A voltage converter mode switching circuit and method for tracking load current

Abstract

The application discloses a voltage converter mode switching circuit and method for tracking load current, and is characterized in that the circuit comprises a mode control unit and an adjusting unit; wherein the mode control unit is used for generating a mode control signal and controlling the voltage converter to switch between a boost mode and a buck mode based on the mode control signal; the adjusting unit is connected with the mode control unit and is used for acquiring an output signal of an error comparator in the voltage converter and generating a feedback current to adjust a flip level of the mode control signal in the mode control unit. The application is ingenious in concept, reasonable and effective in method, fully considers various different load environments of the voltage converter, and fully ensures the stability of output voltages in different environments.

Description

Technical Field

[0001] This invention relates to the field of integrated circuits, and more specifically, to a voltage converter mode switching circuit and method for tracking load current. Background Technology

[0002] A DC-to-DC converter is a commonly used power conversion circuit that converts DC power into DC voltages of varying or near-DC stable output voltages. Due to its wide power range and stable output voltage, it is widely used in various fields.

[0003] In existing technologies, to provide a stable output voltage to downstream loads under different power input conditions, mainstream DC-DC voltage converters can operate in either step-up or step-down modes, and the output voltage is regulated by appropriately adjusting the switching state of the power transistors. Typically, circuit structures such as the mode control unit can determine the operating mode of the voltage converter based on the input voltage magnitude and achieve appropriate switching between step-up and step-down modes. Therefore, the design of the high and low switching levels of the mode control signal plays a crucial role in ensuring the optimal performance of the voltage converter.

[0004] However, in current voltage converter circuits, because the voltage converter may operate in various environments such as no-load, light-load, and heavy-load, the pre-calculated switching level is difficult to ensure that the voltage converter switches modes appropriately under various conditions. This results in, for example, the voltage converter switching to boost mode prematurely under light-load or no-load conditions, causing unnecessary power waste and significant impact on light-load circuits, and even making it difficult to guarantee the safety of downstream circuits.

[0005] To address the aforementioned issues, a new mode switching circuit and mode switching method for voltage converters are urgently needed. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a voltage converter mode switching circuit and method that tracks load current. By adjusting the switching level of the mode control signal in an approximately linear manner following the magnitude of the load current, the voltage converter can maintain reasonable operating mode switching under different load environments.

[0007] The present invention adopts the following technical solution.

[0008] In a first aspect, the present invention relates to a voltage converter mode switching circuit for tracking 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 to switch between boost mode and buck mode based on the mode control signal. The adjustment unit is connected to the mode control unit and is used to acquire the output signal of the error comparator in the voltage converter and generate a feedback current to adjust the flip level of the mode control signal in the mode control unit.

[0009] Preferably, the mode control unit includes a first current source, a second current source, a first voltage divider resistor, a second voltage divider resistor, a current switching transistor, and an operational amplifier; wherein, the first voltage divider resistor R1 and the second voltage divider resistor R2 are connected in series between the input voltage Vin and ground; the first current source I0 is connected in parallel across the second voltage divider resistor R2, one end of the second current source I1 is connected to the high-voltage terminal of the second voltage divider resistor R2, and the other end is connected to the drain of the current switching transistor; the source of the current switching transistor is grounded, and its gate is connected to the output terminal of the operational amplifier; the positive input terminal of the operational amplifier is connected to the reference voltage Vref, the negative input terminal is connected to the junction point between the first voltage divider resistor R1 and the second voltage divider resistor R2 to receive the resistor-divided voltage V-, and the output terminal outputs the mode control signal.

[0010] Preferably, 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 a comparison reference voltage Vref1 and input it into the comparison subunit; the comparison subunit is connected to the reference subunit and the mirror subunit, and is used to receive the comparison reference voltage and the output signal of the error comparator, and generate a feedback current based on the comparison result of the two; the mirror subunit is connected to the mode control unit and is used to mirror the feedback current to the mode control unit.

[0011] Preferably, the reference sub-unit includes a reference transistor Mp1 and a reference current source Iref; wherein, the source of the reference transistor 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 transistor Mp1 serve as the output of the reference sub-unit, providing a comparison reference voltage Vref1 for the comparison sub-unit.

[0012] Preferably, the comparator subunit includes a first input transistor, a second input transistor, a current mirror, and a bridging resistor; wherein the current mirror includes a mirrored MOSFET and two identical mirrored current sources; wherein the drains of the first input transistor and the second input transistor are respectively connected to the drains of the two MOSFETs, and the drains of the first input transistor and the second input transistor are respectively connected to the two mirrored current sources; the gate of the first input transistor is connected to the comparison reference voltage Vref1, and the gate of the second input transistor is connected to the output signal of the error comparator; the bridging resistor is connected between the source of the first input transistor and the source of the second input transistor, and the drain of the first input transistor is connected to the mirror subunit as the output of the comparator subunit.

[0013] Preferably, the output terminal of the mirror subunit is electrically connected to the first voltage divider resistor R1 and the second voltage divider resistor R2 in the mode control unit.

[0014] Preferably, the feedback current is

[0015] ;

[0016] in, The current mirroring ratio of the mirror sub-unit.

[0017] The output voltage of the error comparator.

[0018] For bridging resistors.

[0019] Preferably, as the input voltage Vin gradually decreases, the switching level of the mode control signal in the mode control unit is... ;in, This is the rated output current of the first current source;

[0020] As the input voltage Vin gradually increases, the switching level of the mode control signal in the mode control unit is... ;in, This is the rated output current of the second current source.

[0021] Preferably, the toggling level of the mode control signal in the mode control unit and The voltage level is linearly related to the load current of the voltage converter; the lighter the load of the subsequent stage of the voltage converter, the faster the voltage level will flip. and The smaller the value, the better.

[0022] In a second aspect, the present invention provides a voltage converter mode switching method for tracking load current, the method comprising a voltage converter mode switching circuit for tracking load current as described in the first aspect of the present invention.

[0023] The beneficial effects of this invention are that, compared with the prior art, the voltage converter mode switching circuit and method for tracking load current in this invention can adjust the switching level of the mode control signal in an approximately linear manner following the magnitude of the load current, and ensure that the voltage converter maintains reasonable operating mode switching under different load environments. This invention is ingeniously conceived, and the method is reasonable and effective, fully considering various load environments of the voltage converter and ensuring the stability of the output voltage under different environments.

[0024] The beneficial effects of the present invention also include:

[0025] 1. This invention makes full use of the error amplifier and other related circuits that are generally available 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 very low cost, thereby generating a reasonable compensation current.

[0026] 2. This invention takes into account the linear correlation between the output voltage of the error amplifier and the load current. By adjusting the negative phase input voltage in the mode control unit, it ensures that the switching level of the mode control signal changes approximately linearly with the load current. Therefore, regardless of the load environment under which the voltage converter operates, the switching level of the mode control signal can well match the state of the voltage converter and ensure that the switching time of the voltage converter's operating mode is reasonable and accurate. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the equivalent circuit of a voltage converter in the prior art when it is operating in boost mode.

[0028] Figure 2 This is a schematic diagram of the equivalent circuit of a voltage converter in the prior art when it operates in buck mode.

[0029] Figure 3 This is a schematic diagram of the circuit structure of a mode control unit for a voltage converter in the prior art;

[0030] Figure 4 This is a schematic diagram of the circuit structure of a voltage converter mode switching circuit for tracking load current according to the present invention.

[0031] Figure 5 This is a schematic diagram showing the linear change of the switching level with the load current in a voltage converter mode switching circuit for tracking load current according to the present invention. Detailed Implementation

[0032] The present application will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be construed as limiting the scope of protection of the present application.

[0033] Figure 1 This is a schematic diagram of the equivalent circuit of a voltage converter in the prior art when operating in boost mode. For example... Figure 1 As shown, when the voltage converter is operating in boost mode, switches SW1 and SW2 are turned on simultaneously, as are SW3 and SW4. The four switches are switched on and off in turn by the control of the relevant control unit. The output voltage Vout is achieved by relying on the charging and discharging delay of the capacitor in a charge pump manner. At this time, the voltage of Vout is higher than the input voltage Vin.

[0034] Figure 2 This is a schematic diagram of the equivalent circuit of a voltage converter in the prior art when operating in buck mode. Figure 2 As shown, when the voltage converter operates in buck mode, switches SW2 and SW3 are open, while switches SW1 and SW4 are always on. At this time, the output voltage is slightly lower than the input voltage, and the difference between the output and input voltages is determined by the load current. In this configuration, the voltage converter functions as a low-dropout linear regulator.

[0035] Figure 3 This is a schematic diagram of the circuit structure of a mode control unit for a voltage converter in the prior art. (Example:) Figure 3 As shown, in the prior art, when a voltage converter switches between boost and buck operating modes, there is a corresponding control circuit. This known circuit can divide the input voltage, that is... Figure 3 The high and low levels of V- are used to switch the high and low levels of the Modeflag signal, thereby switching the working mode.

[0036] In the prior art, considering that the input voltage will fluctuate around the flip point and may cause the comparator output to also flip back and forth, the present invention designs the flip level of the Modeflag signal to be not completely consistent when the power supply voltage gradually increases and gradually decreases, thereby causing the circuit output to produce hysteresis and enhancing the system's anti-disturbance capability.

[0037] exist Figure 3 In this type of circuit, the circuit can switch between two different voltage levels depending on whether the current source I1 is connected in series with the switch or not.

[0038] Specifically, when I1 does not supply current to the circuit, the toggling of Modeflag requires Vref to be equal to V-, therefore the equation is as follows: ,Will Substituting into the formula, we get: Solving this formula, we get: On the other hand, if I1 supplies current to the circuit, a similar result can be obtained. .

[0039] In this circuit, if the input voltage gradually decreases, causing the Modeflag signal to toggle, I1 will not provide current to the circuit. Conversely, if the input voltage gradually increases, I1 will provide current to the circuit.

[0040] As can be seen, this circuit has two different switching levels. If Vin decreases from high, the switching level is... If Vin rises from low, the flip level is... .

[0041] However, certain problems still exist in this circuit. For example, it is difficult to select a reasonable switching level when the voltage converter operates under different load conditions. This is because, when the circuit operates in buck mode, the output voltage is determined not only by the input voltage Vin but also by the load current. In this case, the output voltage value... In this formula, For load current, and For power transistors, that is Figure 1 The equivalent resistance when SW1 and SW4 are in the normal conducting state.

[0042] It can be seen that when the parameters of the power transistor are determined, the load current... The magnitude of this value will affect the output voltage. If the circuit operates in light-load mode, the load current... Because the voltage drop across the input voltage Vin is very small, Vout has a relatively small voltage drop relative to Vin. In this case, if the toggle level of the Modeflag signal, i.e., Vref relative to the input voltage Vin, is designed to be high, the circuit will enter boost mode earlier when the input voltage Vin decreases. This will prevent it from maintaining buck mode and achieving a low-dropout linear regulated output voltage while Vin remains high. On the other hand, if the circuit operates in heavy-load mode with a very large load current, the voltage drop across the input voltage Vin will be large. If the toggle level of the Modeflag signal is designed to be low, the input voltage Vin will still be small when the toggle occurs. This will cause the output voltage Vout to fail to meet design requirements, resulting in an excessively low output voltage that cannot provide a stable power supply to the downstream load.

[0043] The above explanation addresses the scenario where the input voltage Vin gradually decreases. However, as the input voltage gradually increases, the circuit also requires the switching level of another Modeflag to switch between boost and buck modes. Similarly, if the switching level is designed to be high under light load conditions, the circuit will enter buck mode later, resulting in lower circuit efficiency. Conversely, if the switching level is designed to be low under heavy load conditions, the circuit will experience excessively low output voltage.

[0044] Figure 4 This is a schematic diagram of the circuit structure of a voltage converter mode switching circuit for tracking load current according to the present invention. Figure 4 As shown, in view of the problems existing in the prior art, the first aspect of the present invention provides a voltage converter mode switching circuit for tracking 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 to switch between boost mode and buck mode based on the mode control signal. The adjustment unit is connected to the mode control unit and is used to acquire the output signal of the error comparator in the voltage converter and generate a feedback current to adjust the flip level of the mode control signal in the mode control unit.

[0045] It is understandable that existing technologies typically include corresponding mode control units. The adjustment unit added in this invention can adjust the magnitude of the feedback current and inject it into the existing mode switching circuit, thereby causing a certain degree of change in the switching level of the control signal in the mode switching circuit. Since the magnitude of the feedback current in this invention is related to the output of the error comparator in the voltage converter, the switching level is actually dynamically adjusted along with the output of the error amplifier.

[0046] Error amplifiers, as commonly used components in voltage converter circuits, can determine the output voltage of the voltage converter based on a preset reference voltage and output a signal that is directly related to the magnitude of the load current.

[0047] Therefore, the method in this invention actually controls the switching level based on the load current of the downstream load, thus solving to some extent the contradiction in selecting the switching level under different conditions such as light load, heavy load, and no load.

[0048] Preferably, the mode control unit includes a first current source, a second current source, a first voltage divider resistor, a second voltage divider resistor, a current switching transistor, and an operational amplifier; wherein, the first voltage divider resistor R1 and the second voltage divider resistor R2 are connected in series between the input voltage Vin and ground; the first current source I0 is connected in parallel across the second voltage divider resistor R2, one end of the second current source I1 is connected to the high-voltage terminal of the second voltage divider resistor R2, and the other end is connected to the drain of the current switching transistor; the source of the current switching transistor is grounded, and its gate is connected to the output terminal of the operational amplifier; the positive input terminal of the operational amplifier is connected to the reference voltage Vref, the negative input terminal is connected to the junction point between the first voltage divider resistor R1 and the second voltage divider resistor R2 to receive the resistor-divided voltage V-, and the output terminal outputs the mode control signal.

[0049] It is understood that the mode control unit in this invention is similar to that in the prior art. Due to the addition of current sources I0 and I1, the voltage division V- of the input voltage Vin can be reduced even further to varying degrees. Therefore, the magnitude of the switching level differs when the input voltage changes in different directions. The switching level Modeflag controls the state of the power transistor on the voltage converter, ensuring that the circuit operates in buck mode when Vin is higher than the switching level and in boost mode when Vin is lower than the switching level.

[0050] Preferably, 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 a comparison reference voltage Vref1 and input it into the comparison subunit; the comparison subunit is connected to the reference subunit and the mirror subunit, and is used to receive the comparison reference voltage and the output signal of the error comparator, and generate a feedback current based on the comparison result of the two; the mirror subunit is connected to the mode control unit and is used to mirror the feedback current to the mode control unit.

[0051] Understandably, the adjustment unit can consist of three basic circuit structures. The reference subunit outputs a reference voltage, which is then provided to the comparison subunit for comparison. The comparison subunit can also receive the output signal from the error amplifier, i.e. Figure 4 The EAOUT function compares the two values ​​to obtain a differential current. This differential current is then output in a specific ratio through a mirror sub-unit, thereby achieving further regulation of the V- voltage.

[0052] Preferably, the reference subunit includes a reference transistor Mp1 and a reference current source Iref; wherein, the source of the reference transistor 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 transistor Mp1 serve as the output of the reference subunit, providing a comparison reference voltage Vref1 for the comparison subunit.

[0053] It is understood that the reference sub-unit in this invention can set the reference current source Iref as a very small current source, for example, outputting only 2μA of current. Simultaneously, the size of the Mp1 transistor is also very small; for example, the size or number of Mp1 transistors can be designed to be 1 / 1500th the size of the power transistors. In this case, the branch formed by the reference sub-unit will not have a significant impact on the power transistors, while saving power consumption in secondary structures within the chip. In this circuit structure, the magnitude of the comparison reference voltage Vref1 is actually variable, for example, it will change with the magnitude of the input voltage Vin. However, since the output of the error amplifier is affected not only by the load current but also by the input voltage Vin, and the current ratio between Vref1 and EAOUT is fixed due to the power transistor and Mp1 current ratio, the comparison between Vref1 and EAOUT only considers the change in load current.

