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WO2016015566A1 - 软启动方法及电路 - Google Patents

软启动方法及电路 Download PDF

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Publication number
WO2016015566A1
WO2016015566A1 PCT/CN2015/084176 CN2015084176W WO2016015566A1 WO 2016015566 A1 WO2016015566 A1 WO 2016015566A1 CN 2015084176 W CN2015084176 W CN 2015084176W WO 2016015566 A1 WO2016015566 A1 WO 2016015566A1
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Prior art keywords
voltage
soft start
soft
mos transistor
terminal
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English (en)
French (fr)
Inventor
唐盛斌
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Mornsun Guangzhou Science and Technology Ltd
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Mornsun Guangzhou Science and Technology Ltd
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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters

Definitions

  • the present invention relates to an integrated circuit, and more particularly to a soft start method and circuit for a switching power supply with a PWM controller.
  • switching power supplies are increasingly demanding in communications, industrial control, computers, and consumer electronics due to their high efficiency and small size.
  • switching power supply there are voltage control mode and double loop control added to the current control mode, but no matter what mode control, when the power is turned on, since the feedback loop has not formed a path, the PWM controller will maximize The duty cycle charges the output capacitor.
  • the switching capacitor power supply especially the high-power power supply, has a large output capacitor value. In this case, the output capacitor is likely to cause the power supply to be turned on.
  • a large inrush current which not only contaminates the power supply network, but also can damage transistors and other devices.
  • the switching power supply of the existing secondary side feedback control if the duty cycle of the power tube at the time of starting exceeds the duty ratio required after the power supply reaches the steady state, the startup output voltage overshoot will be caused.
  • the resistors R1 and R2 are output voltage sampling resistors, and their partial voltages are used as input signals of the voltage regulator TL431.
  • the signals are amplified by a transconductance amplifier composed of a voltage regulator TL431 and an optocoupler and then transmitted to the PWM control.
  • the FB end of the device (the FB terminal is also called the voltage feedback terminal, and the following is simply referred to as the FB terminal).
  • the PWM controller adjusts the duty ratio of the GATE output according to the magnitude of the FB terminal voltage V FB to control the output voltage.
  • the optocoupler draws more current from the FB terminal, so that the FB terminal voltage V FB Decrease, the duty ratio of the GATE output becomes smaller, the output voltage V OUT gradually decreases; when the output voltage V OUT is too small, the optocoupler draws a smaller current from the FB terminal, so that the FB terminal voltage V FB increases, and the GATE output is occupied.
  • the ratio becomes larger, the output voltage V OUT gradually increases. In this way, the output voltage is stabilized within the set value by the constant adjustment of the feedback loop formed by the optocoupler and the PWM controller.
  • the PWM controller gradually rises from zero volts by controlling the threshold of the CS port during power-on startup, the duty cycle can be gradually increased from zero, thereby reducing the surge current during startup.
  • the optocoupler does not pass current, the voltage at the FB terminal of the PWM controller is charged to a maximum value, which is equivalent to a very large overshoot of the FB voltage relative to the final steady state value.
  • FIG. 2 there is a secondary soft start circuit as shown in FIG. 2, which improves the problem of the feedback loop being disconnected during the rising phase of the output voltage V OUT , that is, by connecting the soft start capacitor C S in series with the optocoupler.
  • the optocoupler is turned on before the Zener diode TL431 is turned on, thereby forming a path of the feedback loop. Since the output V OUT rises after a power-on start, and the voltage on the soft-start capacitor C S is zero, as long as the output voltage V OUT is greater than the conduction voltage drop of the main side of the optocoupler, a current flows through the optocoupler.
  • this kind of secondary soft start circuit still has several obvious shortcomings: 1.
  • the PWM controller can gradually expand the duty cycle when starting the machine, otherwise the surge current when starting the machine is also very large, because V After the OUT needs to rise to a certain size, the optocoupler current can limit the rise of the FB voltage. In this period, the PWM controller can only limit the current. 2. After the soft start is over, it is not completely ineffective, and there is a certain loop.
  • the soft start circuit can not be integrated, and because the value of R BIS is relatively small, to ensure a certain soft start time, the value of the capacitor C S is relatively large, requiring several tens of micro
  • the method has a large capacitance, especially a product with a high steady-state voltage of the output voltage V OUT .
  • the feedback loop formed by the optocoupler and the PWM controller cannot be established before the voltage regulator TL431 is turned on, or the duty cycle of the PWM controller cannot be controlled according to the circuit design.
  • the voltage of the FB terminal needs to decrease from the maximum value to the steady state value, and the swing of the voltage is large. Because of the existence of the compensation capacitor C C1 , the response of the loop has a certain delay, and the duty ratio cannot be reduced rapidly in time. As a result, the output voltage overshoots when starting up. Especially in the case of no-load conditions.
  • the soft start method of the switching power supply that can avoid the excessive surge of the startup surge and eliminate the overshoot of the output voltage at the start of the machine.
  • another object of the present invention is to provide a phase in which the output voltage V OUT rises during power-on, and a very small average current is charged to the soft-start capacitor to pre-control the duty of the PWM controller.
  • the soft start circuit of the switching power supply can avoid the overshoot of the startup surge and eliminate the overshoot of the output voltage at the start of the machine.
  • the soft start method of the present invention includes the following steps: during the rising phase of the output voltage of the power-on starting, the power supply supplies a small current to charge the soft start capacitor, due to slow charging.
  • the voltage on the soft-start capacitor is small, so that the transistor is turned on, so that the current flowing out of the voltage feedback terminal mainly flows back to the ground through the transistor to limit the voltage rise of the voltage feedback terminal; at the end of the soft-start capacitor
  • the voltage at the output of the transistor follows the terminal voltage of the soft-start capacitor to gradually increase the duty cycle of the PWM controller from zero when the output voltage rises, and the voltage at the voltage feedback terminal gradually rises.
  • the transistor selects a PNP type transistor; the voltage at the output end of the transistor follows the terminal voltage of the soft start capacitor, and the voltage of the emitter of the transistor follows the terminal voltage of the soft start capacitor; the soft start circuit After the output voltage reaches the steady state value, the PNP transistor is in the reverse biased state, and the soft start circuit no longer acts on the loop.
  • the transistor selects a P-channel MOS transistor; the voltage at the output end of the transistor follows the terminal voltage of the soft start capacitor, and the source voltage of the P-channel MOS transistor follows the terminal voltage of the soft start capacitor. After the output voltage reaches a steady state value, the P-channel MOS transistor is in a reverse biased off state, and the soft start circuit no longer acts on the loop.
  • the soft start method of the present invention when the transistor is a PP type transistor or a P-channel MOS transistor, when the power is turned off, the diode rapidly discharges the charge on the soft start capacitor, thereby making the switching power supply continuous.
  • the soft start circuit can also work normally in the state of fast switching.
  • the transistor adopts a P-channel MOS transistor and an N-channel MOS transistor, and the P-channel MOS transistor is controlled to be turned on by a soft start capacitor, and the N-channel MOS transistor is enabled.
  • the signal control logic controls that when the N-channel MOS transistor is turned off, the small current generated by the soft-start control circuit charges the soft-start capacitor; the voltage at the output end of the transistor follows the soft-start capacitor terminal voltage, which is a P-channel MOS.
  • the source voltage of the tube follows the terminal voltage of the soft-start capacitor.
  • the first soft start circuit provided by the present invention is applicable to a switching power supply circuit with a PWM controller having a voltage feedback terminal, the soft start circuit including, The starting unit, during the rising phase of the output voltage of the power-on starting, the power supply supplies a small current to charge the soft-start capacitor, and at the same time, the voltage on the soft-start capacitor is small, so that the transistor is turned on, thereby limiting the voltage of the voltage feedback terminal. Rising; when the voltage of the soft-start capacitor gradually rises, the voltage at the output of the transistor follows the voltage of the soft-start capacitor to increase the duty cycle of the PWM controller from zero when the output voltage rises, and the voltage at the voltage feedback terminal Gradually rising.
  • the soft start unit includes a power input terminal, a clamp terminal, a ground terminal, a resistor, a PNP type transistor, and a soft start capacitor, and the power input terminal is respectively connected to the soft start capacitor through a resistor.
  • the soft start circuit further includes a bleed unit
  • the bleeder unit includes a diode, and the power input end is connected to the anode of the soft start capacitor via a reverse connection diode, that is, the power input end is connected to the cathode of the diode, and the anode of the diode is connected to the anode of the soft start capacitor for After the power input is de-energized, the diode quickly vents the charge on the soft-start capacitor.
  • the soft start unit includes a power input terminal, a clamp terminal, a ground terminal, a resistor, a P-channel MOS transistor, and a soft start capacitor.
  • the power input terminal is respectively connected to the positive electrode of the soft start capacitor and the gate of the P-channel MOS transistor via the resistor, the negative ground of the soft start capacitor, the drain ground of the P-channel MOS transistor, and the source of the P-channel MOS transistor.
  • the soft start circuit further includes a bleeder unit, the bleeder unit includes a diode, and the power input end is connected to the positive pole of the soft start capacitor via a reverse connection diode, that is, the power input end and the cathode of the diode Connected, the anode of the diode is connected to the positive terminal of the soft-start capacitor to quickly discharge the charge on the soft-start capacitor by the diode after the power input is powered off.
  • the third improvement provided by the present invention includes the soft start terminal, the clamp terminal, the current source, the P-channel MOS transistor, and the N-channel MOS transistor.
  • the current source is respectively connected to the soft start terminal, the drain of the N-channel MOS transistor, and the gate of the P-channel MOS transistor, and the gate of the N-channel MOS transistor is connected with the enable signal control logic, and the N-channel MOS transistor is connected.
  • the source is grounded, the source of the P-channel MOS transistor is connected to the voltage feedback terminal, and the drain of the P-channel MOS transistor is grounded.
  • the soft start unit comprises a soft start current control circuit, an enable signal control logic, a P-channel MOS transistor, an N-channel MOS transistor and a soft start capacitor, wherein the soft start current control circuit and the positive start of the soft start capacitor and the N-channel MOS transistor respectively
  • the drain is connected to the gate of the P-channel MOS transistor, the negative terminal of the soft-start capacitor is grounded; the gate of the N-channel MOS transistor is connected to the enable signal control logic, and the source of the N-channel MOS transistor is grounded; P-channel MOS The source of the tube is connected to the voltage feedback terminal, and the drain of the P-channel MOS transistor is grounded.
  • the soft start method and the integrated circuit of the present invention have the beneficial effects that
  • 1 is a soft start circuit of a prior art switching power supply
  • FIG. 2 is a soft start circuit in the prior art which improves some of the problems in the circuit of FIG. 1;
  • FIG. 3 is an application circuit diagram of a soft start circuit according to a first embodiment of the present invention.
  • FIG. 4 is an overall circuit of a soft start circuit applied to a switching power supply according to a first embodiment of the present invention
  • FIG. 5 is a test waveform diagram of a soft start circuit according to a first embodiment of the present invention.
  • FIG. 6 is a circuit diagram showing an application of a soft start circuit according to a second embodiment of the present invention.
  • FIG. 7 is a circuit diagram showing an application of a soft start circuit according to a third embodiment of the present invention.
  • FIG. 8 is a circuit diagram showing an application of a soft start circuit according to a fourth embodiment of the present invention.
  • the circuit indicated by the virtual frame 10 in FIG. 4 is the same as the circuit shown in FIG. 3 , and is a soft start circuit suitable for a switching power supply circuit with a PWM controller, and the PWM controller has an FB terminal.
  • the FB terminal is also called the voltage feedback terminal, and the following is simply referred to as the FB terminal.
  • the soft start circuit includes a soft start unit, and is composed of a power input terminal Vcc, a clamp terminal CV, a ground terminal GND, a resistor Rss, a capacitor Css, and a PNP type transistor T1.
  • the power input terminal Vcc is connected to the anode of the capacitor Css and the base of the transistor T1 via the resistor Rss, the cathode ground GND of the capacitor Css, the collector ground GND of the transistor T1, and the emitter of the transistor T1 to the clamp terminal CV;
  • the soft start circuit further comprises a bleeder unit, the bleeder unit is mainly composed of a diode D0, and the power input terminal Vcc is connected to the anode of the capacitor Css via the reverse diode D0, that is, the power input terminal Vcc is connected to the cathode of the diode D0, and the diode D0 is The anode is connected to the anode of the capacitor Css.
  • control steps of the soft start circuit are as follows:
  • the voltage on the soft-start capacitor is small, and the transistor is turned on, thereby limiting the rise of the FB voltage, that is, the current flowing from the FB terminal mainly flows back to the ground via the transistor T1, instead of The voltage at the place is charged; at the same time, the current generated by the resistor Rss charges the capacitor Css;
  • the voltage of the emitter of the transistor T1 changes according to the change of the base voltage, that is, the voltage V FB of the clamp terminal CV changes with the change of the voltage of the capacitor Css terminal to rise at the output voltage V OUT .
  • the duty ratio of the PWM controller is gradually increased from zero, and the voltage V FB at the FB terminal is gradually increased.
  • the voltage of the FB port is smaller than the voltage on the soft start capacitor, and the transistor T1 is in the reverse biased off state, and the soft start circuit no longer functions.
  • the diode quickly vents the charge on the soft-start capacitor, so that the soft-start circuit can work normally even in the continuous fast-switching state of the switching power supply.
  • the working principle of the soft start circuit of the present invention in the switching power supply is that the power input terminal Vcc of the soft start circuit is connected to the power supply, and the ground GND of the circuit is connected to the main side of the switching power supply, "ground", and the clamp end.
  • CV is connected to the FB terminal of the switching power supply PWM controller, and the FB terminal can also be externally connected with the compensation capacitor Cc1;
  • the capacitor Css When the power is turned on, since the voltage on the capacitor Css is zero volt, the capacitor Css is charged by the power supply input terminal Vcc through the resistor Rss over time, and the voltage on the capacitor Css is gradually increased, thereby making the clamp terminal The voltage of the CV follows the gradual increase in voltage across the capacitor Css.
  • the transistor T1 is a clamp follower tube.
  • the voltage of the compensation capacitor Cc1 is only one voltage drop (about 0.7 V) larger than the voltage on the capacitor Css, and gradually rises following the voltage on the capacitor Css.
  • the current flowing from the FB terminal of the PWM controller is only a small part of the charging current used to charge the compensation capacitor Cc1, and thus has no effect on the charging speed of the compensation capacitor Cc1. Therefore, the magnitude of the charging current of the compensation capacitor Cc1 is determined by The charging current of the capacitor Css.
  • the base voltage of the transistor T1 is greater than the emitter voltage, and the emitter junction is in a reverse bias state, so that the transistor T1 is in an off state, that is, after the circuit enters a steady state, the soft start circuit is no longer connected to the ring.
  • the road works and does not affect the normal operation of the switching power supply. After the switching power supply is turned off, there is no power supply in the soft start circuit, and the charge on the starting capacitor can be quickly discharged through the charge bleeder diode D0 to be quickly discharged by the diode D0 after the power input terminal is powered off.
  • the soft start circuit also works properly during continuous fast on/off operation.
  • the duty ratio of the PWM controller can be realized by adjusting the charging current of the capacitor Css.
  • the control thus controls the duty cycle of the PWM controller to gradually increase from zero without being quickly charged to a higher voltage, thereby reducing the impact of the startup surge current.
  • the soft start can be realized directly on the main side, and the duty ratio is gradually developed to avoid large inrush current during the startup and damage the device. Because it is easy to integrate in the controller on the main side, reduce the peripheral circuit.
  • the voltage on the compensation capacitor CC1 following the clamp terminal CV rises slowly.
  • the process of the secondary side voltage regulator TL431 and the optocoupler starting to form a feedback loop During the delay time, the voltage of the compensation capacitor CC1 does not rise much, so as to control the voltage on the compensation capacitor CC1 to rise to the voltage required for the operation of the Zener diode TL431 and the optocoupler, and the feedback loop is also A pathway is formed.
  • the soft-start circuit not only utilizes the inherent delay time of the circuit to provide the required formation time for the feedback loop forming path, but also eliminates the excessive swing of the FB terminal voltage in the conventional technology, so that the circuit rises in the output voltage V OUT phase. A smooth transition between steady states.
  • the test waveform diagram of the soft start circuit of the present invention is the waveform of the output voltage rising when the machine is on, and the curve 200 is the waveform of the voltage rise of the FB terminal. It can be seen that when the power is turned on, the output voltage rise curve is smooth and there is no overshoot voltage at all; the voltage at the FB terminal gradually rises, and the control duty ratio gradually expands, thereby indirectly controlling the rising process of the output voltage. When the output voltage rises to near the steady state value, the voltage at the FB terminal also rises just to the steady state value of the voltage value at the FB terminal.
  • the voltage feedback loop forms a closed loop, and the FB terminal voltage has an overshoot voltage.
  • the amplitude is small, so there is no need for a large secondary adjustment, which effectively controls the overshoot of the output voltage.
  • the circuit is simple, and the soft start time constant is easily designed according to the power level of the switching power supply, and is also easily integrated inside the PWM controller.
  • FIG. 6 is a circuit schematic diagram of a second embodiment of the soft start circuit of the present invention.
  • a soft start circuit is different from the first embodiment in that a P-channel MOS transistor MP is used instead of the PNP transistor T1. , its specific connection relationship is,
  • the power input terminal Vcc is connected to the positive electrode of the capacitor Css and the gate of the MOS transistor MP via the resistor Rss, the negative ground terminal GND of the capacitor Css, the drain ground GND of the MOS transistor MP, and the source terminal of the MOS transistor MP.
  • the power input terminal Vcc is also connected to the anode of the capacitor Css via the reverse diode D0, that is, the power input terminal Vcc is connected to the cathode of the diode D0, and the anode of the diode D0 is connected to the anode of the capacitor Css.
  • control steps of the soft start circuit are as follows:
  • the voltage of the soft-start capacitor is small, so that the MOS transistor MP is turned on, thereby limiting the voltage rise of the voltage feedback terminal, and the current flowing out of the FB terminal is mainly returned to the ground through the MOS tube MP.
  • the current charges the capacitor Css via the resistor Rss;
  • the voltage of the source of the MOS transistor MP changes in accordance with the change of the gate voltage, that is, the voltage V FB of the clamp terminal CV changes in accordance with the change of the voltage of the capacitor Css terminal, so as to be at the output voltage V OUT
  • the duty cycle of the PWM controller is gradually increased from zero, and the voltage V FB at the FB terminal is gradually increased.
  • the MOS transistor MP After the output voltage V OUT reaches the steady state value, the MOS transistor MP is in the reverse biased off state, and the soft start circuit no longer functions.
  • the charge on the capacitor Css is discharged by the diode D0, so that the soft start circuit can work normally in the continuous fast on/off state of the switching power supply.
  • the resistance RSS needs to be designed to be smaller, so that the charging current of the capacitor CSS is mainly determined by the current passing through the resistor RSS. However, it is less affected by the base current of the PNP tertiary tube T1. After the P-channel MOS transistor MP is used, there is no base current, and the soft-start time is completely determined by RSS and CSS.
  • the soft start circuit of the present invention is also easily integrated inside the PWM controller, as shown in FIG. 7, which is a circuit schematic diagram of a third embodiment of the soft start circuit of the present invention, a soft start circuit, and the first embodiment.
  • the bias resistor Rss is replaced by a current source
  • the PNP transistor T1 is replaced by a P-channel MOS transistor MP
  • the N-channel MOS transistor MN is added, that is, the soft start circuit includes a soft start terminal SS, a current source
  • the signal control logic, the P-channel MOS transistor MP and the N-channel MOS transistor MN are enabled, and the specific connection relationship is
  • the current source is respectively connected to the soft start terminal SS, the drain of the MOS transistor MN and the gate of the MOS transistor MP, the gate of the MOS transistor MN is connected to the enable signal control logic, and the source of the MOS transistor MN is grounded;
  • the source of the MOS transistor MP is connected to the FB terminal, and the drain of the MOS transistor MP is grounded.
  • control steps of the soft start circuit are as follows:
  • the voltage of the soft-start capacitor is small, so that the MOS transistor MP is turned on, thereby limiting the voltage rise of the voltage feedback terminal, and letting the current flowing out of the FB terminal mainly flow back to the ground through the MOS tube MP.
  • the current I ref provided by the current source is output through the soft start terminal SS when the MOS transistor MN is turned off, and is supplied to the external capacitor Css for charging.
  • the soft start terminal SS can be connected to the external capacitor Css, and the potential of the soft start terminal SS is the voltage of the capacitor Css terminal.
