CN102801300A - Primary-side feedback controlled switching power line loss compensating system and method - Google Patents

Abstract

The invention discloses a primary-side feedback controlled switching power line loss compensating system and method. The system comprises a sampling and holding circuit, a constant voltage loop error amplifier, a compensating network, an adjustable low-pass filter and a voltage-current converter, wherein the sampling and holding circuit, the constant voltage loop error amplifier, the adjustable low-pass filter and the voltage-current converter are connected in sequence; the output of the voltage-current converter is connected with the sampling and holding circuit; and the compensating network is connected with the input and the output of the constant voltage loop error amplifier respectively. The primary-side feedback controlled switching power line loss compensating system and method provided by the invention can be applied to the line loss compensation which does not need external compensation of capacitor or resistor in the field of primary-side feedback, and is capable of compensating the line loss pressure drop of an output wire so as to realize constant output voltage.

Description

The Switching Power Supply line loss bucking-out system and the method for former limit FEEDBACK CONTROL

Technical field

The invention belongs to technical field of integrated circuits, relate to the Switching Power Supply of a kind of former limit FEEDBACK CONTROL, relate in particular to the Switching Power Supply line loss bucking-out system of a kind of former limit FEEDBACK CONTROL; Simultaneously, the invention still further relates to the Switching Power Supply line loss compensation method of a kind of former limit FEEDBACK CONTROL.

Background technology

Supply convertor is a requisite assembly in the electronic system.As everyone knows, power conversion rises and comprises linear transformations device and two kinds of main types of switching power converters, on conversion regime, can be divided into isolated and non-isolated two types again.Switching power converters can be realized high conversion efficiency, thus in obtained widely using to large-power occasions, and, be main with linear quantizer in the small-power occasion system below several watts particularly.In recent years, in present small-power occasion, switching power converters also begins progressively to replace linear quantizer, and one of them key factor to be exactly switching power converters begin on system cost progressively near the cost of linear quantizer.In present energy-saving and cost-reducing today that becomes trend, become trend of the times with high efficiency switch supply convertor instead of linear converter.In the Switching Power Supply occasion, what extensively be suitable for is isolated converter, because the isolation type switching power supply converter can protect load to avoid the impacting with high pressure and the damage of inlet highway, in telecommunications wireless network, automobile and Medical Devices, possesses widely and uses.In the various topologys of isolated converter; Because anti exciting converter (flyback converter) topology need not output inductor; Circuit structure is simple, output is isolated, cost is low; In the application of terminal equipment, occupy very high ratio, Fig. 1 has shown traditional isolated anti exciting converter application drawing that can be applied in the charger occasion, and Fig. 2 is this system power voltage curve of output.

As can beappreciated from fig. 1; Usually the sampled signal of isolation type switching power supply converter output voltage adopts the optocoupler feedback to realize that (CV, Constant Voltage0 comprise TL431 and isolated feedback compensating network thereof to the output constant voltage; Also has secondary constant-current (CC, Constant Current) control circuit.Can know that from Fig. 1 adopt the anti exciting converter complex circuit designs that can be applied in the charger occasion of isolated feedback, application cost is higher, is not suitable for being applied to the small-power occasion.In the anti exciting converter topology, former limit modulation (PSR, Primary Side Regulation) technology occurred in recent years, former limit modulation technique need not secondary optocoupler, and secondary control circuits such as Tl431 and secondary constant-current are so system cost greatly descends.Because in small-power charger occasion, small size and low cost are the factors that direct requirement is considered, such as for 3, the charger for mobile phone of 5W, the cost of resistance all is very important, lets alone the big or small of PCB and other some factors.

Released the IC of the former limit of a lot of employings modulation technique in the market, these IC based on system works at discontinuous mode (DCM, Discontinuous Conduction Mode); Adopted different constant current constant voltage (CC/CV) control; Had at present a lot of China and foreign countries patent with the document description of delivering different implementations, such as patent CN200810093354.X, CN200610057268.4; Or the like, just enumerate no longer one by one at this.Its main thought is following:

Suppose that system works under discontinuous (DCM) pattern, its power delivery equation is:

$P=\frac{\mathrm{\η}}{2}\×L_m\×I_{\mathrm{pk}}^2\×f_S=V_o\×I_o---\left(1\right)$

In above-mentioned equation, P is a power output, and Vo and Io are respectively system's output voltage and electric current; η is system's conversion efficiency, and Lm is a transformer inductance, and fs is a system frequency; Ipk is the peak value of system's inductive current in each switch periods, and we are assumed to the peak value of former limit inductive current in following formula.Under the DCM pattern, signal waveforms is as shown in Figure 3 in the switch periods.

