Browse Prior Art Database

Supplementary Power Circuit in a Multiple Power Supply System

IP.com Disclosure Number: IPCOM000117966D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Narita, I: AUTHOR [+2]

Abstract

Disclosed is a supplementary power circuit fort with a multiple power supply system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 81% of the total text.

Supplementary Power Circuit in a Multiple Power Supply System

      Disclosed is a supplementary power circuit fort with a multiple
power supply system.

      In a multiple power supply system, a start-up timing of each
Direct Current/Direct Current (DC/DC) converter is not the same, so
that there is a time difference between each output voltage.  Such a
difference might cause some problems or bring electrical stress to
devices in a power supplied system.  With the present supplementary
power circuit, each output voltage appears at the same time even if
the DC/DC converter's start-up timing is different.

      The Figure shows the multiple power supply system having the
present supplementary power circuit.  The system is composed of a
Micro Processing Unit (MPU), 3.3V DC/DC converter, 2.5V DC/DC
converter and the supplementary power circuit.  At the power-ON time,
the 2.5V DC/DC converter outputs Vcc2 after the 3.3V DC/DC converter
outputs Vcc1, because the input of the 2.5V DC/DC converter is the
output of the 3.3V DC/DC converter.  But, at the time, 2.5V (Vcc2) is
supplied by the supplementary circuit.  The operation is as follows:
When the 3.3V DC/DC converter starts up, Vcc2 is supplied through Q1
and D1 because Q2 becomes ON at the time.  After the predetermined
time by C1 and R3, Q3 becomes OFF and Q1 becomes OFF.  This
predetermined time is defined longer than the start-up delay time of
the 2.5V DC/DC converter.  After the predetermined time, V...