US4888548A — Programmatically generated in-circuit test of dig…

Claim 1

Independent Claim 138 words

A module for programmatic testing of a digital to analog converter that is connected to components in a circuit comprising: direct current voltage generator means remote from the circuit for generating a precision direct current signal; analog overdriving amplifier means for amplifying said precision direct current voltage signal to isolate said digital to analog converter from upstream analog components; overdriving digital driver means for stimulating clock and data input ports of said digital to analog converter to isolate and stimulate said digital to analog converter; measuring op-amp means with a direct current detector means for measuring an output current from said digital to analog converter; guard connection means for disabling all downstream circuitry for isolation of said digital to analog converter from said downstream circuitry during testing; comparator means for comparing said output measurements with an expected response.

Claim 2

Dependent Claim 138 words

A module for programmatic testing of a digital to analog converter that is connected to components in a circuit comprising: direct current voltage generator means remote from the circuit for generating a precision direct current signal; analog overdriving amplifier means for amplifying said precision direct current voltage signal to isolate said digital to analog converter from upstream analog components; overdriving digital driver means for stimulating clock and data input ports of said digital to analog converter to isolate and stimulate said digital to analog converter; measuring op-amp means with a direct current detector means for measuring an output current from said digital to analog converter; guard connection means for disabling all downstream circuitry for isolation of said digital to analog converter from said downstream circuitry during testing; comparator means for comparing said output measurements with an expected response.

Claim 3

Dependent Claim 33 words

The module of claim 1 wherein said direct current voltage generator means comprises: means for generating a range of ±10.0 volts at a minimum resolution of 3.0 mV and an accuracy of ±0.1%.

Claim 4

Dependent Claim 29 words

The module of claim 1 wherein said analog overdriving amplifier means comprises: means for generating a minimum output current of 150 mA with maximum output impedance of 3.0 ohms.

Claim 5

Dependent Claim 35 words

The module of claim 1 wherein said overdriving digital driver means comprises: means for generating a range of -3.5 to 5.0 volts at a minimum resolution of 5.0 mV, and current capability of ±500 mA.

Claim 6

Dependent Claim 40 words

The module of claim 1 wherein said measurement operational amplifier means comprises: means for generating an output voltage range of ±10.0 volts, with a minimum output current of ±150 MA, and with an output resistance of less than 3.0 ohms.

Claim 7

Dependent Claim 139 words

A process for programmatically performing in-circuit pin checks and gross functionality tests of a digital to analog converter which is a component in a circuit, comprising the steps of: providing a test module having a precision DC source means for providing a desired reference signal; connecting the test module to the circuit; isolating the digital to analog converter under test from surrounding circuitry; applying the reference signal to a reference input of said digital to analog converter and an appropriate bit pattern to digital data inputs of said digital to analog converter; measuring an output current of said digital to analog converter under test; comparing said output current to an expected response for said digital to analog converter; evaluating the digital to analog converter performance using deterministic and non-deterministic bit evaluation techniques for testing high and low order bits.

Claim 8

Dependent Claim 139 words

A process for programmatically performing in-circuit pin checks and gross functionality tests of a digital to analog converter which is a component in a circuit, comprising the steps of: providing a test module having a precision DC source means for providing a desired reference signal; connecting the test module to the circuit; isolating the digital to analog converter under test from surrounding circuitry; applying the reference signal to a reference input of said digital to analog converter and an appropriate bit pattern to digital data inputs of said digital to analog converter; measuring an output current of said digital to analog converter under test; comparing said output current to an expected response for said digital to analog converter; evaluating the digital to analog converter performance using deterministic and non-deterministic bit evaluation techniques for testing high and low order bits.

Claim 9

Dependent Claim 87 words

The process of claim 6, further comprising the steps of: connecting the precision DC source means through a remote sensed analog overdriving amplifier to a reference input of said digital to analog converter; connecting overdriving digital drivers to data input ports and clock input port of said digital to analog converter; connecting a measuring operating amplifier and a DC detector to a current output port of said digital to analog converter under test; connecting a guard line to disable circuitry downstream of said digital to analog converter.

Claim 10

Dependent Claim 107 words

The process of claim 6, wherein said deterministic bit evaluation for high order bits of said digital to analog converter further comprises the steps of: applying said appropriate bit pattern to said digital data inputs and clock inputs of said digital to analog converter under test; waiting for conversion delay and settling of transients in said circuit; measuring said output current of said digital to analog converter under test using said measuring operating amplifier and precision DC detector to produce a measured result; evaluating said measured results against an expected response for said bit configuration; repeating said preceding steps to test each given high order bit configuration.

Claim 11

Dependent Claim 128 words

The process of claim 6, wherein said nondeterministic evaluation of low order bits of said digital to analog converter further comprises the steps of: applying said appropriate bit pattern to said digital data inputs and clock input of said digital to analog converter; waiting for conversion delay and settling of transients in said circuit under test; measuring said current output of said digital to analog converter using said measuring operating amplifier and precision DC detector to produce a measured result; repeating said previous steps with a one bit change in said applied digital bit pattern a "1" to "0" or "0" to "1"; evaluating said measured results by calculating a difference between said two measured configurations; repeating said preceding steps to test each given low order bit configuration.

Claim 12

Dependent Claim 45 words

The module of claim 1 wherein the analog overdriving amplifier means applies a direct current voltage signal to a reference input of the digital to analog converter and includes a remote sense input for measuring the actual direct current signal applied to the reference input.

Claim 13

Dependent Claim 36 words

The module of claim 1 further comprising a computer interface for supplying digital data to the overdriving digital driver means, controlling the direct current voltage generator means and receiving data from the direct current detector means.

Claim 14

Dependent Claim 35 words

The module of claim 1 wherein the direct current voltage generator means operates under control of a computer to apply a desired voltage directly to a reference voltage input of the digital to analog converter.

Claim 15

Dependent Claim 33 words

The module of claim 1 wherein the measuring op amp includes a remote sense input for measuring an output of an I/V converter coupled to the output of the digital to analog converter.

Claim 16

Dependent Claim 85 words

The module of claim 1 wherein the analog overdriving amplifier means applies a direct current voltage signal to a reference input of the digital to analog converter and an I/V converter is coupled to an output of the digital to analog converter, further comprising a remote sense input on the analog overdriving amplifier means for measuring the actual direct current signal applied to the reference input and a remote sense input on the measuring op amp means for measuring an output of the I/V converter.

Claim 17

Dependent Claim 54 words

The module of claim 1 wherein an I/V converter is coupled to an output of the digital to analog converter and the guard means disables the I/V converter by holding an output thereof at ground potential, current from the output of the digital to analog converter being shunted to the measuring op amp means.

Claim 18

Dependent Claim 24 words

The module of claim 1 further comprising means for deterministically and non-deterministically testing high and low order bits of the digital to analog converter.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-12-18	1993-06-19	1993-12-19	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-12-18	1997-06-19	1997-12-19	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-12-18	2001-06-19	2001-12-19	$7700.00	Window Closed / Lapsed

Programmatically generated in-circuit test of digital to analog converters

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