Thanks, Bob - There's a TI app note on ADC terminology; Google promptly turned up some good Linear Tech app notes, once I knew what to ask for; in this case, "ADC + differential bipolar inputs" ... TI data sheets are a bit terse, for this amateur... :) thanks again, Jack --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .