparator connects via delay circuit with the grid of the NMOS discharge tubes, the anti-phase input of the comparator terminates the feedback voltage, the drain electrode of the NMOS discharge tubes connects with the normal phase input end of the comparator, the source class of the NMOS discharge tubes connects with ground, and the connecting node of the current source and electric capacity is as output end to export triangular signal.3rd, circuit according to claim 2, it is characterised in that:The delay circuit withThe connecting node of the grid of NMOS discharge tubes is as another output end to export clock signal.4th, circuit according to claim 1, it is characterised in that:The current limit circuit includes limitation current generating circuit and sample rate current generation circuit,The limitation current generating circuit produces the limitation electric current being directly proportional to feedback voltage; the sample rate current generation circuit produces the sample rate current being directly proportional to the inductive current of primary side; the limitation electric current carries out electric current competition with the sample rate current in competition node; when limiting electric current more than sample rate current; compete node and export invalid overcurrent protection signal, in limitation electricity When stream is less than sample rate current, competition node exports effective overcurrent protection signal.5th, circuit according to claim 4, it is characterised in that:The limitation current generating circuit includes operational amplifier, 3rd resistor, the 4th NMOS pipes, the 5th PMOS and the 6th PMOS,The normal phase input end of the operational amplifier connects the feedback voltage, output termination the 4thThe grid of NMOS tube, the source electrode of 4th NMOS tube connects with 3rd resistor, the inverting input of operational amplifier is connected with the connecting node of the 4th NMOS tube and 3rd resistor, the other end ground connection of 3rd resistor, the drain electrode of 5th PMOS is connected with the drain electrode of the 4th NMOS tube and the grid of the 5th PMOS, the source electrode of 5th PMOS connects power supply and is connected, the grid of 5th PMOS is connected with the grid of the 6th PMOS, the source electrode of 6th PMOS connects power supply and is connected, and the drain electrode of the 6th PMOS exports the limitation electric current.6th, circuit according to claim 4, it is characterised in that:The limitation current generating circuit includes the first limitation current generating circuit, the second limitation current generating circuit and mirror image circuit,The first limitation current generating circuit includes the 13rd NMOS pipes, the 17thPMOS, 18th PMOS and the 4th resistance, the reversed feedthrough voltage of grid of 13rd NMOS tube, the source electrode of 13rd NMOS tube is connected to the ground by the 4th resistance, the drain electrode of 13rd NMOS tube is connected with the drain electrode of the 17th PMOS, the drain electrode of 17th PMOS is connected with the grid of the 17th PMOS, the grid of 17th PMOS is connected with the grid of the 18th PMOS, the source electrode of 17th PMOS is connected with power supply, the source electrode of 18th PMOS is connected with power supply, the drain electrode output first of 18th PMOS limits electric current;The second limitation current generating circuit includes the 15th NMOS pipes, the 22nd NMOS tube, the 19th PMOS, the 20th PMOS, the PMOSs of the 2nd ^ mono- and the 5th resistance, the source electrode of 22nd NMOS pipes is connected to the ground via the 5th resistance, 22nd NMOS tube grid is connected with the drain electrode of the 15th NMOS tube, the drain electrode of 22nd NMOS tube is connected with the drain electrode of the 21st PMOS The source electrode of 15th NMOS tube is connected to the ground, the grid of 15th NMOS tube is connected with the source electrode of the 22nd NMOS tube, the drain electrode of 15th NMOS tube is connected with the drain electrode of the 20th PMOS pipes, the grid of 20th PMOS is connected with the grid of the 21st PMOS, 20th PMOS source electrode connects power supply, the drain electrode of 21st PMOS is connected with its grid, the source electrode of 21st PMOS connects power supply, the source electrode of 19th PMOS connects power supply, the grid of 19th PMOS connects the grid of the 20th PMOS, the drain electrode output second of 19th PMOS limits electric current;The mirror image circuit includes the 14th NMOS tube and the 16th NMOS tube, 23rd PMOS and the 24th PMOS, the drain electrode of 14th NMOS tube is connected with the 19th PMOS and the drain electrode of the 18th PMOS and the grid of the 14th NMOS tube, the source ground of 14th NMOS pipes, the grid of 14th NMOS pipes connects the grid of the 16th NMOS tube, the source ground of 16th NMOS tube, the drain electrode of 16th NMOS tube connects the drain electrode of the 23rd PMOS, the drain electrode of 23rd PMOS is connected with its grid, the grid of 23rd PMOS is connected with the grid of the 24th PMOS, the source electrode of 23rd PMOS connects power supply, the source electrode of 24th PMOS connects power supply, the drain electrode of 24th PMOS exports the limitation electric current,4th resistance is equal to the 5th resistance, the gate source voltage of 13rd NMOS tube is equal to the gate source voltage of the 15th NMOS tube, and the current replication ratio between the 18th PMOS and the 17th PMOS is equal to the current replication ratio between the 19th PMOS and the PMOSs