CN204886731U - Switching power supply controller and switching power supply including the switching power supply controller - Google Patents

Abstract

The utility model provides a switching power supply controller and contain the switching power supply of this switching power supply controller. This switching power supply controller includes that zero cross detection circuit, variable turn -on time length control circuit and drive signal produce the circuit. The drive signal of offset voltage and switch tube is received to this variable turn -on time length control circuit, makes square being inversely proportional to of turn -on time, and square being directly proportional of the on off cycle of switch tube of switching power supply's switch tube with turn -off time of switch tube to produce and turn -off the signal. This drive signal produces the circuit and produces drive signal according to zero cross signal and shutoff signal, and drive signal transmits to the bars end of switch tube, and in response to the zero cross signal, the drive signal control switch piping leads to, and in response to turn -offing the signal, drive signal control switch manages the shutoff. The utility model discloses the critical mode control's of switching on of step -down structure switching power supply's power factor can be optimized, total harmonic distortion is reduced.

Description

Translated fromChinese

开关电源控制器以及包含该开关电源控制器的开关电源Switching power supply controller and switching power supply including the switching power supply controller

技术领域technical field

本实用新型涉及开关电源技术，尤其涉及一种降压结构中具有功率因数调整功能、临界导通模式控制的开关电源控制器，以及包含该开关电源控制器的开关电源。The utility model relates to switching power supply technology, in particular to a switching power supply controller with power factor adjustment function and critical conduction mode control in a step-down structure, and a switching power supply including the switching power supply controller.

背景技术Background technique

传统的交流供电的、带功率因数调整(PFC)功能、临界导通模式的降压结构LED恒流驱动器如图1所示，主要包括：AC输入整流电路101、交流输入源102、输入电容Cin、电感L1、开关管M1、采样电阻Rs、续流二极管D1，输出电容Cbulk、恒流开关电源控制器100。其中，恒流开关电源控制器100用于接收反馈信号FB，采样电阻Rs采样输出电流，以此驱动开关管M1。The traditional AC power supply, with power factor adjustment (PFC) function, critical conduction mode step-down structure LED constant current driver is shown in Figure 1, mainly includes: AC input rectification circuit 101, AC input source 102, input capacitor Cin , an inductor L1 , a switching tube M1 , a sampling resistor Rs, a freewheeling diode D1 , an output capacitor Cbulk, and a constant current switching power supply controller 100 . Wherein, the constant current switching power supply controller 100 is used to receive the feedback signal FB, and the sampling resistor Rs samples the output current to drive the switch tube M1.

其中，恒流开关电源控制器100包括：过零检测电路125，用于检测表示驱动信号GD结束后的电感L1电流过零的反馈信号FB，在电感L1电流过零时给出开关管M1的导通信号，导通开关管M1；恒流计算电路120，通过对采样电阻Rs上的电压Vcs进行采样计算得到输出电流；误差放大器121，将恒流计算电路120计算出的输出电流与基准电流做误差放大，输出补偿电压Vcomp，补偿电压Vcomp连接补偿电容103，使得环路稳定后，补偿电压Vcomp基本固定；固定导通时间控制电路122，控制开关管M1的导通时间，当开关管M1开始导通时开始定时，当达到设定的导通时间时，输出关断信号给触发器123，去关断开关管M1，在环路稳定后，补偿电压Vcomp固定时，开关管M1的导通时间恒定，由此实现功率因数调整；触发器123，接收过零检测电路125输出的过零信号ZCD和固定导通时间控制电路122输出的关断信号；驱动器124，连接触发器123和开关管M1的栅端，实现对开关管M1的导通和关断驱动。Wherein, the constant current switching power supply controller 100 includes: a zero-crossing detection circuit 125, which is used to detect the feedback signal FB indicating that the current of the inductor L1 crosses zero after the end of the driving signal GD, and provides the current of the switching tube M1 when the current of the inductor L1 crosses zero. Turn on the signal to turn on the switch tube M1; the constant current calculation circuit 120 calculates the output current by sampling the voltage Vcs on the sampling resistor Rs; the error amplifier 121 compares the output current calculated by the constant current calculation circuit 120 with the reference current Do error amplification, output compensation voltage Vcomp, and the compensation voltage Vcomp is connected to the compensation capacitor 103, so that after the loop is stable, the compensation voltage Vcomp is basically fixed; the fixed conduction time control circuit 122 controls the conduction time of the switch tube M1, and when the switch tube M1 Timing starts when the conduction starts, and when the set conduction time is reached, the turn-off signal is output to the trigger 123 to turn off the switch tube M1. After the loop is stabilized and the compensation voltage Vcomp is fixed, the conduction of the switch tube M1 The on-time is constant, thereby realizing power factor adjustment; the trigger 123 receives the zero-crossing signal ZCD output by the zero-crossing detection circuit 125 and the shutdown signal output by the fixed on-time control circuit 122; the driver 124 is connected to the trigger 123 and the switch The gate terminal of the transistor M1 realizes the turn-on and turn-off driving of the switch transistor M1.

开关管M1导通时，输入电流流经采样电阻Rs、电感L1、输出电容Cbulk、输出端Vout，流经电感L1的电流增加，电感L1存储能量。开关管M1关断后，流经电感L1的电流经续流二极管D1续流，流经电感L1的电流逐渐减小，电感L1释放能量到输出电容Cbulk和输出端Vout。当流经电感L1的电流降为零时，过零检测电路125检测出电感L1电流过零的反馈信号FB，产生过零信号ZCD并传输至触发器123，经驱动器124导通开关管M1。开关管M1重复上面的开关动作，电路持续工作，始终处于电感电流临界导通模式。When the switch tube M1 is turned on, the input current flows through the sampling resistor Rs, the inductor L1, the output capacitor Cbulk, and the output terminal Vout, the current flowing through the inductor L1 increases, and the inductor L1 stores energy. After the switching tube M1 is turned off, the current flowing through the inductor L1 continues to flow through the freewheeling diode D1, and the current flowing through the inductor L1 gradually decreases, and the inductor L1 releases energy to the output capacitor Cbulk and the output terminal Vout. When the current flowing through the inductor L1 drops to zero, the zero-crossing detection circuit 125 detects the feedback signal FB of the zero-crossing of the inductor L1 current, generates a zero-crossing signal ZCD and transmits it to the trigger 123 , and turns on the switch tube M1 through the driver 124 . The switch tube M1 repeats the above switching action, the circuit continues to work, and is always in the critical conduction mode of the inductor current.

