CN201063531Y - Power supply converting circuit and pulse width modulation controller - Google Patents

Abstract

The utility model discloses a pulse width modulation PWM controller. The input end of a line voltage compensation circuit in the PWM controller is connected to an output pin of a peak current comparator of the PWM controller, the output end of the line voltage compensation circuit is connected with a PWM comparator of the PWM controller. The utility model also discloses an electrical source conversion circuit which uses the PWM controller. The PWM controller and the electrical source conversion circuit of the utility model can limit the maximum value of the peak current Ipk at the moment of output short circuit; at the same time, the discharge input end of the PWM controller discharges to prolong the restart cycle of the whole circuit system, which has effective short-circuit protection effect.

Description

Power converting circuit and Pwm controller thereof

Technical field

The utility model relates to the power management techniques field, more particularly, relate to and adopt pulse width modulation mode to carry out the power management techniques of power conversion, especially low power pulse width modulation controlled scheme particularly has the power converting circuit of line voltage compensation and the PWM controller of use thereof.

Background technology

The PWM technology is in the widely used technology of field of power conversion, can be used for controlling and adjustment output voltage and power output in the AC-DC of the adapter of realizing portable equipment and charger scheme uses.The scheme of present lower wattage power supply converter mainly is that transformer time limit employing discharge circuit is realized constant current, and voltage reference circuit is realized constant voltage, or adopts voltage reference circuit to realize constant voltage and triode realization constant current.In actual use, each scheme all needs to add various defencive functions such as over-voltage and over-current, permanent power, short circuit and open-circuit-protection, protects whole supply convertor, in order to avoid cause nonvolatil damage.Widely used at present various PWM controllers nearly all are to adopt gate driving, and the power input of monitoring PWM controller is realized short-circuit protection function.

A kind of novel PWM controller adopts the emitter type of drive, has reduced the pin of PWM controller, compares with the PWM controller of traditional employing gate driving, has reduced system cost.Its power input is again the optocoupler feedback end simultaneously, and after system's output short circuit, output voltage descends; enter the pattern of restarting; peak inrush current is along with the rising of line voltage is restricted, and discharge path works simultaneously, unites and plays effective short-circuit protection effect.

Following formula shows the relation between power output of the present invention and each parameter:

$P_{\mathrm{out}}=\frac{{V_{\mathrm{out}}}^2}{R_{\mathrm{out}}}=P_{\mathrm{in}}*\mathrm{\&eta;}=\frac{1}{2}{L}_{\mathrm{<figure-callout\; id="2"\; label="P\; I\; pk"\; filenames="Y20072015568900241.png"\; state="\{\{state\}\}">P</figure-callout>}}{I_{\mathrm{pk}}}^{}{{}_{}}^2*f*\mathrm{\&eta;}$

$I_{\mathrm{PK}}=\frac{V_{\mathrm{IN}}}{L_P}*t_{\mathrm{ON}}$ $P_{\mathrm{out}}=\frac{V_{\mathrm{IN}}^2*t_{\mathrm{ON}}^2*\mathrm{\&eta;}}{2*T*L_P}$

Wherein, P _OutBe power output, V _OutBe output voltage, R _OutBe output resistance, P _InBe input power, L _pBe the former limit of transformer inductance, I _PkBe that former limit peak current, f are that frequency of oscillation, the T of PWM controller is the cycle of oscillation of PWM controller, conversion efficiency, the t that η is supply convertor _OnIt is the opening time of former limit controller.

By top formula as seen, the peak power output of entire circuit system increases with the rising of line voltage, and the input range of line voltage is 90-264V (ac), and the maximum power PH of high pressure section will be 8.6 times of maximum power PL of low pressure stage.,, need be further improved to eliminate this danger because of the too big overheated danger that aircraft bombing occurs of generating device easily of input power at high pressure section this circuit for this reason.

The utility model content

The purpose of this utility model is to provide a kind of have the PWM controller of line voltage compensation function and the power converting circuit that uses this controller, this circuit still adopts the PWM controller of emitter type of drive, in the compensation of the basic enterprising line voltage that makes full use of the emitter type of drive, eliminate the excessive and danger of the aircraft bombing that causes of power effectively.

According to an aspect of the present utility model, a kind of pulse width modulation (PWM) controller is provided, the input of the line voltage compensation circuit in this PWM controller is connected the output pin of the peak current comparator of this PWM controller, and the output of this line voltage compensation circuit connects the PWM comparator of this PWM controller.