of the 2nd ^ mono-.7th, circuit according to claim 4, it is characterised in that:The sample rate current generation circuit includes forming the 7th NMOS tube and the 8th NMOS tube of current mirror, the electric current for flowing through the 8th NMOS tube is initial sample electric current, initial sample electric current obtains flowing through the sample rate current of the 7th NMOS tube after image copying, and the initial sample electric current is directly proportional to the inductive current of primary side.8th, a kind of AC-DC power supply changeover devices, it includes:The power switch of primary side; Voltage sampling circuit, sampling characterizes the feedback voltage of the output voltage of AC-DC power supply changeover devices;Current sampling circuit, sampling characterizes the sample rate current of the inductive current of primary side;Current modulating circuit includes:Oscillator, produces the clock signal that frequency is inversely proportional with feedback voltage;Current limit circuit; compare sample rate current and limitation electric current; the limitation electric current is directly proportional to feedback voltage; when the sample rate current is less than the limitation electric current; the invalid overcurrent protection signal of output; when the sample rate current is more than the limitation electric current, effective overcurrent protection signal is exported;WithCircuit is controlled, the power switch is opened based on the clock signal, goes to turn off the power switch when the overcurrent protection signal is effective.9th, power supply changeover device according to claim 8, it is characterised in that:The oscillator includes constant current source, charging capacitor, NMOS discharge tubes, comparator and delay circuit, the current source and charging capacitor are sequentially connected in series between power supply and ground, the current source connects with the connecting node of charging capacitor with the normal phase input end of the comparator, the output end of the comparator connects via delay circuit with the grid of the NMOS discharge tubes, the anti-phase input of the comparator terminates the feedback voltage, the drain electrode of the NMOS discharge tubes connects with the normal phase input end of the comparator, the source class of the NMOS discharge tubes connects with ground, the connecting node of the current source and electric capacity is as output end to export triangular signal.10th, power supply changeover device according to claim 9, it is characterised in that:The connecting node of the grid of the delay circuit and NMOS discharge tubes is as another output end to export clock signal.11st, power supply changeover device according to claim 8, it is characterised in that:The current limit circuit includes limitation current generating circuit,The limitation current generating circuit produces the limitation electric current being directly proportional to feedback voltage based on feedback voltage; the limitation electric current carries out electric current competition with the sample rate current in competition node; when limiting electric current more than sample rate current; compete node and export invalid overcurrent protection signal; when limiting electric current less than sample rate current, competition node exports effective overcurrent protection signal.12nd, power supply changeover device according to claim 11, it is characterised in that: The limitation current generating circuit includes operational amplifier, 3rd resistor, the 4th NMOS pipes, the 5th PMOS and the 6th PMOS,The normal phase input end of the operational amplifier connects the feedback voltage, the grid of output the 4th NMOS tube of termination, the source electrode of 4th NMOS tube connects with 3rd resistor, the inverting input of operational amplifier is connected with the connecting node of the 4th NMOS tube and 3rd resistor, the other end ground connection of 3rd resistor, the drain electrode of 5th PMOS is connected with the drain electrode of the 4th NMOS tube and the grid of the 5th PMOS, the source electrode of 5th PMOS connects power supply and is connected, the grid of 5th PMOS is connected with the grid of the 6th PMOS, the source electrode of 6th PMOS connects power supply and is connected, the drain electrode of 6th PMOS exports the limitation electric current.
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PCT/CN2010/074467 WO2011160305A1 (en) | 2010-06-25 | 2010-06-25 | Ac-dc power supply converter and current modulation circuit therein |
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CN102823125B CN102823125B (en) | 2015-08-05 |
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CN201080060222.2A Expired - Fee Related CN102823125B (en) | 2010-06-25 | 2010-06-25 | AC-DC power supply changeover device and interior current modulating circuit thereof |
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CN109873615A (en) * | 2018-12-29 | 2019-06-11 | 上海琪埔维半导体有限公司 | A kind of pulse width filter |
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CN102823125B (en) | 2015-08-05 |
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Address after: 214028 Jiangsu New District of Wuxi, Taihu international science and Technology Park Jia Qing 530 building 10 layer Patentee after: WUXI ZHONGGAN MICROELECTRONIC CO., LTD. Address before: 214028 Jiangsu New District of Wuxi, Taihu international science and Technology Park Jia Qing 530 building 10 layer Patentee before: Wuxi Vimicro Co., Ltd. |
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