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Method of Checking an Electronic Circuit Card's Low Ohm Resistor at a Manufacturing Functional Test

IP.com Disclosure Number: IPCOM000028138D
Original Publication Date: 2004-Apr-27
Included in the Prior Art Database: 2004-Apr-27
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Abstract

Method of checking an electronic circuit card's sense resistor's low resistance value at a manufacturing functional test

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Method of Checking an Electronic Circuit Card's Low Ohm Resistor at a Manufacturing Functional Test

Many electronic circuit cards have low resistance value resistors on them, as current sense resistors in on-card regulator circuits. The sense resistor has such a low resistance value that it is difficult to check the resistance value at a manufacturing test. Disclosed is a circuit that utilizes the electronics that already are on the card to provide load current through the sense resistor, in a manufacturing functional test.

     See the figure below for operation. The manufacturing functional test causes the on-card load through the sense resistor to be active. The voltage drop across the sense resistor is differentially sensed and amplified by the differential amplifier. The manufacturing connector provides a voltage reference (Vref), which is compared against the a voltage divided output of the differential amplifier. The amplifier used as a comparator gives a output, which can be processed digitally by the manufacturing functional tester as Pass or Fail (P/F).

     The test would run twice: once with a voltage reference to check that the sense resistor value is not lower than expected, and a second time with a different voltage reference to check that the sense resistor value is not higher than expected. Both runs giving output "Pass" means that the resistor value is within expected upper and lower value limits.

     Overall it's a simple circuit and a simple manufacturing i...