  • the source voltage of the MOS transistor MP changes in accordance with the change of the gate voltage, that is, the source voltage V FB of the MOS transistor MP changes in accordance with the change of the voltage of the capacitor Css terminal to the output voltage.
  • the duty cycle of the PWM controller is gradually increased from zero, and the voltage V FB at the FB terminal is gradually increased.
  • the MOS transistor MP After the output voltage V OUT reaches the steady state value, the MOS transistor MP is in the reverse biased off state, and the soft start circuit no longer functions.
  • the enable signal control logic When the PWM controller chip is just started, the enable signal control logic outputs a high level signal to turn on the MOS transistor MN to initialize the voltage of the capacitor Css to zero volts. After a short period of time, the enable signal control logic output goes low, the MOS transistor MN turns off, and the reference current I ref supplied from the current source flows from the SS port of the PWM controller to the external capacitor Css to charge The voltage at the FB terminal gradually increases as the voltage at the Css terminal increases. Therefore, by calculating the required soft start time Tss according to the power level of the switching power supply and the size of the output capacitor, the size of the external capacitor Css of the PWM controller can be set. Since a reference current I ref is easily generated in an integrated circuit, other devices of the circuit are also easily integrated inside the PWM controller.
  • FIG. 8 is a circuit schematic diagram of a fourth embodiment of the soft start circuit of the present invention.
  • a soft start circuit is different from the third embodiment in that a capacitor Css is integrated inside the PWM controller, that is,
  • the soft start circuit includes a soft start current control circuit, a capacitor Css, an enable signal control logic, a P-channel MOS transistor MP and an N-channel MOS transistor MN, and the specific connection relationship is
  • the soft start current control circuit is respectively connected to the positive pole of the capacitor Css, the drain of the MOS transistor MN and the gate of the MOS transistor MP, and the negative pole of the capacitor Css is grounded; the gate of the MOS transistor MN is connected with the enable signal control logic, and the MOS transistor MN The source is grounded;
  • the source of the MOS transistor MP is connected to the FB terminal, and the drain of the MOS transistor MP is grounded.
  • control steps of the soft start circuit are as follows:
  • the soft-start current control circuit provides a very small average current to charge the capacitor Css when the MOS transistor MN is turned off.
  • the source voltage of the MOS transistor MP changes in accordance with the change of the gate voltage, that is, the source voltage V FB of the MOS transistor MP changes in accordance with the change of the voltage of the capacitor Css terminal to the output voltage.
  • the duty cycle of the PWM controller is gradually increased from zero, and the voltage V FB at the FB terminal is gradually increased.
  • the MOS transistor MP After the output voltage V OUT reaches the steady state value, the MOS transistor MP is in the reverse biased off state, and the soft start circuit no longer functions.