In Fig. 3, chip internal need produce an erase signal DEM, writes down transformer inductance erasing time Tdem in each switch periods, utilizes this information to do CC/CV control.

Suppose that system gets into the CC pattern, at this time has:

$I_o=\frac{\mathrm{\η}\×L_m\×I_{\mathrm{pk}}^2\×f_S}{2V_o}---\left(2\right)$

Under the CC pattern, need make Io is steady state value, and this value needs and Vo, Lm, and input line voltage all has nothing to do.As everyone knows, under the DCM pattern, transformer erasing time Tdem and output voltage V o, the relation of Lm is following:

$\frac{V_o}{L_m}\×T_{\mathrm{dem}}=\frac{N_S}{N_P}\×I_{\mathrm{pk}}---\left(3\right)$

In following formula, Np and Ns are respectively the former limit of transformer and the secondary number of turn.In conjunction with (2) (3) formula, have

$I_o=\frac{\mathrm{\η}}{2}\×I_{\mathrm{pk}}\×\frac{N_P}{N_S}\×f_S\×T_{\mathrm{dem}}---\left(4\right)$

Can know that through (4) formula realize that CC has two kinds of methods, a kind of method is PFM (Pulse Frequency Modulation) control, specifically be embodied as: making Ipk is fixed value, and the product that makes fs and Tdem in addition is a constant.Io is constant like this, and with output voltage V o, transformer sensibility reciprocal Lm and input line voltage all have nothing to do.Second kind of method that realizes CC is PWM (Pulse Width Modulation), specifically is embodied as, and making fs is fixed value, and the product that makes Tdem and Ipk in addition is a constant, just through detected Tdem information modulation duty cycle.No matter be PFM, or PWM, all be to realize through overcurrent protection OCP (Over current protection), difference is exactly: in PFM, the compare threshold of this overcurrent protector is a fixed value; In PWM control, this overcurrent protection compare threshold is a changing value, modulated by Tdem.In these two kinds of implementation methods, all need accurately detect, otherwise can cause CC deleterious (can know) according to 4 formulas to the transformer inductance electric current.

After CC realizes; Can realize CV; As long as before Tdem finishes to the land regions of assisting winding Naux output voltage sample (" platform sampling " as shown in Figure 3); In concrete the realization, the voltage of auxiliary winding Naux in the electric resistance partial pressure sample graph 1 capable of using (winding voltage in Fig. 1 before the rectifier diode D1), this voltage is proportional at value and output voltage that GATE closes the land regions before demagnetization finishes of having no progeny; Proportionality coefficient is auxiliary winding and secondary winding turn ratio, i.e. Naux/Ns.The information of voltage that utilization samples carries out CV control.

In sum, in isolated former limit modulation constant-current constant-voltage controller, need sampling transformer inductance demagnetization information in power controller, to obtain the demagnetization pulsewidth.Utilize this demagnetization pulse width information to carry out CC/CV and handle, method can have PFM or PWM, and the both needs accurately to detect the transformer inductance electric current to obtain accurate CC value.

Yet the constant current constant voltage system is controlled on the former limit of adopting such scheme and version thereof and designing individual significant deficiency is arranged: in the ordinary course of things, voltage stabilizing is regulated to variable of load and is regulated.But in fields such as practical application especially charger for mobile phone, along with the specification of power supply output lead is different, length is different, and the resistance R cable of output lead can be very big, and it also can cause the instability of output voltage.Be shown in the following figure:

When output cable resistance R cable existed, the detection feedback pin FB of chip U1 closed the detected auxiliary winding Naux actual platform voltage (seeing Fig. 3 and Fig. 4) of having no progeny at Q1 and is:

$V_{\mathrm{FB}}=\frac{R3}{R2+R3}\×\frac{N_{\mathrm{aux}}}{N_S}\×(\mathrm{Vout}+\mathrm{Vd}+\mathrm{Iout}*\mathrm{Rcable})$

In the following formula, Iout is an output current, and Vd is the pressure drop of output rectifier diode D1, and Naux is auxiliary umber of turn, and Ns is the secondary winding number of turn, and R2 and R3 see Fig. 4 for auxiliary winding divider resistance.So the Vout virtual voltage is:

$\mathrm{Vout}=\frac{R2+R3}{R2}*\frac{N_S}{N_{\mathrm{aux}}}-\mathrm{Vd}-\mathrm{Iout}*\mathrm{Rcable}$

Can know from following formula; After output lead is selected; Its conductor resistance Rcable is a fixing value, but output current Iout is an amount along with load variations, and control loop only carries out the voltage stabilizing adjusting to variable of Vout; Iout is not carried out voltage stabilizing and regulate, so control loop has lost the voltage stabilizing control to output.

