HIGH_SPEED_DATA_ACQUISITION_SYSTEM

Published:2009/6/30 23:17:00 Author:May | From:SeekIC

This diagram shows a high-speed data acquisition system with 8 differential inputs and 12-bit resolution using the AM-543. If the control logic is timed so that the Sample-Hold-ADC section is converting one analog value while the mux-amplifier section is al-lowed to settle to the next input value, throughout rates greater than 156 KHz can be achieved. The AM-543 is used with Datel's ADV-817, a 12-bit hybrid A/D with a 2 μSec conversion rate, the SHM-6, a 0.01%, 1 psec hybrid Sample-Hold, and the MX-1616,a low cost, high-speed monolithic analog multiplexer. The system works as follows:The μP selects a channel and initiates a conversion at G = 1 and then looks at the MSB of the conversion result. If the MSB = 1, the μP will store the value. If the MSB = 0, the μP will select G = 2. The μP will repeat the cycle of gain incrementing, comparison, and analog-to-digital conversion until the MSB = 1. The μP will then test for an output of all 1's, as this is the full-scale output of the A/D. If the output is all 1's, the μP will decrement the gain by 1 step and perform the final conversion.



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