Power supply device

Abstract

An object of the present invention is to provide a power supply device capable of suppressing acoustic noise caused by vibration of a capacitor due to voltage fluctuations in the generated output voltage. [Configuration] The present invention comprises a voltage generation circuit that generates a DC voltage and outputs it as an output voltage, a phase compensation circuit that performs phase compensation on this output voltage, a microphone that picks up ambient sound and generates a sound pickup signal, and a control unit that adjusts the response speed of the phase compensation of the phase compensation circuit based on this sound pickup signal.

Description

[Technical Field]

[0001] The present invention relates to a power supply device that generates a DC output voltage with a constant voltage value. [Background technology]

[0002] Such power supply devices are provided with a phase compensation circuit to suppress phase shifts caused by the many capacitors and inductors mounted on the power supply board, thereby ensuring stable operation.

[0003] Also, a technique has been proposed for switching the response characteristics of a phase compensation circuit included in such a power supply device in accordance with the state of a load that receives the supply of the output voltage output from the power supply device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-45021 Summary of the Invention [Problem to be solved by the invention]

[0005] In the power supply device described above, if the response characteristics of the phase compensation circuit are set to improve, the risk of oscillation increases, while if the response characteristics are set to decrease, the phase margin increases but fluctuations in the output voltage cannot be suppressed. In this case, if the output voltage fluctuates, depending on the frequency of the fluctuations, problems such as vibrations in the capacitor mounted on the power supply board and the generation of noise may occur.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power supply device that is capable of suppressing noise caused by vibration of the capacitor. [Means for solving the problem]

[0007] The power supply device of the present invention includes a voltage generation circuit that generates a DC voltage and outputs it as an output voltage, a phase compensation circuit that performs phase compensation of the output voltage, a microphone that collects ambient sounds and generates a sound pickup signal, and a control unit that adjusts the response speed of the phase compensation of the phase compensation circuit based on the sound pickup signal. [Effects of the Invention]

[0008] In the power supply device according to the present invention, when audible noise is detected from an audio signal that has been generated based on a sound signal picked up by a microphone installed on a circuit board on which the power supply circuit is mounted, the power supply device switches over to a direction that improves the response characteristics of the phase compensation circuit, thereby making it possible to suppress audible noise. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration of a power supply circuit 100 as a power supply circuit according to the present invention. [Figure 2] 10 is a flowchart showing a procedure for a phase compensation control process. DETAILED DESCRIPTION OF THE INVENTION

[0010] FIG. 1 is a block diagram showing the configuration of a power supply device 100 according to the present invention.

[0011] The power supply device 100 is a power supply that generates a DC output voltage VDD by performing feedback control so as to output a constant voltage value corresponding to a reference voltage Vref.

[0012] As shown in FIG. 1, the power supply device 100 includes a regulator 11, a phase compensation circuit 12, a microphone 13, an acoustic detection circuit 14, a control unit 15, a capacitor C0, and resistors Rf1 and Rf2, all mounted on a substrate 10.

[0013] The regulator 11 generates an output voltage VDD at the output node nd0 by sending a current corresponding to the difference between the feedback voltage Vfb received at its feedback terminal FB and the reference voltage Vref from its output terminal OUT to the output node nd0.

[0014] One end of the resistor Rf1 is connected to the output node nd0, and the other end is connected to one end of the resistor Rf2. The other end of the resistor Rf2 is connected to the ground potential. With this configuration, the resistors Rf1 and Rf2 divide the voltage of the output node nd0 according to their respective resistance ratios, and supply the resulting voltage to the feedback terminal FB of the regulator 11 as the feedback voltage Vfb.

[0015] The capacitor C0 suppresses noise and fluctuations occurring in the voltage of the output node nd0. For example, the capacitor C0 is a ceramic capacitor, one end of which is connected to the output node nd0, and the other end of which is connected to the ground potential.

[0016] The phase compensation circuit 12 includes RC circuits U1 to U3 and a selector SEL.