[0054] In the embodiment mentioned above, if Iref is 2μA and the size of Mp1 is 1 / 1500 of the power transistor, then the value of Vref1 can always remain consistent with the output of the error amplifier when the load current is 3mA, regardless of how the input voltage Vin changes. Therefore, this circuit can accurately determine the state of the load current. For example, when the load current is greater than 3mA, there is a corresponding feedback current output in the circuit, while if the load current is equal to or less than 3mA, there will be no feedback current output. This function is specifically implemented by the comparison subunit.

[0055] Preferably, the comparator subunit includes a first input transistor, a second input transistor, a current mirror, and a bridging resistor; wherein the current mirror includes a mirrored MOSFET and two identical mirrored current sources; wherein the drains of the first input transistor and the second input transistor are respectively connected to the drains of the two MOSFETs, and the drains of the first input transistor and the second input transistor are respectively connected to the two mirrored current sources; the gate of the first input transistor is connected to the comparison reference voltage Vref1, and the gate of the second input transistor is connected to the output signal of the error comparator; the bridging resistor is connected between the source of the first input transistor and the source of the second input transistor, and the drain of the first input transistor is connected to the mirror subunit as the output of the comparator subunit.

[0056] It is understood that the comparator subunit in this invention can compare Vref1 and EAOUT. When EAOUT is less than Vref1, the drain-source current on the first input transistor is greater than the drain-source current on the second input transistor; therefore, there is no current output at the output terminal of the comparator subunit. However, when Vref1 is less than EAOUT, the drain-source current on the first input transistor is less than the drain-source current on the second input transistor, and the excess current generated by the mirrored MOS transistors will be output from the output terminal of the comparator subunit. Specifically, the magnitude of this current should be... .

[0057] Preferably, the output terminal of the mirror subunit is electrically connected to the first voltage divider resistor R1 and the second voltage divider resistor R2 in the mode control unit.

[0058] In the mirror sub-unit, there are multiple mirror MOS transistors that can mirror the output of the comparator sub-unit according to a certain ratio. In this invention, this ratio coefficient is k.

[0059] Preferably, the feedback current is

[0060]

[0061] in, The current mirroring ratio of the mirror sub-unit.

[0062] The output voltage of the error comparator.

[0063] For bridging resistors.

[0064] In this case, the formula for calculating the feedback current can be determined. It is evident that if EAOUT is too small, meaning the load current is large, the value of I2 will increase as the load current increases.

[0065] Preferably, the toggling level of the mode control signal in the mode control unit and The voltage level is linearly related to the load current of the voltage converter; the lighter the load of the subsequent stage of the voltage converter, the faster the voltage level will flip. and The smaller the value, the better.

[0066] Figure 5 This is a schematic diagram illustrating the linear change in the switching level with the load current in a voltage converter mode switching circuit for tracking load current according to the present invention. Figure 5 As shown, it can be understood that the value of I2 changes with the load current, and this change is approximately linear when the power transistor is operating in the saturation region. Furthermore, due to the switching level... and Since the value of I2 is also linear, the switching level can be deduced. and It has a linear relationship with the load current of the voltage converter.

[0067] Preferably, as the input voltage Vin gradually decreases, the switching level of the mode control signal in the mode control unit is... As the input voltage Vin gradually increases, the switching level of the mode control signal in the mode control unit is... .

[0068] Understandably, the switching level changes further after the feedback current is added. However, since the magnitude of I2 changes linearly with the load current, it can provide a very reasonable switching level regardless of whether the circuit is operating in any mode, whether it is light load, no load, or heavy load, and can switch the operating mode at a reasonable time.

[0069] A second aspect of the present invention relates to a voltage converter mode switching method for tracking load current, the method comprising a voltage converter mode switching circuit for tracking load current as described in the first aspect of the present invention.

[0070] The beneficial effects of this invention are that, compared with the prior art, the voltage converter mode switching circuit and method for tracking load current in this invention can adjust the switching level of the mode control signal in an approximately linear manner following the magnitude of the load current, and ensure that the voltage converter maintains reasonable operating mode switching under different load environments. This invention is ingeniously conceived, and the method is reasonable and effective, fully considering various load environments of the voltage converter and ensuring the stability of the output voltage under different environments.

[0071] The applicant of this invention has provided a detailed description of the embodiments of the invention in conjunction with the accompanying drawings. However, those skilled in the art should understand that the above embodiments are merely preferred embodiments of the invention. The detailed description is only intended to help readers better understand the spirit of the invention and is not intended to limit the scope of protection of the invention. On the contrary, any improvements or modifications made based on the inventive spirit of the invention should fall within the scope of protection of the invention.

Claims

1. A voltage converter mode switching circuit for tracking load current, characterized in that: The voltage converter mode switching circuit includes a mode control unit and an adjustment unit; wherein... The mode control unit includes a first current source, a second current source, a first voltage divider resistor, a second voltage divider resistor, a current switching transistor, and an operational amplifier. The first voltage divider resistor R1 and the second voltage divider resistor R2 are connected in series between the input voltage Vin and ground. The first current source I0 is connected in parallel across the second voltage divider resistor R2. One end of the second current source I1 is connected to the high-voltage terminal of the second voltage divider resistor R2, and the other end is connected to the drain of the current switching transistor. The source of the current switching transistor is grounded, and its gate is connected to the output terminal of the operational amplifier. The positive input terminal of the operational amplifier is connected to a reference voltage Vref, and its negative input terminal is connected to the junction between the first voltage divider resistor R1 and the second voltage divider resistor R2 to receive the resistor-divided voltage V-. The output terminal outputs a mode control signal, and based on the mode control signal, controls the voltage converter to switch between boost mode and buck mode. The adjustment unit includes a reference subunit, a comparison subunit, and a mirror subunit. The reference subunit receives the input voltage Vin to generate a comparison reference voltage Vref1, which is then input into the comparison subunit. The comparison subunit, connected to both the reference and mirror subunits, receives the comparison reference voltage, acquires the output signal of the error comparator in the voltage converter, and generates a feedback current based on the comparison result. The mirror subunit, connected to the mode control unit, mirrors the feedback current to the mode control unit to adjust the toggle level of the mode control signal in the mode control unit.

2. The voltage converter mode switching circuit for tracking load current according to claim 1, characterized in that: The reference subunit includes a reference transistor Mp1 and a reference current source Iref; The source of the reference transistor 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 transistor Mp1 serve as the output of the reference sub-unit, providing a comparison reference voltage Vref1 to the comparison sub-unit.

3. The voltage converter mode switching circuit for tracking load current according to claim 2, characterized in that: The comparator subunit includes a first input transistor, a second input transistor, a current mirror, and a bridging resistor; The current mirror includes a mirrored MOS transistor and two identical mirrored current sources; The drains of the first input transistor and the second input transistor are respectively connected to the drains of two MOSFETs, and the drains of the first input transistor and the second input transistor are respectively connected to two mirror current sources. The gate of the first input transistor is connected to the comparison reference voltage Vref1, and the gate of the second input transistor is connected to the output signal of the error comparator; The bridging resistor is connected between the source of the first input transistor and the source of the second input transistor, and the drain of the first input transistor is connected to the mirror subunit as the output of the comparator subunit.

4. The voltage converter mode switching circuit for tracking load current according to claim 3, characterized in that: The output terminal of the mirror subunit is electrically connected to the first voltage divider resistor R1 and the second voltage divider resistor R2 in the mode control unit.

5. A voltage converter mode switching circuit for tracking load current according to claim 4, characterized in that: The feedback current is ； in, The current mirroring ratio of the mirror subunit. The output voltage of the error comparator is... The bridging resistor is mentioned above.

6. The voltage converter mode switching circuit for tracking load current according to claim 5, characterized in that: As the input voltage Vin gradually decreases, the switching level of the mode control signal in the mode control unit is... ; in, This is the rated output current of the first current source; As the input voltage Vin gradually increases, the switching level of the mode control signal in the mode control unit is... ; in, This is the rated output current of the second current source.

7. A voltage converter mode switching circuit for tracking load current according to claim 4, characterized in that: The toggling level of the mode control signal in the mode control unit and It has a linear relationship with the load current of the voltage converter; The lighter the load after the voltage converter, the lower the switching level. and The smaller the value, the better.

8. A voltage converter mode switching method for tracking load current, characterized in that: The method is implemented using a voltage converter mode switching circuit for tracking load current as described in any one of claims 1-7.

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