为实现较好的功率因数调整效果，要求每个开关周期的AC输入电流都能很好的跟随输入电压的变化。在临界导通模式的降压结构中，忽略输入整流管压降、开关管导通时的压降，每个开关周期的平均输入电流为：In order to achieve a better power factor adjustment effect, it is required that the AC input current of each switching cycle can well follow the change of the input voltage. In the step-down structure of the critical conduction mode, ignoring the voltage drop of the input rectifier and the voltage drop when the switch is turned on, the average input current of each switching cycle is:

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>2</span>2</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>u</span>u</span>}\mathrm{<span><span>t</span>t</span>}}}{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{{\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>n</span>no</span>}}}{\mathrm{<span><span>L</span>L</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span><span><span>(</span>(</span>{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}<span><span>-</span>-</span>{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>u</span>u</span>}\mathrm{<span><span>t</span>t</span>}}<span><span>)</span>)</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>1</span>1</span>}<span><span>)</span>)</span>$

其中，V_out为输出电压，V_in为输入电压，I_in为输入电流，T_on为导通时间，L为电感L1的电感值。然而，采用固定导通时间(T_on恒定)、临界导通模式控制时，输入电流I_in不能完全跟随输入电压V_in变化，功率因数变差，总谐波失真加大，所以目前传统的电路的功率因数并不是特别理想，总谐波失真也较大。Wherein, V_out is the output voltage, V_in is the input voltage, I_in is the input current, T_on is the on-time, and L is the inductance value of the inductor L1. However, when using fixed on-time (T_on constant) and critical conduction mode control, the input current I_in cannot completely follow the change of the input voltage V_in , the power factor will deteriorate, and the total harmonic distortion will increase. Therefore, the current traditional circuit The power factor is not particularly ideal, and the total harmonic distortion is also relatively large.

实用新型内容Utility model content

本实用新型要解决的技术问题是提供一种运用于降压结构的开关电源控制器及包含该开关电源控制器的开关电源，能够优化临界导通模式控制的开关电源的功率因数，减小总谐波失真。The technical problem to be solved by the utility model is to provide a switching power supply controller used in a step-down structure and a switching power supply including the switching power supply controller, which can optimize the power factor of the switching power supply controlled by the critical conduction mode and reduce the overall Harmonic distortion.

为解决上述技术问题，本实用新型提供了一种开关电源控制器，包括：In order to solve the above technical problems, the utility model provides a switching power supply controller, including:

过零检测电路，对输入的反馈信号进行过零检测并产生过零信号；The zero-crossing detection circuit performs zero-crossing detection on the input feedback signal and generates a zero-crossing signal;

可变导通时间长度控制电路，接收补偿电压以及开关管的驱动信号，使开关电源的开关管的导通时间的平方与开关管的关断时间成反比、与开关管的开关周期的平方成正比，并产生关断信号；以及The variable conduction time length control circuit receives the compensation voltage and the driving signal of the switch tube, so that the square of the switch tube conduction time of the switching power supply is inversely proportional to the switch off time of the switch tube, and is proportional to the square of the switch cycle of the switch tube proportional, and generates a shutdown signal; and

驱动信号产生电路，根据所述过零信号和关断信号产生驱动信号，所述驱动信号传输至所述开关管的栅端，以控制所述开关管的导通和关断。The driving signal generation circuit generates a driving signal according to the zero-crossing signal and the off signal, and transmits the driving signal to the gate terminal of the switching tube to control the switching on and off of the switching tube.

根据本实用新型的一个实施例，所述可变导通时间长度控制电路包括：According to an embodiment of the utility model, the variable on-time length control circuit includes:

导通时间检测电路，对所述开关电源内的开关管的导通时间进行检测，以得到导通时间定时电压；The conduction time detection circuit detects the conduction time of the switching tube in the switching power supply to obtain the conduction time timing voltage;

关断时间检测电路，对所述开关电源内的开关管的导通时间进行检测，以得到关断时间定时电压；The off-time detection circuit detects the on-time of the switching tube in the switching power supply to obtain the off-time timing voltage;

开关周期时间检测电路，对所述开关管的开关周期时间进行检测，以得到开关周期时间定时电压；The switching cycle time detection circuit detects the switching cycle time of the switching tube to obtain the switching cycle time timing voltage;

定时电流产生电路，根据所述导通时间定时电压、关断时间定时电压、开关周期时间定时电压，产生定时电流，所述的定时电流与导通时间定时电压成正比、与关断时间定时电压成正比、与开关周期时间定时电压的平方成反比；The timing current generating circuit generates a timing current according to the on-time timing voltage, off-time timing voltage, and switching cycle time timing voltage, and the timing current is proportional to the on-time timing voltage and is proportional to the off-time timing voltage. Proportional to and inversely proportional to the square of the switching cycle time timing voltage;

定时电容和比较器，在开关管导通期间，所述的定时电流对定时电容充电，并与补偿电压比较，得到关断信号。A timing capacitor and a comparator. During the conduction period of the switch tube, the timing current charges the timing capacitor and compares it with the compensation voltage to obtain a shutdown signal.

根据本实用新型的一个实施例，所述可变导通时间长度控制电路包括：According to an embodiment of the utility model, the variable on-time length control circuit includes:

关断时间检测电路，对所述开关电源内的开关管的导通时间进行检测，以得到关断时间定时电压；The off-time detection circuit detects the on-time of the switching tube in the switching power supply to obtain the off-time timing voltage;

开关周期时间检测电路，对所述开关管的开关周期时间进行检测，以得到开关周期时间定时电压；The switching cycle time detection circuit detects the switching cycle time of the switching tube to obtain the switching cycle time timing voltage;

定时电流产生电路，根据所述关断时间定时电压、开关周期时间定时电压，产生定时电流，所述的定时电流与关断时间定时电压得平方根成正比、与开关周期时间定时电压成反比；The timing current generation circuit generates a timing current according to the off-time timing voltage and the switching cycle time timing voltage, and the timing current is proportional to the square root of the off-time timing voltage and inversely proportional to the switching cycle time timing voltage;

定时电容和比较器，在所述开关管导通期间，所述的定时电流对定时电容充电，并与补偿电压比较，得到关断信号。A timing capacitor and a comparator. During the conduction period of the switch tube, the timing current charges the timing capacitor and compares it with the compensation voltage to obtain a shutdown signal.

根据本实用新型的一个实施例，所述导通时间检测电路得到的导通时间定时电压表示所述开关管在前一个开关周期内的导通时间，或者表示所述开关管在前多个开关周期内的导通时间的平均值。According to an embodiment of the present invention, the on-time timing voltage obtained by the on-time detection circuit indicates the on-time of the switching tube in the previous switching cycle, or indicates that the switching tube is in the previous switching cycle. The average value of the on-time over the period.

根据本实用新型的一个实施例，所述关断时间检测电路得到的关断时间定时电压表示所述开关管在前一个开关周期内的关断时间，或者表示所述开关管在前多个开关周期内的关断时间的平均值。According to an embodiment of the present invention, the off-time timing voltage obtained by the off-time detection circuit indicates the off-time of the switching tube in the previous switching cycle, or indicates that the switching tube is in the previous switching cycle. The average value of the off-time within the cycle.

根据本实用新型的一个实施例，所述开关周期时间检测电路得到的开关周期时间定时电压表示所述开关管在前一个开关周期内的开关周期时间，或者表示所述开关管在前多个开关周期内的开关周期时间的平均值。According to an embodiment of the present invention, the switching cycle time timing voltage obtained by the switching cycle time detection circuit indicates the switching cycle time of the switching tube in the previous switching cycle, or indicates that the switching tube is in the previous switching cycle. Average of the switching cycle times within the period.

根据本实用新型的一个实施例，所述导通时间检测电路的输入端与所述开关管的栅端直接连接，以对所述开关管的导通时间进行检测。According to an embodiment of the present invention, the input terminal of the on-time detection circuit is directly connected to the gate terminal of the switch tube, so as to detect the on-time of the switch tube.

