I want to power some DS1821 temp units from a microprocessor circuit. They could be on leads as long as 12 feet.

My processor does a lot of ADC work, so I want things to be as quite as possible during the ADC readings.

Since the DS1821 can be powered by 3 volts, I am currently powering them from an I/O pin, but I could power them from the 5 volt circuit supply. One advantage of I/O pin power is I can turn them off when not needed, or if not getting correct info from them, saving battery power.

What power scheme would be the less likely to cause noise within the processor, I/O power or supply power?
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist