TWI826114B - Regulator circuit module and voltage control method - Google Patents

Abstract

A regulator circuit module and a voltage control method are disclosed. The method includes: generating an output voltage at a voltage output terminal of a first regulator circuit; providing the output voltage to a voltage input terminal of a payload device through a power transmission path; detecting a voltage value of the voltage input terminal of the payload device; and in response to a change of the voltage value, adjusting, by a second regulator circuit, an impedance value provided to the voltage output terminal of the first regulator circuit.

Description

Voltage stabilizing circuit module and voltage control method

The present invention relates to a voltage adjustment technology, and in particular, to a voltage stabilizing circuit module and a voltage control method.

Voltage stabilizing circuits such as low-dropout regulators (LDO) are commonly used in various electronic devices to meet the stable power supply requirements for electronic devices. Generally speaking, a voltage stabilizing circuit can continuously track its output voltage through a feedback mechanism and maintain the output voltage at a stable state. However, in practice, even if the voltage stabilizing circuit keeps the output voltage as stable as possible at its voltage output terminal, after this output voltage is transmitted to the load device through the power conduction path, unexpected voltage may still occur at the voltage input terminal of the load device. Unexpected events such as drop or sudden shutdown of the device. These unexpected events occurring at the voltage input end of the load device may seriously affect the power supply stability of the electronic device.

The invention provides a voltage stabilizing circuit module and a voltage control method, which can improve the stability of power supply to a load device.

An embodiment of the present invention provides a voltage stabilizing circuit module, which includes a first voltage stabilizing circuit and a second voltage stabilizing circuit. The first voltage stabilizing circuit is coupled to the load device via a power conduction path. The second voltage stabilizing circuit is coupled to the voltage output terminal of the first voltage stabilizing circuit and the voltage input terminal of the load device. The first voltage stabilizing circuit is used to generate an output voltage at the voltage output terminal. The output voltage is provided to the voltage input of the load device via the power conduction path. The second voltage stabilizing circuit is used to: detect the voltage value of the voltage input terminal of the load device; and adjust the voltage output provided to the first voltage stabilizing circuit in response to changes in the voltage value. The impedance value of the terminal.

An embodiment of the present invention further provides a voltage control method, which includes: generating an output voltage at a voltage output terminal of a first voltage stabilizing circuit; providing the output voltage to a voltage input terminal of a load device through a power conduction path; detecting a voltage value of the voltage input terminal of the load device; and in response to a change in the voltage value, the second voltage stabilizing circuit adjusts the impedance value provided to the voltage output terminal of the first voltage stabilizing circuit.

Based on the above, after the first voltage stabilizing circuit generates an output voltage at the voltage output terminal, the output voltage can be provided to the voltage input terminal of the load device through the power conduction path. At the same time, the voltage value of the voltage input terminal of the load device can continue to be detected. In particular, in response to changes in the voltage value, the second voltage stabilizing circuit can automatically adjust the impedance value provided to the voltage output terminal of the first voltage stabilizing circuit. This can effectively improve the stability of power supply to the load device.

FIG. 1 is a schematic diagram of a voltage stabilizing circuit module according to an embodiment of the present invention. Referring to FIG. 1 , the voltage stabilizing circuit module 10 can be coupled to the load device 100 to provide power to the load device 100 . For example, the load device 100 can be any type of electronic circuit or chip in various electronic devices such as smartphones, tablets, laptops, desktop computers, servers or game consoles, and the type of the load device 100 is not limited to this. Both the voltage stabilizing circuit module 10 and the load device 100 can be disposed in the electronic device.

The voltage stabilizing circuit module 10 may include a voltage stabilizing circuit (also called a first voltage stabilizing circuit) 11 and a voltage stabilizing circuit (also called a second voltage stabilizing circuit) 12 . The voltage stabilizing circuit 11 may be coupled to the load device 100 via the power conduction path 101 . In particular, the voltage stabilizing circuit 11 can be used to generate the output voltage V(out) at its voltage output terminal. For example, the voltage stabilizing circuit 11 may include at least part of the circuit structure of various voltage stabilizing circuits such as a low-dropout regulator (LDO) or a buck converter (Buck Converter) to generate the output voltage V according to the reference voltage. (out).

The output voltage V(out) may be provided to the voltage input terminal of the load device 100 via the power conduction path 101, as shown in FIG. 1 . In particular, the output voltage V(out) transmitted to the voltage input terminal of the load device 100 via the power conduction path 101 can generate an input voltage V(in) at the voltage input terminal of the load device 100 . The input voltage V(in) is available to the load device 100 .

The voltage stabilizing circuit 12 is coupled to the voltage output terminal of the voltage stabilizing circuit 11 and the voltage input terminal of the load device 100 . The voltage stabilizing circuit 12 can be used to detect the voltage value of the voltage input terminal of the load device 100 (ie, the voltage value of the input voltage V(in)). In particular, in response to changes in this voltage value, the voltage stabilizing circuit 12 can adjust the impedance value provided to the voltage output terminal of the voltage stabilizing circuit 11 . By adjusting the impedance value provided to the voltage output terminal of the voltage stabilizing circuit 11, the voltage values of the output voltage V(out) and the input voltage V(in) can be adjusted accordingly.

In one embodiment, the voltage stabilizing circuit 11 can maintain stability of the output voltage V(out) at the voltage output end of the voltage stabilizing circuit 11 through a preset adjustment mechanism, for example, maintaining the voltage value of the output voltage V(out) at Default value. However, in practice, even if the output voltage V(out) can remain stable, the input voltage V(in) may still undergo a sudden drop or other change after being conducted through the power conduction path 101 . Such changes may not be detected and compensated by the preset adjustment mechanism of the voltage stabilizing circuit 11 .

In one embodiment, the voltage stabilizing circuit 12 can detect changes such as a sudden drop in the input voltage V(in). In response to changes in the input voltage V(in), the voltage stabilizing circuit 12 can dynamically adjust the impedance value of the voltage output terminal of the voltage stabilizing circuit 11 so that the input voltage V(in) quickly returns to a stable state, for example, the input voltage V(in) ) voltage value returns to the default value. For example, in response to a sudden drop in the input voltage V(in), the voltage stabilizing circuit 12 may dynamically adjust the impedance value of the voltage output terminal of the voltage stabilizing circuit 11 . The adjusted impedance value can quickly increase the output voltage V(out). The increased output voltage V(out) can also increase the input voltage V(in), thereby quickly returning the input voltage V(in) to a stable state. Thereby, no matter whether the current abnormal voltage condition occurs at the voltage output end of the voltage stabilizing circuit 11 or the voltage input end of the load circuit 100, the abnormal voltage condition can be quickly detected and resolved.

FIG. 2 is a schematic diagram of a voltage stabilizing circuit module according to an embodiment of the present invention. Referring to FIG. 2 , a low dropout voltage regulator (LDO) is used as an example of the voltage stabilizing circuit 11 . The voltage stabilizing circuit 11 may include pins VIN, VOUT, FB, EN, and GND.

Pin VIN can be used to receive the reference voltage. The pin VOUT can be used to send the output voltage V(out). For example, according to the reference voltage received by the pin VIN, the voltage stabilizing circuit 11 can generate the output voltage V(out) at the voltage output terminal through the pin VOUT. For example, the voltage stabilizing circuit 11 may boost or step down the reference voltage to generate the output voltage V(out). The output voltage V(out) may then be provided to the voltage input terminal of the load device 100 via the power conduction path 101 to form the input voltage V(in). The load device 100 can receive the input voltage V(in) through the pin VIN.

On the other hand, the pin FB can be used to receive the feedback voltage corresponding to the output voltage V(out). The voltage stabilizing circuit 11 can dynamically adjust the output voltage V(out) according to the feedback voltage to maintain the output voltage V(out) in a stable state. In addition, the pin GND can be coupled to the reference ground voltage, and the pin EN can be used to receive the enable signal. For example, the enable signal can be used to activate the voltage stabilizing circuit 11 . It should be noted that in one embodiment, the voltage stabilizing circuit 11 may also include at least part of the circuit structure of various voltage stabilizing circuits such as a buck converter, which is not limited by the present invention.

The voltage stabilizing circuit 12 may include an impedance adjustment circuit 21 and a voltage dividing circuit 22 . The impedance adjustment circuit 21 is coupled to the voltage input terminal (eg, pin VIN) of the load device 100 . The voltage dividing circuit 22 is coupled to the impedance adjustment circuit 21 , the voltage output terminal (eg pin VOUT) of the voltage stabilizing circuit 11 and the voltage feedback terminal (eg pin FB) of the voltage stabilizing circuit 11 .

In particular, the impedance adjustment circuit 21 can detect the voltage value of the input voltage V(in). In response to changes in the voltage value of the input voltage V(in), the impedance adjustment circuit 21 may adjust the impedance value of the voltage dividing circuit 22 . The adjusted impedance value of the voltage dividing circuit 22 can be used to quickly increase or decrease the output voltage V(out).

In one embodiment, the voltage stabilizing circuit 11 can monitor the status of the output voltage V(out) through the feedback voltage of the pin FB (ie, the voltage feedback terminal). For example, the voltage stabilizing circuit 11 can monitor whether the voltage value of the output voltage V(out) changes through the pin FB. In response to changes in the voltage value of the output voltage V(out), the voltage stabilizing circuit 11 can dynamically adjust the output voltage V(out) to maintain a stable output voltage V(out).

It should be noted that there is a power conduction path 101 between the voltage output terminal of the voltage stabilizing circuit 11 and the voltage input terminal of the load device 100, as shown in FIG. 2 . Therefore, in some cases, the feedback voltage on pin FB cannot directly or immediately reflect changes in the input voltage V(in). Therefore, in some cases, when the input voltage V(in) changes suddenly, relying solely on the voltage stabilizing mechanism of the voltage stabilizing circuit 11 may not quickly return the input voltage V(in) to a stable state.

In one embodiment, the impedance adjustment circuit 21 adjusts the impedance value of the voltage dividing circuit 22 according to changes in the input voltage V(in), before the voltage stabilizing circuit 11 actually detects an abnormality in the output voltage V(out). , directly adjust the output voltage V(out) (such as raising or lowering the output voltage V(out)). Once the output voltage V(out) is adjusted, the input voltage V(in) will be adjusted together, thereby achieving the effect of quickly returning the input voltage V(in) to a stable state.

In one embodiment, the impedance adjustment circuit 21 may include a control circuit 211, an impedance compensation circuit 212 and a switch circuit 213. The control circuit 211 is coupled to the voltage input terminal (ie, pin VIN) of the load device 100 . The switch circuit 213 is coupled to the control circuit 211 , the impedance compensation circuit 212 and the voltage dividing circuit 22 . For example, the control circuit 211 may include various controllers or control chips such as an embedded controller (EC) or a microcontroller. The switch circuit 213 may include various electronic components that can be used as switches, such as Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET).

The control circuit 211 can detect the voltage value of the input voltage V(in). The control circuit 211 can determine whether the voltage value of the input voltage V(in) is lower than a threshold value (also called a first threshold value). In response to the voltage value of the input voltage V(in) being lower than the first threshold value, the control circuit 211 can control the switch circuit 213 to conduct the impedance compensation circuit 212 to the voltage dividing circuit 22 to adjust the voltage division through the impedance compensation circuit 212. The impedance value of circuit 22. In one embodiment, connecting the impedance compensation circuit 212 to the voltage dividing circuit 22 can be regarded as a signal conduction path between the impedance compensation circuit 212 and the voltage dividing circuit 22 .

In one embodiment, the voltage dividing circuit 22 includes an impedance element (also called a first impedance element) R1 and an impedance element (also called a second impedance element) R2 connected in series, and the impedance compensation circuit 212 includes an impedance element. (also called the third impedance element) R3. For example, the impedance elements R1 to R3 may include resistance or reactance respectively. The first terminal of the impedance element R1 is coupled to the voltage output terminal (ie, the pin VOUT) of the voltage stabilizing circuit 11 . The second end of the impedance element R1 is coupled to the voltage feedback end (ie, pin FB) of the voltage stabilizing circuit 11 , the first end of the impedance element R2 and the switch circuit 213 . The second terminal of the impedance element R2 may be coupled to the reference ground voltage. In addition, the switch circuit 213 may be coupled between the impedance element R1 and the impedance element R2. For example, the switch circuit 213 may be coupled to the second terminal of the impedance element R1 and the first terminal of the impedance element R2.

FIG. 3 is a schematic diagram of conducting the impedance compensation circuit to the voltage dividing circuit according to an embodiment of the present invention.

Referring to FIG. 3 , in one embodiment, in response to the voltage value of the input voltage V(in) being lower than the first threshold, the control circuit 211 can control the switch circuit 213 to conduct the impedance compensation circuit 212 to the voltage dividing circuit 22 . In a state where the impedance compensation circuit 212 is turned on to the voltage dividing circuit 22, the impedance element R3 may be connected in parallel to the impedance element R2. At this time, the impedance value provided by the parallel-connected impedance elements R2 and R3 will be smaller than the original impedance value provided by the impedance element R2 alone. In response to the impedance value provided by the impedance elements R2 and R3 together being less than the original impedance value provided by the impedance element R2 alone, the output voltage V(out) may be pulled up. In response to the output voltage V(out) being pulled high, the output voltage V(in) will also be pulled high accordingly. Thereby, the output voltage V(in) can be quickly restored to a stable state (eg, restored to a preset voltage value) before the voltage stabilizing circuit 11 actually detects an abnormality in the output voltage V(out).

On the other hand, after the impedance compensation circuit 212 is turned on to the voltage dividing circuit 22, the control circuit 211 can continue to detect the voltage value of the input voltage V(in). At the same time, the control circuit 211 can determine whether the voltage value of the input voltage V(in) is higher than another threshold value (also called the second threshold value). The second critical value is greater than the first critical value.

In one embodiment, in response to the voltage value of the input voltage V(in) being higher than the second threshold value, the control circuit 211 may control the switch circuit 213 to disconnect the impedance compensation circuit 212 from the voltage dividing circuit 22 . Thereby, the output voltage V(out) and the input voltage V(in) can be prevented from being excessively high. In one embodiment, disconnecting the impedance compensation circuit 212 from the voltage dividing circuit 22 can be regarded as cutting off the signal conduction path between the impedance compensation circuit 212 and the voltage dividing circuit 22 .

FIG. 4 is a schematic diagram of disconnecting the impedance compensation circuit from the voltage dividing circuit according to an embodiment of the present invention.

Referring to FIG. 4 , in response to the voltage value of the input voltage V(in) being higher than the second critical value, the control circuit 211 may control the switch circuit 213 to disconnect the impedance compensation circuit 212 from the voltage dividing circuit 22 . When the impedance compensation circuit 212 is turned off, the impedance compensation circuit 212 will not be able to affect the impedance value of the voltage dividing circuit 22 (or the impedance element R2). At this time, the impedance value of the voltage dividing circuit 22 can be restored to the original impedance value of the voltage dividing circuit 22 . In response to the impedance value of the voltage dividing circuit 22 returning to the original impedance value, the output voltage V(out) may be reduced. In response to the output voltage V(out) being reduced, the output voltage V(in) is correspondingly reduced. This can prevent the output voltage V(out) and the input voltage V(in) from being excessively high after the impedance compensation circuit 212 is turned on to the voltage dividing circuit 22 .

In one embodiment, by automatically controlling the switch circuit 213 to turn on or off the signal conduction path between the impedance compensation circuit 212 and the voltage dividing circuit 22, the stability of the input voltage V(in) can be effectively improved. The relevant operation details have been described in detail above and will not be repeated here.

FIG. 5 is a flowchart of a voltage control method according to an embodiment of the present invention.

Referring to FIG. 5 , in step S501 , an output voltage is generated at the voltage output terminal of the first voltage stabilizing circuit. In step S502, the output voltage is provided to the voltage input terminal of the load device via the power conduction path. In step S503, the voltage value of the voltage input terminal of the load device is detected. In step S504, in response to the change in the voltage value, the second voltage stabilizing circuit adjusts the impedance value provided to the voltage output terminal of the first voltage stabilizing circuit.

FIG. 6 is a flowchart of a voltage control method according to an embodiment of the present invention.

Referring to FIG. 6 , in step S601 , the voltage value of the voltage input terminal of the load device is detected. In step S602, it is determined whether the voltage value is less than a first threshold value. If (or in response to) the voltage value is not less than the first threshold value, step S601 may be repeated. If (or in response to) the voltage value is less than the first threshold value, in step S603, the switch circuit is controlled to conduct the impedance compensation circuit to the voltage dividing circuit to increase the output voltage of the first voltage stabilizing circuit. For example, the voltage dividing circuit is coupled to the voltage output terminal and the voltage feedback terminal of the first compensation circuit.

After the impedance compensation circuit is turned on to the voltage dividing circuit, in step S604, it is determined whether the voltage value is still less than the first threshold value. If the voltage value is still less than the first threshold value, it means that the voltage value of the voltage input terminal of the current load device cannot be increased to the preset value (ie, the first threshold value) through the additional impedance value provided by the impedance compensation circuit. Therefore, in response to the voltage value being still less than the first critical value, in step S605, the current output voltage information (such as the voltage value of the output voltage) of the voltage output terminal of the first voltage stabilizing circuit is recorded for subsequent analysis and maintenance. use.

On the other hand, after the impedance compensation circuit is turned on to the voltage dividing circuit, if (in response to) the voltage value of the voltage input terminal of the load device is successfully increased higher than the preset value due to the influence of the additional impedance value provided by the impedance compensation circuit (that is, the first threshold value), then in step S606, it is determined whether the voltage value is greater than the second threshold value. The second critical value is greater than the first critical value. If the voltage value is not greater than the second critical value, it means that the voltage value of the voltage input terminal of the load device is well maintained in a stable state (ie, between the first critical value and the second critical value). At this time, step S604 may be repeatedly executed.

However, after the impedance compensation circuit is turned on to the voltage dividing circuit, if the voltage value of the voltage input terminal of the load device is greater than the second critical value, it means that the voltage value of the voltage input terminal of the load device is excessively increased at this time. Therefore, in response to the voltage value of the voltage input terminal of the load device being greater than the second critical value, in step S607, the switch circuit is controlled to disconnect the impedance compensation circuit from the voltage dividing circuit, so that the voltage value of the voltage input terminal of the load device decreases.

However, each step in Figure 5 and Figure 6 has been described in detail above and will not be described again here. It is worth noting that each step in Figure 5 and Figure 6 can be implemented as multiple program codes or circuits, and is not limited in this case. In addition, the methods in Figures 5 and 6 can be used in conjunction with the above example embodiments or can be used alone, and are not limited in this case.

In summary, the voltage stabilizing circuit module and the voltage control method proposed by the exemplary embodiments of the present invention can automatically and dynamically adjust the voltage output provided to the first voltage stabilizing circuit according to changes in the voltage value of the voltage input terminal of the load device. The impedance value of the terminal. This can effectively improve the stability of power supply to the load device.

Although this case has been disclosed as above using embodiments, they are not intended to limit this case. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of this case. Therefore, the protection of this case The scope shall be determined by the appended patent application scope.

10: Voltage stabilizing circuit module

11, 12: Voltage stabilizing circuit

100:Load device

101:Power conduction path

V(out): output voltage

V(in): input voltage

21: Impedance adjustment circuit

211:Control circuit

212: Impedance compensation circuit

213: Switch circuit

22: Voltage dividing circuit

R1~R3: impedance element

VIN, VOUT, FB, EN, GND: pins

S501~S504, S601~S607: steps

FIG. 1 is a schematic diagram of a voltage stabilizing circuit module according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a voltage stabilizing circuit module according to an embodiment of the present invention. FIG. 3 is a schematic diagram of conducting the impedance compensation circuit to the voltage dividing circuit according to an embodiment of the present invention. FIG. 4 is a schematic diagram of disconnecting the impedance compensation circuit from the voltage dividing circuit according to an embodiment of the present invention. FIG. 5 is a flowchart of a voltage control method according to an embodiment of the present invention. FIG. 6 is a flowchart of a voltage control method according to an embodiment of the present invention.

10: Voltage stabilizing circuit module

11,12: Voltage stabilizing circuit

100:Load device

101:Power conduction path

V(out): output voltage

V(in): input voltage

Claims (12)

A voltage stabilizing circuit module includes: a first voltage stabilizing circuit coupled to a load device via a power conduction path; and a second voltage stabilizing circuit coupled to the voltage output end of the first voltage stabilizing circuit and the load device. a voltage input terminal, wherein the first voltage stabilizing circuit is used to generate an output voltage at the voltage output terminal, the output voltage is provided to the voltage input terminal of the load device through the power conduction path, and the second voltage stabilizing circuit is used to : affecting the adjustment of the output voltage of the first voltage stabilizing circuit through the first feedback path; detecting the voltage value of the voltage input terminal of the load device; and in response to changes in the voltage value, adjusting the output voltage through the second feedback path. The impedance value of the voltage output end of the first voltage stabilizing circuit, wherein the second feedback path does not pass through the first voltage stabilizing circuit. The voltage stabilizing circuit module of claim 1, wherein the second voltage stabilizing circuit includes: an impedance adjustment circuit coupled to the voltage input end of the load device; and a voltage dividing circuit coupled to the impedance adjustment circuit circuit, the voltage output end of the first voltage stabilizing circuit and the voltage feedback end of the first voltage stabilizing circuit, wherein the impedance adjustment circuit is used to: adjust the impedance of the voltage dividing circuit in response to the change in the voltage value value. The voltage stabilizing circuit module of claim 2, wherein the impedance adjustment circuit includes: a control circuit coupled to the voltage input end of the load device; an impedance compensation circuit; and a switching circuit coupled to the control circuit, The impedance compensation circuit and the voltage dividing circuit, wherein the control circuit is used to: in response to the voltage value being lower than a first threshold value, control the switch circuit to conduct the impedance compensation circuit to the voltage dividing circuit, so as to The impedance compensation circuit adjusts the impedance value of the voltage dividing circuit. The voltage stabilizing circuit module of claim 3, wherein the voltage dividing circuit includes a first impedance element and a second impedance element connected in series, the impedance compensation circuit includes a third impedance element, and when the impedance compensation circuit is turned on In the state of the voltage dividing circuit, the third impedance element is connected in parallel to the second impedance element. The voltage stabilizing circuit module of claim 4, wherein the first end of the first impedance element is connected to the voltage output end of the first voltage stabilizing circuit, and the second end of the first impedance element is coupled to The voltage feedback terminal of the first voltage stabilizing circuit, the first terminal of the second impedance element and the switching circuit. The voltage stabilizing circuit module of claim 3, wherein the control circuit is further used to: in response to the voltage value being higher than the second critical value, control the switch circuit to reduce the impedance. The compensation circuit is disconnected from the voltage dividing circuit, wherein the second threshold value is greater than the first threshold value. A voltage control method, including: generating an output voltage at a voltage output terminal of a first voltage stabilizing circuit; providing the output voltage to a voltage input terminal of a load device via a power conduction path; influencing the first voltage stabilizing circuit via a first feedback path Adjusting the output voltage; detecting the voltage value of the voltage input terminal of the load device; and in response to changes in the voltage value, adjusting the voltage provided to the first voltage stabilizing circuit through the second feedback path by the second voltage stabilizing circuit The impedance value of the voltage output terminal, wherein the second feedback path does not pass through the first voltage stabilizing circuit. The voltage control method of claim 7, wherein in response to a change in the voltage value, the step of adjusting the impedance value provided to the voltage output end of the first voltage stabilizing circuit by the second voltage stabilizing circuit includes: responding to The change in the voltage value adjusts the impedance value of the voltage dividing circuit, wherein the voltage dividing circuit is coupled to the voltage output terminal of the first voltage stabilizing circuit and the voltage feedback terminal of the first voltage stabilizing circuit. The voltage control method according to claim 8, wherein in response to the change in the voltage value, the step of adjusting the impedance value of the voltage dividing circuit includes: in response to the voltage value being lower than a first critical value, controlling the switching circuit The impedance compensation circuit is connected to the voltage dividing circuit to adjust the voltage dividing circuit through the impedance compensation circuit. of this impedance value. The voltage control method of claim 9, wherein the voltage dividing circuit includes a first impedance element and a second impedance element connected in series, the impedance compensation circuit includes a third impedance element, and when the impedance compensation circuit is connected to the In the state of the voltage dividing circuit, the third impedance element is connected in parallel to the second impedance element. The voltage control method of claim 10, wherein the first end of the first impedance element is connected to the voltage output end of the first voltage stabilizing circuit, and the second end of the first impedance element is coupled to the first The voltage feedback terminal of a voltage stabilizing circuit, the first terminal of the second impedance element and the switching circuit. The voltage control method of claim 9, wherein in response to the change in the voltage value, the step of adjusting the impedance value of the voltage dividing circuit further includes: in response to the voltage value at the voltage input terminal of the load device being high At a second critical value, the switching circuit is controlled to disconnect the impedance compensation circuit from the voltage dividing circuit, wherein the second critical value is greater than the first critical value.

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