According to an embodiment, this PWM controller comprises five outside input/output interfaces: the output drive end that drives the external power pipe; The power supply input anode of this PWM controller; The sampling input of detection line change in voltage; The power supply input negative terminal of this PWM controller; The discharge input that possesses discharging function.

According to an embodiment, this PWM controller comprises:

Start-up circuit, be connected with the output drive end with power supply input anode, be also connected to the first undervoltage lockout UVLO comparator, by UVLO comparator control, start-up circuit determines the minimum operating voltage of this power supply input anode when starting instantaneous threshold operating voltage and operate as normal;

Clock circuit, the square-wave signal of generation fixed frequency, the output of this clock circuit is connected to the PWM logical circuit;

The internal reference circuit produces a reference voltage, and this reference voltage is the reference level as each comparator input terminal;

The one UVLO comparator, an input termination power input anode of a UVLO comparator, another input termination reference voltage, start-up circuit and PWM logical circuit are received in the output of a UVLO comparator respectively;

Error amplifier, one input termination power input anode of this error amplifier, another input termination input error voltage, this error voltage is that an input of PWM comparator is received in the output of this error amplifier as the control signal of regulating the output signal duty ratio;

The current peak comparator, the current sampling signal of connection output driving circuit is realized the current loop feedback, the output of this current peak comparator is connected to an input of line voltage compensation circuit;

The line voltage compensation circuit, one input of this line voltage compensation circuit connects the sampling input, another input connects the output of current peak comparator, and this line voltage compensation circuit is realized line voltage compensation control and current feedback signal and voltage feedback signal are outputed to the PWM comparator;

The PWM comparator receives the output from error amplifier and line voltage compensation circuit, is applied to the PWM logic control circuit with the form output signal of error signal;

The PWM logical circuit, the output of receive clock circuit, square-wave signal in response to clock circuit output, also receive the error signal of PWM comparator output, the duty ratio of decision output driving pulse, the output of PWM logical circuit is received driving tube by drive circuit and is passed through output drive end output drive signal;

The 2nd UVLO comparator, the threshold voltage of the supply voltage the during conducting of decision discharge loop;

Discharge tube is connected to the discharge input that possesses discharging function, and discharge tube reduces system voltage;

Charge/discharge control circuit, the switch of control discharge tube.

According to an embodiment, the current peak comparator comprises with the line voltage compensation circuit: be connected in series first branch road that forms successively by the 7th resistance, the 8th resistance and the 9th resistance, and be connected in series second branch road that forms successively by the tenth resistance, the 11 resistance and the 12 resistance; Wherein, the 9th resistance and the 12 grounding through resistance, the sampling input of detection line change in voltage are connected between the 7th resistance and the 8th resistance, and the input of current peak comparator is between the 8th resistance and the 9th resistance, and the tenth resistance is connected to the PWM comparator.

According on the other hand of the present utility model, a kind of power converting circuit is provided, the input of the line voltage compensation circuit of the pulse width modulation (PWM) controller in this power converting circuit is connected the output pin of the peak current comparator of this PWM controller, and the output of this line voltage compensation circuit connects the PWM comparator of this PWM controller.

According to an embodiment, this power converting circuit comprises:

The PWM controller, have five outside input/output interfaces, comprise: the output drive end of driving external power pipe, power supply input anode, the sampling input of detection line change in voltage, power supply are imported negative terminal and are possessed the discharge input of discharging function, wherein, power supply input negativing ending grounding, power supply input anode is connected to one the 3rd electric capacity;

Power tube is connected to the output drive end of PWM controller;

Transformer, the winding of one side is connected to power tube, and the winding of opposite side connects output voltage, and the sampling input collection of the detection line change in voltage of PWM controller connects the line voltage of the winding of power tube one side;

Optocoupler, the power supply that is connected to the PWM controller is imported anode and the discharge input that possesses discharging function, also couples feedback control loop;

Feedback control loop comprises the 4th resistance, the 5th resistance, the 6th resistance, the 4th electric capacity and voltage reference circuit.

According to an embodiment, the PWM controller in this power converting circuit comprises:

Start-up circuit, be connected with the output drive end with power supply input anode, be also connected to the first undervoltage lockout UVLO comparator, by UVLO comparator control, start-up circuit determines the minimum operating voltage of this power supply input anode when starting instantaneous threshold operating voltage and operate as normal;

Clock circuit, the square-wave signal of generation fixed frequency, the output of this clock circuit is connected to the PWM logical circuit;

The internal reference circuit produces a reference voltage, and this reference voltage is the reference level as each comparator input terminal;

The one UVLO comparator, an input termination power input anode of a UVLO comparator, another input termination reference voltage, start-up circuit and PWM logical circuit are received in the output of a UVLO comparator respectively;

Error amplifier, one input termination power input anode of this error amplifier, another input termination input error voltage, this error voltage is that an input of PWM comparator is received in the output of this error amplifier as the control signal of regulating the output signal duty ratio;

The current peak comparator, the current sampling signal of connection output driving circuit is realized the current loop feedback, the output of this current peak comparator is connected to an input of line voltage compensation circuit;

The line voltage compensation circuit, one input of this line voltage compensation circuit connects the sampling input, another input connects the output of current peak comparator, and this line voltage compensation circuit is realized line voltage compensation control and current feedback signal and voltage feedback signal are outputed to the PWM comparator;

The PWM comparator receives the output from error amplifier and line voltage compensation circuit, is applied to the PWM logic control circuit with the form output signal of error signal;

The PWM logical circuit, the output of receive clock circuit, square-wave signal in response to clock circuit output, also receive the error signal of PWM comparator output, the duty ratio of decision output driving pulse, the output of PWM logical circuit is received driving tube by drive circuit and is passed through output drive end output drive signal;

The 2nd UVLO comparator, the threshold voltage of the supply voltage the during conducting of decision discharge loop;

Discharge tube is connected to the discharge input that possesses discharging function, and discharge tube reduces system voltage;

Charge/discharge control circuit, the switch of control discharge tube.

According to an embodiment, PWM controller in this power converting circuit, its current peak comparator comprises with the line voltage compensation circuit: be connected in series first branch road that forms successively by the 7th resistance, the 8th resistance and the 9th resistance, and be connected in series second branch road that forms successively by the tenth resistance, the 11 resistance and the 12 resistance; Wherein, the 9th resistance and the 12 grounding through resistance, the sampling input of detection line change in voltage are connected between the 7th resistance and the 8th resistance, and the input of current peak comparator is between the 8th resistance and the 9th resistance, and the tenth resistance is connected to the PWM comparator.

PWM controller of the present utility model and power converting circuit can be at output short-circuit constantly with peak current I _PkMaximum limit, the discharge input of PWM controller discharge is simultaneously elongated the entire circuit system and is restarted the cycle, plays effective short-circuit protection effect.

Description of drawings

The above and other feature of the present utility model, character and advantage will by below in conjunction with accompanying drawing to the description of embodiment and more obvious, in the accompanying drawings, identical Reference numeral is represented identical feature all the time, wherein,

Fig. 1 shows the structure chart according to the PWM controller of an embodiment of the present utility model;

Fig. 2 shows a kind of circuit diagram of realizing of current peak comparator and line voltage compensation circuit and part correlation circuit in the PWM controller of the foregoing description;

Fig. 3 shows the oscillogram of the main signal of circuit shown in Figure 2;

Fig. 4 shows the oscillogram of signal of each port of the PWM controller of embodiment shown in Figure 1;

Fig. 5 shows the structure chart according to the embodiment of a power converting circuit of the present utility model.

Embodiment

The purpose of this utility model is to provide a kind of have the PWM controller of line voltage compensation function and the power converting circuit that uses this controller, this circuit still adopts the PWM controller of emitter type of drive, in the compensation of the basic enterprising line voltage that makes full use of the emitter type of drive, eliminate the excessive and danger of the aircraft bombing that causes of power effectively.

According to the utility model, a kind of pulse width modulation (PWM) controller at first is provided, the input of the line voltage compensation circuit in this PWM controller is connected the output pin of the peak current comparator of this PWM controller, and the output of this line voltage compensation circuit connects the PWM comparator of this PWM controller.

According to an embodiment, this PWM controller comprises five outside input/output interfaces, is respectively: the output drive end OUT that drives the external power pipe; The power supply input anode VCC of this PWM controller; The sampling input VS of detection line change in voltage; The power supply input negative terminal GND of this PWM controller; The discharge input VA that possesses discharging function.

With reference to embodiment shown in Figure 1, this PWM controller 100 comprises:

Start-up circuit 201, be connected with output drive end OUT with power supply input anode VCC, be also connected to the first undervoltage lockout UVLO comparator 203, by a UVLO comparator 203 controls, the minimum operating voltage of start-up circuit 201 decisions this power supply input anode VCC when starting instantaneous threshold operating voltage and operate as normal;

Clock circuit 208, the square-wave signal of generation fixed frequency, the output of this clock circuit 208 is connected to PWM logical circuit 206;

Internal reference circuit 202 produces a reference voltage V ref, and this reference voltage V ref is the reference level as inner each comparator input terminal;

One input termination power input anode VCC of the one UVLO comparator 203, the one UVLO comparators 203, another input termination reference voltage V ref, start-up circuit 201 and PWM logical circuit 206 are received in the output of a UVLO comparator 203 respectively;

Error amplifier 204, one input termination power input anode VCC of this error amplifier 204, another input termination input error voltage VCC_Err, this error voltage VCC_Err is that an input of PWM comparator 205 is received in the output of this error amplifier 204 as the control signal of regulating the output signal duty ratio;

Current peak comparator 210, the current sampling signal of connection output driving circuit 209 is realized the current loop feedback, the output of this current peak comparator 210 is connected to an input of line voltage compensation circuit 211;

Line voltage compensation circuit 211, one input of this line voltage compensation circuit 211 connects sampling input VS, another input connects the output of current peak comparator 210, this line voltage compensation circuit 211 is realized line voltage compensation control and current feedback signal and voltage feedback signal is outputed to PWM comparator 205;

PWM comparator 205 receives the output from error amplifier 204 and line voltage compensation circuit 211, is applied to PWM logic control circuit 206 with the form output signal of error signal;

PWM logical circuit 206, the output of receive clock circuit 208, square-wave signal in response to clock circuit 208 outputs, also receive the error signal of PWM comparator 205 outputs, the duty ratio of decision output driving pulse, the output of PWM logical circuit 206 receives driving tube 209 by drive circuit 207 and by output drive end OUT output drive signal, this drive signal will drive the power tube Q1 of PWM controller 100 outsides;

The 2nd UVLO comparator 212, the threshold voltage of the supply voltage the during conducting of decision discharge loop;

Discharge tube 214 is connected to the discharge input VA that possesses discharging function, and discharge tube 214 reduces system voltage; The cycle is restarted in the broadening system, and the associating max power constraint reaches effective short-circuit protection effect;

Charge/discharge control circuit 213, the switch of control discharge tube 214.

With reference to figure 2, Fig. 2 shows a kind of circuit diagram of realizing of current peak comparator and line voltage compensation circuit and part correlation circuit in the PWM controller of the foregoing description.According to this embodiment, current peak comparator 210 comprises with line voltage compensation circuit 211:

Be connected in series first branch road that forms successively by the 7th resistance R 11, the 8th resistance R 21 and the 9th resistance R 31, and

Be connected in series second branch road that forms successively by the tenth resistance R the 12, the 11 resistance R 22 and the 12 resistance R 32;

Wherein, the 9th resistance R 31 and the 12 resistance R 32 ground connection, the sampling input VS of detection line change in voltage is connected between the 7th resistance R 11 and the 8th resistance R 21, the input of current peak comparator 210 is between the 8th resistance R 21 and the 9th resistance R 31, and the tenth resistance R 12 is connected to PWM comparator 205.

First branch road is also connected to the first metal-oxide-semiconductor M1, second branch road is also connected to the second metal-oxide-semiconductor M2, be drawn out to the negative input end of PWM comparator 205 between the first metal-oxide-semiconductor M1 and the 7th resistance R 11, be drawn out to the positive input terminal of PWM comparator 205 between the second metal-oxide-semiconductor M2 and the tenth resistance R 12.The first metal-oxide-semiconductor M1 also connects reference voltage V ref, and the second metal-oxide-semiconductor M2 also connects error voltage VCC_Err.The first metal-oxide-semiconductor M1 and the second metal-oxide-semiconductor M2 together constitute error amplifier 204.

According to circuit diagram shown in Figure 2, when positive input voltage VCC reduces, when maximum duty cycle Dmax occurring, error voltage VCC_Err is less than reference voltage V ref, the bias current Ibias second metal-oxide-semiconductor M2 that almost all flows through, and the peak current of this moment is:

Ibias*(R12+R22+R32)＝Iline*(R21+R31)+Isense*R31；

Isense＝Ipk/K；

Iline＝Vin/R1；

$\mathrm{Ipk}=\frac{\mathrm{Ibias}*(R12+R22+R32)-\mathrm{Vin}*(R21+R31)/R1}{R31}*K;$

Wherein, I _BiasBe the bias current of error amplifier, I _LineElectric current for the introducing of line voltage.I _PkBe the former limit of transformer peak current, I _SenseBe the proportional current of former limit peak current, wherein proportionality coefficient is K, V _InBe line voltage, the 7th resistance R 11 is a line voltage compensation resistance, and the 8th resistance R 21, the 9th resistance R 31, the tenth resistance R the 12, the 11 resistance R 22 and the 12 resistance R 32 are the load resistance of error amplifier.