Present PSR chip product on the market mainly is to realize the line loss compensation through non-essential resistance or electric capacity, such as the AP3706/3708/3768/3770 of BCD company and the OB2520 of Ang Bao company, or the like.Therefore but outside line loss compensating device can increase system cost, presses for the variation that a kind of built-in line loss compensation circuit compensates the output voltage that Iout causes.Thereby, realize exporting accurately voltage regulation result.

Summary of the invention

Technical problem to be solved by this invention is: the Switching Power Supply line loss bucking-out system that a kind of former limit FEEDBACK CONTROL is provided; Can be applicable to the line loss compensation field, that need not external compensation electric capacity or resistance of former limit feedback; It can compensate the line loss pressure drop of output lead, thereby realizes the constant of output voltage.

In addition; The present invention also provides the Switching Power Supply line loss compensation method of a kind of former limit FEEDBACK CONTROL; Can be applicable to the line loss compensation field, that need not external compensation electric capacity or resistance of former limit feedback, it can compensate the line loss pressure drop of output lead, thereby realizes the constant of output voltage.

For solving the problems of the technologies described above, the present invention adopts following technical scheme:

The Switching Power Supply line loss bucking-out system of a kind of former limit FEEDBACK CONTROL, said system comprises: sampling hold circuit, constant voltage loop error amplifier, compensating network, tunable low pass filter, voltage current adapter;

Said sampling hold circuit, constant voltage loop error amplifier, tunable low pass filter, voltage current adapter connect successively; The output of voltage current adapter inserts sampling hold circuit, and said compensating network connects the input and the output of constant voltage loop error amplifier respectively;

Said sampling hold circuit carries out the platform sampling to auxiliary winding, and output voltage is designated as voltage V_SH;

Voltage V SH carries out error ratio through constant voltage loop error amplifier and reference voltage Vref and amplifies, and output voltage V comp is to tunable low pass filter;

The control signal of said tunable low pass filter is the PWM output signal of chip, and tunable low pass filter is output as voltage V_Lpf;

Voltage V_Lpf is through voltage current adapter output line loss offset current Icable; Line loss offset current Icable compensates the pressure drop of output cable Rcable.

As a kind of preferred version of the present invention, said constant voltage loop error amplifier is trsanscondutance amplifier Gm;

Building-out capacitor Cc and compensating resistance Rc that said compensating network comprises series connection carry out series compensation to constant voltage loop error amplifier;

The end ground connection of said building-out capacitor Cc, the other end connects the end of compensating resistance Rc, and the other end of compensating resistance Rc connects the output of trsanscondutance amplifier Gm.

As a kind of preferred version of the present invention, said constant voltage loop error amplifier is a fixed gain amplifier;

Said compensating network comprises the first resistance R c1, the second resistance R c2; The end of the first resistance R c1 connects reference voltage Vref, and the other end connects the negative pole of fixed gain amplifier; The end of the second resistance R c2 connects the negative pole of fixed gain amplifier, and the other end connects the output of fixed gain amplifier; Voltage V_SH inserts the positive pole of fixed gain amplifier.

As a kind of preferred version of the present invention, said tunable low pass filter comprises inverter INV1, first switch S 1, second switch S1b, first capacitor C 1, second capacitor C 2;

The Frequency point of said tunable low pass filter is controlled by pwm signal; The output voltage V comp of constant voltage loop error amplifier is connected with an end of first switch S 1, and the other end of first switch S 1 is connected with second switch S1b;

First switch S 1 connects first capacitor C 1, and second switch S1b connects second capacitor C 2; The control signal of first switch S 1, second switch S1b is reverse, and INV1 controls through inverter; First switch S 1 is connected with the end of inverter INV1, and second switch S1b is connected with the other end of inverter INV1.

As a kind of preferred version of the present invention, said voltage current adapter comprises that operational amplifier A 2, the 3rd resistance R 1, NMOS manage M1, and the current mirror formed of PMOS pipe M2, PMOS pipe M3;

The output of the grid concatenation operation amplifier A2 of NMOS pipe M1; The source electrode of NMOS pipe M1 connects an end of the 3rd resistance R 1, the input of the same end concatenation operation amplifier A2 of the 3rd resistance R 1;

The drain electrode of NMOS pipe M1 connects drain electrode, the grid of PMOS pipe M2, and the grid of PMOS pipe M3.

The compensation process of the Switching Power Supply line loss bucking-out system of a kind of above-mentioned former limit FEEDBACK CONTROL, said method comprises the steps:

Step S1, sampling hold circuit carry out the platform sampling to auxiliary winding, and output voltage is designated as voltage V_SH;

Step S2, voltage V_SH carry out error ratio through constant voltage loop error amplifier and reference voltage Vref and amplify, and output voltage V comp is to tunable low pass filter;

The control signal of step S3, tunable low pass filter is the PWM output signal of chip, and tunable low pass filter is output as voltage V_Lpf;

Step S4, voltage V_Lpf are through voltage current adapter output line loss offset current Icable; Line loss offset current Icable compensates the pressure drop of output cable Rcable.

As a kind of preferred version of the present invention, said constant voltage loop error amplifier is trsanscondutance amplifier Gm;

Building-out capacitor Cc and compensating resistance Rc that said compensating network comprises series connection carry out series compensation to constant voltage loop error amplifier;

The end ground connection of said building-out capacitor Cc, the other end connects the end of compensating resistance Rc, and the other end of compensating resistance Rc connects the output of trsanscondutance amplifier Gm.

As a kind of preferred version of the present invention, said constant voltage loop error amplifier is a fixed gain amplifier;

Said compensating network comprises the first resistance R c1, the second resistance R c2; The end of the first resistance R c1 connects reference voltage Vref, and the other end connects the negative pole of fixed gain amplifier; The end of the second resistance R c2 connects the negative pole of fixed gain amplifier, and the other end connects the output of fixed gain amplifier; Voltage V_SH inserts the positive pole of fixed gain amplifier.

As a kind of preferred version of the present invention, said tunable low pass filter comprises inverter INV1, first switch S 1, second switch S1b, first capacitor C 1, second capacitor C 2;

The Frequency point of said tunable low pass filter is controlled by pwm signal; The output voltage V comp of constant voltage loop error amplifier is connected with an end of first switch S 1, and the other end of first switch S 1 is connected with second switch S1b;

First switch S 1 connects first capacitor C 1, and second switch S1b connects second capacitor C 2; The control signal of first switch S 1, second switch S1b is reverse, and INV1 controls through inverter; First switch S 1 is connected with the end of inverter INV1, and second switch S1b is connected with the other end of inverter INV1.

As a kind of preferred version of the present invention, said voltage current adapter comprises that operational amplifier A 2, the 3rd resistance R 1, NMOS manage M1, and the current mirror formed of PMOS pipe M2, PMOS pipe M3;

The output of the grid concatenation operation amplifier A2 of NMOS pipe M1; The source electrode of NMOS pipe M1 connects an end of the 3rd resistance R 1, the input of the same end concatenation operation amplifier A2 of the 3rd resistance R 1;

The drain electrode of NMOS pipe M1 connects drain electrode, the grid of PMOS pipe M2, and the grid of PMOS pipe M3.

Beneficial effect of the present invention is: the Switching Power Supply line loss bucking-out system and the method for the former limit FEEDBACK CONTROL that the present invention proposes; Can be applicable to the line loss compensation field, that need not external compensation electric capacity or resistance of former limit feedback; Can compensate the line loss pressure drop of output lead, thereby realize the constant of output voltage.

Description of drawings

Fig. 1 is traditional isolated anti exciting converter application drawing that can be applied in the charger occasion.

Fig. 2 is this system power voltage output curve diagram.

Fig. 3 is a signal waveforms in the next switch periods of DCM pattern.

Fig. 4 controls the composition sketch map of constant current constant voltage system for existing former limit.

Fig. 5 is the composition sketch map of line loss bucking-out system of the present invention.

Fig. 6 is the composition sketch map of CV loop error amplifier and compensating network thereof.

Fig. 7 is another composition sketch map of CV loop error amplifier and compensating network thereof.

Fig. 8 is the composition sketch map of tunable low pass filter.

Fig. 9 is the amplitude-frequency response figure of tunable low pass filter.

Figure 10 is the composition sketch map of voltage current adapter.

Embodiment

Specify the preferred embodiments of the present invention below in conjunction with accompanying drawing.

Embodiment one

See also Fig. 5, the present invention has disclosed the Switching Power Supply line loss bucking-out system of a kind of former limit FEEDBACK CONTROL, and said system comprises: sampling hold circuit 10, constant voltage loop error amplifier 20, compensating network 30, tunable low pass filter 40, voltage current adapter 50.Said sampling hold circuit 10, constant voltage loop error amplifier 20, tunable low pass filter 40, voltage current adapter 50 connect successively, and the output of voltage current adapter 50 inserts sampling hold circuit 10; Said compensating network 30 connects the input and the output of constant voltage loop error amplifier 20 respectively.

Sampling hold circuit 10 carries out the platform sampling through the FB pin to auxiliary winding, and as shown in Figure 3, output voltage is V_SH.Voltage V_SH carries out error ratio through constant voltage loop error amplifier 20 and reference voltage Vref and amplifies, and output Vcomp give tunable low pass filter 40.The control signal of tunable low pass filter 40 is the PWM output signal of chip, the signal of the GATE of Fig. 4 output just, and tunable low pass filter 40 is output as VLpf.V_Lpf is through voltage current adapter output line loss offset current Icable.Line loss offset current Icable compensates the pressure drop of exporting cable Rcable through R2 among Fig. 4 and R3.

See also Fig. 6, in the present embodiment, said constant voltage loop error amplifier 20 is trsanscondutance amplifier Gm; Building-out capacitor Cc and compensating resistance Rc that said compensating network comprises series connection carry out series compensation to constant voltage loop error amplifier 20, are output as PI compensation (compensating resistance Rc and building-out capacitor Cc series compensation); The end ground connection of said building-out capacitor Cc, the other end connects the end of compensating resistance Rc, and the other end of compensating resistance Rc connects the output of trsanscondutance amplifier Gm.

See also Fig. 8, said tunable low pass filter 40 comprises inverter INV1, first switch S 1, second switch S1b, first capacitor C 1, second capacitor C 2.Said tunable low pass filter-the 3dB Frequency point controlled F_PWM as shown in Figure 8 by pwm signal.First switch S 1, second switch S1b and first capacitor C 1, second capacitor C 2 have been formed the switching capacity low pass filter, are output as V_Lpf.

The output voltage V comp of constant voltage loop error amplifier 20 is connected with an end of first switch S 1, and the other end of first switch S 1 is connected with second switch S1b.First switch S 1 connects first capacitor C 1, and second switch S1b connects second capacitor C 2; The control signal of first switch S 1, second switch S1b is reverse, and INV1 controls through inverter; First switch S 1 is connected with the end of inverter INV1, and second switch S1b is connected with the other end of inverter INV1.

It among Fig. 9 the amplitude-frequency response of tunable low pass filter.Can find out that therefrom the F_PWM frequency is high more, filter-the 3dB dot frequency is just high more.The F_PWM frequency is low more, filter-the 3dB dot frequency is just low more.

See also Figure 10, said voltage current adapter 50 comprises that operational amplifier A 2, the 3rd resistance R 1, NMOS manage M1, and the current mirror formed of PMOS pipe M2, PMOS pipe M3; Voltage current adapter 50 is realized the electric current and voltage conversion, and the conversion output current is Icable, outputs to chip FB pin, thereby realizes line loss compensation control.

The output of the grid concatenation operation amplifier A2 of NMOS pipe M1; The source electrode of NMOS pipe M1 connects an end of the 3rd resistance R 1, the input of the same end concatenation operation amplifier A2 of the 3rd resistance R 1.The drain electrode of NMOS pipe M1 connects drain electrode, the grid of PMOS pipe M2, and the grid of PMOS pipe M3.

