WO2018161422A1

WO2018161422A1 - Power supply circuit and power supply method

Info

Publication number: WO2018161422A1
Application number: PCT/CN2017/082518
Authority: WO
Inventors: 张洵; 况火根; 晁康洁; 罗红磊
Original assignee: 华为技术有限公司
Priority date: 2017-03-10
Filing date: 2017-04-28
Publication date: 2018-09-13
Also published as: CN109074145A; CN109074145B

Abstract

A power supply circuit. The circuit comprises: a switch circuit (410), for receiving at least one first voltage outputted by at least one step-down direct-current (DC) conversion circuit, wherein each step-down DC conversion circuit is for supplying power to at least one operating circuit; a control circuit (420), for activating the corresponding step-down DC conversion circuit according to a required voltage of the operating circuit and the at least one first voltage; and output circuit (430), for outputting a second voltage according to the first voltage outputted by the activated step-down DC conversion circuit so as to supply power to the operating circuit, wherein a voltage value of the first voltage is greater than or equal to a voltage value of the second voltage. The circuit effectively achieves high efficiency and reduction of peripheral components by multiplexing the step-down DC conversion circuit in a power management unit, thereby saving costs.

Description

Power supply circuit and power supply method

Technical field

The embodiments of the present application relate to the field of electronic technologies, and in particular, to a power supply circuit and a power supply method.

Background technique

In audio circuits, the most power-consuming part is often the power amplifier Power Amplifier, PA. By reducing the power consumption of the PA or improving the conversion efficiency of the PA, not only can the terminal device (such as a mobile phone) obtain a longer battery life, but also reduce the heat generated and reduce the heat generation problem during the use of the terminal device.

Currently, the industry generally adopts the G-class architecture and the H-class architecture in the traditional PA architecture to implement high-fidelity (Hi-Fi)-level music playback, as shown in FIGS. 1 and 2.

However, only two types of voltage-selected Class G power amplifiers have limited efficiency improvements, and for three or more voltages, multiple capacitors are required, resulting in a complicated circuit structure. Class H power amplifiers provide tens or even hundreds of voltage gears through a combination of BUCK circuit and charge pump (CP), which is more efficient. However, because Class H amplifiers require separate BUCK circuits for each CP, as well as corresponding off-chip inductors and capacitors, this not only increases the design complexity inside the chip, but also increases the cost of chip design and package testing. The increase of off-chip components is not only costly, but also occupies a large number of Printed Circuit Board (PCB) layout areas, which is not conducive to the thinning of mobile phones.

Summary of the invention

The embodiment of the invention provides a power supply circuit and a power supply method. By multiplexing the BUCK circuit in the Power Management Unit (PMU), the high efficiency and the purpose of reducing peripheral components are effectively achieved, and the cost is saved.

In a first aspect, a power supply circuit is provided, which circuit can include: a switching circuit, a control circuit, and an output circuit. The switching circuit is configured to connect at least one first voltage outputted by the at least one step-down DC conversion circuit, and each step-down DC conversion circuit is configured to supply power to the at least one working circuit. The control circuit is configured to turn on the corresponding step-down DC conversion circuit according to the voltage required by the working circuit and the at least one first voltage. The output circuit is configured to output a second voltage according to the first voltage outputted by the step-down DC conversion circuit that is turned on to supply power to the working circuit, wherein the voltage value of the first voltage is greater than or equal to the voltage value of the second voltage. By multiplexing the BUCK circuit in the power management unit, the circuit effectively achieves high efficiency, saves cost, and reduces peripheral components required for the BUCK circuit, thereby reducing chip area and eliminating potential performance interference risks. Conducive to the thin and light design of the mobile phone.

In an optional implementation, the control circuit is further configured to turn on the corresponding step-down type according to the voltage required by the working circuit, the at least one first voltage, and the operating state of the corresponding step-down DC conversion circuit that outputs the at least one first voltage. DC conversion circuit.

In an optional implementation, the switch circuit includes at least one first control switch and at least one second control switch, the first control switch and the second control switch are equal in number and one-to-one correspondence, and at least one first control switch is used At least one first voltage that is coupled to the output of the at least one circuit. The control circuit is specifically configured to use when the first voltage is greater than or equal to When the voltage required by the circuit is made, the signal is triggered to the output of the corresponding second control switch. The second control switch is configured to trigger the corresponding first control switch to turn on the step-down DC converter circuit that outputs the first voltage according to the trigger signal.

