WO2024032465A1 - 一种追踪负载电流的电压转换器模式切换电路及方法 - Google Patents

一种追踪负载电流的电压转换器模式切换电路及方法 Download PDF

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Publication number
WO2024032465A1
WO2024032465A1 PCT/CN2023/111006 CN2023111006W WO2024032465A1 WO 2024032465 A1 WO2024032465 A1 WO 2024032465A1 CN 2023111006 W CN2023111006 W CN 2023111006W WO 2024032465 A1 WO2024032465 A1 WO 2024032465A1
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Prior art keywords
voltage
current
mode control
voltage converter
subunit
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PCT/CN2023/111006
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English (en)
French (fr)
Inventor
金正扬
于翔
肖飞
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圣邦微电子(苏州)有限责任公司
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Publication of WO2024032465A1 publication Critical patent/WO2024032465A1/zh

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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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection

Definitions

  • the present invention relates to the field of integrated circuits, and more specifically, to a voltage converter mode switching circuit and method for tracking load current.
  • DC-to-DC converter is a commonly used power conversion circuit that can convert DC power into DC of different voltages, or a stable voltage close to DC for output. It is widely used in various fields because of its good characteristics such as large power range and stable output voltage.
  • mainstream DC-DC voltage converters can work in step-up (Step-up) or step-down (Step- down) in different modes, and adjust the output voltage by reasonably adjusting the switching state of the power tube.
  • circuit structures such as the mode control unit can determine the working mode of the voltage converter based on the input voltage and realize reasonable switching of the voltage converter between boost mode and buck mode. Therefore, the design of the flipping level of the mode control signal plays a crucial role in whether the working performance of the voltage converter is reasonable.
  • the voltage converter since the voltage converter may operate in many different environments such as no-load, light load, heavy load, etc., the pre-calculated flip level is difficult to maintain the voltage in various environments.
  • the converter implements mode switching under reasonable circumstances. This causes, for example, under light load or no-load conditions, the voltage converter switches to the boost mode in advance, causing unnecessary waste of power and a greater impact on the light-load circuit, and even making it difficult to ensure the safety of the subsequent circuits.
  • the purpose of the present invention is to provide a voltage converter mode switching circuit and method that tracks the load current, and adjusts the flip level of the mode control signal in an approximately linear manner by following the size of the load current. size to ensure that the voltage converter can maintain reasonable working mode switching in different load environments.
  • the present invention adopts the following technical solutions.
  • a first aspect of the present invention relates to a voltage converter mode switching circuit that tracks load current.
  • the circuit includes a mode control unit and an adjustment unit; the mode control unit is used to generate a mode control signal and control the voltage converter based on the mode control signal. Switch between boost mode and buck mode; the adjustment unit is connected to the mode control unit and is used to obtain the output signal of the error comparator in the voltage converter and generate a feedback current to adjust the flip of the mode control signal in the mode control unit level.
  • the mode control unit includes a first current source, a second current source, a first voltage dividing resistor, a second voltage dividing resistor, a current switch tube and an operational amplifier; wherein, the first voltage dividing resistor R1 and the second voltage dividing resistor R2 is connected in series and connected between the input current Vin and ground; the first current source I0 is connected in parallel to both ends of the second voltage dividing resistor R2, one end of the second current source I1 is connected to the high voltage end of the second voltage dividing resistor R2, and the other end It is connected to the drain of the current switch tube; the source of the current switch tube is connected to ground, and the gate is connected to the output terminal of the op amp; the positive input terminal of the op amp is connected to the reference voltage Vref, and the negative input terminal is connected to the first voltage dividing resistor.
  • the connection point between R1 and the second voltage dividing resistor R2 is connected to receive the resistor divided voltage V-, and the output terminal outputs a mode control signal.
  • the adjustment unit includes a reference subunit, a comparison subunit, and a mirror subunit; wherein, the reference subunit is used to receive the input voltage Vin to generate the comparison reference voltage Vref1 and input it into the comparison subunit; the comparison subunit, and The reference subunit is connected to the mirror subunit and is used to receive the comparison reference voltage and the output signal of the error comparator, and generate a third current based on the comparison results between the two; the mirror subunit is connected to the mode control unit and is used to connect the third The current is mirrored into the mode control unit.
  • the reference subunit includes a reference tube Mp1 and a reference current source Iref; wherein, the source of the reference tube Mp1 is connected to the power supply voltage, and the drain and gate are both grounded through the reference current source Iref; the drain and gate of the reference tube Mp1 pole as the output of the reference subunit, providing the comparison reference voltage Vref1 for the comparison subunit.
  • the comparison subunit includes a first input tube, a second input tube, a current mirror, and a crossing resistor; wherein the current mirror includes a mirror-connected MOS tube and two identical mirror current sources; wherein the first input tube, the The drains of the two input tubes are respectively connected to the drains of the two MOS tubes, and the drains of the first input tube and the second input tube are respectively connected to the two mirror current sources; the gate of the first input tube is connected to the comparison The reference voltage Vref1, the gate of the second input tube is connected to the output signal of the error comparator; the crossing resistor is connected between the source of the first input tube and the source of the second input tube, and the drain of the first input tube The pole is connected to the mirror subunit as the output of the comparison subunit.
