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Coulomb Programmable Supply

IP.com Disclosure Number: IPCOM000090653D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Sabatterie, RA: AUTHOR

Abstract

The coulomb programmable supply PCS system is used to set up a multiplicity of analog signals and provides programmable power supplies when a large number of such supplies are required and are to be programmed in a short period of time. The system tolerates circuits which are nominal, +10%, in comparison with those which are required otherwise, +0.1%. The CPS system tolerates these inaccuracies because the output is fed back and compared with the input. By keeping the overall gain of the system high, the voltage developed at the output is equal to the input.

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Coulomb Programmable Supply

The coulomb programmable supply PCS system is used to set up a multiplicity of analog signals and provides programmable power supplies when a large number of such supplies are required and are to be programmed in a short period of time. The system tolerates circuits which are nominal, +10%, in comparison with those which are required otherwise, +0.1%. The CPS system tolerates these inaccuracies because the output is fed back and compared with the input. By keeping the overall gain of the system high, the voltage developed at the output is equal to the input.

In drawing 1, one digital-to-analog converter DAC is used to set up many analog reference levels. DAC, which can use a summing network, establishes an accurate and stable reference voltage which is applied to an operational amplifier. The output of the operational amplifier is multiplexed to one of several CPS circuits. The outputs of the CPS circuits are multiplexed back to the amplifier input. The output function of this reference source depends on the amount of electrical charge added to or removed from the CPS circuit during setup. In operation, the multiplexers associated with a selected CPS circuit are closed. The CPS circuit output assumes a voltage equivalent to the DAC output voltage. Either scaling or inversion or both can be altered by a suitable input arrangement on the differential amplifier. Following set up, the A1 multiplexer switch is opened and then switch B1 is opened. Due to the very high input impedance of the CPS circuit, capacitor C1 discharges very slowly. The output voltage V1 is maintained as long as C1 can retain its charge.

In drawing 2, voltages VA1 and VA2 are the actual analog levels provided by the CPS circuits. However, during setup, the feedback. to the coulomb source is the output of the driver rather than the actual CPS circuit output. The circuit is used to control a driver which provides an output level 1 or 0 through 50 ohm impedance R1. The voltage of each 1 and 0 level ca...