根据本实用新型的一个实施例，所述关断时间检测电路的输入端与所述开关管的栅端直接连接，以对所述开关管的导通时间进行检测。According to an embodiment of the present invention, the input end of the off-time detection circuit is directly connected to the gate end of the switch tube, so as to detect the turn-on time of the switch tube.

根据本实用新型的一个实施例，所述开关周期时间检测电路的输入端与所述开关管的栅端直接连接，以对所述开关管的开关周期时间进行检测。According to an embodiment of the present invention, the input terminal of the switching cycle time detection circuit is directly connected to the gate terminal of the switching tube, so as to detect the switching cycle time of the switching tube.

根据本实用新型的一个实施例，所述导通时间检测电路包括：According to an embodiment of the utility model, the on-time detection circuit includes:

电流源；Battery;

第一开关，其第一端连接所述电流源的输出端；a first switch, the first terminal of which is connected to the output terminal of the current source;

第二开关，其第一端连接所述第一开关的第二端，其第二端接地；a second switch, the first end of which is connected to the second end of the first switch, and the second end of which is grounded;

第一电容，其第一端连接所述第一开关的第二端和第二开关的第一端，其第二端接地；a first capacitor, the first end of which is connected to the second end of the first switch and the first end of the second switch, and the second end of which is grounded;

电压跟随器，其输入端连接所述第一电容的第一端；a voltage follower, the input end of which is connected to the first end of the first capacitor;

第三开关，其第一端连接所述电压跟随器的输出端；及a third switch, the first terminal of which is connected to the output terminal of the voltage follower; and

第二电容，其第一端连接所述第三开关的第二端，其第二端接地，所述第二电容的第二端用于输出所述导通时间定时电压。A second capacitor whose first end is connected to the second end of the third switch and whose second end is grounded, and the second end of the second capacitor is used to output the on-time timing voltage.

根据本实用新型的一个实施例，所述驱动信号产生电路包括：According to an embodiment of the present utility model, the driving signal generating circuit includes:

触发器，其置位输入端接收所述过零信号，其复位输入端接收所述关断信号，其输出端产生所述驱动信号；及a flip-flop whose set input terminal receives the zero-crossing signal, its reset input terminal receives the shutdown signal, and its output terminal generates the drive signal; and

驱动器，所述驱动信号经由所述驱动器传输至所述开关管的栅端。A driver, the driving signal is transmitted to the gate terminal of the switch tube through the driver.

根据本实用新型的一个实施例，通过对采样电阻上的电压进行采样计算得到输出电流，并将输出电流与基准电流进行误差放大，以输出补偿电压。According to an embodiment of the present invention, the output current is obtained by sampling and calculating the voltage on the sampling resistor, and the error between the output current and the reference current is amplified to output the compensation voltage.

根据本实用新型的一个实施例，通过对开关电源的输出端电压进行采样得到采样电压，并将采样电压与基准电压进行误差放大，以输出补偿电压。According to an embodiment of the present invention, the sampling voltage is obtained by sampling the voltage at the output terminal of the switching power supply, and the error amplification between the sampling voltage and the reference voltage is performed to output the compensation voltage.

本实用新型还提供一种开关电源，其特征在于，包括：The utility model also provides a switching power supply, which is characterized in that it includes:

如上所述的降压结构的开关电源控制器；以及A switching power supply controller with a step-down structure as described above; and

与所述开关电源控制器相连的外围电路。Peripheral circuits connected with the switching power supply controller.

根据本实用新型的一个实施例，所述外围电路包括：交流信号源、整流桥、输入电容、开关管、采样电阻、环路补偿电容、续流二极管、输出电容和电感；其中，所述输入电容的第一端连接输入电压接入端，其第二端接地；所述开关管的源端连接输入电压接入端，其漏端连接采样电阻的第一端，其栅端接收驱动信号；所述电感的第一端连接采样电阻的第二端，电感的第二端连接输出电容的第一端；所述续流二极管的阴极连接采样电阻的第一端，其阳极连接输出电容的第二端，所述输出电容用于与负载并联。According to an embodiment of the present invention, the peripheral circuit includes: an AC signal source, a rectifier bridge, an input capacitor, a switch tube, a sampling resistor, a loop compensation capacitor, a freewheeling diode, an output capacitor, and an inductor; wherein, the input The first end of the capacitor is connected to the input voltage input end, and the second end thereof is grounded; the source end of the switch tube is connected to the input voltage input end, the drain end is connected to the first end of the sampling resistor, and the gate end receives the driving signal; The first end of the inductor is connected to the second end of the sampling resistor, and the second end of the inductor is connected to the first end of the output capacitor; the cathode of the freewheeling diode is connected to the first end of the sampling resistor, and its anode is connected to the first end of the output capacitor. Two terminals, the output capacitor is used in parallel with the load.

根据本实用新型的一个实施例，所述外围电路包括：交流信号源、整流桥、输入电容、开关管、采样电阻、环路补偿电容、续流二极管、输出电容和电感；其中，所述输入电容的第一端连接输入电压接入端，其第二端接地；所述续流二极管的阴极连接输入电压接入端；所述输出电容的第一端连接续流二极管的阴极，所述输出电容用于与负载并联；所述电感的第一端连接续流二极管的阳极，其第二端连接输出电容的第二端；所述开关管的源端连接电感的第一端，其漏端连接采样电阻的第一端，经由采样电阻接地，其栅端接收驱动信号。According to an embodiment of the present invention, the peripheral circuit includes: an AC signal source, a rectifier bridge, an input capacitor, a switch tube, a sampling resistor, a loop compensation capacitor, a freewheeling diode, an output capacitor, and an inductor; wherein, the input The first end of the capacitor is connected to the input voltage input end, and the second end thereof is grounded; the cathode of the freewheeling diode is connected to the input voltage input end; the first end of the output capacitor is connected to the cathode of the freewheeling diode, and the output The capacitor is used to connect in parallel with the load; the first end of the inductor is connected to the anode of the freewheeling diode, and the second end is connected to the second end of the output capacitor; the source end of the switch tube is connected to the first end of the inductor, and the drain end The first end of the sampling resistor is connected to the ground through the sampling resistor, and the gate terminal thereof receives the driving signal.

与现有技术相比，本实用新型具有以下优点：Compared with the prior art, the utility model has the following advantages:

本实用新型的开关电源控制器对开关管的导通时间进行控制，使其和开关管的前一个或前多个开关周期的导通时间、关断时间、开关周期时间相关联，从而提高了电路的功率因数，减小了开关电源的总谐波失真。The switching power supply controller of the utility model controls the conduction time of the switch tube so that it is associated with the conduction time, the turn-off time, and the switch cycle time of the previous one or multiple switching cycles of the switch tube, thereby improving the The power factor of the circuit reduces the total harmonic distortion of the switching power supply.