  • the soft start circuit of the embodiment is completely integrated inside the control chip. Since it is difficult to integrate a large capacitance inside the chip, the soft start voltage is generated by the soft start control circuit and the capacitor Css.
  • the purpose of the soft-start control circuit is to provide a very small average current to charge the capacitor Css, which may be a control circuit that generates a micro-current source in the prior art, or a digital control circuit that is a current pulse.
  • This soft-start circuit which is completely built into the PWM controller, has a soft start-up time that is fixed, but further simplifies the circuit outside the PWM controller, improving reliability and integration.

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Abstract

软启动方法，包括如下步骤：在上电启机的输出电压上升阶段，供电电源提供一个很小的电流给软启动电容充电，使晶体管导通，从而让电压反馈端流出的电流主要经晶体管流回地端，以限制电压反馈端电压的上升；在软启动电容的端电压逐渐上升时，晶体管输出端的电压跟随软启动电容的端电压，以在输出电压上升时，使PWM控制器的占空比从零逐渐增加，且电压反馈端的电压逐渐上升。相对于现有技术，本发明软启动方法，直接在主边实现软启动，逐渐展开占空比，避免开机时产生大的浪涌电流而损坏器件，且该电路简单，无需大电容，体积小，软启动时间常数也容易根据开关电源功率级别的大小而随意设计，还易于集成在PWM控制内部。

Description

软启动方法及电路 技术领域
本发明涉及集成电路，特别涉及带PWM控制器的开关电源的软启动方法及电路。
背景技术
目前，开关电源以效率高、体积小等特点，在通信、工控、计算机以及消费电子中的需求越来越大。在常用的开关电源中，有电压控制模式以及加入电流控制模式的双环控制，但是不管是什么模式的控制，在上电启机时，由于反馈环路还没有形成通路，PWM控制器会以最大占空比给输出电容进行充电，为了得到较理想的负载瞬态响应，开关电源特别是大功率的电源所选用的输出电容容值很大，这样的话，输出电容就易导致电源在开机时产生很大的浪涌电流，这不仅会污染供电电源网络，而且有可能损坏晶体管和其它器件。
如图1所示，为现有副边反馈控制的开关电源，如果启机时功率管的占空比超过电源达到稳态后所需的占空比，将会导致开机输出电压过冲。它的工作原理是：电阻R1和R2是输出电压采样电阻，它们的分压作为稳压管TL431的输入信号，该信号经过由稳压管TL431和光耦组成的跨导放大器放大后传输到PWM控制器的FB端(FB端又称电压反馈端，以下统一简称为FB端)。PWM控制器根据FB端电压VFB的大小调节GATE输出的占空比大小来控制输出电压，当输出电压VOUT偏高时，光耦从FB端抽取更多的电流，使FB端电压VFB下降，GATE输出的占空比变小，输出电压VOUT逐渐下降；当输出电压VOUT偏小时，光耦从FB端抽取更小的电流，使FB端电压VFB增加，GATE输出的占空比变大，输出电压VOUT逐渐增加。如此，通过光耦与PWM控制器所形成的反馈环路的不断调整，使输出电压稳定在设定值的范围内。
虽然在上电启机过程中，PWM控制器通过控制CS端口的阈值从零伏逐渐上升，可以控制占空比从零逐渐增加，从而减小了开机的浪涌电流。但是，在输出电压VOUT的上升阶段，稳压管TL431没来得及导通之前，光耦上没有电流，反馈环路是断开的。由于光耦不通过电流，PWM控制器FB端的电压会被充电到最大值，相当于FB电压相对于最终的稳态值来说有非常大的过冲。当输出电压VOUT上升达到非常接近最终稳态值时，例如最终稳态值偏下50mV(决定于输出电压 VOUT到FB端口电压的增益)之内，光耦才开始有电流通过，使FB端的电压开始下降。由于FB端电压需要从最大值下降到FB端的稳态值，电压的摆幅大，所以FB端的电压泄放存在延时，延时时间Td＝(CC1·ΔVFB)/IC1，ΔVFB，为FB端电压的摆幅，IC1为从补偿电容CC1抽取的电流。正是因为这个延迟时间的存在，使得占空比不能及时迅速地减小，从而导致启机时输出电压过冲。特别是在空载情况下尤为严重。
现有技术中，有如图2所示的副边软启动电路，改进了在输出电压VOUT上升阶段的反馈环路断开的问题，即通过在光耦端串联软启动电容CS，以使光耦提前于稳压管TL431导通之前开启，从而形成反馈环路的通路。由于上电启机一段时间后输出VOUT上升，而软启动电容CS上的电压为零，所以只要输出电压VOUT大于光耦主边的导通压降，光耦上就有电流流过，这样的话在输出电压VOUT到达最终的稳态值之前，反馈环路已经是通路状态，从而理论上可防止出现开机输出电压过冲的问题。但是，这种副边软启动电路还是存在几个明显的缺点：1、在刚启机时必需PWM控制器能逐渐展开占空比，否则刚启机时的浪涌电流也是很大，因为VOUT需要上升到一定大小后光耦电流才能限制FB电压的上升，在这一段时间只能靠PWM控制器限制电流；2、软启动结束后不是完全不起作用，还会对环路有一定的影响，特别是在大动态跳变过程中；3、该软启动电路无法集成，又因为RBIS的值比较小，要保证一定的软启动时间，电容CS的值比较大，需要几十微法，电容体积大，特别是输出电压VOUT的稳态电压高的产品。
现就现有PWM控制器的软启动电路，对其不足总结如下：
1、在稳压管TL431没来得及导通之前，无法建立光耦与PWM控制器所形成的反馈环路，或无法依电路设计实现对PWM控制器的占空比的控制。
2、刚启机时反馈环路的负反馈不起作用，使PWM控制器的占空比不能充分被限制为由小往大逐渐增加，从而很难把开机浪涌冲击减小到可接受的范围之内。
3、FB端电压需要从最大值下降到稳态值，电压的摆幅大，且由于补偿电容CC1的存在使环路的响应存在一定的延时，占空比不能及时迅速地减小，从而导致启机时输出电压过冲。在空载情况下尤为严重。
发明内容
有鉴于此，本发明的目的是，提供一种在上电启机时的输出电压VOUT上升阶段，有一个非常小的平均电流给软启动电容充电，以预先控制PWM控制器的占空比大小，从而既能够避免开机浪涌冲击过大，又能够消除启机时的输出电压过冲的开关电源的软启动方法。
与此相应，本发明另一个目的是，提供一种在上电启机时的输出电压VOUT上升阶段，有一个非常小的平均电流给软启动电容充电，以预先控制PWM控制器的占空比大小，从而既能够避免开机浪涌冲击过大，又能够消除启机时的输出电压过冲的开关电源的软启动电路。
就开关电源的软启动方法而言，本发明的软启动方法，包括如下步骤：在上电启机的输出电压上升阶段，供电电源提供一个很小的电流给软启动电容充电，由于充电较慢，刚启机时软启动电容上的电压较小，使晶体管导通，从而让电压反馈端流出的电流主要经晶体管流回地端，以限制电压反馈端电压的上升；在软启动电容的端电压逐渐上升时，晶体管输出端的电压跟随软启动电容的端电压，以在输出电压上升时，使PWM控制器的占空比从零逐渐增加，且电压反馈端的电压逐渐上升。
作为本发明软启动方法的改进，所述晶体管选用PNP型三极管；所述晶体管输出端的电压跟随软启动电容的端电压，是三极管发射极的电压跟随软启动电容的端电压；所述软启动电路在输出电压达到稳态值后，PNP型三极管处于反偏截止状态，软启动电路不再对环路起作用。
作为本发明软启动方法的改进，所述晶体管选用P沟道MOS管；所述晶体管输出端的电压跟随软启动电容的端电压，是P沟道MOS管的源极电压跟随软启动电容的端电压；所述软启动电路在输出电压达到稳态值后，P沟道MOS管处于反偏截止状态，软启动电路不再对环路起作用。
作为本发明软启动方法的改进，所述晶体管选用PP型三极管或是P沟道MOS管时，在电源断电时，由二极管迅速泄放软启动电容上的电荷，从而使开关电源在连续的快速开关机状态下，软启动电路也能正常工作。
作为本发明软启动方法的改进，所述晶体管采用P沟道MOS管和N沟道MOS管，所述P沟道MOS管由软启动电容控制导通，所述N沟道MOS管由使能信号控制逻辑控制，在N沟道MOS管关断时，软启动控制电路产生的微小电流对软启动电容进行充电；所述晶体管输出端的电压跟随软启动电容端电压，是P沟道MOS 管的源极电压跟随软启动电容的端电压。
就开关电源的软启动电路而言，本发明提供的第一种软启动电路，适用于带PWM控制器的开关电源电路，所述PWM控制器具有电压反馈端，所述软启动电路包括，软启动单元，在上电启机的输出电压上升阶段，供电电源提供一个很小的电流给软启动电容充电，同时，软启动电容上的电压小，使晶体管导通，从而限制电压反馈端电压的上升；在软启动电容的端电压逐渐上升时，晶体管输出端的电压跟随软启动电容的端电压，以在输出电压上升时，使PWM控制器的占空比从零逐渐增加，且电压反馈端的电压逐渐上升。
作为本发明软启动电路的改进，所述软启动单元，包括电源输入端、钳位端、地端、电阻、PNP型三极管和软启动电容，所述电源输入端经电阻分别与软启动电容的正极及PNP型三极管的基极连接，软启动电容的负极接地端，所述PNP型三极管的集电极接地端，PNP型三极管的发射极接钳位端；所述软启动电路还包括泄放单元，所述泄放单元包括二极管，所述电源输入端经反接二极管与软启动电容的正极连接，即电源输入端与二极管的阴极连接，二极管的阳极与软启动电容的正极连接，用以在电源输入端断电后，由二极管迅速泄放软启动电容上的电荷。
就开关电源的软启动电路而言，本发明提供的第二种改进，所述软启动单元，包括电源输入端、钳位端、地端、电阻、P沟道MOS管和软启动电容，所述电源输入端经电阻分别与软启动电容的正极及P沟道MOS管的栅极连接，软启动电容的负极接地端，P沟道MOS管的漏极接地端，P沟道MOS管的源极接钳位端；所述软启动电路还包括泄放单元，所述泄放单元包括二极管，所述电源输入端经反接二极管与软启动电容的正极连接，即电源输入端与二极管的阴极连接，二极管的阳极与软启动电容的正极连接，用以在电源输入端断电后，由二极管迅速泄放软启动电容上的电荷。
就开关电源的软启动电路而言，本发明提供的第三种改进，所述软启动单元，包括软启动端、钳位端、电流源、P沟道MOS管和N沟道MOS管，所述电流源分别与软启动端、N沟道MOS管的漏极及P沟道MOS管的栅极连接，N沟道MOS管的栅极与使能信号控制逻辑连接，N沟道MOS管的源极接地，P沟道MOS管的源极与电压反馈端连接，P沟道MOS管的漏极接地。
就开关电源的软启动电路而言，本发明提供的第四种改进，所述软启动单元， 包括软启动电流控制电路、使能信号控制逻辑、P沟道MOS管、N沟道MOS管和软启动电容，所述软启动电流控制电路分别与软启动电容的正极、N沟道MOS管的漏极及P沟道MOS管的栅极连接，软启动电容的负极接地；N沟道MOS管的栅极与使能信号控制逻辑连接，N沟道MOS管的源极接地；P沟道MOS管的源极与电压反馈端连接，P沟道MOS管的漏极接地。
相对于现有技术，本发明软启动方法及集成电路的有益效果是，
1、直接在主边实现软启动，逐渐展开占空比，避免开机时产生大的浪涌电流而损坏器件。因为在主边，容易集成在控制器中，减小外围电路。
2、由于直接控制FB端口的电压缓慢上升，待输出电压达到稳态值时FB无过冲，无需FB电压再次调节所引起的延时；而且FB电压上升慢，有足够的时间等待光耦的导通与反馈，从而可以防止开机过冲现象的产生。
3、无需大电容，体积小，易于设计。
附图说明
图1为现有技术开关电源的软启动电路；
图2为现有技术中改进了图1电路中的部分问题的软启动电路；
图3为本发明第一实施例的软启动电路的应用电路图；
图4为本发明第一实施例软启动电路应用在开关电源中的整体电路；
图5为本发明第一实施例软启动电路的测试波形图；
图6为本发明第二实施例的软启动电路的应用电路图；
图7为本发明第三实施例的软启动电路的应用电路图；
图8为本发明第四实施例的软启动电路的应用电路图。
具体实施方式
第一实施例
请参阅图3和图4，图4中虚框10所指的电路同图3所示的电路，为一种软启动电路,适用于带PWM控制器的开关电源电路，PWM控制器具有FB端，FB端又称电压反馈端，以下统一简称为FB端，
该软启动电路包括软启动单元，由电源输入端Vcc、钳位端CV、地端GND、电阻Rss、电容Css和PNP型三极管T1构成，
电源输入端Vcc经电阻Rss分别与电容Css的正极及三极管T1的基极连接，电容Css的负极接地端GND，三极管T1的集电极接地端GND，三极管T1的发射极接钳位端CV；
该软启动电路还包括泄放单元，泄放单元主要由二极管D0构成，电源输入端Vcc经反接二极管D0与电容Css的正极连接，即电源输入端Vcc与二极管D0的阴极连接，二极管D0的阳极与电容Css的正极连接。
该软启动电路的控制步骤如下：
在上电启机的输出电压VOUT上升阶段，软启动电容上的电压小，使三极管导通，从而限制FB电压的上升，即FB端流出的电流主要经由三极管T1流回地端，而不会把该处的电压充高；同时，经电阻Rss产生的电流对电容Css进行充电；
在电容Css端电压逐渐上升时，三极管T1发射极的电压跟随基极电压的变化而变化，即钳位端CV的电压VFB跟随电容Css端电压的变化而变化，以在输出电压VOUT上升时，使PWM控制器的占空比从零逐渐增加，且FB端的电压VFB逐渐上升。
在输出电压VOUT达到稳态值后，FB端口的电压比软启动电容上的电压小，三极管T1处于反偏截止状态，软启动电路不再起作用。在电源断电时，由二极管迅速泄放软启动电容上的电荷，从而开关电源在连续的快速开关机状态下，软启动电路也能正常工作。
如图4所示，本发明软启动电路在开关电源中的工作原理是，软启动电路的电源输入端Vcc接供电电源，电路的地端GND接开关电源的主边“地”，钳位端CV接开关电源PWM控制器的FB端，FB端还可外接补偿电容Cc1；
刚上电启机时，由于电容Css上的电压为零伏特，随着时间的推移，由电源输入端Vcc通过电阻Rss给电容Css充电，在电容Css上的电压逐渐增加，从而使钳位端CV的电压跟随电容Css上电压的逐渐增加。此处的三极管T1为钳位跟随管。
此时，补偿电容Cc1电压只比电容Css上的电压大一个二极管的压降(约0.7V)，并且跟随电容Css上的电压而逐渐上升。而从PWM控制器的FB端流出的电流仅是用来给补偿电容Cc1充电电流的很小一部分，因而对补偿电容Cc1的充电快慢基本没影响，因此，补偿电容Cc1的充电电流的大小决定于电容Css的充电电流。
等到开关电源的反馈环路形成通路后，三极管T1的基极电压大于发射极电压，发射结处于反偏状态使三极管T1处于截止状态，即电路进入稳态后，该软启动电路不再对环路起作用，也不影响开关电源的正常工作。在开关电源关断后，该软启动电路内无供电电源，启动电容上的电荷通过电荷泄放二极管D0可迅速泄放掉用以在电源输入端断电后，由二极管D0迅速泄放软启动电容上的电荷，电容Css上的电压很快掉到零伏，避免了由于电源开关机速度过快，电容Css的电荷没能来得及泄放完毕而导致无软启动效果的情况，从而使开关电源在连续地快速开关机操作时，软启动电路也能正常工作。
由上述的工作原理可知，由于补偿电容CC1的端电压跟随电容Css的端电压由零开始逐渐上升，如此即可通过对电容Css的充电电流的调节，而实现对PWM控制器的占空比大小的控制，从而控制PWM控制器的占空比由零开始逐渐增加，而不会很快地被充电到较高电压，因而减小了开机浪涌电流的冲击。即可直接在主边实现软启动，逐渐展开占空比，避免开机时产生大的浪涌电流而损坏器件。因为在主边，容易集成在控制器中，减小外围电路。
同时，因跟随钳位端CV的补偿电容CC1上的电压上升得较慢，在开关电源输出电压接近最终稳态值前，副边稳压管TL431、光耦开始工作而形成反馈环路的过程所延迟的时间内，并不会使补偿电容CC1的电压上升多少，以控制补偿电容CC1上的电压正好上升至稳压管TL431、光耦工作所需的导通电压，此时反馈环路也形成了通路。如此，由于直接控制FB端口的电压缓慢上升，待输出电压达到稳态值时FB无过冲，无需FB电压再次调节所引起的延时；而且FB电压上升慢，有足够的时间等待光耦的导通与反馈，从而可以防止开机过冲现象的产生。软启动电路既利用电路固有的延迟时间为反馈环路形成通路提供了所需要的形成时间，又消除了传统技术中FB端电压的摆幅过大问题，使电路在输出电压VOUT上升阶段与稳态之间平稳过渡。
如图5所示，为本发明软启动电路的测试波形图，曲线100(电压稳态值高的那条)为上机时输出电压上升的波形，曲线200为FB端电压上升的波形。可以看出，上电启机时，输出电压上升曲线光滑，完全无过冲电压；FB端电压逐渐上升，控制占空比逐渐展开，从而间接控制输出电压的上升过程。待输出电压上升到接近稳态值时，FB端电压也恰好上升到FB端电压值的稳态值附近。因为需要等待稳压管TL431导通，电压反馈环路形成闭环，FB端电压有过冲电压， 但是幅值很小，所以不需要进行大幅度的二次调整，有效地控制了输出电压的过冲。
并且，该电路简单，软启动时间常数容易根据开关电源功率级别的大小而随意设计，也容易集成在PWM控制器内部。
第二实施例
如图6所示，为本发明软启动电路的第二实施例的电路原理图，一种软启动电路,与第一实施例的不同之处在于，采用P沟道MOS管MP替代PNP三极管T1，其具体连接关系是，
电源输入端Vcc经电阻Rss分别与电容Css的正极及MOS管MP的栅极连接，电容Css的负极接地端GND，MOS管MP的漏极接地端GND，MOS管MP的源极接钳位端CV；
电源输入端Vcc还经反接二极管D0与电容Css的正极连接，即电源输入端Vcc与二极管D0的阴极连接，二极管D0的阳极与电容Css的正极连接。
该软启动电路的控制步骤如下：
在上电启机的输出电压VOUT上升阶段，软启动电容的电压小，使MOS管MP导通，从而限制电压反馈端电压的上升，让FB端流出的电流主要经MOS管MP流回地端；同时，该电流经电阻Rss对电容Css进行充电；
在电容Css端电压逐渐上升时，MOS管MP源极的电压跟随栅极电压的变化而变化，即钳位端CV的电压VFB跟随电容Css端电压的变化而变化，以在输出电压VOUT的逐渐上升过程中，使PWM控制器的占空比从零逐渐增加，且FB端的电压VFB逐渐上升。
在输出电压VOUT达到稳态值后，MOS管MP处于反偏截止状态，软启动电路不再起作用。在电源断电时，由二极管D0泄放电容Css上的电荷，从而使开关电源在连续的快速开关机状态下，软启动电路也能正常工作。
虽然选用三极管成本低，但是为了使得通过三极管T1基极的电流对软启动时间常数的影响小，需要将电阻RSS设计得小一些，从而使电容CSS的充电电流主要由通过电阻RSS的电流决定，而受PNP三级管T1的基极电流影响小。采用P沟道MOS管MP后，不存在基极电流，则软启动时间完全由RSS和CSS决定。
第三实施例
本发明的软启动电路也很容易集成在PWM控制器的内部，如图7所示，为本发明软启动电路的第三实施例的电路原理图，一种软启动电路,与第一实施例的不同之处在于，用电流源替代偏置电阻Rss，用P沟道MOS管MP替代PNP三极管T1，并增加N沟道MOS管MN，即该软启动电路包括软启动端SS、电流源、使能信号控制逻辑、P沟道MOS管MP和N沟道MOS管MN，其具体连接关系是，
电流源分别与软启动端SS、MOS管MN的漏极及MOS管MP的栅极连接，MOS管MN的栅极与使能信号控制逻辑连接，MOS管MN的源极接地；
MOS管MP的源极与FB端连接，MOS管MP的漏极接地。
该软启动电路的控制步骤如下：
在上电启机的输出电压VOUT上升阶段，软启动电容的电压小，使MOS管MP导通，从而限制电压反馈端电压的上升，让FB端流出的电流主要经MOS管MP流回地端；同时，电流源所提供的电流Iref在MOS管MN关断时经软启动端SS输出，提供给外置的电容Css充电。软启动端SS可外接电容Css,软启动端SS的电位即电容Css端电压。
在电容Css的端电压逐渐上升时，MOS管MP的源极电压跟随栅极电压的变化而变化，即MOS管MP的源极电压VFB跟随电容Css端电压的变化而变化，以在输出电压VOUT的逐渐上升过程中，使PWM控制器的占空比从零逐渐增加，且FB端的电压VFB逐渐上升。
在输出电压VOUT达到稳态值后，MOS管MP处于反偏截止状态，软启动电路不再起作用。
在PWM控制器芯片刚启动时，使能信号控制逻辑输出高电平信号，使MOS管MN导通以初始化电容Css的电压为零伏特。一小段时间过后，使能信号控制逻辑输出变为低电平，MOS管MN关断，电流源所提供的基准电流Iref从PWM控制器的SS端口流出给外置的电容Css充电，以使FB端的电压跟随着电容Css端电压的增加而逐渐增加。所以，只要根据开关电源的功率等级和输出电容的大小计算所需要的软启动时间Tss后，设定PWM控制器外置的电容Css的大小便可。由于在集成电路中很容易产生一个基准电流Iref，该电路的其他器件也很容易集成在PWM控制器的内部。
第四实施例
如图8所示，为本发明软启动电路的第四实施例的电路原理图，一种软启动电路,与第三实施例的不同之处在于，将电容Css集成于PWM控制器内部，即该软启动电路包括软启动电流控制电路、电容Css、使能信号控制逻辑、P沟道MOS管MP和N沟道MOS管MN，其具体连接关系是，
软启动电流控制电路分别与电容Css的正极、MOS管MN的漏极及MOS管MP的栅极连接，电容Css的负极接地；MOS管MN的栅极与使能信号控制逻辑连接，MOS管MN的源极接地；
MOS管MP的源极与FB端连接，MOS管MP的漏极接地。
该软启动电路的控制步骤如下：
在上电启机的输出电压VOUT上升阶段，软启动电容的电压小，使MOS管MP导通，从而限制电压反馈端电压的上升，让FB端流出的电流主要经MOS管MP流回地端；同时，该软启动电流控制电路提供一个非常小的平均电流在MOS管MN关断时给电容Css充电。
在电容Css的端电压逐渐上升时，MOS管MP的源极电压跟随栅极电压的变化而变化，即MOS管MP的源极电压VFB跟随电容Css端电压的变化而变化，以在输出电压VOUT的逐渐上升过程中，使PWM控制器的占空比从零逐渐增加，且FB端的电压VFB逐渐上升。
在输出电压VOUT达到稳态值后，MOS管MP处于反偏截止状态，软启动电路不再起作用。
与实施例三相比，本实施例的软启动电路完全集成在控制芯片内部。由于芯片内部难以集成大容值的电容，软启动电压的产生由软启动控制电路和电容Css共同完成。软启动控制电路的目的是为了提供一个非常小的平均电流给电容Css充电，它可以是现有技术中产生微电流源的控制电路，也可以是电流脉冲的数字式控制电路。这种完全内置在PWM控制器内部的软启动电路，虽然软启动时间是固定的，但是进一步简化了PWM控制器外围的电路，提高了可靠性和集成度。
以上仅是本发明的优选实施方式，应当指出的是，上述优选实施方式不应视为对本发明的限制。对于本技术领域的普通技术人员来说，在不脱离本发明的精神和范围内，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围，这里不再用实施例赘述，如在本发明的软启动电路的基础上，通过集成 电路内电路的等效变换器件进行功能替换等，本发明的保护范围应当以权利要求所限定的范围为准。

Claims (10)

  1. 一种软启动方法,用于PWM控制器集成电路，所述PWM控制器具有电压反馈端，其特征在于：所述软启动方法的控制步骤如下，
    在上电启机的输出电压上升阶段，供电电源提供一个很小的电流给软启动电容充电，同时，软启动电容上的电压小，使晶体管导通，从而限制电压反馈端电压的上升；
    在软启动电容的端电压逐渐上升时，晶体管输出端的电压跟随软启动电容的端电压，以在输出电压上升时，使PWM控制器的占空比从零逐渐增加，且电压反馈端的电压逐渐上升。
  2. 根据权利要求1所述的软启动方法，其特征在于：所述晶体管选用PNP型三极管；所述晶体管输出端的电压跟随软启动电容的端电压，是三极管发射极的电压跟随软启动电容的端电压；所述软启动电路在输出电压达到稳态值后，PNP型三极管处于反偏截止状态，软启动电路不再起作用。
  3. 根据权利要求1所述的软启动方法，其特征在于：所述晶体管选用P沟道MOS管；所述晶体管输出端的电压跟随软启动电容的端电压，是P沟道MOS管的源极电压跟随软启动电容的端电压；所述软启动电路在输出电压达到稳态值后，P沟道MOS管处于反偏截止状态，软启动电路不再起作用。
  4. 根据权利要求2或3所述的软启动方法，其特征在于：所述软启动方法，还包括在电源断电时，由二极管迅速泄放软启动电容上的电荷，从而使开关电源在连续的快速开关机状态下，软启动电路也能正常工作。
  5. 根据权利要求1所述的软启动方法，其特征在于：所述晶体管采用P沟道MOS管和N沟道MOS管，所述P沟道MOS管由软启动电容控制导通，所述N沟道MOS管由使能信号控制逻辑控制，在N沟道MOS管关断时，软启动控制电路产生的微小电流对软启动电容进行充电；所述晶体管输出端的电压跟随软启动电容端电压，是P沟道MOS管的源极电压跟随软启动电容的端电压。
  6. 一种软启动电路,适用于带PWM控制器的开关电源电路，所述PWM控制器具有电压反馈端，其特征在于：所述软启动电路包括，
    软启动单元，在上电启机的输出电压上升阶段，供电电源提供一个很小的电流给软启动电容充电，同时，软启动电容上的电压小，使晶体管导通，从而限制 电压反馈端电压的上升；在软启动电容的端电压逐渐上升时，晶体管输出端的电压跟随软启动电容的端电压，以在输出电压上升时，使PWM控制器的占空比从零逐渐增加，且电压反馈端的电压逐渐上升。
  7. 根据权利要求6所述的软启动电路，其特征在于：
    所述软启动单元，包括电源输入端、钳位端、地端、电阻、PNP型三极管和软启动电容，所述电源输入端经电阻分别与软启动电容的正极及PNP型三极管的基极连接，软启动电容的负极接地端，所述PNP型三极管的集电极接地端，PNP型三极管的发射极接钳位端；
    所述软启动电路还包括泄放单元，所述泄放单元包括二极管，所述电源输入端经反接二极管与软启动电容的正极连接，即电源输入端与二极管的阴极连接，二极管的阳极与软启动电容的正极连接，用以在电源输入端断电后，由二极管迅速泄放软启动电容上的电荷。
  8. 根据权利要求6所述的软启动电路，其特征在于：
    所述软启动单元，包括电源输入端、钳位端、地端、电阻、P沟道MOS管和软启动电容，所述电源输入端经电阻分别与软启动电容的正极及P沟道MOS管的栅极连接，软启动电容的负极接地端，P沟道MOS管的漏极接地端，P沟道MOS管的源极接钳位端；
    所述软启动电路还包括泄放单元，所述泄放单元包括二极管，所述电源输入端经反接二极管与软启动电容的正极连接，即电源输入端与二极管的阴极连接，二极管的阳极与软启动电容的正极连接，用以在电源输入端断电后，由二极管迅速泄放软启动电容上的电荷。
  9. 根据权利要求6所述的软启动电路，其特征在于：
    所述软启动单元，包括软启动端、钳位端、电流源、P沟道MOS管和N沟道MOS管，所述电流源分别与软启动端、N沟道MOS管的漏极及P沟道MOS管的栅极连接，N沟道MOS管的栅极与使能信号控制逻辑连接，N沟道MOS管的源极接地，P沟道MOS管的源极与电压反馈端连接，P沟道MOS管的漏极接地。
  10. 根据权利要求6所述的软启动电路，其特征在于：
    所述软启动单元，包括软启动电流控制电路、使能信号控制逻辑、P沟道MOS管、N沟道MOS管和软启动电容，所述软启动电流控制电路分别与软启动电容的正极、N沟道MOS管的漏极及P沟道MOS管的栅极连接，软启动电容的负极接地； N沟道MOS管的栅极与使能信号控制逻辑连接，N沟道MOS管的源极接地；P沟道MOS管的源极与电压反馈端连接，P沟道MOS管的漏极接地。
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2924914Y (zh) * 2006-05-26 2007-07-18 广州金升阳科技有限公司 微功率电源模块中的软启动电路
CN101355293A (zh) * 2007-07-24 2009-01-28 青岛海信电器股份有限公司 电源软启动电路
CN201846229U (zh) * 2010-09-30 2011-05-25 冠捷投资有限公司 软启动电路
CN103166443A (zh) * 2011-12-12 2013-06-19 海洋王照明科技股份有限公司 一种软启动控制电路及一种恒流源驱动电路
US20140042994A1 (en) * 2011-04-25 2014-02-13 Fairchild Semiconductor Corporation Soft-Start Control Techniques for a Switched-Mode Power Supply
CN104135146A (zh) * 2014-07-29 2014-11-05 广州金升阳科技有限公司 软启动方法及电路

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2924914Y (zh) * 2006-05-26 2007-07-18 广州金升阳科技有限公司 微功率电源模块中的软启动电路
CN101355293A (zh) * 2007-07-24 2009-01-28 青岛海信电器股份有限公司 电源软启动电路
CN201846229U (zh) * 2010-09-30 2011-05-25 冠捷投资有限公司 软启动电路
US20140042994A1 (en) * 2011-04-25 2014-02-13 Fairchild Semiconductor Corporation Soft-Start Control Techniques for a Switched-Mode Power Supply
CN103166443A (zh) * 2011-12-12 2013-06-19 海洋王照明科技股份有限公司 一种软启动控制电路及一种恒流源驱动电路
CN104135146A (zh) * 2014-07-29 2014-11-05 广州金升阳科技有限公司 软启动方法及电路

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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US10396654B2 (en) 2017-10-25 2019-08-27 Schneider Electric Solar Inverters Usa, Inc. Start-up circuit
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CN109194109A (zh) * 2018-09-27 2019-01-11 广州金升阳科技有限公司 一种补偿电路
CN109217665A (zh) * 2018-10-25 2019-01-15 广州金升阳科技有限公司 一种驱动信号增强电路
CN109217665B (zh) * 2018-10-25 2024-04-12 广州金升阳科技有限公司 一种驱动信号增强电路
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CN109672255A (zh) * 2019-02-25 2019-04-23 威胜信息技术股份有限公司 后备电容充放电电路、充放电方法及其故障指示器
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