In an optional implementation, the control circuit is further configured to: when the first voltage is greater than or equal to the voltage required by the working circuit, and the step-down DC conversion circuit that outputs the first voltage is not fully loaded, to the corresponding second control switch The trigger signal is output. The second control switch is configured to trigger the corresponding first control switch to turn on the step-down DC converter circuit that outputs the first voltage according to the trigger signal.

In an optional implementation, the first end of each of the at least one first control switch is an input of the power supply circuit, and the second end of each of the at least one first control switch The terminal is connected to the first input end of the output circuit, and the output end of the output circuit is an output end of the power supply circuit; the third end of each of the at least one first control switch and the at least one second control switch a first end of each second control switch is connected, and a second end of each of the at least one second control switch is connected to a first output of the at least one first output of the control circuit, at least A third end of each of the second control switches is grounded, and the three second outputs of the control circuit are respectively coupled to the three second inputs of the output circuit.

In an alternative implementation, the first control switch is a PMOS or NMOS, or a combination of NMOS and PMOS.

In a second aspect, a power supply method is provided, the method may include: accessing at least one first voltage output by at least one step-down DC conversion circuit, and each step-down DC conversion circuit is configured to supply power to at least one working circuit . The corresponding step-down DC conversion circuit is turned on according to the voltage required by the working circuit and the at least one first voltage. And outputting a second voltage according to the first voltage outputted by the step-down DC conversion circuit that is turned on to supply power to the working circuit, wherein the voltage value of the first voltage is greater than or equal to the voltage value of the second voltage. By multiplexing the BUCK circuit in the power management unit, the method effectively achieves high efficiency, saves cost, and reduces peripheral components required for the BUCK circuit, thereby reducing chip area and eliminating potential performance interference risks. Conducive to the thin and light design of the mobile phone.

In an optional implementation, the corresponding step-down DC conversion circuit is turned on according to the voltage required by the working circuit and the at least one first voltage, including: at least one first voltage and at least one output according to the required voltage of the working circuit The working state of the corresponding step-down DC conversion circuit of a voltage turns on the corresponding step-down DC conversion circuit.

In an optional implementation, the corresponding BUCK circuit is turned on according to the voltage required by the working circuit and the at least one first voltage, including: when the first voltage is greater than or equal to the voltage required by the working circuit, to the corresponding second control switch The trigger signal is output. According to the trigger signal, the corresponding first control switch is triggered to turn on the step-down DC converter circuit that outputs the first voltage.

In an optional implementation, when the first voltage is greater than or equal to a voltage required by the working circuit, and the buck DC conversion circuit that outputs the first voltage is not fully loaded, to the corresponding second control switch The trigger signal is output. According to the trigger signal, the corresponding first control switch is triggered to turn on the step-down DC converter circuit that outputs the first voltage.

DRAWINGS

1 is a schematic structural view of a conventional class G power amplifier;

2 is a schematic structural view of a conventional class H power amplifier;

3 is a schematic structural diagram of a circuit system according to an embodiment of the present invention;

4 is a schematic structural diagram of a power supply circuit according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an output circuit according to an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of another power supply circuit according to an embodiment of the present disclosure;

FIG. 7 is a schematic structural diagram of still another power supply circuit according to an embodiment of the present disclosure;

FIG. 8 is a schematic structural diagram of still another power supply circuit according to an embodiment of the present disclosure;

FIG. 9 is a schematic structural diagram of still another power supply circuit according to an embodiment of the present disclosure;

FIG. 10 is a schematic structural diagram of still another power supply circuit according to an embodiment of the present disclosure;

FIG. 11 is a schematic structural diagram of still another power supply circuit according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of still another power supply circuit according to an embodiment of the present disclosure;

FIG. 13 is a schematic flowchart diagram of a power supply method according to an embodiment of the present invention.

detailed description

The technical solutions of the present application are further described in detail below through the accompanying drawings and embodiments.