Choose the resistance ratio, peak current I _PkBasicly stable with the rising of line voltage;

$P_{\mathrm{out}}=\frac{{V_{\mathrm{out}}}^2}{R_{\mathrm{out}}}=P_{\mathrm{in}}*\mathrm{\&eta;}=\frac{1}{2}{L}_{\mathrm{<figure-callout\; id="2"\; label="P\; I\; pk"\; filenames="Y20072015568900241.png"\; state="\{\{state\}\}">P</figure-callout>}}{I_{\mathrm{pk}}}^{}{{}_{}}^2*f*\mathrm{\&eta;}$

Like this peak power output can be improved significantly.

Fig. 3 shows the oscillogram of the main signal of circuit shown in Figure 2, and wherein, abscissa is represented input voltage, and ordinate is represented peak current.Wherein,

Waveform I _Pk1Expression: the peak current curve that does not add line voltage compensation

Waveform I _Pk2Expression: the actual peak current slope curve in compensation back.

Waveform I _{Line_current}Expression: be the line voltage compensation current curve that adds.

The formula that reference is following:

Ipk2＝Ipk1-Iline_current

As seen, after the peak current that does not add line voltage compensation deducts the line voltage compensation electric current of adding, be the peak current curve after the compensation.

With reference to figure 4, Fig. 4 shows the oscillogram of signal of each port of the PWM controller of embodiment shown in Figure 1.This PWM controller has five ports that outwards connect, the V among Fig. 4 _OutBe expressed as the waveform of the power converting circuit system output that the PWM controller of embodiment uses.VCC represents the waveform of input voltage VCC at the power supply input anode VCC place of PWM controller.VA represents to possess the waveform of discharge voltage VA at the discharge input VA place of discharging function.DRV represents to drive the waveform of outputting drive voltage at the output drive end OUT place of external power pipe.IPK represents the waveform of the crest voltage Ipk in the entire circuit system.

According on the other hand of the present utility model, a kind of power converting circuit also is provided, the input of the line voltage compensation circuit of the pulse width modulation (PWM) controller in this power converting circuit is connected the output pin of the peak current comparator of this PWM controller, and the output of this line voltage compensation circuit connects the PWM comparator of this PWM controller.

With reference to shown in Figure 5, Fig. 5 shows the structure chart according to the embodiment of a power converting circuit of the present utility model.This power converting circuit comprises:

PWM controller U1, have five outside input/output interfaces, comprise: the output drive end OUT of driving external power pipe, power supply input anode VCC, the sampling input VS of detection line change in voltage, power supply are imported negative terminal GND and are possessed the discharge input VA of discharging function, wherein, power supply input negative terminal GND ground connection, power supply input anode VCC is connected to one the 3rd capacitor C 3;

Power tube Q1 is connected to the output drive end OUT of PWM controller U1;

Transformer T1, the winding of one side is connected to power tube Q1, and the winding of opposite side connects output voltage, and the sampling input VS of the detection line change in voltage of PWM controller U1 gathers the line voltage of the winding that connects power tube Q1 one side;

Optocoupler U3, the power supply that is connected to PWM controller U1 is imported anode VCC and the discharge input VA that possesses discharging function, also couples feedback control loop;

Feedback control loop comprises the 4th resistance R 4, the 5th resistance R 5, the 6th resistance R 6, the 4th capacitor C 4 and voltage reference circuit U2.

The operation principle of this power converting circuit is: by the output drive end OUT of the line voltage Vin after the rectification via first resistance R 1, PWM controller U1, VCC provides the startup energy to power supply input anode, finishes the start-up course of system.The power supply energy of PWM controller U1 then mainly is provided from the auxiliary winding 103 of transformer T1 during operate as normal.PWM controller U1 driving power pipe Q1, the winding 101 by transformer T1 and 102 provides energy to output drive end OUT, and the voltage of output drive end OUT is raise; When output drive end OUT arrives rated voltage,, make optocoupler U3 conducting by feedback control loop, the VCC terminal voltage of PWM controller is raise, thereby reduce to export duty of ratio (ton/T), reduce to be delivered to the energy of output drive end OUT, make Vout keep constant.

Equally, in this power converting circuit, this PWM controller can comprise following structure, and itself and top 1,2 described PWM controllers in conjunction with the accompanying drawings have same structure:

Start-up circuit 201, be connected with output drive end OUT with power supply input anode VCC, be also connected to the first undervoltage lockout UVLO comparator 203, by a UVLO comparator 203 controls, the minimum operating voltage of start-up circuit 201 decisions this power supply input anode VCC when starting instantaneous threshold operating voltage and operate as normal;

Clock circuit 208, the square-wave signal of generation fixed frequency, the output of this clock circuit 208 is connected to PWM logical circuit 206;

Internal reference circuit 202 produces a reference voltage V ref, and this reference voltage V ref is the reference level as inner each comparator input terminal;

One input termination power input anode VCC of the one UVLO comparator 203, the one UVLO comparators 203, another input termination reference voltage V ref, start-up circuit 201 and PWM logical circuit 206 are received in the output of a UVLO comparator 203 respectively;

Error amplifier 204, one input termination power input anode VCC of this error amplifier 204, another input termination input error voltage VCC_Err, this error voltage VCC_Err is that an input of PWM comparator 205 is received in the output of this error amplifier 204 as the control signal of regulating the output signal duty ratio;

Current peak comparator 210, the current sampling signal of connection output driving circuit 209 is realized the current loop feedback, the output of this current peak comparator 210 is connected to an input of line voltage compensation circuit 211;

Line voltage compensation circuit 211, one input of this line voltage compensation circuit 211 connects sampling input VS, another input connects the output of current peak comparator 210, this line voltage compensation circuit 211 is realized line voltage compensation control and current feedback signal and voltage feedback signal is outputed to PWM comparator 205;

PWM comparator 205 receives the output from error amplifier 204 and line voltage compensation circuit 211, is applied to PWM logic control circuit 206 with the form output signal of error signal;

PWM logical circuit 206, the output of receive clock circuit 208, square-wave signal in response to clock circuit 208 outputs, also receive the error signal of PWM comparator 205 outputs, the duty ratio of decision output driving pulse, the output of PWM logical circuit 206 receives driving tube 209 by drive circuit 207 and by output drive end OUT output drive signal, this drive signal will drive the power tube Q1 of PWM controller 100 outsides;

The 2nd UVLO comparator 212, the threshold voltage of the supply voltage the during conducting of decision discharge loop;

Discharge tube 214 is connected to the discharge input VA that possesses discharging function, and discharge tube 214 reduces system voltage; The cycle is restarted in the broadening system, and the associating max power constraint reaches effective short-circuit protection effect;

Charge/discharge control circuit 213, the switch of control discharge tube 214.

Similarly, a kind of circuit diagram of realizing of current peak comparator and line voltage compensation circuit and part correlation circuit in this PWM controller.According to this embodiment, current peak comparator 210 comprises with line voltage compensation circuit 211:

Be connected in series first branch road that forms successively by the 7th resistance R 11, the 8th resistance R 21 and the 9th resistance R 31, and

Be connected in series second branch road that forms successively by the tenth resistance R the 12, the 11 resistance R 22 and the 12 resistance R 32;

Wherein, the 9th resistance R 31 and the 12 resistance R 32 ground connection, the sampling input VS of detection line change in voltage is connected between the 7th resistance R 11 and the 8th resistance R 21, the input of current peak comparator 210 is between the 8th resistance R 21 and the 9th resistance R 31, and the tenth resistance R 12 is connected to PWM comparator 205.

First branch road is also connected to the first metal-oxide-semiconductor M1, second branch road is also connected to the second metal-oxide-semiconductor M2, be drawn out to the negative input end of PWM comparator 205 between the first metal-oxide-semiconductor M1 and the 7th resistance R 11, be drawn out to the positive input terminal of PWM comparator 205 between the second metal-oxide-semiconductor M2 and the tenth resistance R 12.The first metal-oxide-semiconductor M1 also connects reference voltage V ref, and the second metal-oxide-semiconductor M2 also connects error voltage VCC_Err.The first metal-oxide-semiconductor M1 and the second metal-oxide-semiconductor M2 together constitute error amplifier 204.

PWM controller of the present utility model and power converting circuit can limit the maximum of peak current Ipk constantly at output short-circuit; the discharge input of PWM controller discharge simultaneously; elongate the entire circuit system and restart the cycle, play effective short-circuit protection effect.