[0017] The RC circuit U1 includes a capacitor C1 having one end connected to the output node nd0 and a resistor R1 having one end connected to the other end of the capacitor C1. The RC circuit U2 includes a capacitor C2 having one end connected to the output node nd0 and a resistor R2 having one end connected to the other end of the capacitor C2. The RC circuit U3 includes a capacitor C3 having one end connected to the output node nd0 and a resistor R3 having one end connected to the other end of the capacitor C3.

[0018] Each of the RC circuits U1 to U3 functions as a phase compensation circuit 12 to perform phase compensation for the output voltage VDD, and each has a different response characteristic to voltage fluctuations in the output voltage VDD. For example, among the RC circuits U1 to U3, U1 has the slowest response speed and U3 has the fastest response speed. Therefore, the resistance values ​​of the resistors R1 to R3 and the capacitances of the capacitors C1 to C3 are selected so that the response speeds of the RC circuits U1, U2, and U3 are slowest in this order.

[0019] The selector SEL includes input terminals a to c and an output terminal Y. The input terminal a of the selector SEL is connected to the other end of the resistor R1 included in the RC circuit U1, the input terminal b is connected to the other end of the resistor R2 included in the RC circuit U2, and the input terminal c is connected to the other end of the resistor R3 included in the RC circuit U3. The output terminal Y of the selector SEL is connected to the feedback terminal FB of the regulator 11. The selector SEL selects one of the RC circuits U1 to U3 in response to a response characteristic adjustment signal Rcs supplied from the control unit 15, and connects the other end of the resistor included in the selected RC circuit to the feedback terminal FB of the regulator 11.

[0020] That is, the selector SEL selects one of the RC circuits U1 to U3 in response to the response characteristic adjustment signal Rcs, and connects the selected RC circuit between the output node nd0 and the feedback terminal FB of the regulator 11. Note that, in the initial stage when the power supply device 100 is shipped from the factory, the selector SEL selects the RC circuit U1, which has the slowest response speed, of the RC circuits U1 to U3, and connects it between the output node nd0 and the feedback terminal FB of the regulator 11.

[0021] The microphone 13 picks up surrounding sounds and supplies a picked-up sound signal AS corresponding to the surrounding sounds to the sound detection circuit 14.

[0022] The sound detection circuit 14 receives the picked-up sound signal AS and detects the level of each of a plurality of bands, including, for example, the 15,000 Hz band, of the audible frequency band contained in the picked-up sound signal AS, in which sound (referred to as sound) is generated by vibration of the capacitor due to voltage fluctuations in the output voltage VDD. The sound detection circuit 14 then determines whether the maximum level of each of the plurality of bands is equal to or greater than a predetermined value (for example, 20 dB). If the sound detection circuit 14 determines that the maximum level is less than the predetermined value, the sound detection circuit 14 indicates "no sound generation," whereas if the maximum level is equal to or greater than the predetermined value, the sound detection circuit 14 generates a sound detection signal SDS indicating "no sound generation" and supplies this to the control unit 15.

[0023] When the maximum level mentioned above transitions from a state where it is less than a predetermined value to a state where it is equal to or greater than the predetermined value, if the maximum level does not fall below the predetermined value even after a predetermined period of time has elapsed since the transition, the sound detection circuit 14 stops sending the sound detection signal SDS indicating that "sound is being generated."

[0024] The control unit 15 controls the operation of the phase compensation circuit 12 by executing a phase compensation control process in accordance with a program stored in a memory built into the control unit 15 itself.

[0025] FIG. 2 is a flowchart showing the procedure of the phase compensation control process.

[0026] In FIG. 2, first, the control unit 15 receives the sound detection signal SDS (step S11), and determines whether the sound detection signal SDS indicates "sound generation" (step S12).

[0027] In step S12, if it is determined that the sound detection signal SDS does not indicate "sound is present," that is, if sound is not occurring in the capacitor mounted on the substrate 10, the control unit 15 returns to step S11 and performs the series of operations from step S11 to S13 described above again.

[0028] During this time, if it is determined in step S12 that the sound detection signal SDS indicates "sound generation," the control unit 15 sends a response characteristics adjustment signal Rcs to the phase compensation circuit 12 to instruct the selector SEL to switch the RC circuit currently selected to an RC circuit having a phase compensation response speed that is one step faster than the RC circuit currently selected (step S13). By executing step S13, the selector SEL of the phase compensation circuit 12 switches the currently selected RC circuit out of the RC circuits U1 to U3 to another RC circuit having a phase compensation response speed that is one step faster than the RC circuit currently selected.

[0029] Next, the control unit 15 receives the sound detection signal SDS (step S14), and determines whether the sound detection signal SDS indicates "sound generation" (step S15).

[0030] In step S15, if it is determined that the sound detection signal SDS indicates "sound generation", that is, if the sound generation has not stopped, the control unit 15 returns to step S13 and performs the series of operations from step S13 to S15 described above.

[0031] Meanwhile, if it is determined in step S15 that the sound detection signal SDS does not indicate "sound generation," the control unit 15 executes the following step S16. That is, in step S16, the control unit 15 sends a response characteristics adjustment signal Rcs to the phase compensation circuit 12 to instruct it to switch the RC circuit currently selected by the selector SEL to an RC circuit whose phase compensation response speed is one step slower than that of the RC circuit (step S16). By executing step S16, the selector SEL of the phase compensation circuit 12 switches the currently selected RC circuit out of the RC circuits U1 to U3 to another RC circuit whose phase compensation response speed is one step slower than that of the RC circuit currently selected.

[0032] After executing step S16, the control unit 15 returns to step S11 and performs the series of operations from steps S11 to S16 again.

[0033] The operation of the power supply device 100 having the above configuration will be described below.

[0034] First, the power supply device 100 determines whether or not audible noise of a predetermined level or greater is occurring due to capacitor vibration, based on the sound signal picked up by the microphone 13 (S12). If it determines that audible noise is occurring, it increases the phase compensation response speed of the phase compensation circuit 12 by one level (S13). This reduces the voltage fluctuation of the output voltage VDD, thereby reducing the capacitor vibration due to the voltage fluctuation and reducing the level of the audible noise. Therefore, the power supply device 100 again determines whether or not audible noise of a predetermined level or greater is occurring in this state (S15). If it determines that audible noise is occurring, that is, if the audible noise does not stop even after increasing the phase compensation response speed of the phase compensation circuit 12, the power supply device 100 further increases the phase compensation response speed of the phase compensation circuit 12 (S13). This further reduces the voltage fluctuation of the output voltage VDD, further reducing the capacitor vibration due to the voltage fluctuation and reducing the level of the audible noise. Therefore, in this state, the power supply device 100 determines whether or not a sound of a predetermined volume or greater is occurring (S15).

[0035] If it is determined that no audible noise is occurring, the power supply device 100 reduces the response speed of the phase compensation of the phase compensation circuit 12 by one step (S16). As a result, the response speed of the phase compensation of the phase compensation circuit 12 decreases, but the phase margin increases accordingly, improving stability. Note that reducing the response speed of the phase compensation of the phase compensation circuit 12 in this manner may cause audible noise to occur again. Therefore, the power supply device 100 continues to determine whether audible noise is occurring (S12, S13), and if it determines that audible noise is occurring, it again increases the response speed of the phase compensation of the phase compensation circuit 12 (S13).

[0036] By repeating this series of steps (S16, S11 to S15), a state in which audible noise occurs but there is a phase margin and a state in which no audible noise occurs are alternately repeated, thereby reducing the audible loudness of the audible noise.

[0037] In this way, in the power supply device 100, when audible noise caused by vibration of the capacitor is detected from the sound signal AS picked up by the microphone 13, the audible noise is suppressed by adjusting the response speed of the phase compensation of the phase compensation circuit 12.