The power supply circuit provided by the present application can be applied to an audio device that needs to be used for audio playback of a terminal device (such as a mobile phone, a tablet computer, etc.), a hearing aid, a virtual reality device, and the like. As shown in FIG. 3, the audio device can include a power management unit 310, a power supply circuit 320 (such as a charge pump circuit), and at least one operational circuit 330 (such as a power amplifier).

The power management unit 310 includes at least one BUCK (including BUCK1, BUCK2 to BUCKn) for outputting a power supply voltage, wherein each BUCK circuit can power at least two of the working circuits 330.

The power supply circuit 320 is configured to receive the power supply voltage output by the at least one BUCK circuit in the power management unit 310, and select a corresponding BUCK circuit in the power management unit 310 according to an operating mode of the working circuit 330 (such as a music mode, a video mode, etc.). The working circuit 330 provides an operating voltage. That is, the working circuit can multiplex the BUCK circuit in the power management unit 310 through the power supply circuit 320.

The application multiplexes the BUCK circuit of the power management unit according to the working mode of the working circuit by the power supply circuit, effectively achieves high efficiency, saves cost, reduces peripheral components required by the BUCK circuit, and thereby reduces chip area.

It should be noted that the BUCK circuit that the power supply circuit 320 selects to provide the working voltage to the working circuit 330 may not be the BUCK circuit in the power management unit 310, and the BUCK circuit in other units or modules is also applicable, and the embodiment of the present invention does not do this. limit.

The following is a detailed description of the BUCK circuit in the multiplexed power management unit.

FIG. 4 is a schematic structural diagram of a power supply circuit according to an embodiment of the present invention. As shown in FIG. 4, the power supply circuit may include a switch circuit 410, a control circuit 420, and an output circuit 430.

The switch circuit 410 may include at least one first control switch K and at least one second control switch S, the first control switch K and the second control switch S being equal in number and one-to-one correspondence.

The first end of each of the at least one first control switch K is an input end of the power supply circuit, and the second end of each of the at least one first control switch K is connected to the output circuit The first input end of the 430 is connected, and the output end of the output circuit 430 is an output end of the power supply circuit; the third end of each of the at least one first control switch K and the at least one second control switch S The first end of each of the second control switches S is connected, and the second end of each of the at least one second control switch S and the first end of the at least one first output of the control circuit 420 are first The outputs are connected, and the third end of each of the at least one second control switch S is grounded. The three second outputs of control circuit 420 are coupled to three second inputs of output circuit 440, respectively.

At least one first control switch K of the switch circuit 410 is configured to access at least one first voltage output by the at least one BUCK circuit. Wherein, each BUCK circuit can supply power to at least one working circuit.

Optionally, the voltage values of the first voltage output by the at least one BUCK circuit may all be the same, partially the same, or completely different. For example, the voltage values of the first voltages output by the four BUCK circuits may be uniform voltage distributions of 1.2V, 1.4V, 1.6V, and 1.8V.

The control circuit 420 is configured to turn on the corresponding BUCK circuit according to the voltage required by the working circuit and the at least one first voltage.

The control circuit 420 compares the voltage required by the working circuit with the at least one first voltage, respectively. When the first voltage is greater than or equal to the voltage required by the working circuit, the control circuit 420 passes the first output terminal to the corresponding second control switch S. The trigger signal is output. The second control switch S triggers the corresponding first control switch K to turn on the BUCK circuit that outputs the first voltage according to the trigger signal.

Optionally, the control circuit 420 may further activate the corresponding BUCK according to the required voltage of the working circuit, the at least one first voltage, and the working state of the corresponding BUCK circuit that outputs the at least one first voltage (such as a full load state or an unloaded state). Circuit.

The control circuit 420 compares the voltage required by the working circuit with the at least one first voltage. When the first voltage is greater than or equal to the voltage required by the working circuit, and the BUCK circuit that outputs the first voltage is not fully loaded, the control circuit 420 passes The first output terminal outputs a trigger signal to the corresponding second control switch S. The second control switch S triggers the corresponding first control switch K to turn on the step-down DC converter circuit that outputs the first voltage according to the trigger signal.

Optionally, when there are at least two first voltages greater than or equal to a voltage required by the working circuit, and the BUCK circuits outputting the at least two first voltages are not fully loaded, the control circuit 420 may select the first voltage according to design requirements. , thereby turning on the BUCK circuit corresponding to the first voltage. For example, the control circuit 420 may preferentially select the first voltage corresponding to the idle BUCK circuit, the first voltage closest to the voltage required by the working circuit, or the multiplexing according to design requirements (such as increasing the usage rate of the BUCK circuit, reducing the cost, etc.). The first voltage corresponding to the BUCK circuit with the least working circuit.

It is to be understood that the selection manner in the embodiment of the present invention is not limited to the above three modes, and other selection manners may be used, and the embodiments of the present invention are not described herein again.

In one example, taking the working circuit as a PA, the control circuit 420 stores information about at least one BUCK circuit at time t, and the related information can be as shown in Table 1.

Table 1

BUCK电路BUCK circuit	第一电压(V)First voltage (V)	工作状态Working status
BUCK1BUCK1	1.21.2	空闲idle
BUCK2BUCK2	1.41.4	未满载Not full
BUCK3BUCK3	1.71.7	满载Full load
BUCK4BUCK4	1.91.9	未满载Not full

As shown in Table 1, the first voltage output of the BUCK1 circuit is 1.2V, which is in an idle state; the first voltage outputted by the BUCK2 circuit is 1.4V, which is in an unloaded state; the first voltage outputted by the BUCK3 circuit is 1.7V, which is at full load. State; the first voltage output of the BUCK4 circuit is 1.9V, which is in an unloaded state.

When the required voltage of the PA is 1.2V, the control circuit is controlled because the BUCK3 circuit corresponding to 1.7V is in a full load state. The path 420 can select any one of a BUCK1 circuit, a BUCK2 circuit, and a BUCK4 circuit corresponding to 1.2V, 1.4V, and 1.9V. Therefore, the control circuit 420 sends a trigger signal to the second control switch S where the BUCK1 circuit, the BUCK2 circuit or the BUCK4 circuit is located to turn on the BUCK1 circuit, the BUCK2 circuit or the BUCK4 circuit. When the required voltage of the PA is 1.5V, the control circuit 420 will select a suitable first voltage from 1.7V and 1.9V. Since the BUCK3 circuit corresponding to 1.7V is in the full load state, the control circuit 420 is in the second position of the BUCK4 circuit. The control switch S sends a trigger signal to turn on the BUCK4 circuit.

It can be seen that the control circuit 420 selects an appropriate BUCK to supply power to the working circuit by selecting at least one first voltage output by the at least one BUCK circuit.

It can be understood that when the multiplexed at least one BUCK circuit has sufficient gear positions and the output power supply voltage distribution is uniform, the power method including the power supply circuit is almost equivalent to the conventional class H power method. However, the additional inductance and capacitance required by the Class H power method are not required, which saves cost and reduces peripheral components.

The output circuit 430 is configured to output a second voltage according to the first voltage output by the turned-on BUCK circuit to supply power to the working circuit. Wherein, the voltage value of the first voltage is greater than or equal to the voltage value of the second voltage.

Alternatively, the output circuit 430 may include a control switch k1, a control switch k2, a control switch k3, a capacitor C1, and a capacitor C2, as shown in FIG. The first end of the capacitor C1 is the first input end of the output circuit 430, the first end of the control switch k1 is connected to the first end of the capacitor C1, and the second end of the capacitor C1 is connected to the second end of the control switch k2, and the switch is controlled The first end of k2 is connected to the first end of the capacitor C2, the third end of the control switch k2 is the first second input end of the output circuit 430; the first end of the control switch k3 is connected to the second end of the capacitor C1, The second end of the control switch k3 is grounded, the third end of the control switch k3 is the second second input end of the output circuit 430; the intersection of the second end of the capacitor C2 and the second end of the control switch k1 is the output of the output circuit 430 end. The control switch k1, the control switch k2, and the control switch k3 may be NMOS or PMOS.

Alternatively, the first control switch K may be a PMOS (as shown in FIG. 6), an NMOS (as shown in FIG. 7), or a combination of NMOS and PMOS (as shown in FIG. 8). The second control switch S may be a three-terminal controllable switch, or may be a PMOS, an NMOS or a combination of NMOS and PMOS.

