Browse Prior Art Database

SERVI BRIDGE AMPLIFIER DIAGNOSTICS

IP.com Disclosure Number: IPCOM000025867D
Original Publication Date: 1988-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 57K

Publishing Venue

Xerox Disclosure Journal

Abstract

The high power switching transistors in a bridge amplifier operate at high stress and therefore have lower reliability than other electronic circuits. A simple technique is shown for verifying bridge operation by testing the function of each power transistor, with or without a load connected. It could be included in a PCBA (printed circuit board assembly) 'self test' that is executed every time the host machine is powered up.

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:EROX DISCLOSURE JOURNAL

SERVI BRIDGE AMPLIFIER DIAGNOSTICS
Lawrence P. Lavery

Proposed Classification US. C1.355/14R
Int. C1. G03g 15/00

+ SUPPLY VOLTAGE

LOAD

-

-SUPPLY VOLTAGE

I I

REFERENCE LOGIC

VOLTAGE SIGNAL

OUTPUT

The high power switching transistors in a bridge amplifier operate at high stress and therefore have lower reliability than other electronic circuits. A simple technique is shown for verifying bridge operation by testing the function of each power transistor, with or without a load connected. It could be included in a PCBA (printed circuit board assembly) 'self test' that is executed every time the host machine is powered up.

Most bridge switching amplifiers have the ability of being run in either 'Full Bridge' or 'Unipolar' modes. When operated in the 'Unipolar' mode, the control system has independent control over each switching transistor. The voltage across the load can be sensed by a voltage comparator while the amplifier transistors are switched through a sequence that logically tests for proper function.

With reference to the drawing, transistors A,B,C,D are bridge output switching transistors, R1 and R2 are enable test with no load connected, and R3 and R4 are a voltage divider.

Volume 13 Number 4 July/August 1988 215

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  XEROX DISCLOSURE JOURNAL Volume 13 Number 4 July/August 1988

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