More than introduced the composition of the Switching Power Supply line loss bucking-out system of the former limit of the present invention FEEDBACK CONTROL; The present invention is when disclosing said system; Also disclose the compensation process of the Switching Power Supply line loss bucking-out system of a kind of above-mentioned former limit FEEDBACK CONTROL, said method comprises the steps:

[step S1] sampling hold circuit carries out the platform sampling to auxiliary winding, and output voltage is designated as voltage V_SH;

[step S2] voltage V_SH carries out error ratio through constant voltage loop error amplifier and reference voltage Vref and amplifies, and output voltage V comp is to tunable low pass filter;

The control signal of [step S3] tunable low pass filter is the PWM output signal of chip, and tunable low pass filter is output as voltage V_Lpf;

[step S4] voltage V_Lpf is through voltage current adapter output line loss offset current Icable; Line loss offset current Icable compensates the pressure drop of output cable Rcable.

Embodiment two

See also Fig. 7, the difference of present embodiment and embodiment one is that in the present embodiment, said constant voltage loop error amplifier 20 is a fixed gain amplifier.Said compensating network comprises the first resistance R c1, the second resistance R c2; The end of the first resistance R c1 connects reference voltage Vref, and the other end connects the negative pole of fixed gain amplifier; The end of the second resistance R c2 connects the negative pole of fixed gain amplifier, and the other end connects the output of fixed gain amplifier; Voltage V_SH inserts the positive pole of fixed gain amplifier.It is the function of Rc2/Rc1 that constant voltage loop error amplifier 20 is accomplished the amplification fixed gain.

In sum; The Switching Power Supply line loss bucking-out system and the method for the former limit FEEDBACK CONTROL that the present invention proposes; Can be applicable to the line loss compensation field, that need not external compensation electric capacity or resistance of former limit feedback, can compensate the line loss pressure drop of output lead, thereby realize the constant of output voltage.

The present invention only is that the mode with example is applied to supply convertor.But will be appreciated that the present invention has more wide applications.

Here description of the invention and application is illustrative, is not to want with scope restriction of the present invention in the above-described embodiments.Here the distortion of the embodiment that is disclosed and change are possible, and the replacement of embodiment is known with the various parts of equivalence for those those of ordinary skill in the art.Those skilled in the art are noted that under the situation that does not break away from spirit of the present invention or substantive characteristics, and the present invention can be with other form, structure, layout, ratio, and realize with other assembly, material and parts.Under the situation that does not break away from the scope of the invention and spirit, can carry out other distortion and change here to the embodiment that is disclosed.

Claims (10)

1. the Switching Power Supply line loss bucking-out system of a former limit FEEDBACK CONTROL is characterized in that said system comprises: sampling hold circuit, constant voltage loop error amplifier, compensating network, tunable low pass filter, voltage current adapter;

Said sampling hold circuit, constant voltage loop error amplifier, tunable low pass filter, voltage current adapter connect successively; The output of voltage current adapter inserts sampling hold circuit, and said compensating network connects the input and the output of constant voltage loop error amplifier respectively;

Said sampling hold circuit carries out the platform sampling to auxiliary winding, and output voltage is designated as voltage VSH;

Voltage V_SH carries out error ratio through constant voltage loop error amplifier and reference voltage Vref and amplifies, and output voltage V comp is to tunable low pass filter;

The control signal of said tunable low pass filter is the PWM output signal of chip, and tunable low pass filter is output as voltage V_Lpf;

Voltage V_Lpf is through voltage current adapter output line loss offset current Icable; Line loss offset current Icable compensates the pressure drop of output cable Rcable.

2. the Switching Power Supply line loss bucking-out system of former limit according to claim 1 FEEDBACK CONTROL is characterized in that:

Said constant voltage loop error amplifier is trsanscondutance amplifier Gm;

Building-out capacitor Cc and compensating resistance Rc that said compensating network comprises series connection carry out series compensation to constant voltage loop error amplifier;

The end ground connection of said building-out capacitor Cc, the other end connects the end of compensating resistance Rc, and the other end of compensating resistance Rc connects the output of trsanscondutance amplifier Gm.

3. the Switching Power Supply line loss bucking-out system of former limit according to claim 1 FEEDBACK CONTROL is characterized in that:

Said constant voltage loop error amplifier is a fixed gain amplifier;

Said compensating network comprises the first resistance R c1, the second resistance R c2; The end of the first resistance R c1 connects reference voltage Vref, and the other end connects the negative pole of fixed gain amplifier; The end of the second resistance R c2 connects the negative pole of fixed gain amplifier, and the other end connects the output of fixed gain amplifier; Voltage V_SH inserts the positive pole of fixed gain amplifier.

