ADC0851 Datasheet | National Semiconductor

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 parison time g 8 Bits LSB or g 1 LSB 50 m W 18 ms Channel 2 ms Limit Features Y Y Y Y Y Watchdog operation signals processor when any channel is outside user programmed window limits Frees microprocessor from continually monitoring analog signals and simplifies applications software 2 (ADC0851) or 8 (ADC0858) analog input channels Single ended or differential input pairs input for DC offsetting of input voltage 4 (ADC0851) and 16 (ADC0858) 8-bit programmable limits NSC MICROWIRETM interface Power fail detection Auto A D conversion feature Single 5V supply Window limits are user programmable via serial interface Applications Instrumentation...