Switching-power supply unit for reducing power consumption in a stand-by-mode

• US 6,549,429 B2
• Filed: 01/31/2001
• Issued: 04/15/2003
• Est. Priority Date: 01/31/2000
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Konno, Akira
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US09/774,898
• Publication Number:
  US 20010010638A1
• Time in Patent Office: 804 Days
• Field of Search: 363/20, 363/21.01, 363/21.04, 363/21.05, 363/21.09, 363/97
• US Class Current: 363/21.04
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

In a normal operation mode, a mode changeover controller 8 continuously operates a PWM control circuit 6 so as to operate a switching element 5 at the basic oscillation frequency. In a standby mode, the mode changeover controller 8 intermittently operates the PWM control circuit 6 so as to turn on the switching element 5 at a given repetition interval and for a given time period. This repetition interval is shorter than a time for decreasing an output voltage from a rectifying and smoothing circuit 20 down to a guaranteed load operating voltage due to power consumption of the load and the rectifying and smoothing circuit 20 in the standby mode and is longer than a time for entering a sonic frequency band. That time period is longer than a time for stabilizing an output from the rectifying and smoothing circuit 20 and is longer than a time for entering a sonic frequency band.

Claims

1. A pulse-width modulation switching power-supply unit having a rectifier circuit for converting an alternating current from an alternating power supply to a direct current, a switching element for switching a current rectified by this rectifier circuit, and a primary coil for supplying a current to be switched by this switching element, said switching power-supply unit further comprising:

a transformer having a secondary coil for inducing power corresponding to current supplied to this primary coil;

DC output means for rectifying and smoothing a power induced at this transformer'"'"'s secondary coil to output direct current power;

voltage control means for generating an error voltage based on a comparison between said direct current power output from said DC output means and a reference voltage;

pulse-width modulation controller for controlling a switching operation of said switching element according to said error voltage; and

control means for controlling operations of said pulse-width modulation controller,

wherein said control means, in a normal operation mode, continuously operates said pulse-width modulation controller so as to operate said switching element at a basic oscillation frequency, wherein said control means, in a standby mode, intermittently operates said pulse-width modulation controller so as to turn on said switching element at a given repetition interval and for a given time period, wherein that repetition interval is shorter than a time for decreasing an output voltage from said DC output means down to a guaranteed load operating voltage due to power consumption of the load and said DC output means in the standby mode and is longer than a time for entering a sonic frequency band, and wherein that time period is longer than a time for stabilizing an output from said DC output means and is longer than a time for entering a sonic frequency band, and wherein said control means further comprises a microcontroller and uses program software to variably set a control time such as a repetition interval in said standby mode using a watchdog timer and to supply a wakeup signal to a starter circuit of the pulse-width modulation controller at the repetition interval so as to stabilize a secondary output voltage.

2. The pulse-width modulation switching power-supply unit according to claim 1, wherein the voltage control means detects when a load current drops below a specified value, and wherein said control means performs a control operation for a standby mode when said current detection means detects a load current below a specified value for a specified period in a normal operation mode.