US-20260128667-A1 - POWER SUPPLY SEMICONDUCTOR DEVICE AND POWER SUPPLY APPARATUS

US20260128667A1US 20260128667 A1US20260128667 A1US 20260128667A1US-20260128667-A1

Abstract

A full-rectified voltage of an alternating-current is generated on a target wiring, and another rectification voltage is fed to a first input terminal. A second input terminal is connected to the target wiring. A main capacitor is provided between a potential control terminal and the target wiring. A first switching element is provided between the potential control terminal and the ground. In the supply period of the alternating-current voltage, the first switching element is turned on and off based on the voltages at the first input terminal and the potential control terminal. When power failure is sensed, an interphase capacitor is discharged via the first input terminal and a second switching element and then the main capacitor is discharged via the first and second switching elements.

Inventors

Natsuki Yamamoto
Satoru Nate

Assignees

ROHM CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20251219
Priority Date: 20220707

Claims (11)

1 . A power supply semiconductor device used in a power supply apparatus, comprising: a first input terminal; a second input terminal; a potential control terminal; a first switching element provided between the potential control terminal and a ground; a power failure sense circuit configured to sense a power failure; a second switching element configured to open and close a first discharging path and a second discharging path to the ground; and a control circuit configured to control the first and second switching elements, wherein the first discharging path includes the first input terminal and the second switching element, wherein the second discharging path includes the second input terminal and the second switching element, and wherein the control circuit is configured to, in response to the power failure being sensed by the power failure sense circuit: execute a first discharge operation by controlling the first switching element to an off state and controlling the second switching element to an on state, and thereafter, execute a second discharge operation by controlling the first switching element to an on state and controlling the second switching element to an on state.
2 . The power supply semiconductor device according to claim 1 , wherein the control circuit is further configured to, during a power supply period when the power failure is not sensed, turn on and off the first switching element based on a voltage at the first input terminal and a voltage at the potential control terminal.
3 . The power supply semiconductor device according to claim 1 , wherein the control circuit is further configured to start the first discharge operation after a predetermined wait time passes since the power failure sense circuit sensed the power failure.
4 . The power supply semiconductor device according to claim 3 , wherein the predetermined wait time is a first wait time, and the control circuit is further configured to start the second discharge operation after a predetermined second wait time, which is longer than the first wait time, passes since the power failure sense circuit sensed the power failure.
5 . The power supply semiconductor device according to claim 3 , wherein the control circuit is further configured to end the first discharge operation after a predetermined discharge time passes since starting the first discharge operation.
6 . The power supply semiconductor device according to claim 3 , wherein the control circuit is further configured to end the first discharge operation in response to a divided value of a voltage at the first input terminal becoming lower than a predetermined reference value after starting the first discharge operation.
7 . The power supply semiconductor device according to claim 1 , wherein the control circuit is further configured to end the second discharge operation when a voltage at the second input terminal becomes equal to or lower than a predetermined lower limit voltage after starting the second discharge operation.
8 . The power supply semiconductor device according to claim 1 , further comprising: a first normally-on transistor provided on the first discharging path between the first input terminal and the second switching element, wherein the first normally-on transistor is configured to limit a current during the first discharge operation.
9 . The power supply semiconductor device according to claim 8 , further comprising: a second normally-on transistor provided on the second discharging path between the second input terminal and the second switching element; and a third switching element connected in series with the second normally-on transistor.
10 . The power supply semiconductor device according to claim 9 , wherein the control circuit is further configured to control the third switching element to an off state during the first discharge operation and to an on state during the second discharge operation.