进一步而言，本实用新型实施例的开关电源控制器使得开关管的导通时间的平方与开关管的关断时间成反比、与开关管的开关周期的平方成正比，即开关管的导通时间T_on、关断时间T_off、开关周期T满足保持固定，使得输入电流很好的跟随输入电压变化，实现良好的功率因数性能。Furthermore, the switching power supply controller of the embodiment of the utility model makes the square of the turn-on time of the switch tube inversely proportional to the turn-off time of the switch tube, and proportional to the square of the switching period of the switch tube, that is, the turn-on time of the switch tube Time T_on , off time T_off , switching period T satisfy Keep it fixed so that the input current follows the input voltage well and achieves good power factor performance.

附图说明Description of drawings

图1是现有技术中的一种降压结构中具有功率因数调整功能、采用固定导通时间控制、临界导通模式控制的LED恒流驱动器的结构示意图；FIG. 1 is a structural schematic diagram of an LED constant current driver with a power factor adjustment function in a step-down structure in the prior art, which adopts constant conduction time control and critical conduction mode control;

图2是本实用新型实施例一中降压结构中具有功率因数调整功能、采用可变导通时间控制、临界导通模式控制的LED恒流驱动器的结构示意图；Fig. 2 is a structural schematic diagram of an LED constant current driver with a power factor adjustment function, variable on-time control, and critical conduction mode control in a step-down structure in Embodiment 1 of the present invention;

图3是本实用新型实施例一中一种可变导通时间控制电路的结构示意图；Fig. 3 is a schematic structural diagram of a variable on-time control circuit in Embodiment 1 of the present invention;

图4是本实用新型实施例一中另一种可变导通时间控制电路的结构示意图；Fig. 4 is a schematic structural diagram of another variable on-time control circuit in Embodiment 1 of the present invention;

图5本实用新型实施例一中导通时间检测电路的结构示意图；Fig. 5 is a schematic structural diagram of the on-time detection circuit in Embodiment 1 of the utility model;

图6是本实用新型实施例二中降压结构中具有功率因数调整功能、采用可变导通时间控制、临界导通模式控制的LED恒流驱动器的结构示意图。Fig. 6 is a schematic structural diagram of an LED constant current driver with power factor adjustment function, variable on-time control, and critical conduction mode control in the step-down structure of the second embodiment of the present invention.

具体实施方式Detailed ways

根据背景技术中的公式(1)可知，由于输入电流不能完全跟随输入电压变化是由于固定导通时间控制所导致的，所以为了优化功率因数，优化总谐波失真，可以修改导通时间，把固定导通时间长度修改为不是固定量，而是与前一个或前多个开关周期的导通时间、关断时间、开关周期时间相关联。According to the formula (1) in the background technology, it can be known that the input current cannot completely follow the change of the input voltage due to the fixed on-time control. Therefore, in order to optimize the power factor and optimize the total harmonic distortion, the on-time can be modified. The fixed on-time length is modified not to be a fixed amount, but to be associated with the on-time, off-time, and switching cycle time of the previous one or more switching cycles.

进一步地，把公式(1)换算成如下公式：Further, the formula (1) is converted into the following formula:

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>2</span>2</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{{\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>n</span>no</span>}}}{\mathrm{<span><span>T</span>T</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{{\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>n</span>no</span>}}}{\mathrm{<span><span>L</span>L</span>}}<span><span>\&CenterDot;</span>\&CenterDot;</span>\frac{{\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>f</span>f</span>}\mathrm{<span><span>f</span>f</span>}}}{\mathrm{<span><span>T</span>T</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>i</span>i</span>}\mathrm{<span><span>n</span>no</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}<span><span>)</span>)</span>$

其中T为开关周期时间，T_off为关断时间。Among them, T is the switching cycle time, and T_off is the off time.

为了能够实现较好的功率因数，需要输入电流完全跟随输入电压变化，因此需要保证固定，从而改善功率因数，即开关管的导通时间T_on的平方与开关管的关断时间T_of成反比、与开关管的开关周期T的平方成正比。In order to achieve a better power factor, the input current needs to completely follow the input voltage change, so it is necessary to ensure fixed, thereby improving the power factor, that is, the square of the on-time T_on of the switch is inversely proportional to the off-time T_{of of} the switch, and proportional to the square of the switching period T of the switch.

在本产品的运用领域，开关电源中的相邻的几个开关周期的导通时间和开关周期时间基本上相同，可以使用前一个开关周期的导通时间和开关周期时间来确定控制下一个开关周期的导通时间，从而实现开开关管的导通时间的平方与开关管的关断时间成正比、与开关管的开关周期成正比。In the field of application of this product, the conduction time and switching cycle time of several adjacent switching cycles in the switching power supply are basically the same, and the conduction time and switching cycle time of the previous switching cycle can be used to determine the control of the next switch. The turn-on time of the cycle, so that the square of the turn-on time of the switch tube is proportional to the turn-off time of the switch tube, and is proportional to the switching period of the switch tube.

下面结合具体实施例和附图对本实用新型作进一步说明，但不应以此限制本实用新型的保护范围。The utility model will be further described below in conjunction with specific embodiments and accompanying drawings, but the protection scope of the utility model should not be limited thereby.

参考图2，图2示出了实施例一的降压拓扑开关电源的电路结构示意图，该降压拓扑开关电源可以用作LED驱动器。如图2所述，该开关电源包括：交流信号源102、整流桥101、输入电容Cin、开关管M1、采样电阻Rs、环路补偿电容103、续流二极管D1、输出电容Cbulk以及开关电源控制器200。上述各个部件的整体连接方式与常规的降压开关电源相同，例如与背景技术中图1的整体连接结构相同。即，输入电容Cin的第一端连接输入电压接入端Vin，其第二端接地；开关管M1的源端连接输入电压接入端Vin，其漏端连接采样电阻Rs的第一端，其栅端接收驱动信号GD；电感L1的第一端连接采样电阻Rs的第二端，电感L1的第二端连接输出电容Cbulk的第一端；续流二极管D1的阴极连接采样电阻Rs的第一端，其阳极连接输出电容Cbulk的第二端；输出电容Cbulk用于与负载并联，例如与LED负载并联。Referring to FIG. 2 , FIG. 2 shows a schematic circuit structure diagram of a step-down topology switching power supply according to Embodiment 1, and the step-down topology switching power supply can be used as an LED driver. As shown in Figure 2, the switching power supply includes: AC signal source 102, rectifier bridge 101, input capacitor Cin, switching tube M1, sampling resistor Rs, loop compensation capacitor 103, freewheeling diode D1, output capacitor Cbulk, and switching power supply control device 200. The overall connection of the above components is the same as that of a conventional step-down switching power supply, for example, the same as the overall connection structure of FIG. 1 in the background art. That is, the first terminal of the input capacitor Cin is connected to the input voltage input terminal Vin, and its second terminal is grounded; the source terminal of the switch tube M1 is connected to the input voltage input terminal Vin, and its drain terminal is connected to the first terminal of the sampling resistor Rs, which The gate terminal receives the drive signal GD; the first terminal of the inductor L1 is connected to the second terminal of the sampling resistor Rs, and the second terminal of the inductor L1 is connected to the first terminal of the output capacitor Cbulk; the cathode of the freewheeling diode D1 is connected to the first terminal of the sampling resistor Rs terminal, the anode of which is connected to the second terminal of the output capacitor Cbulk; the output capacitor Cbulk is used for parallel connection with the load, for example, parallel connection with the LED load.