  • the output end of the mirror subunit is electrically connected to the connection of the first voltage dividing resistor R1 and the second voltage dividing resistor R2 in the mode control unit.
  • the feedback current is
  • the flipping level of the mode control signal in the mode control unit is ;
  • the flip level of the mode control signal in the mode control unit is .
  • the flip level of the mode control signal in the mode control unit has a linear relationship with the load current of the voltage converter; the lighter the subsequent load of the voltage converter, the higher the level will be. and The smaller the value.
  • a second aspect of the present invention is a voltage converter mode switching method that tracks load current.
  • the method includes the voltage converter mode switching circuit that tracks load current described in the first aspect of the present invention.
  • the beneficial effect of the present invention is that, compared with the prior art, the voltage converter mode switching circuit and method for tracking the load current in the present invention can follow the flipping voltage of the adjustment mode control signal that is approximately linear in size of the load current. flat size and ensure that the voltage converter maintains reasonable working mode switching in different load environments.
  • the invention has an ingenious conception, a reasonable and effective method, fully considers various different load environments of the voltage converter, and fully ensures the stability of the output voltage under different environments.
  • the present invention makes full use of the error amplifier and other related circuits generally provided in voltage converter circuits in the prior art, and realizes the calculation between the output voltage of the error amplifier and the comparison reference voltage at a very small cost, thus generating a reasonable compensation current.
  • the present invention takes into account the linear correlation between the output voltage of the error amplifier and the load current, and ensures that the flipping level of the mode control signal can change with the change of the load current by adjusting the negative phase input voltage in the mode control unit. Approximately linear changes occur. Therefore, no matter what load environment the voltage converter is in, the flip level of the mode control signal can well match the state of the voltage converter, and ensure that the working mode switching time of the voltage converter is reasonable and accurate.
  • Figure 1 is a schematic diagram of an equivalent circuit of a voltage converter operating in boost mode in the prior art
  • Figure 2 is a schematic diagram of an equivalent circuit of a voltage converter in the prior art when operating in buck mode
  • Figure 3 is a schematic circuit structure diagram of a mode control unit of a voltage converter in the prior art
  • Figure 4 is a schematic circuit structure diagram of a voltage converter mode switching circuit that tracks load current according to the present invention
  • FIG. 5 is a schematic diagram illustrating the linear change of the flip level with the load current in a voltage converter mode switching circuit that tracks load current according to the present invention.
  • FIG. 1 is a schematic diagram of an equivalent circuit of a voltage converter operating in boost mode in the prior art.
  • switches SW1 and SW2 are turned on at the same time
  • SW3 and SW4 are turned on at the same time
  • the above four switches rely on the control of the relevant control unit to realize switching on and off in turn.
  • the charging and discharging delay of the capacitor to realize the output of the output voltage Vout in a charge pump manner.
  • the voltage of Vout is higher than the input voltage Vin.
  • FIG. 2 is a schematic diagram of an equivalent circuit of a voltage converter in the prior art when operating in a buck mode.
  • switches SW2 and SW3 are in the off state, and switches SW1 and SW4 are in the long-pass state at this time.
  • the output voltage is slightly lower than the input voltage.
  • the difference between the output voltage and the input voltage is determined by the load current.
  • the voltage converter is equivalent to a low dropout linear regulator.
  • FIG. 3 is a schematic circuit structure diagram of a mode control unit of a voltage converter in the prior art.
  • This known circuit can divide the voltage according to the input voltage, that is, in Figure 3
  • the high and low of V- realizes the high and low level switching of the Modeflag signal, thereby realizing the switching of the working mode.
  • the circuit can flip at two different levels as the series switch of the current source I1 is turned on or off.
  • the load current The size of will affect the value of the output voltage. If the circuit operates in light load mode, the load current Very small, so the voltage drop of Vout relative to Vin is small. At this time, if the flip level of the Modeflag signal, that is, Vref is designed to be higher relative to the input voltage Vin, then when the input voltage Vin decreases, the circuit will enter the boost mode earlier and cannot operate while Vin is still relatively high. When high, the buck operating mode is maintained and the output of a low dropout linear regulated voltage is achieved. On the other hand, if the circuit operates in heavy load mode and the load current is very large, the voltage drop of Vout relative to Vin will be large at this time.
  • the flipping level of the Modeflag signal is designed to be low, then when flipping occurs, the input voltage Vin is still small, which will cause the output voltage Vout to be difficult to meet the design requirements. The output voltage is too low to achieve normal and stable operation for the subsequent load. powered by.
  • the circuit also requires another Modeflag flipping level to achieve conversion between boost and buck modes. Similarly, if the flip level is designed to be higher in the light load state, the circuit will enter the buck mode later, resulting in lower efficiency of the circuit. And if the flip level is designed to be lower in the overload state, the circuit will also have the problem of low output voltage.
  • FIG. 4 is a schematic circuit structure diagram of a voltage converter mode switching circuit that tracks load current according to the present invention.
  • the circuit includes a mode control unit and an adjustment unit; wherein, the mode control unit The unit is used to generate a mode control signal and control the voltage converter to switch between the boost mode and the buck mode based on the mode control signal; the adjustment unit is connected to the mode control unit and is used to obtain the error comparator in the voltage converter. The output signal and generates a feedback current to adjust the flip level of the mode control signal in the mode control unit.
  • the newly added adjustment unit in the present invention can adjust the feedback current and inject the feedback current into the original mode switching circuit, thereby causing the control signal in the mode switching circuit to flip the level to a certain extent. changes in. Since the size of the feedback current in the present invention is related to the output of the error comparator in the voltage converter, the flipping level is actually dynamically adjusted with the output of the error amplifier.
  • the error amplifier as a common component in voltage converter circuits, can determine the output voltage of the voltage converter based on a preset reference voltage and output a signal directly related to the load current.
  • the control of the flip level is actually realized according to the load current of the subsequent load, thereby solving the problem to a certain extent under different conditions such as light load, heavy load, no load, etc. Contradictions in the selection of flip levels.
  • the mode control unit includes a first current source, a second current source, a first voltage dividing resistor, a second voltage dividing resistor, a current switch tube and an operational amplifier; wherein, the first voltage dividing resistor R1 and the second voltage dividing resistor R2 is connected in series and connected between the input current Vin and ground; the first current source I0 is connected in parallel to both ends of the second voltage dividing resistor R2, one end of the second current source I1 is connected to the high voltage end of the second voltage dividing resistor R2, and the other end It is connected to the drain of the current switch tube; the source of the current switch tube is connected to ground, and the gate is connected to the output terminal of the op amp; the positive input terminal of the op amp is connected to the reference voltage Vref, and the negative input terminal is connected to the first voltage dividing resistor.
  • the connection point between R1 and the second voltage dividing resistor R2 is connected to receive the resistor divided voltage V-, and the output terminal outputs a mode control signal.
  • the mode control unit in the present invention is similar to the mode control unit in the prior art. Due to the addition of the current sources I0 and I1, the divided voltage V- of the input voltage Vin can be reduced to varying degrees respectively. Therefore, when the input voltage changes from different directions, the magnitude of the flip level is different.
  • the flip level Modeflag can control the state of the power tube on the voltage converter, so that when Vin is higher than the flip level, the circuit operates in the buck mode, and when Vin is lower than the flip level, the circuit operates in the boost mode.
  • the adjustment unit includes a reference subunit, a comparison subunit, and a mirror subunit; wherein, the reference subunit is used to receive the input voltage Vin to generate the comparison reference voltage Vref1 and input it into the comparison subunit; the comparison subunit, and The reference subunit is connected to the mirror subunit and is used to receive the comparison reference voltage and the output signal of the error comparator, and generate a third current based on the comparison results between the two; the mirror subunit is connected to the mode control unit and is used to connect the third The current is mirrored into the mode control unit.
  • the adjustment unit can be composed of three basic circuit structures, in which the reference subunit can output a base reference voltage, thereby providing it to the comparison subunit for comparison.
  • the comparison subunit can also receive the output signal of the error amplifier, which is EAOUT in Figure 4, and compare the two to obtain a differential current.
  • the differential current here is then output at a certain ratio through the mirror subunit, thereby achieving further adjustment of the V-voltage.
  • the reference subunit includes a reference tube Mp1 and a reference current source Iref; wherein, the source of the reference tube Mp1 is connected to the power supply voltage, and the drain and gate are both grounded through the reference current source Iref; the drain and gate of the reference tube Mp1 pole as the output of the reference subunit, providing the comparison reference voltage Vref1 for the comparison subunit.
  • the reference subunit in the present invention can set the reference current source Iref to a very small current source, for example, only outputting a current of 2 ⁇ A.
  • the size of MP1 tubes is also very small.
  • the size or quantity of MP1 can be designed to be 1/1500 of the size of the power tube.
  • the branch circuit formed by the reference subunit will not have much impact on the power tube, and at the same time, the power consumption of the secondary structure in the chip is saved.
  • the magnitude of the comparison reference voltage Vref1 is actually variable, for example, it changes with the magnitude of the input voltage Vin.
  • Vref1 can always be consistent with the output of the error amplifier when the load current is 3mA, regardless of the input voltage. How the size of Vin changes. Therefore, this circuit can accurately determine the state of the load current at this time. For example, when the load current is greater than 3mA, there is a corresponding feedback current output in the circuit, and if the load current is equal to or less than 3mA, the circuit will not have any Feedback current output. This function is specifically implemented by the comparison subunit.
  • the comparison subunit includes a first input tube, a second input tube, a current mirror, and a crossing resistor; wherein the current mirror includes a mirror-connected MOS tube and two identical mirror current sources; wherein the first input tube, the The drains of the two input tubes are respectively connected to the drains of the two MOS tubes, and the drains of the first input tube and the second input tube are respectively connected to the two mirror current sources; the gate of the first input tube is connected to the comparison The reference voltage Vref1, the gate of the second input tube is connected to the output signal of the error comparator; the crossing resistor is connected between the source of the first input tube and the source of the second input tube, and the drain of the first input tube The pole is connected to the mirror subunit as the output of the comparison subunit.
  • the comparison subunit in the present invention can realize the comparison between Vref1 and EAOUT.
  • EAOUT is less than Vref1
  • the drain-source current on the first input tube is greater than the drain-source current on the second input tube. Therefore, there is no current output at the output end of the comparison subunit.
  • Vref1 is less than EAOUT
  • the drain-source current on the first input tube is less than the drain-source current on the second input tube, and the excess current generated by the mirror-connected MOS tube will flow from the output end of the comparison subunit. output.
  • the magnitude of this current should be .
  • the output end of the mirror subunit is electrically connected to the connection of the first voltage dividing resistor R1 and the second voltage dividing resistor R2 in the mode control unit.
  • this proportional coefficient is k.
  • the feedback current is
  • the calculation formula of the feedback current can be determined. It can be seen that if EAOUT is too small, that is, when the load current is large, as the load current increases, the value of I2 will also increase.
  • the flip level of the mode control signal in the mode control unit has a linear relationship with the load current of the voltage converter; the lighter the subsequent load of the voltage converter, the higher the level will be. and The smaller the value.
  • FIG. 5 is a schematic diagram illustrating the linear change of the flip level with the load current in a voltage converter mode switching circuit that tracks load current according to the present invention.
  • the value of I2 also changes, and this change is an approximately linear change when the power tube is operating in the saturation zone.
  • the flipping level and It is also linear with the value of I2, therefore, it can be inferred that the flip level and It is linearly related to the load current of the voltage converter.
  • the flipping level of the mode control signal in the mode control unit is ;
  • the flip level of the mode control signal in the mode control unit is .
  • a second aspect of the present invention relates to a voltage converter mode switching method that tracks load current.
  • the method includes a voltage converter mode switching circuit that tracks load current described in the first aspect of the present invention.
  • the beneficial effect of the present invention is that, compared with the prior art, the voltage converter mode switching circuit and method for tracking the load current in the present invention can follow the flipping voltage of the adjustment mode control signal that is approximately linear in size of the load current. flat size and ensure that the voltage converter maintains reasonable working mode switching in different load environments.