11 . A power supply apparatus comprising: a diode bridge; a full-wave rectifier circuit; an interphase capacitor; a main capacitor; a power supply semiconductor device; and a power conversion circuit configured to convert a terminal-to-terminal voltage across the main capacitor into another voltage, wherein the power supply semiconductor device comprises: a first input terminal connected to the full-wave rectifier circuit; a second input terminal connected to the diode bridge; a potential control terminal connected to the main capacitor; a first switching element provided between the potential control terminal and a ground; a power failure sense circuit configured to sense a power failure; a second switching element configured to open and close a first discharging path and a second discharging path to the ground; and a control circuit configured to control the first and second switching elements, wherein the first discharging path includes the first input terminal and the second switching element, wherein the second discharging path includes the second input terminal and the second switching element, and wherein the control circuit is configured to, in response to the power failure being sensed by the power failure sense circuit: execute a first discharge operation by controlling the first switching element to an off state and controlling the second switching element to an on state, and thereafter, execute a second discharge operation by controlling the first switching element to an on state and controlling the second switching element to an on state.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. Patent Application No. 18/347,944, filed July 6, 2023, which claims priority under 35 U.S.C. §119(a) on Patent Application No. 2022-109553 filed in Japan on July 7, 2022, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE DISCLOSURE Field of the Invention The present disclosure relates to a power supply semiconductor device and to a power supply apparatus. Description of Related Art A power supply apparatus that can generate from an alternating-current voltage a direct-current voltage often includes an interphase capacitor and a main capacitor. The interphase capacitor is often called an X capacitor. The interphase capacitor is connected to a pair of input terminals that receives the alternating-current voltage. The main capacitor is connected to a wiring fed with a full-rectified voltage of the alternating-current voltage. Patent Document 1: Japanese Patent Application published as No. 2015-177687 When the supply of the alternating-current voltage to the power supply apparatus is cut off, from the perspective of ensuring safety and the like, the interphase capacitor and the main capacitor should be discharged. However, it is challenging in many aspects to work out a technique of discharging both the interphase capacitor and the main capacitor; thus, expectations are high for the development of a practical discharge technique. SUMMARY OF THE DISCLOSURE The present disclosure is aimed at providing a power supply semiconductor device and a power supply apparatus that, on occurrence of power failure, can discharge an interphase capacitor and a main capacitor (in particular, for example, achieve that with a simple configuration). According to one aspect of the present disclosure, a power supply semiconductor device is used in a power supply apparatus that feeds to a diode bridge an alternating-current voltage applied to a pair of input terminals to generate a full-rectified voltage on a target wiring. The power supply semiconductor device includes: a first input terminal configured to receive a rectification voltage obtained by feeding the alternating-current voltage applied to the pair of input terminals to a full-wave rectifier circuit different from the diode bridge; a second input terminal configured to be connected to the target wiring; a potential control terminal configured to be connected to the target wiring through a main capacitor; a first switching element provided between the potential control terminal and the ground; a power failure sense circuit configured to sense, based on the voltage at the first input terminal; power failure in which the supply of the alternating-current voltage to the pair of input terminals is cut off; a second switching element configured to, when power failure is sensed, pass to the ground a current for discharging an interphase capacitor provided between the pair of input terminals and a current for discharging the main capacitor; and a control circuit configured to control the first and second switching elements. The control circuit, in the supply period of the alternating-current voltage to the pair of input terminals, turns on and off the first switching element based on the voltage at the first input terminal and the voltage at the potential control terminal. The control circuit, when power failure is sensed, performs first discharge operation and then second discharge operation. In the first discharge operation, the first switching element is kept off and the second switching element is kept on so that the interphase capacitor is discharged through a first discharging path that runs across the full-wave rectifier circuit, the first input terminal, and the second switching element. The first discharging path includes the ground. In the second discharge operation, the first and second switching elements are kept on so that the main capacitor is discharged through a second discharging path that runs across the first switching element, the second input terminal, and the second switching element. The second discharging path includes the ground. According to the present disclosure, it is possible to provide a power supply semiconductor device and a power supply apparatus that, on occurrence of power failure, can discharge an interphase capacitor and a main capacitor (in particular, achieve that with a simple configuration). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a power supply apparatus according to an embodiment of the present disclosure. FIG. 2 is a configuration diagram of a power failure sense circuit according to the embodiment of the present disclosure. FIG. 3 is a diagram illustrating the operation of the power failure sense circuit according to the embodiment of the present disclosure. FIG. 4 is a diagram showing voltages, signal waveforms, and the like at relevant points in the power supply apparatus according to the