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Off-Line Power Supply Control Using a Single Transformer to Back Three Control Signals

IP.com Disclosure Number: IPCOM000099241D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 3 page(s) / 125K

Publishing Venue

IBM

Related People

Christensen, JJ: AUTHOR [+4]

Abstract

Disclosed is a circuit that provides for the of an off-line power supply. It uses a single transformer to transfer three separate control from the secondary side to the primary side of the supply. While it is common to use interface or optocouplers in the feedback loop of a power to maintain output voltage regulation, if additional such as fault (overvoltage, undervoltage) or synchronization is needed, multiple devices required. This increases the cost of the power supply well as PC board area. With this circuit, a single pulse is made to transfer regulation, fault protection synchronization data.

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Off-Line Power Supply Control Using a Single Transformer to Back Three Control Signals

       Disclosed is a circuit that provides for the of an
off-line power supply.  It uses a single transformer to transfer
three separate control from the secondary side to the primary side of
the supply.  While it is common to use interface or optocouplers in
the feedback loop of a power to maintain output voltage regulation,
if additional such as fault (overvoltage, undervoltage) or
synchronization is needed, multiple devices required.  This increases
the cost of the power supply well as PC board area.  With this
circuit, a single pulse is made to transfer regulation, fault
protection synchronization data.

      This circuit is designed to operate in conjunction with shelf
control modules (i.e., 5562, 3524, 3842, that will operate the
primary side of a power supply.  As shown in the the secondary side
is composed of three circuit  a oscillator, a fault detector and an
error

      The oscillator applies pulses of bias voltage, Vcc, to side of
the interface transformer T1.  The other side of is driven by the
error amp output through a buffer.  The amp adjusts its output to try
to hold the output Vo, to the reference voltage, Vref.  If Vo is than
Vref, the error amp output decreases which, in increases the voltage
of the pulses across T1. if Vo is less that Vref, the error amp
decreases voltage across T1.

      The oscillator has a sync input which forces alignment the Vcc
pulses to an incoming pulse train.  The natural of the oscillator
must be less that the lowest of the sync input because the oscillator
only has to increase its frequency, not decrease it.

      The overvoltage/undervoltage (OV/UV) circuit detects Vo is
outside the acceptable limits and drives Q2.  This will inhibit the
Vcc pulses from being to T1.

      On the primary side, three circuit blocks decode the present on
the windings of T1.  One circuit the peak (or the average) of the
output pulses and this signal to the primary IC error amp.  If a peak
(instead of an averager) is used, a bleed resistor be chosen to allow
this voltage to compensate for input transients and load transients.
The primary IC amp is configured to have a small fixed gain and a
that is greater that the overall power supply but less that the T1
pulse train frequency.  That it must be fast enough not to interfere
with the overall loop compensa...