本实施例中，开关电源控制器200包括：恒流计算电路120、误差放大器121、可变导通时间控制电路122、触发器123、驱动器124以及过零检测电路125。In this embodiment, the switching power supply controller 200 includes: a constant current calculation circuit 120 , an error amplifier 121 , a variable on-time control circuit 122 , a flip-flop 123 , a driver 124 and a zero-crossing detection circuit 125 .

其中，过零检测电路125，检测表示驱动信号GD结束后的电感L1电流过零的反馈信号FB，响应于电感电流过零，输出过零信号ZCD，在电感L1电流过零时给出开关管M1的导通信号，导通开关管M1。过零检测电路125的输入端可以连接至开关管M1的漏端，通过检测开关管M1的漏端信号来实现对电感电流的过零检测，从而产生过零信号ZCD。Among them, the zero-crossing detection circuit 125 detects the feedback signal FB indicating that the inductor L1 current crosses zero after the end of the drive signal GD, and outputs the zero-crossing signal ZCD in response to the zero-crossing of the inductor current, and gives the switching tube when the inductor L1 current crosses zero. The conduction signal of M1 turns on the switch tube M1. The input terminal of the zero-crossing detection circuit 125 can be connected to the drain terminal of the switch tube M1, and the zero-crossing detection of the inductor current is realized by detecting the drain terminal signal of the switch tube M1, thereby generating the zero-crossing signal ZCD.

恒流计算电路120，通过对采样电阻Rs上的电压Vcs进行采样计算得到输出电流。误差放大器121，将输出电流与基准电流做误差放大，输出补偿电压Vcomp，补偿电压Vcomp连接补偿电容103，使得环路稳定后，补偿电压Vcomp基本固定。The constant current calculation circuit 120 calculates the output current by sampling the voltage Vcs on the sampling resistor Rs. The error amplifier 121 amplifies the error between the output current and the reference current, and outputs the compensation voltage Vcomp. The compensation voltage Vcomp is connected to the compensation capacitor 103, so that the compensation voltage Vcomp is basically constant after the loop is stable.

可变导通时间控制电路122，控制开关管M1的导通时间，当开关管M1开始导通时开始定时，当达到设定的导通时间时，输出关断信号给触发器123，去关断开关管M1，在环路稳定后，补偿电压Vcomp固定时，开关管M1的导通时间满足以下关系，导通时间的平方与开关管的关断时间成正比、与开关管的开关周期成正比，由此实现功率因数调整。The variable conduction time control circuit 122 controls the conduction time of the switch tube M1, starts timing when the switch tube M1 starts to conduct, and outputs a turn-off signal to the trigger 123 when the set conduction time is reached, to turn off Turn off the switching tube M1, after the loop is stable, when the compensation voltage Vcomp is fixed, the conduction time of the switching tube M1 satisfies the following relationship, the square of the switching tube M1 is proportional to the off time of the switching tube, and is proportional to the switching period Proportional to achieve power factor adjustment.

触发器123，接收过零检测电路125输出的过零信号ZCD和可变导通时间控制电路122输出的关断信号。驱动器124，连接触发器123和开关管M1的栅端，实现对开关管M1的导通和关断驱动。即，由触发器123和驱动器124组成的驱动信号产生电路，根据所述过零信号和关断信号产生驱动信号，响应于所述过零信号，所述驱动信号控制开关管M1导通，响应于所述关断信号，所述驱动信号控制开关管M1关断。The flip-flop 123 receives the zero-crossing signal ZCD output by the zero-crossing detection circuit 125 and the turn-off signal output by the variable on-time control circuit 122 . The driver 124 is connected to the flip-flop 123 and the gate terminal of the switching tube M1 to realize the on and off driving of the switching tube M1. That is, the driving signal generation circuit composed of the flip-flop 123 and the driver 124 generates a driving signal according to the zero-crossing signal and the shutdown signal, and in response to the zero-crossing signal, the driving signal controls the switching tube M1 to be turned on. Based on the turn-off signal, the drive signal controls the switch tube M1 to turn off.

图3是一种可变导通时间控制电路的结构示意图。如图3所示，可变导通时间控制电路122包括：导通时间检测电路401、关断时间检测电路402、定时电流产生电路403、定时电容203以及比较器404。FIG. 3 is a schematic structural diagram of a variable on-time control circuit. As shown in FIG. 3 , the variable on-time control circuit 122 includes: an on-time detection circuit 401 , an off-time detection circuit 402 , a timing current generation circuit 403 , a timing capacitor 203 and a comparator 404 .

导通时间检测电路401检测开关管的导通时间，并将该导通时间转换成电压信号并且保持，记为导通时间定时电压V_ton；The conduction time detection circuit 401 detects the conduction time of the switch tube, and converts the conduction time into a voltage signal and maintains it, which is recorded as the conduction time timing voltage V_ton ;

关断时间检测电路402检测开关管的关断时间，并将该导通时间转换成电压信号并且保持，记为关断时间定时电压V_off；The off-time detection circuit 402 detects the off-time of the switch tube, and converts the on-time into a voltage signal and maintains it, which is recorded as the off-time timing voltage V_off ;

开关周期检测电路403检测开关管的开关周期时间，并将该开关周期时间转换成电压信号并且保持，记为开关周期时间定时电压V_T；The switching cycle detection circuit 403 detects the switching cycle time of the switching tube, and converts the switching cycle time into a voltage signal and maintains it, which is recorded as the switching cycle time timing voltage V_T ;

定时电流产生电路404，根据导通时间定时电压V_ton、关断时间定时电压V_off、开关周期时间定时电压V_T得到定时电流I1，定时电流I1与导通时间定时电压V_ton成正比、与关断时间定时电压V_off成正比、与开关周期时间定时电压V_T的平方成反比，即：The timing current generating circuit 404 obtains the timing current I1 according to the on-time timing voltage V_ton , the off-time timing voltage V_off , and the switching cycle time timing voltage V_T , and the timing current I1 is proportional to the on-time timing voltage V_ton and is proportional to the on-time timing voltage V ton. The off-time timing voltage V_off is proportional to the square of the switching cycle time timing voltage V_T , that is:

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>\&times;</span>\&times;</span>\frac{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>n</span>no</span>}}}{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>T</span>T</span>}}}<span><span>\&times;</span>\&times;</span>\frac{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>f</span>f</span>}\mathrm{<span><span>f</span>f</span>}}}{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>T</span>T</span>}}}$

或表示为：or expressed as:

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>\&times;</span>\&times;</span>\frac{{\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>n</span>no</span>}}}{\mathrm{<span><span>T</span>T</span>}}<span><span>\&times;</span>\&times;</span>\frac{{\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>f</span>f</span>}\mathrm{<span><span>f</span>f</span>}}}{\mathrm{<span><span>T</span>T</span>}}$

其中K1、K2为常数。Among them, K1 and K2 are constants.

定时电流I1对定时电容203充电，再与补偿电压Vcomp比较，比较器404输出开关管的关断信号，以确定导通时间，此时:The timing current I1 charges the timing capacitor 203, and then compares it with the compensation voltage Vcomp, and the comparator 404 outputs the turn-off signal of the switching tube to determine the conduction time. At this time:

${\mathrm{<span><span>T</span>T</span>}}_{\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>n</span>no</span>}}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>c</span>c</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>m</span>m</span>}\mathrm{<span><span>p</span>p</span>}}<span><span>\&CenterDot;</span>\&CenterDot;</span>{\mathrm{<span><span>C</span>C</span>}}_{\mathrm{<span><span>203</span>203</span>}}}{{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>1</span>1</span>}}}$

代入I1的电流表达式，可以实现固定。Substituting the current expression of I1, it can be realized fixed.

具体而言，导通时间检测电路401得到的导通时间定时电压可以表示开关管M1在前一个开关周期内的导通时间，也可以表示开关管M1在前多个开关周期内的导通时间的平均值。关断时间检测电路402得到的关断时间定时电压表示开关管M1在前一个开关周期内的关断时间，或者表示开关管M1在前多个开关周期内的关断时间的平均值。开关周期时间检测电路403得到的开关周期时间定时电压表示开关管M1在前一个开关周期内的开关周期时间，或者表示开关管M1在前多个开关周期内的开关周期时间的平均值。Specifically, the on-time timing voltage obtained by the on-time detection circuit 401 may indicate the on-time of the switch tube M1 in the previous switching cycle, or the on-time of the switch tube M1 in the previous several switching cycles. average of. The off-time timing voltage obtained by the off-time detection circuit 402 represents the off-time of the switch tube M1 in the previous switching cycle, or represents the average value of the off-time of the switch tube M1 in the previous switching cycles. The switching cycle time timing voltage obtained by the switching cycle time detection circuit 403 represents the switching cycle time of the switching tube M1 in the previous switching cycle, or represents the average value of the switching cycle time of the switching tube M1 in the previous switching cycles.

在一实施例中，导通时间检测电路401的输入端与开关管M1的栅端直接连接，以对开关管M1的导通时间进行检测；关断时间检测电路402的输入端也与开关管M1的栅端直接连接，以对开关管M1的导通时间进行检测；同样，开关周期时间检测电路403的输入端与开关管M1的栅端直接连接，以对开关管M1的开关周期时间进行检测。In one embodiment, the input terminal of the on-time detection circuit 401 is directly connected to the gate terminal of the switch tube M1 to detect the on-time of the switch tube M1; the input terminal of the off-time detection circuit 402 is also connected to the gate terminal of the switch tube M1. The gate terminal of M1 is directly connected to detect the conduction time of the switch tube M1; similarly, the input terminal of the switch cycle time detection circuit 403 is directly connected to the gate terminal of the switch tube M1 to detect the switch cycle time of the switch tube M1 detection.

图4是另一种可变导通时间控制电路的结构示意图。如图4所示，可变导通时间控制电路122包括：关断时间检测电路501、开关周期检测电路502、定时电流产生电路503、定时电容203以及比较器404。FIG. 4 is a schematic structural diagram of another variable on-time control circuit. As shown in FIG. 4 , the variable on-time control circuit 122 includes: an off-time detection circuit 501 , a switching period detection circuit 502 , a timing current generation circuit 503 , a timing capacitor 203 and a comparator 404 .

关断时间检测电路501检测开关管的关断时间，并将该导通时间转换成电压信号并且保持，记为关断时间定时电压V_off；The off-time detection circuit 501 detects the off-time of the switch tube, and converts the on-time into a voltage signal and maintains it, which is recorded as the off-time timing voltage V_off ;

开关周期检测电路502检测开关管的开关周期时间，并将该开关周期时间转换成电压信号并且保持，记为开关周期时间定时电压V_T；The switching cycle detection circuit 502 detects the switching cycle time of the switching tube, and converts the switching cycle time into a voltage signal and maintains it, which is recorded as the switching cycle time timing voltage V_T ;

定时电流产生电路503，根据关断时间定时电压V_off、开关周期时间定时电压V_T得到定时电流I2，定时电流I2与关断时间定时电压V_off的平方根成正比、与开关周期时间定时电压V_T成反比，即：The timing current generating circuit 503 obtains the timing current I2 according to the off-time timing voltage V_off and the switching cycle time timing voltage V_T , and the timing current I2 is proportional to the square root of the off-time timing voltage V_off and is proportional to the switching cycle time timing voltage V_T is inversely proportional, that is:

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>4</span>4</span>}}}{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>T</span>T</span>}}}\sqrt{{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>3</span>3</span>}}<span><span>\&times;</span>\&times;</span>{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>t</span>t</span>}\mathrm{<span><span>o</span>o</span>}\mathrm{<span><span>f</span>f</span>}\mathrm{<span><span>f</span>f</span>}}}$

其中K3、K4为常数。Among them, K3 and K4 are constants.

定时电流I2对定时电容203充电，再与补偿电压Vcomp比较，比较器404输出开关管的关断信号，以确定导通时间，经过与前面相似的推导，同样可以实现固定。The timing current I2 charges the timing capacitor 203, and then compares it with the compensation voltage Vcomp, and the comparator 404 outputs the turn-off signal of the switch tube to determine the conduction time. After a derivation similar to the previous one, it can also be realized fixed.

参考图5，图5示出了导通时间检测电路401的一种实现电路，包括：电流源601、第一开关S1、第二开关S2、第三开关S3、第一电容604、电压跟随器605以及第二电容607。Referring to FIG. 5, FIG. 5 shows an implementation circuit of the on-time detection circuit 401, including: a current source 601, a first switch S1, a second switch S2, a third switch S3, a first capacitor 604, and a voltage follower 605 and the second capacitor 607.

其中，第一开关S1，其第一端连接电流源601的输出端；第二开关S2，其第一端连接第一开关S1的第二端，其第二端接地；第一电容604，其第一端连接第一开关S1的第二端和第二开关S2的第一端，其第二端接地；电压跟随器605，其输入端连接第一电容604的第一端；第三开关S3，其第一端连接电压跟随器605的输出端；第二电容607，其第一端连接第三开关S3的第二端，其第二端接地，第二电容607的第二端用于输出导通时间定时电压V_Ton。Wherein, the first switch S1, its first end is connected to the output end of the current source 601; the second switch S2, its first end is connected to the second end of the first switch S1, and its second end is grounded; the first capacitor 604, its The first end is connected to the second end of the first switch S1 and the first end of the second switch S2, the second end of which is grounded; the voltage follower 605, whose input end is connected to the first end of the first capacitor 604; the third switch S3 , its first end is connected to the output end of the voltage follower 605; the second capacitor 607, its first end is connected to the second end of the third switch S3, its second end is grounded, and the second end of the second capacitor 607 is used for output On-time timing voltage V_Ton .

进一步而言，开关管M1导通时，第一开关S1被控制为导通，第二开关S2被控制为关断，第三开关S3被控制为关断，电流源601的输出电流I3对第一电容604充电，第一电容604两端的电压与开关管M1的导通时间成正比，能够直接反应导通时间；开关管M1关断时，第一开关S1被控制为关断，第二开关S2被控制为关断，第三开关S3被控制为导通，第一电容607两端的电压被维持，第一电容604两端的电压经电压跟随器605、第三开关S3传递到第二电容607上，从而在第二电容607的两端得到表示导通时间的导通时间定时电压V_Ton；经过预设时间后，第一开关S1关断，第二开关S2导通，第三开关S3关断，第一电容604两端的电压清零，第二电容607两端的电压维持不变。接下来，等待下一个开关周期，重新检测导通时间。Further, when the switch tube M1 is turned on, the first switch S1 is controlled to be turned on, the second switch S2 is controlled to be turned off, the third switch S3 is controlled to be turned off, and the output current I3 of the current source 601 has an effect on the first A capacitor 604 is charged, and the voltage across the first capacitor 604 is proportional to the conduction time of the switch tube M1, which can directly reflect the conduction time; when the switch tube M1 is turned off, the first switch S1 is controlled to be off, and the second switch S2 is controlled to be turned off, the third switch S3 is controlled to be turned on, the voltage across the first capacitor 607 is maintained, and the voltage across the first capacitor 604 is transferred to the second capacitor 607 through the voltage follower 605 and the third switch S3 , so that the on-time timing voltage V_Ton representing the on-time is obtained at both ends of the second capacitor 607; after a preset time, the first switch S1 is turned off, the second switch S2 is turned on, and the third switch S3 is turned off is off, the voltage across the first capacitor 604 is cleared, and the voltage across the second capacitor 607 remains unchanged. Next, wait for the next switching cycle and retest the on-time.

可以理解的是，开关周期时间检测电路403的实现电路以及关断时间检测电路403的实现电路可以和导通时间检测电路401相同。例如，也可以采用图5所示的电路结构。It can be understood that the implementation circuit of the switching cycle time detection circuit 403 and the implementation circuit of the off-time detection circuit 403 may be the same as the on-time detection circuit 401 . For example, the circuit structure shown in FIG. 5 may also be used.

触发器123的置位输入端接收过零信号ZCD，复位输入端接收来自可变导通时间长度控制电路301的关断信号，其输出端产生驱动信号以控制开关管M1的导通和关断。作为一个非限制性的例子，该驱动信号经由驱动器124后传输至开关管M1的栅端。The set input end of the flip-flop 123 receives the zero-crossing signal ZCD, the reset input end receives the turn-off signal from the variable conduction time length control circuit 301, and its output end generates a drive signal to control the turn-on and turn-off of the switch tube M1 . As a non-limiting example, the driving signal is transmitted to the gate terminal of the switch M1 after passing through the driver 124 .

图6是本实用新型实施例二中降压结构中具有功率因数调整功能、采用可变导通时间控制、临界导通模式控制的LED恒流驱动器的结构示意图。在图6所示的实施例中，将图2中的开关电源控制器300应用于实地的降压结构的开关电源中。参考图6所示，输入电容Cin的第一端连接输入电压接入端Vin，其第二端接地；续流二极管D1的阴极连接输入电压接入端Vin；输出电容Cbulk的第一端连接续流二极管D1的阴极，输出电容Cbulk用于与负载并联，例如和LED负载并联；电感L1的第一端连接续流二极管D1的阳极，其第二端连接输出电容Cbulk的第二端。开关管M1的源端连接电感L1的第一端，其漏端连接采样电阻Rcs的第一端，经由采样电阻Rcs接地，其栅端接收驱动信号GT。如此，电感L1的第一端经由开关管M1和采样电阻Rcs形成对地的通路。采样电阻Rcs将流经电感L1、开关管M1的电感电流转换为采样电压CS。Fig. 6 is a structural diagram of an LED constant current driver with power factor adjustment function, variable on-time control, and critical conduction mode control in the step-down structure of the second embodiment of the present invention. In the embodiment shown in FIG. 6 , the switching power supply controller 300 shown in FIG. 2 is applied to a switching power supply with a step-down structure. Referring to Figure 6, the first end of the input capacitor Cin is connected to the input voltage input terminal Vin, and its second end is grounded; the cathode of the freewheeling diode D1 is connected to the input voltage input terminal Vin; the first end of the output capacitor Cbulk is connected to the continuous The cathode of the freewheeling diode D1 and the output capacitor Cbulk are used to connect in parallel with the load, for example, in parallel with the LED load; the first end of the inductor L1 is connected to the anode of the freewheeling diode D1, and the second end thereof is connected to the second end of the output capacitor Cbulk. The source terminal of the switching tube M1 is connected to the first terminal of the inductor L1, the drain terminal thereof is connected to the first terminal of the sampling resistor Rcs, grounded via the sampling resistor Rcs, and the gate terminal thereof receives the driving signal GT. In this way, the first end of the inductor L1 forms a path to the ground via the switch tube M1 and the sampling resistor Rcs. The sampling resistor Rcs converts the inductor current flowing through the inductor L1 and the switch tube M1 into a sampling voltage CS.

本领域技术人员应当理解，图2和图6所示的实施例中采用的是恒流控制环路，其控制的是LED输出电流，其中环路补偿电容103用于环路补偿。如果采用恒压控制环路，将控制量换为输出电压Vout，则环路补偿电容103用于补偿电压环路的稳定性，补偿电压Vcomp是误差放大电压。具体而言，将图6中的恒流计算电路120更换为电压采样电路，对开关电源的输出端Vout电压进行采样，得到采样电压；而误差放大器121改为对电压采样电路输出的采样电压与预设的基准电压进行误差放大，输出补偿电压，该补偿电压施加在环路补偿电容103上；其他电路结构不变，即可实现功率因数调整，同时实现输出电压恒定。上文以开关电源控制器配置有恒流计算电路或者电压采样电路的方式进行了详细的介绍，然而应当认识到，只要可变导通时间控制电路能够接收到补偿电压以及开关管的驱动信号即可，所述恒流控制环路或电压采样电路也可配置在外围电路中而非限定在开关电源控制器内部。Those skilled in the art should understand that the embodiments shown in FIG. 2 and FIG. 6 use a constant current control loop, which controls the LED output current, and the loop compensation capacitor 103 is used for loop compensation. If a constant voltage control loop is adopted and the control variable is replaced by the output voltage Vout, the loop compensation capacitor 103 is used to compensate the stability of the voltage loop, and the compensation voltage Vcomp is an error amplification voltage. Specifically, the constant current calculation circuit 120 in FIG. 6 is replaced with a voltage sampling circuit, and the voltage at the output terminal Vout of the switching power supply is sampled to obtain a sampling voltage; and the error amplifier 121 is changed to compare the sampling voltage output by the voltage sampling circuit with Error amplification is performed on the preset reference voltage, and a compensation voltage is output, and the compensation voltage is applied to the loop compensation capacitor 103; other circuit structures remain unchanged, so that the power factor adjustment can be realized, and the output voltage can be kept constant at the same time. The above describes in detail that the switching power supply controller is equipped with a constant current calculation circuit or a voltage sampling circuit. However, it should be recognized that as long as the variable on-time control circuit can receive the compensation voltage and the drive signal of the switch tube , the constant current control loop or voltage sampling circuit can also be configured in the peripheral circuit instead of being limited inside the switching power supply controller.

本实用新型公开了具有功率因数调整功能，临界导通模式控制的开关电源控制器，并且参照附图描述了本实用新型的具体实施方式和效果。应该理解到的是上述实施例只是对本实用新型的说明，而不是对本实用新型的限制，任何不超出本实用新型实质精神范围内的实用新型创造，包括过零检测电路、导通时间长度控制电路、触发器电路，对电路的局部构造的变更、对元器件的类型或型号的替换，以及其他非实质性的替换或修改，均落入本实用新型保护范围之内。The utility model discloses a switching power supply controller with power factor adjustment function and critical conduction mode control, and describes the specific implementation and effects of the utility model with reference to the accompanying drawings. It should be understood that the above-mentioned embodiment is only an illustration of the utility model, rather than a limitation of the utility model, and any utility model creation within the scope of the essential spirit of the utility model, including zero-crossing detection circuit, conduction time length control circuit , Trigger circuit, changes to the local structure of the circuit, replacement of the type or model of components, and other insubstantial replacements or modifications all fall within the protection scope of the present utility model.

Claims (14)

1. a switch power controller, is characterized in that, comprising:

Zero cross detection circuit, carries out zero passage detection to the feedback signal of input and produces zero cross signal;

Variable ON time length control circuit, receive the drive singal of bucking voltage and switching tube, make square being inversely proportional to the turn-off time of switching tube of the ON time of the switching tube of Switching Power Supply, to square being directly proportional of the switch periods of switching tube, and produce cut-off signals; And

Drive signal generation circuit, produce drive singal according to described zero cross signal and cut-off signals, described drive singal transfers to the grid end of described switching tube, to control the turn-on and turn-off of described switching tube.

2. switch power controller as claimed in claim 1, it is characterized in that, described variable ON time length control circuit comprises:

ON time testing circuit, detects the ON time of the switching tube in described Switching Power Supply, to obtain ON time timing voltage;

Turn-off time testing circuit, detects the ON time of the switching tube in described Switching Power Supply, to obtain turn-off time timing voltage;

Switch periods time detection circuit, detected the switch periods time of described switching tube, to obtain switch periods time timing voltage;

Timing circuit produces circuit, according to described ON time timing voltage, turn-off time timing voltage, switch periods time timing voltage, produce timing circuit, described timing circuit be directly proportional to ON time timing voltage, be directly proportional to turn-off time timing voltage, and square being inversely proportional to of switch periods time timing voltage;

Timing capacitor and comparator, in switching tube conduction period, described timing circuit charges to timing capacitor, and compares with bucking voltage, obtains cut-off signals.

3. switch power controller as claimed in claim 1, it is characterized in that, described variable ON time length control circuit comprises:

Turn-off time testing circuit, detects the ON time of the switching tube in described Switching Power Supply, to obtain turn-off time timing voltage;

Switch periods time detection circuit, detected the switch periods time of described switching tube, to obtain switch periods time timing voltage;

Timing circuit produces circuit, according to described turn-off time timing voltage, switch periods time timing voltage, produces timing circuit, described timing circuit is directly proportional to the square root of turn-off time timing voltage, is inversely proportional to switch periods time timing voltage;

Timing capacitor and comparator, in described switching tube conduction period, described timing circuit charges to timing capacitor, and compares with bucking voltage, obtains cut-off signals.

4. switch power controller as claimed in claim 2, it is characterized in that, the ON time timing voltage that described ON time testing circuit obtains represents the ON time of described switching tube in previous switch periods, or represents the mean value of the ON time of described switching tube in front multiple switch periods.

5. switch power controller as claimed in claim 2 or claim 3, it is characterized in that, the turn-off time timing voltage that described turn-off time testing circuit obtains represents the turn-off time of described switching tube in previous switch periods, or represents the mean value of the turn-off time of described switching tube in front multiple switch periods.

6. switch power controller as claimed in claim 2 or claim 3, it is characterized in that, the switch periods time timing voltage that described switch periods time detection circuit obtains represents the switch periods time of described switching tube in previous switch periods, or represents the mean value of the switch periods time of described switching tube in front multiple switch periods.

7. switch power controller as claimed in claim 2, it is characterized in that, the input of described ON time testing circuit is directly connected with the grid end of described switching tube, to detect the ON time of described switching tube.

8. switch power controller as claimed in claim 2 or claim 3, it is characterized in that, the input of described turn-off time testing circuit is directly connected with the grid end of described switching tube, to detect the ON time of described switching tube.

9. switch power controller as claimed in claim 2 or claim 3, it is characterized in that, the input of described switch periods time detection circuit is directly connected with the grid end of described switching tube, to detect the switch periods time of described switching tube.

10. switch power controller as claimed in claim 2, it is characterized in that, it is characterized in that, described ON time testing circuit comprises:

Current source;

First switch, its first end connects the output of described current source;

Second switch, its first end connects the second end of described first switch, its second end ground connection;

First electric capacity, its first end connects the second end of described first switch and the first end of second switch, its second end ground connection;

Voltage follower, its input connects the first end of described first electric capacity;

3rd switch, its first end connects the output of described voltage follower; And

Second electric capacity, its first end connects the second end of described 3rd switch, and its second end ground connection, the second end of described second electric capacity is for exporting described ON time timing voltage.

11. switch power controllers as claimed in claim 1, it is characterized in that, described drive signal generation circuit comprises:

Trigger, its set input receives described zero cross signal, and its RESET input receives described cut-off signals, and its output produces described drive singal; And

Driver, described drive singal transfers to the grid end of described switching tube via described driver.

12. 1 kinds of Switching Power Supplies, is characterized in that, comprising:

Switch power controller according to any one of claim 1 to 11; And

The peripheral circuit be connected with described switch power controller.

13. Switching Power Supplies as claimed in claim 12, it is characterized in that, described peripheral circuit comprises: alternating message source, rectifier bridge, input capacitance, switching tube, sampling resistor, loop compensation electric capacity, fly-wheel diode, output capacitance and inductance; Wherein, the first end of described input capacitance connects input voltage incoming end, its second end ground connection; The source of described switching tube connects input voltage incoming end, and its drain terminal connects the first end of sampling resistor, and its grid termination receives drive singal; The first end of described inductance connects the second end of sampling resistor, and the second end of inductance connects the first end of output capacitance; The negative electrode of described fly-wheel diode connects the first end of sampling resistor, and its anode connects the second end of output capacitance, and described output capacitance is used in parallel with load.

14. Switching Power Supplies as claimed in claim 12, it is characterized in that, described peripheral circuit comprises: alternating message source, rectifier bridge, input capacitance, switching tube, sampling resistor, loop compensation electric capacity, fly-wheel diode, output capacitance and inductance; Wherein, the first end of described input capacitance connects input voltage incoming end, its second end ground connection; The negative electrode of described fly-wheel diode connects input voltage incoming end; The first end of described output capacitance connects the negative electrode of fly-wheel diode, and described output capacitance is used in parallel with load; The first end of described inductance connects the anode of fly-wheel diode, and its second end connects the second end of output capacitance; The source of described switching tube connects the first end of inductance, and its drain terminal connects the first end of sampling resistor, and via sampling resistor ground connection, its grid termination receives drive singal.