Semiconductor device for controlling power source

Patent metadata

Field	Value
Publication number	US-2018019656-A1
Application number	US-201615552653-A
Country	US
Kind code	A1
Filing date	Feb 17, 2016
Priority date	Feb 23, 2015
Publication date	Jan 18, 2018
Grant date	—

Abstract

A semiconductor device for power supply control includes an on/off control signal generation circuit which generates a control signal to turn on or off the switching element, a high-voltage input start terminal to which alternating-current voltage of AC input or voltage rectified in a diode bridge is input, a high-voltage input monitoring circuit connected to the high-voltage input start terminal and monitoring voltage of the high-voltage input start terminal, and a discharging unit connected between the high-voltage input start terminal and a ground point. When the high-voltage input monitoring circuit detects that a time for which the voltage of the high-voltage input start terminal is not lower than a predetermined voltage value for a predetermined period, the discharging unit is turned on.

First claim

1 . A semiconductor device for power supply control, that generates and outputs a driving pulse to turn on or off a switching element which intermittently supplies current to a primary-side winding wire of a transformer for voltage conversion, by inputting voltage in proportion to current flowing in the primary-side winding wire of the transformer and an output voltage detection signal from a secondary side of the transformer, the semiconductor device comprising:
an on/off control signal generation circuit which generates a control signal to turn on or off the switching element; a high-voltage input start terminal to which alternating-current voltage of AC input or voltage rectified in a diode bridge is input; a high-voltage input monitoring circuit which is connected to the high-voltage input start terminal and monitors voltage of the high-voltage input start terminal; and a discharging unit which is connected between the high-voltage input start terminal and a ground point, wherein when the high-voltage input monitoring circuit has detected that a time for which the voltage of the high-voltage input start terminal is not lower than a predetermined voltage value for a predetermined period, the discharging unit is turned on.

2 . The semiconductor device for power supply control according to claim 1 , further comprising:
a power supply terminal to which voltage induced by an auxiliary winding wire of the transformer is input; and a switching unit which is provided between the high-voltage input start terminal and the power supply terminal, wherein the discharging unit is connected in series with the switching unit between the high-voltage input start terminal and the ground point and when the high-voltage input monitoring circuit has detected that the time for which the voltage of the high-voltage input start terminal is not lower than the predetermined voltage value for a predetermined period, the switching unit and the discharging unit are turned on.

3 . The semiconductor device for power supply control according to claim 2 , further comprising a starting circuit which monitors the voltage of the high-voltage input start terminal and controls the switching unit, wherein the switching unit is controlled to be turned on or off in accordance with a value obtained by implementing an OR operation of an output of the high-voltage input monitoring circuit and an output of the starting circuit.

4 . The semiconductor device for power supply control according to claim 1 , the high-voltage input monitoring circuit comprising:
a voltage division circuit which is connected to the high-voltage input start terminal and divides the voltage of the high-voltage input start terminal; a peak holding circuit which holds a peak voltage of the voltage divided by the voltage division circuit; a voltage comparison circuit which compares the voltage divided by the voltage division circuit and a voltage obtained by proportionally reducing the voltage held in the peak holding circuit; and a timer circuit which measures a time for which the voltage divided by the voltage division circuit is not lower than the proportionally reduced voltage on the basis of an output of the voltage comparison circuit, wherein, when the timer circuit has measured a predetermined time that is determined in advance, the discharging unit, or the switching unit and the discharging unit are turned on.

5 . The semiconductor device for power supply control according to claim 2 , the high-voltage input monitoring circuit comprising:
a voltage division circuit which is connected to the high-voltage input start terminal and divides the voltage of the high-voltage input start terminal; a peak holding circuit which holds a peak voltage of the voltage divided by the voltage division circuit; a voltage comparison circuit which compares the voltage divided by the voltage division circuit and a voltage obtained by proportionally reducing the voltage held in the peak holding circuit; and a timer circuit which measures a time for which the voltage divided by the voltage division circuit is not lower than the proportionally reduced voltage on the basis of an output of the voltage comparison circuit, wherein, when the timer circuit has measured a predetermined time that is determined in advance, the discharging unit, or the switching unit and the discharging unit are turned on.

6 . The semiconductor device for power supply control according to claim 3 , the high-voltage input monitoring circuit comprising:
a voltage division circuit which is connected to the high-voltage input start terminal and divides the voltage of the high-voltage input start terminal; a peak holding circuit which holds a peak voltage of the voltage divided by the voltage division circuit; a voltage comparison circuit which compares the voltage divided by the voltage division circuit and a voltage obtained by proportionally reducing the voltage held in the peak holding circuit; and a timer circuit which measures a time for which the voltage divided by the voltage division circuit is not lower than the proportionally reduced voltage on the basis of an output of the voltage comparison circuit, wherein,
when the timer circuit has measured a predetermined time that is determined in advance, the discharging unit, or the switching unit and the discharging unit are turned on.

Assignees

• Mitsumi Electric Co Ltd

Inventors

• Matsuda Hiroki
• Murata Yukio

Classifications

• H02M1/08 Primary

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M3/33523

  with galvanic isolation between input and output of both the power stage and the feedback loop · CPC title

• H02M2001/0012

  Electricity · mapped topic

• G01R15/04

  Voltage dividers · CPC title