ADC0851

ADC0851 and ADC0858 8-Bit Analog Data Acquisition and Monitoring Systems January 1995 ADC0851 and ADC0858 8-Bit Analog Data Acquisition and Monitoring Systems General Description The ADC0851 and ADC0858 are 2 and 8 input analog data acquisition systems They can function as conventional multiple input A D converters automatic scanning A D converters or programmable analog ‘‘watchdog’’ systems In ‘‘watchdog’’ mode they monitor analog inputs and determine whether these inputs are inside or outside user programmed window limits This monitoring process takes place independent of the host processor When any input falls outside of its programmed window limits an interrupt is automatically generated which flags the processor the chip can then be interrogated as to exactly which channels crossed which limits The advantage of this approach is that its frees the processor from having to frequently monitor analog variables It can consequently save having to insert many A D subroutine calls throughout real time application code In control systems where many variables are continually being monitored this can significantly free up the processor especially if the variables are DC or slow varying signals The Auto A D conversion feature allows the device to scan through selected input channels performing an A D conversion on each channel without the need to select a new channel after each conversion Key Specifications Y Y Y Y Y Resolution Total error Low power Conversion time Limit compari...