The foregoing description provides to being familiar with the person in the art and realizes or use of the present utility model; those skilled in the art can be under the situation that does not break away from invention thought of the present utility model; the foregoing description is made various modifications or variation; thereby protection range of the present utility model do not limit by the foregoing description, and should be the maximum magnitude that meets the inventive features that claims mention.

Claims (8)

1. a pulse width modulation (PWM) controller is characterized in that,

The input of the line voltage compensation circuit in this PWM controller is connected the output pin of the peak current comparator of this PWM controller, and the output of this line voltage compensation circuit connects the PWM comparator of this PWM controller.

2. PWM controller as claimed in claim 1 is characterized in that, this PWM controller comprises five outside input/output interfaces:

Drive the output drive end (OUT) of external power pipe;

The power supply input anode (VCC) of this PWM controller;

The sampling input (VS) of detection line change in voltage;

The power supply input negative terminal (GND) of this PWM controller;

The discharge input (VA) that possesses discharging function.

3. PWM controller as claimed in claim 2 is characterized in that, this PWM controller comprises:

Start-up circuit (201), be connected with output drive end (OUT) with power supply input anode (VCC), be also connected to the first undervoltage lockout UVLO comparator (203), by a UVLO comparator (203) control, described start-up circuit (201) determines the minimum operating voltage of this power supply input anode (VCC) when starting instantaneous threshold operating voltage and operate as normal;

Clock circuit (208), the square-wave signal of generation fixed frequency, the output of this clock circuit (208) is connected to PWM logical circuit (206);

Internal reference circuit (202) produces a reference voltage (Vref), and this reference voltage (Vref) is the reference level as each comparator input terminal;

The one UVLO comparator (203), one input termination power input anode (VCC) of the one UVLO comparator (203), another imports termination reference voltage (Vref), and start-up circuit (201) and PWM logical circuit (206) are received in the output of a UVLO comparator (203) respectively;

Error amplifier (204), the one input termination power input anode (VCC) of this error amplifier (204), another imports termination input error voltage (VCC_Err), this error voltage (VCC_Err) is that an input of PWM comparator (205) is received in the output of this error amplifier (204) as the control signal of regulating the output signal duty ratio;

Current peak comparator (210), the current sampling signal of connection output driving circuit (209) is realized the current loop feedback, the output of this current peak comparator (210) is connected to an input of line voltage compensation circuit (211);

Line voltage compensation circuit (211), one input of this line voltage compensation circuit (211) connects sampling input (VS), another input connects the output of current peak comparator (210), this line voltage compensation circuit (211) is realized line voltage compensation control and current feedback signal and voltage feedback signal is outputed to PWM comparator (205);

PWM comparator (205) receives the output from error amplifier (204) and line voltage compensation circuit (211), is applied to PWM logic control circuit (206) with the form output signal of error signal;

PWM logical circuit (206), the output of receive clock circuit (208), square-wave signal in response to clock circuit (208) output, also receive the error signal of PWM comparator (205) output, the duty ratio of decision output driving pulse, the output of PWM logical circuit (206) is received driving tube (209) by drive circuit (207) and is passed through output drive end (OUT) output drive signal;

The 2nd UVLO comparator (212), the threshold voltage of the supply voltage the during conducting of decision discharge loop;

Discharge tube (214) is connected to the discharge input (VA) that possesses discharging function, and discharge tube (214) reduces system voltage;

Charge/discharge control circuit (213), the switch of control discharge tube (214).

4. PWM controller as claimed in claim 3 is characterized in that, described current peak comparator (210) comprising with line voltage compensation circuit (211):

Be connected in series first branch road that forms successively by the 7th resistance R 11, the 8th resistance R 21 and the 9th resistance R 31, and

Be connected in series second branch road that forms successively by the tenth resistance R the 12, the 11 resistance R 22 and the 12 resistance R 32;

Wherein, the 9th resistance R 31 and the 12 resistance R 32 ground connection, the sampling input (VS) of detection line change in voltage is connected between the 7th resistance R 11 and the 8th resistance R 21, the input of current peak comparator (210) is between the 8th resistance R 21 and the 9th resistance R 31, and the tenth resistance R 12 is connected to PWM comparator (205).

5. a power converting circuit is characterized in that,

The input of the line voltage compensation circuit of the pulse width modulation (PWM) controller in this power converting circuit is connected the output pin of the peak current comparator of this PWM controller, and the output of this line voltage compensation circuit connects the PWM comparator of this PWM controller.

6. power converting circuit as claimed in claim 5 is characterized in that, this power converting circuit comprises:

PWM controller (U1), have five outside input/output interfaces, comprise: the output drive end (OUT) of driving external power pipe, power supply input anode (VCC), the sampling input (VS) of detection line change in voltage, power supply are imported negative terminal (GND) and are possessed the discharge input (VA) of discharging function, wherein, power supply input negative terminal (GND) ground connection, power supply input anode (VCC) is connected to one the 3rd electric capacity (C3);

Power tube (Q1) is connected to the output drive end (OUT) of PWM controller (U1);

Transformer (T1), the winding of one side are connected to power tube (Q1), and the winding of opposite side connects output voltage, and the collection of the sampling input (VS) of the detection line change in voltage of PWM controller (U1) connects the line voltage of the winding of power tube (Q1) side;

Optocoupler (U3) is connected to the power supply input anode (VCC) of PWM controller (U1) and possesses the discharge input (VA) of discharging function, also couples feedback control loop;

Feedback control loop comprises the 4th resistance (R4), the 5th resistance (R5), the 6th resistance (R6), the 4th electric capacity (C4) and voltage reference circuit (U2).

7. power converting circuit as claimed in claim 6 is characterized in that, this PWM controller comprises:

Start-up circuit (201), be connected with output drive end (OUT) with power supply input anode (VCC), be also connected to the first undervoltage lockout UVLO comparator (203), by a UVLO comparator (203) control, described start-up circuit (201) determines the minimum operating voltage of this power supply input anode (VCC) when starting instantaneous threshold operating voltage and operate as normal;

Clock circuit (208), the square-wave signal of generation fixed frequency, the output of this clock circuit (208) is connected to PWM logical circuit (206);

Internal reference circuit (202) produces a reference voltage (Vref), and this reference voltage (Vref) is the reference level as each comparator input terminal;

The one UVLO comparator (203), one input termination power input anode (VCC) of the one UVLO comparator (203), another imports termination reference voltage (Vref), and start-up circuit (201) and PWM logical circuit (206) are received in the output of a UVLO comparator (203) respectively;

Error amplifier (204), the one input termination power input anode (VCC) of this error amplifier (204), another imports termination input error voltage (VCC_Err), this error voltage (VCC_Err) is that an input of PWM comparator (205) is received in the output of this error amplifier (204) as the control signal of regulating the output signal duty ratio;

Current peak comparator (210), the current sampling signal of connection output driving circuit (209) is realized the current loop feedback, the output of this current peak comparator (210) is connected to an input of line voltage compensation circuit (211);

Line voltage compensation circuit (211), one input of this line voltage compensation circuit (211) connects sampling input (VS), another input connects the output of current peak comparator (210), this line voltage compensation circuit (211) is realized line voltage compensation control and current feedback signal and voltage feedback signal is outputed to PWM comparator (205);

PWM comparator (205) receives the output from error amplifier (204) and line voltage compensation circuit (211), is applied to PWM logic control circuit (206) with the form output signal of error signal;

PWM logical circuit (206), the output of receive clock circuit (208), square-wave signal in response to clock circuit (208) output, also receive the error signal of PWM comparator (205) output, the duty ratio of decision output driving pulse, the output of PWM logical circuit (206) is received driving tube (209) by drive circuit (207) and is passed through output drive end (OUT) output drive signal;

The 2nd UVLO comparator (212), the threshold voltage of the supply voltage the during conducting of decision discharge loop;

Discharge tube (214) is connected to the discharge input (VA) that possesses discharging function, and discharge tube (214) reduces system voltage;

Charge/discharge control circuit (213), the switch of control discharge tube (214).

8. power converting circuit as claimed in claim 7 is characterized in that, described current peak comparator (210) comprising with line voltage compensation circuit (211):

Be connected in series first branch road that forms successively by the 7th resistance (R11), the 8th resistance (R21) and the 9th resistance (R31), and

Be connected in series second branch road that forms successively by the tenth resistance (R12), the 11 resistance (R22) and the 12 resistance (R32);

Wherein, the 9th resistance (R31) and the 12 resistance (R32) ground connection, the sampling input (VS) of detection line change in voltage is connected between the 7th resistance (R11) and the 8th resistance (R21), the input of current peak comparator (210) is between the 8th resistance (R21) and the 9th resistance (R31), and the tenth resistance (R12) is connected to PWM comparator (205).

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