4. according to the Switching Power Supply line loss bucking-out system of the described former limit of one of claim 1 to 3 FEEDBACK CONTROL, it is characterized in that:

Said tunable low pass filter comprises inverter INV1, first switch S 1, second switch S1b, first capacitor C 1, second capacitor C 2;

The Frequency point of said tunable low pass filter is controlled by pwm signal; The output voltage V comp of constant voltage loop error amplifier is connected with an end of first switch S 1, and the other end of first switch S 1 is connected with second switch S1b;

First switch S 1 connects first capacitor C 1, and second switch S1b connects second capacitor C 2; The control signal of first switch S 1, second switch S1b is reverse, and INV1 controls through inverter; First switch S 1 is connected with the end of inverter INV1, and second switch S1b is connected with the other end of inverter INV1.

5. according to the Switching Power Supply line loss bucking-out system of the described former limit of one of claim 1 to 3 FEEDBACK CONTROL, it is characterized in that:

Said voltage current adapter comprises that operational amplifier A 2, the 3rd resistance R 1, NMOS manage M1, and the current mirror formed of PMOS pipe M2, PMOS pipe M3;

The output of the grid concatenation operation amplifier A2 of NMOS pipe M1; The source electrode of NMOS pipe M1 connects an end of the 3rd resistance R 1, the input of the same end concatenation operation amplifier A2 of the 3rd resistance R 1;

The drain electrode of NMOS pipe M1 connects drain electrode, the grid of PMOS pipe M2, and the grid of PMOS pipe M3.

6. the compensation process of the Switching Power Supply line loss bucking-out system of the said former limit of claim 1 FEEDBACK CONTROL is characterized in that said method comprises the steps:

Step S1, sampling hold circuit carry out the platform sampling to auxiliary winding, and output voltage is designated as voltage V_SH;

Step S2, voltage V_SH carry out error ratio through constant voltage loop error amplifier and reference voltage Vref and amplify, and output voltage V comp is to tunable low pass filter;

The control signal of step S3, tunable low pass filter is the PWM output signal of chip, and tunable low pass filter is output as voltage V_Lpf;

Step S4, voltage V_Lpf are through voltage current adapter output line loss offset current Icable; Line loss offset current Icable compensates the pressure drop of output cable Rcable.

7. compensation process according to claim 6 is characterized in that:

Said constant voltage loop error amplifier is trsanscondutance amplifier Gm;

Building-out capacitor Cc and compensating resistance Rc that said compensating network comprises series connection carry out series compensation to constant voltage loop error amplifier;

The end ground connection of said building-out capacitor Cc, the other end connects the end of compensating resistance Rc, and the other end of compensating resistance Rc connects the output of trsanscondutance amplifier Gm.

8. compensation process according to claim 6 is characterized in that:

Said constant voltage loop error amplifier is a fixed gain amplifier;

Said compensating network comprises the first resistance R c1, the second resistance R c2; The end of the first resistance R c1 connects reference voltage Vref, and the other end connects the negative pole of fixed gain amplifier; The end of the second resistance R c2 connects the negative pole of fixed gain amplifier, and the other end connects the output of fixed gain amplifier; Voltage V_SH inserts the positive pole of fixed gain amplifier.

9. according to claim 7 or 8 described compensation processes, it is characterized in that:

Said tunable low pass filter comprises inverter INV1, first switch S 1, second switch S1b, first capacitor C 1, second capacitor C 2;

The Frequency point of said tunable low pass filter is controlled by pwm signal; The output voltage V comp of constant voltage loop error amplifier is connected with an end of first switch S 1, and the other end of first switch S 1 is connected with second switch S1b;

First switch S 1 connects first capacitor C 1, and second switch S1b connects second capacitor C 2; The control signal of first switch S 1, second switch S1b is reverse, and INV1 controls through inverter; First switch S 1 is connected with the end of inverter INV1, and second switch S1b is connected with the other end of inverter INV1.

10. according to claim 7 or 8 described compensation processes, it is characterized in that:

Said voltage current adapter comprises that operational amplifier A 2, the 3rd resistance R 1, NMOS manage M1, and the current mirror formed of PMOS pipe M2, PMOS pipe M3;

The output of the grid concatenation operation amplifier A2 of NMOS pipe M1; The source electrode of NMOS pipe M1 connects an end of the 3rd resistance R 1, the input of the same end concatenation operation amplifier A2 of the 3rd resistance R 1;

The drain electrode of NMOS pipe M1 connects drain electrode, the grid of PMOS pipe M2, and the grid of PMOS pipe M3.

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