The method for selecting the switch type of the first control switch may depend on a difference between a first voltage provided by the at least one BUCK circuit and a voltage required by the working circuit, and if the difference is greater than a threshold voltage of the PMOS, selecting a PMOS; If the difference is smaller than the threshold voltage of the PMOS, the NMOS is selected, and the selection method can effectively reduce the chip area. However, the method for selecting the type of the switch of the first control switch is not limited to the above method, and may be selected by other means, such as the method of actual design calculation, which is not described herein again.

Optionally, the power supply circuit may further include an error method EA, as shown in FIG. The first input of the EA inputs the voltage required by the working circuit, the second input of the EA inputs the first voltage output by the open BUCK circuit, and the output of the EA and each of the at least one second control switch S The third end of S is connected to output a difference between a voltage required by the working circuit and the first voltage.

The EA is used to provide closed-loop control of the BUCK by using the EA to control the output of the power supply circuit to the voltage value required by the operating circuit. In the control loop, the error amplifier amplifies the error signal to achieve the PSRR (supply voltage rejection ratio) of the power supply provided by the BUCK to improve the sensitivity of the control system and improve the adjustment accuracy (reducing the adjustment error). Due to the complicated power supply environment of the BUCK circuit, noise sources visible in the audio band may be generated. Therefore, by increasing the EA, the PSRR of 40 dB or more can be provided, so that the output of the working circuit (such as PA) is not easily interfered.

Alternatively, the number of EAs may be at least one, and one EA may be connected to at least one second control switch S.

It should be noted that, in the output circuit 430, the EA can also control any one of the control switch k1, the control switch k2, and the control switch k3, as shown in FIGS. 10-12.

It can be seen that the power supply circuit provided by the present application effectively multiplexes the BUCK circuit in the power management unit, effectively achieves high efficiency, saves cost, and reduces peripheral components required for the BUCK circuit, thereby reducing chip area. Eliminate the potential performance interference risk, which is conducive to the thin and light design of the mobile phone.

An embodiment of the present invention corresponding to the above power supply circuit further provides a power supply method. As shown in FIG. 13, the method may include:

Step 1310: Connect at least one first voltage output by the at least one step-down DC conversion circuit, and each step-down DC conversion circuit is configured to supply power to the at least one working circuit.

Step 1320: Turn on a corresponding step-down DC conversion circuit according to a voltage required by the working circuit and at least one first voltage.

Step 1330: Output a second voltage according to the first voltage outputted by the step-down DC conversion circuit that is turned on to supply power to the working circuit. Wherein, the voltage value of the first voltage is greater than or equal to the voltage value of the second voltage.

Optionally, the corresponding BUCK circuit is turned on according to the voltage required by the working circuit and the at least one first voltage, including:

The corresponding step-down DC conversion circuit is turned on according to the voltage required by the working circuit, the at least one first voltage, and the operating state of the corresponding step-down DC conversion circuit that outputs at least one first voltage.

When the first voltage is greater than or equal to the voltage required by the working circuit, the output trigger signal to the corresponding second control switch, and according to the trigger signal, trigger the corresponding first control switch to open the step-down DC converter outputting the first voltage Circuit.

Optionally, when the first voltage is greater than or equal to the voltage required by the working circuit, and the step-down DC conversion circuit that outputs the first voltage is not fully loaded, the output trigger signal to the corresponding second control switch is triggered according to the trigger signal. The corresponding first control switch turns on the step-down DC converter circuit that outputs the first voltage.

By multiplexing the BUCK circuit of the power management unit, the method realizes the BUCK circuit dedicated to removing the class H power amplifier, reduces the chip area, saves the cost, and eliminates the potential interference sources.

A person skilled in the art should further appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both, in order to clearly illustrate hardware and software. Interchangeability, the composition and steps of the various examples have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present application.

It will be understood by those skilled in the art that all or part of the steps of implementing the above embodiments may be performed by a program, and the program may be stored in a computer readable storage medium, which is non-transitory ( Non-transitory medium, such as random access memory, read only memory, flash memory, hard disk, solid state disk, magnetic tape, floppy disk, optical disc, and any combination thereof.