[0038] In the embodiment shown in FIG. 1, the response speed of the phase compensation circuit 12 is controlled by three RC circuits (U1 to U Although the phase compensation circuit 12 is configured to be adjustable in three stages by the resistor 3), the number of RC circuits may be two, four, or more. That is, n (n is an integer equal to or greater than two) RC circuits are provided in the phase compensation circuit 12, so that the response speed of the phase compensation of this phase compensation circuit 12 can be adjusted in n stages. Alternatively, the number of RC circuits in the phase compensation circuit 12 may be one, and the response speed of the phase compensation of the phase compensation circuit 12 may be adjusted by changing the resistance value of this RC circuit.

[0039] In addition, in the embodiment shown in FIG. 1, the sound detection circuit 14 determines whether or not a sound is being generated based on the picked-up sound signal AS, but such determination may be included in the phase compensation control processing shown in FIG. 2 and may be performed by software processing in the control unit 15.

[0040] 2, if it is determined in step S15 that no acoustic noise is occurring, step S16 is executed to reduce the response speed of the phase compensation of the phase compensation circuit 12 by one stage, but step S16 may be omitted. That is, if it is determined in step S15 that no acoustic noise is occurring, the control unit 15 returns to step S11 and repeatedly executes the series of processes from step S11 to S15.

[0041] In short, the power supply device 100 may include a voltage generation circuit (11) that generates a DC voltage and outputs it as an output voltage (VDD), a phase compensation circuit (12) that performs phase compensation of the output voltage, a microphone (13) that collects ambient sounds and generates a sound pickup signal (AS), and a control unit (15) that adjusts the response speed of the phase compensation of the phase compensation circuit based on the sound pickup signal. [Explanation of symbols]

[0042] 10 Substrate 11 Regulator 12 Phase compensation circuit 13. Mike 14 Sound detection circuit 15 Control Unit 100 Power supply

Claims

1. a voltage generating circuit that generates a DC voltage and outputs it as an output voltage to an output node; a phase compensation circuit for performing phase compensation for the output voltage; A microphone that picks up surrounding sounds and generates a pickup signal; a control unit that adjusts a response speed of the phase compensation of the phase compensation circuit based on the picked-up sound signal.

2. The power supply device according to claim 1, wherein the control unit adjusts the phase compensation circuit to increase the response speed of phase compensation of the phase compensation circuit when the level of a predetermined frequency band in the picked-up signal is equal to or greater than a predetermined value.

3. 3. The power supply device according to claim 2, wherein, after making an adjustment to increase the response speed of phase compensation of the phase compensation circuit, the control unit subsequently determines whether the level of the predetermined frequency band in the picked-up signal is equal to or greater than the predetermined value, and if it is determined in the determination that the level of the predetermined frequency band in the picked-up signal is equal to or greater than the predetermined value, makes an adjustment to increase the response speed of phase compensation of the phase compensation circuit by another step, whereas if it is determined that the level of the predetermined frequency band in the picked-up signal is not equal to or greater than the predetermined value, makes an adjustment to decrease the response speed of phase compensation of the phase compensation circuit by one step.

4. a ceramic capacitor for noise removal connected to the output node; 3. The power supply device according to claim 2, wherein the predetermined frequency band is a band including a frequency of audible noise caused by vibration of the ceramic capacitor due to fluctuations in the output voltage.

5. The power supply device according to any one of claims 1 to 4, characterized in that the voltage generating circuit is a regulator that includes an output terminal and a feedback terminal, and generates the output voltage having a voltage value corresponding to the reference voltage by sending from the output terminal to the output node a current corresponding to the difference between a feedback voltage received at the feedback terminal and a predetermined reference voltage.

6. a resistor voltage divider circuit that divides the output voltage to generate the feedback voltage and supplies the feedback voltage to the feedback terminal of the regulator; The phase compensation circuit first to n-th RC circuits each having a different response characteristic; a selector that selects one RC circuit from the first to n-th RC circuits in response to a response characteristic adjustment signal supplied from the control unit, and connects the selected one RC circuit between the feedback terminal and the output node of the regulator.

7. 5. The power supply device according to claim 4, further comprising a substrate on which the voltage generating circuit, the phase compensation circuit, the microphone, the control unit, and the ceramic capacitor are mounted.

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