  • the invention has an ingenious conception, a reasonable and effective method, fully considers various different load environments of the voltage converter, and fully ensures the stability of the output voltage under different environments.

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  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

一种追踪负载电流的电压转换器模式切换电路及方法，其特征在于：所述电路包括模式控制单元和调节单元；其中，所述模式控制单元，用于生成模式控制信号，并基于所述模式控制信号控制所述电压转换器在升压模式和降压模式之间进行切换；所述调节单元，与所述模式控制单元连接，用于获取所述电压转换器中误差比较器的输出信号并生成反馈电流，以调节所述模式控制单元中模式控制信号的翻转电平。本发明构思巧妙，方法合理有效，充分考虑到电压转换器的多种不同负载环境，并充分确保不同环境下的输出电压的稳定。

Description

一种追踪负载电流的电压转换器模式切换电路及方法 技术领域
本发明涉及集成电路领域，更具体的，涉及一种追踪负载电流的电压转换器模式切换电路及方法。
 背景技术
直流-直流电压转换器（DC-to-DC converter）是一种常用的电能转换电路，能够将直流电源转换为不同电压的直流，或近似直流的稳定电压进行输出。因其功率范围大、输出电压稳定等良好特性被广泛应用在各个领域。
现有技术中，为了在不同的电源输入情况下，均实现为后级负载提供稳定的输出电压，主流的直流-直流电压转换器能够工作在升压（Step-up）或降压（Step-down）的不同模式下，并通过合理调节功率管的开关状态而实现输出电压的调节。通常，模式控制单元等电路结构能够根据输入电压的大小来判断电压转换器的工作模式，并实现电压转换器在升压模式和降压模式之间的合理切换。因此，模式控制信号的翻转电平高低的设计对于电压转换器的工作性能是否合理起着至关重要的作用。
然而，目前的电压转换器电路中，由于电压转换器可能工作在空载、轻载、重载等多种不同的环境中，预先计算得到的翻转电平难以在各种不同环境中均保持电压转换器在合理情形下实现模式切换。这就造成，例如轻载或空载状态下，电压转换器提前切换到升压模式，造成电源的不必要浪费和对轻载电路的较大冲击，甚至难以保证后级电路的安全。
针对上述问题，亟需一种新的电压转换器的模式切换电路和模式切换方法。
 发明内容
为解决现有技术中存在的不足，本发明的目的在于，提供一种追踪负载电流的电压转换器模式切换电路及方法，通过跟随负载电流的大小近似线性化的调节模式控制信号的翻转电平的大小，从而确保电压转换器在不同的负载环境中均能够保持合理的工作模式切换。
本发明采用如下的技术方案。
本发明第一方面，涉及一种追踪负载电流的电压转换器模式切换电路，电路包括模式控制单元和调节单元；模式控制单元，用于生成模式控制信号，并基于模式控制信号控制电压转换器在升压模式和降压模式之间进行切换；调节单元，与模式控制单元连接，用于获取电压转换器中误差比较器的输出信号并生成反馈电流，以调节模式控制单元中模式控制信号的翻转电平。
优选地，模式控制单元包括第一电流源、第二电流源、第一分压电阻、第二分压电阻、电流开关管和运放；其中，第一分压电阻R1和第二分压电阻R2串联后接入输入电流Vin和地之间；第一电流源I0并联在第二分压电阻R2的两端，第二电流源I1一端与第二分压电阻R2的高压端连接，另一端与电流开关管的漏极连接；电流开关管的源极接地，栅极与运放的输出端连接；运放的正相输入端接入参考电压Vref，负相输入端与第一分压电阻R1、第二分压电阻R2之间的连接点连接以接收电阻分压V-，输出端输出模式控制信号。
优选地，调节单元包括参考子单元、比较子单元、镜像子单元；其中，参考子单元，用于接收输入电压Vin，以生成比较参考电压Vref1并输入至比较子单元中；比较子单元，与参考子单元和镜像子单元连接，用于接收比较参考电压、误差比较器的输出信号，并基于二者的比较结果生成第三电流；镜像子单元，与模式控制单元连接，用于将第三电流镜像至模式控制单元中。
优选地，参考子单元包括参考管Mp1和参考电流源Iref；其中，参考管Mp1的源极与电源电压连接，漏极和栅极均经过参考电流源Iref接地；参考管Mp1的漏极和栅极作为参考子单元的输出，为比较子单元提供比较参考电压Vref1。
优选地，比较子单元包括第一输入管、第二输入管、电流镜、跨接电阻；其中，电流镜包括镜像连接的MOS管、两个相同的镜像电流源；其中第一输入管、第二输入管的漏极分别连接至两个MOS管的漏极上，第一输入管、第二输入管的漏极分别连接至两个镜像电流源上；第一输入管的栅极接入比较参考电压Vref1，第二输入管的栅极接入误差比较器的输出信号；跨接电阻接入在第一输入管的源极和第二输入管的源极之间，第一输入管的漏极作为比较子单元的输出与镜像子单元连接。
优选地，镜像子单元的输出端与模式控制单元中第一分压电阻R1、第二分压电阻R2的连接电连接。
优选地，反馈电流为
其中， 为镜像子单元的电流镜像比例，
为误差比较器的输出电压，
为跨接电阻。
优选地，当输入电压Vin逐渐下降时，模式控制单元中模式控制信号的翻转电平为 ；当输入电压Vin逐渐上升时，模式控制单元中模式控制信号的翻转电平为 。
优选地，模式控制单元中模式控制信号的翻转电平 和 与电压转换器的负载电流呈线性关系；电压转换器的后级负载越轻则翻转电平 和 的取值越小。
本发明第二方面，一种追踪负载电流的电压转换器模式切换方法，方法包括本发明第一方面中所述的一种追踪负载电流的电压转换器模式切换电路。
本发明的有益效果在于，与现有技术相比，本发明中的一种追踪负载电流的电压转换器模式切换电路及方法，能够跟随负载电流的大小近似线性化的调节模式控制信号的翻转电平的大小，并确保电压转换器在不同的负载环境中均保持合理的工作模式切换。本发明构思巧妙，方法合理有效，充分考虑到电压转换器的多种不同负载环境，并充分确保不同环境下的输出电压的稳定。
本发明的有益效果还包括：
1、本发明充分利用了现有技术中电压转换器电路一般都具备的误差放大器等相关电路，以极少的代价实现了误差放大器输出电压与比较参考电压之间的计算，从而生成了合理的补偿电流。
2、本发明考虑到误差放大器的输出电压与负载电流之间的线性关联关系，通过调节模式控制单元中的负相输入电压，确保了模式控制信号的翻转电平能够随着负载电流的变化而发生近似线性的变化。因此，无论电压转换器处于何种负载环境下，模式控制信号的翻转电平均能够良好匹配电压转换器的状态，并确保电压转换器的工作模式切换时间合理准确。
 附图说明
图1为现有技术中一种电压转换器工作于升压模式时的等效电路示意图；
图2为现有技术中一种电压转换器工作于降压模式时的等效电路示意图；
图3为现有技术中一种电压转换器的模式控制单元的电路结构示意图；
图4为本发明一种追踪负载电流的电压转换器模式切换电路的电路结构示意图；
图5为本发明一种追踪负载电流的电压转换器模式切换电路中翻转电平随负载电流发生线性变化的示意图。
 实施方式
下面结合附图对本申请作进一步描述。以下实施例仅用于更加清楚地说明本发明的技术方案，而不能以此来限制本申请的保护范围。
图1为现有技术中一种电压转换器工作于升压模式时的等效电路示意图。如图1所示，当电压转换器工作在升压模式时，开关SW1和SW2同时开启、SW3和SW4同时开启，且上述四个开关依靠相关控制单元的控制实现轮流切换的开启和关断，从而依靠电容的充放电延迟以电荷泵方式实现输出电压Vout的输出，此时Vout的电压高于输入电压Vin。
图2为现有技术中一种电压转换器工作于降压模式时的等效电路示意图。如图2所示，当电压转换器的工作模式为降压模式时，开关SW2和SW3处于断开状态，且此时开关SW1和SW4处于长通状态，此时输出电压略低于输入电压，且输出电压与输入电压之差由负载电流的大小决定。此时，电压转换器相当于一个低压差线性稳压器。
图3为现有技术中一种电压转换器的模式控制单元的电路结构示意图。如图3所示，现有技术中，电压转换器在升压和降压工作模式之间进行切换时，存在相应的控制电路，该公知电路，能够根据输入电压分压，也就是图3中V-的高低来实现Modeflag信号的高低电平切换，从而实现工作模式的切换。
现有技术中，考虑到输入电压会在翻转点附近来回抖动，并可能会导致比较器的输出也来回翻转的问题，本发明中将电源电压逐渐升高和逐渐降低时，Modeflag信号的翻转电平设计的不完全一致，从而使得电路输出产生迟滞量，加强了系统的抗扰动能力。
在图3中的这种电路中，随着电流源I1串联开关导通与否，电路能够实现在两个不同的电平下进行翻转。
具体来说，当I1不对电路提供电流时，Modeflag的翻转需要Vref与V-大小相等，因此列出等式为 ，将 代入公式，则有 。对于该公式进行求解，则有 。另一方面，如果I1对电路提供电流时，类似的能够得到 。
由于在该电路中，如果输入电压逐渐降低，从而导致Modeflag信号发生翻转，则此时I1并不会对电路提供电流。反之，如果输入电压逐渐升高，则I1会对电路提供电流。
可见，对于该电路来说，存在两个不同大小的翻转电平，如果Vin由高降低，则翻转电平为 ，而如果Vin由低升高，则翻转电平为 。
然而，这一电路中仍然存在着一定的问题。例如，当电压转换器分别工作在不同的负载环境中时，难以选择合理的翻转电平的大小。这是因为，当电路工作在降压模式时，输出电压的大小不仅仅由输入电压Vin决定，还要考虑到负载电流。此时，输出电压的取值为 。在该公式中， 为负载电流，而 为功率管，也就是图1中SW1和SW4处于正常导通状态时的等效电阻。
可见，当功率管的参数确定时，负载电流 的大小将会影响输出电压的取值。如果电路工作在轻载模式下，负载电流 非常小，因此Vout相对Vin的压降较小。此时，如果Modeflag信号的翻转电平，也就是Vref相对于输入电压Vin的大小设计的较高，则当输入电压Vin降低时，电路会较早进入到升压模式中，无法在Vin仍然较高时，维持降压工作模式，并实现低压差线性稳压电压的输出。另一方面，如果电路工作在重载模式下，负载电流非常大，则此时Vout相对Vin的压降较大。如果Modeflag信号的翻转电平设计的较低，那么当发生翻转时，输入电压Vin仍然较小，这会导致输出电压Vout难以满足设计要求，输出电压过低，无法为后级负载实现正常稳定的供电。
上文针对于输入电压Vin逐渐降低的情况进行说明，而当输入电压逐渐升高时，电路也需要另一个Modeflag的翻转电平实现升压和降压模式之间的转换。类似的，如果在轻载状态，将翻转电平设计的较高，则电路会较晚进入降压模式，导致电路的效率变低。而如果在重载状态，将翻转电平设计的较低，则电路也会出现输出电压过低的问题。
图4为本发明一种追踪负载电流的电压转换器模式切换电路的电路结构示意图。如图4所示，针对现有技术中存在的问题，本发明第一方面中，提供了一种追踪负载电流的电压转换器模式切换电路，电路包括模式控制单元和调节单元；其中，模式控制单元，用于生成模式控制信号，并基于模式控制信号控制电压转换器在升压模式和降压模式之间进行切换；调节单元，与模式控制单元连接，用于获取电压转换器中误差比较器的输出信号并生成反馈电流，以调节模式控制单元中模式控制信号的翻转电平。
可以理解的是，现有技术中通常会存在相应的模式控制单元。而本发明中新增的调节单元，则可以通过调节反馈电流的大小，并将该反馈电流注入至原有的模式切换电路中，从而使得模式切换电路中的控制信号的翻转电平发生一定程度上的变化。由于本发明中反馈电流的大小是与电压转换器中误差比较器的输出相关的，因此，翻转电平实际上也是随着误差放大器的输出进行动态调节的。
而误差放大器，作为电压转换器电路中的常用元件，其能够根据一个预先设定的参考电压来对于电压转换器的输出电压进行判定，并输出与负载电流的大小直接相关的一个信号。
由此，通过本发明中的方法，实际上是根据后级负载的负载电流大小来实现对翻转电平的控制的，从而一定程度上解决了轻载、重载、空载等不同状态下，翻转电平的选取所存在的矛盾。
优选地，模式控制单元包括第一电流源、第二电流源、第一分压电阻、第二分压电阻、电流开关管和运放；其中，第一分压电阻R1和第二分压电阻R2串联后接入输入电流Vin和地之间；第一电流源I0并联在第二分压电阻R2的两端，第二电流源I1一端与第二分压电阻R2的高压端连接，另一端与电流开关管的漏极连接；电流开关管的源极接地，栅极与运放的输出端连接；运放的正相输入端接入参考电压Vref，负相输入端与第一分压电阻R1、第二分压电阻R2之间的连接点连接以接收电阻分压V-，输出端输出模式控制信号。
可以理解的是，本发明中的模式控制单元，与现有技术中的模式控制单元类似。由于增加了电流源I0和I1，因此，能够分别从不同程度上将输入电压Vin的分压V-降低的更低。因此，当输入电压从不同方向上变化时，翻转电平的大小是不同的。而翻转电平Modeflag则能够控制电压转换器上功率管的状态，使得在Vin高于翻转电平时，电路工作在降压模式下，Vin低于翻转电平时，电路工作在升压模式下。
优选地，调节单元包括参考子单元、比较子单元、镜像子单元；其中，参考子单元，用于接收输入电压Vin，以生成比较参考电压Vref1并输入至比较子单元中；比较子单元，与参考子单元和镜像子单元连接，用于接收比较参考电压、误差比较器的输出信号，并基于二者的比较结果生成第三电流；镜像子单元，与模式控制单元连接，用于将第三电流镜像至模式控制单元中。
可以理解的是，调节单元可以由三个基本电路结构构成，其中参考子单元能够输出一个基准参考电压，从而提供给比较子单元用于比较。而比较子单元同时还能够接收到误差放大器的输出信号，也就是图4中的EAOUT，并将二者进行比较，从而获取一个差分电流。这里的差分电流再经过镜像子单元以一定的比例进行输出，从而实现了对于V-电压的进一步调节。
优选的，参考子单元包括参考管Mp1和参考电流源Iref；其中，参考管Mp1的源极与电源电压连接，漏极和栅极均经过参考电流源Iref接地；参考管Mp1的漏极和栅极作为参考子单元的输出，为比较子单元提供比较参考电压Vref1。
可以理解的是，本发明中的参考子单元，可以将参考电流源Iref设置为一个非常小的电流源，例如只输出2μA的电流。同时，Mp1管的尺寸也非常小，例如，可以设计Mp1的尺寸或数量为功率管尺寸的1/1500。在这种情况下，参考子单元所构成的支路并不会对功率管造成太大的影响，同时节约了芯片中次要结构的功率消耗。在这种电路结构中，比较参考电压Vref1的大小实际上可可变的，例如，会随着输入电压Vin的大小而发生变化。不过，由于误差放大器的输出也不只受到负载电流的影响，同时也会受到输入电压Vin的影响，而Vref1和EAOUT两者之间由于功率管与Mp1的电流比例固定，从而使得Vref1和EAOUT之间的比较只考虑负载电流的变化。
在上文中提及的实施例中，如果Iref为2μA，Mp1的尺寸为功率管的1/1500，则Vref1的取值就能够与负载电流处于3mA时误差放大器的输出始终保持一致，无论输入电压Vin的大小如何变化。因此，这一电路能够准确的判断出负载电流此时的状态，例如，当负载电流大于3mA时，电路中存在相应的反馈电流输出，而如果负载电流等于或小于3mA，则电路不会出现任何反馈电流的输出。这一功能就是比较子单元具体实现的了。
优选地，比较子单元包括第一输入管、第二输入管、电流镜、跨接电阻；其中，电流镜包括镜像连接的MOS管、两个相同的镜像电流源；其中第一输入管、第二输入管的漏极分别连接至两个MOS管的漏极上，第一输入管、第二输入管的漏极分别连接至两个镜像电流源上；第一输入管的栅极接入比较参考电压Vref1，第二输入管的栅极接入误差比较器的输出信号；跨接电阻接入在第一输入管的源极和第二输入管的源极之间，第一输入管的漏极作为比较子单元的输出与镜像子单元连接。
可以理解的是，本发明中的比较子单元能够实现对Vref1和EAOUT的比较。当EAOUT小于Vref1时，第一输入管上的漏源电流要大于第二输入管上的漏源电流，因此，比较子单元的输出端不存在电流输出。而当Vref1小于EAOUT时，则第一输入管上的漏源电流要小于第二输入管上的漏源电流，则由镜像连接的MOS管所产生的多余电流就会从比较子单元的输出端输出出来。具体来说，这一电流的大小应当为 。
优选地，镜像子单元的输出端与模式控制单元中第一分压电阻R1、第二分压电阻R2的连接电连接。
在镜像子单元中，存在多个镜像MOS管，能够将比较子单元的输出按照一定的比例进行镜像，本发明中这一个比例系数为k。
优选的，反馈电流为
其中， 为镜像子单元的电流镜像比例，
为误差比较器的输出电压，
为跨接电阻。
在这一情况下，反馈电流的计算公式可以确定下来。可见，如果EAOUT过小，也就是负载电流较大时，随着负载电流的升高，I2的取值也会随之增加。
优选地，模式控制单元中模式控制信号的翻转电平 和 与电压转换器的负载电流呈线性关系；电压转换器的后级负载越轻则翻转电平 和 的取值越小。
图5为本发明一种追踪负载电流的电压转换器模式切换电路中翻转电平随负载电流发生线性变化的示意图。如图5所示，可以理解的是，随着负载电流的变化，I2的取值也发生变化，而且这种变化在功率管处于饱和区工作时为近似的线性变化。另外，由于翻转电平 和 与I2的取值也是线性的，因此，可以推知翻转电平 和 与电压转换器的负载电流呈线性关系。
优选地，当输入电压Vin逐渐下降时，模式控制单元中模式控制信号的翻转电平为 ；当输入电压Vin逐渐上升时，模式控制单元中模式控制信号的翻转电平为 。
可以理解的是，在加入了反馈电流后，翻转电平进一步发生了变化，然而，由于I2的大小与负载电流呈线性变化，这使得无论电路工作在轻载、空载、重载的任何模式下，均能够提供非常合理的翻转电平的大小，并在合理的时间上实现工作模式的切换。
本发明第二方面，涉及一种追踪负载电流的电压转换器模式切换方法，方法包括本发明第一方面中所述的一种追踪负载电流的电压转换器模式切换电路。
本发明的有益效果在于，与现有技术相比，本发明中的一种追踪负载电流的电压转换器模式切换电路及方法，能够跟随负载电流的大小近似线性化的调节模式控制信号的翻转电平的大小，并确保电压转换器在不同的负载环境中均保持合理的工作模式切换。本发明构思巧妙，方法合理有效，充分考虑到电压转换器的多种不同负载环境，并充分确保不同环境下的输出电压的稳定。
本发明申请人结合说明书附图对本发明的实施示例做了详细的说明与描述，但是本领域技术人员应该理解，以上实施示例仅为本发明的优选实施方案，详尽的说明只是为了帮助读者更好地理解本发明精神，而并非对本发明保护范围的限制，相反，任何基于本发明的发明精神所作的任何改进或修饰都应当落在本发明的保护范围之内。

Claims (10)

  1. 一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述电路包括模式控制单元和调节单元；其中，
    所述模式控制单元，用于生成模式控制信号，并基于所述模式控制信号控制所述电压转换器在升压模式和降压模式之间进行切换；
    所述调节单元，与所述模式控制单元连接，用于获取所述电压转换器中误差比较器的输出信号并生成反馈电流，以调节所述模式控制单元中模式控制信号的翻转电平。
  2. 根据权利要求1中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述模式控制单元包括第一电流源、第二电流源、第一分压电阻、第二分压电阻、电流开关管和运放；其中，
    第一分压电阻R1和第二分压电阻R2串联后接入输入电流Vin和地之间；
    所述第一电流源I0并联在所述第二分压电阻R2的两端，所述第二电流源I1一端与第二分压电阻R2的高压端连接，另一端与所述电流开关管的漏极连接；
    所述电流开关管的源极接地，栅极与所述运放的输出端连接；
    所述运放的正相输入端接入参考电压Vref，负相输入端与第一分压电阻R1、第二分压电阻R2之间的连接点连接以接收电阻分压V-，输出端输出所述模式控制信号。
  3. 根据权利要求2中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述调节单元包括参考子单元、比较子单元、镜像子单元；
    其中，所述参考子单元，用于接收所述输入电压Vin，以生成比较参考电压Vref1并输入至所述比较子单元中；
    所述比较子单元，与参考子单元和镜像子单元连接，用于接收所述比较参考电压、所述误差比较器的输出信号，并基于二者的比较结果生成第三电流；
    所述镜像子单元，与所述模式控制单元连接，用于将所述第三电流镜像至所述模式控制单元中。
  4. 根据权利要求3中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述参考子单元包括参考管Mp1和参考电流源Iref；
    其中，所述参考管Mp1的源极与电源电压连接，漏极和栅极均经过所述参考电流源Iref接地；
    所述参考管Mp1的漏极和栅极作为所述参考子单元的输出，为所述比较子单元提供比较参考电压Vref1。
  5. 根据权利要求4中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述比较子单元包括第一输入管、第二输入管、电流镜、跨接电阻；
    其中，所述电流镜包括镜像连接的MOS管、两个相同的镜像电流源；
    其中第一输入管、第二输入管的漏极分别连接至两个MOS管的漏极上，第一输入管、第二输入管的漏极分别连接至两个镜像电流源上；
    所述第一输入管的栅极接入所述比较参考电压Vref1，所述第二输入管的栅极接入所述误差比较器的输出信号；
    所述跨接电阻接入在所述第一输入管的源极和所述第二输入管的源极之间，所述第一输入管的漏极作为所述比较子单元的输出与所述镜像子单元连接。
  6. 根据权利要求5中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述镜像子单元的输出端与所述模式控制单元中第一分压电阻R1、第二分压电阻R2的连接电连接。
  7. 根据权利要求6中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述反馈电流为
    其中，  为所述镜像子单元的电流镜像比例，
    为所述误差比较器的输出电压，
    为所述跨接电阻。
  8. 根据权利要求7中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    当所述输入电压Vin逐渐下降时，所述模式控制单元中模式控制信号的翻转电平为  ；
    当所述输入电压Vin逐渐上升时，所述模式控制单元中模式控制信号的翻转电平为  。
  9. 根据权利要求8中所述的一种追踪负载电流的电压转换器模式切换电路，其特征在于：
    所述模式控制单元中模式控制信号的翻转电平  和  与所述电压转换器的负载电流呈线性关系；
    所述电压转换器的后级负载越轻则所述翻转电平  和  的取值越小。
  10. 一种追踪负载电流的电压转换器模式切换方法，其特征在于：
    所述方法采用权利要求1-9任意一项中所述的一种追踪负载电流的电压转换器模式切换电路实现。
PCT/CN2023/111006 2022-08-12 2023-08-03 一种追踪负载电流的电压转换器模式切换电路及方法 WO2024032465A1 (zh)

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