The above description is only a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed in the present application. Replacement should be covered by the scope of this application. Therefore, the scope of protection of the present application should be determined by the scope of protection of the claims.

Claims

A power supply circuit, characterized in that the circuit comprises:

a switching circuit for accessing at least one first voltage outputted by the at least one step-down DC conversion circuit, each of the step-down DC conversion circuits being configured to supply power to the at least one working circuit;

a control circuit, configured to turn on the corresponding step-down DC conversion circuit according to a voltage required by the working circuit and at least one first voltage;

An output circuit, configured to output a second voltage according to the first voltage outputted by the step-down DC conversion circuit that is turned on, to supply power to the working circuit, wherein a voltage value of the first voltage is greater than or equal to The voltage value of the second voltage is described.
The circuit according to claim 1, wherein said control circuit is further configured to: responsive to a voltage required by the operating circuit, at least one first voltage, and a respective step-down DC conversion circuit that outputs said at least one first voltage The working state turns on the corresponding step-down DC conversion circuit.
The circuit of claim 1 wherein said switching circuit comprises at least one first control switch and at least one second control switch, said first control switch being equal in number to said second control switch and a correspondence,

The at least one first control switch is configured to access at least one first voltage output by the at least one circuit;

The control circuit is specifically configured to: when the first voltage is greater than or equal to a voltage required by the working circuit, output a trigger signal to the corresponding second control switch;

The second control switch is configured to trigger, according to the trigger signal, the corresponding first control switch to turn on the buck DC converter circuit that outputs the first voltage.
The circuit according to claim 3, wherein the control circuit is further configured to: when the first voltage is greater than or equal to a voltage required by the working circuit, and output the drop of the first voltage When the voltage-type DC conversion circuit is not fully loaded, a trigger signal is output to the corresponding second control switch;

The second control switch is configured to trigger, according to the trigger signal, the corresponding first control switch to turn on the buck DC converter circuit that outputs the first voltage.
A circuit according to claim 3 or 4, wherein

a first end of each of the at least one first control switch is an input end of the power supply circuit, and a second end of each of the at least one first control switch a first input end of the output circuit is connected, an output end of the output circuit is an output end of the power supply circuit; a third end of each of the at least one first control switch is a first end of each of the at least one second control switch is connected, a second end of each of the at least one second control switch and at least one of the first of the control circuits One of the output ends is connected, the third end of each of the at least one second control switch is grounded, and the three second outputs of the control circuit are respectively connected to the output circuit The three second inputs are connected.
A circuit according to claims 3-5, wherein said first control switch is a PMOS or NMOS, or a combination of NMOS and PMOS.
A power supply method, characterized in that the method comprises:

And connecting at least one first voltage outputted by the at least one step-down DC conversion circuit, and each of the step-down DC conversion circuits is configured to supply power to at least one working circuit;

Turning on a corresponding step-down DC conversion circuit according to a voltage required by the working circuit and at least one first voltage;

And outputting a second voltage to supply power to the working circuit according to the first voltage outputted by the step-down DC conversion circuit, wherein a voltage value of the first voltage is greater than or equal to the second voltage Voltage value.
The method according to claim 7, wherein the opening of the corresponding step-down DC conversion circuit according to the voltage required by the working circuit and the at least one first voltage comprises:

And correspondingly operating the step-down DC conversion circuit according to a voltage required by the working circuit, at least one first voltage, and an operating state of a corresponding step-down DC conversion circuit that outputs the at least one first voltage.
The method according to claim 7, wherein the opening of the corresponding BUCK circuit according to the voltage required by the working circuit and the at least one first voltage comprises:

Outputting a signal to an output of the corresponding second control switch when the first voltage is greater than or equal to a voltage required by the working circuit;

And triggering, according to the trigger signal, the corresponding first control switch to turn on the step-down DC converter circuit that outputs the first voltage.
The method according to claim 8, wherein when the first voltage is greater than or equal to a voltage required by the working circuit, and the step-down DC conversion circuit that outputs the first voltage is not fully loaded, Outputting a signal to the corresponding second control switch;

And triggering, according to the trigger signal, the corresponding first control switch to turn on the step-down DC converter circuit that outputs the first voltage.