For a reference, there's always the lm399h (http://www.national.com/opf/LM/LM399.html#Overview). I first used it more than 30 years ago. I always thought they should put a voltage divider inside the chip to give different precision voltages or at least low tempco. Harold --=20 FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .