They don't disappear....I had a discussion with a factory guy once about this, and he said that the input protection clamping diodes are not as robust for the analog inputs, and thus its easier to blow these ports than the digital ones. I had an issue where I was reading a value that was off by a certain amount on one chip, but was good on others and thats what he told me that it could be off across the port because the subsrate was partially punched thru. I had a divider wrong, where instead of 2.5V I was putting 3.5V on the input, and running the device at 3.3V Spehro Pefhany wrote:At 06:36 AM 11/1/2005 -0800, you wrote: >Well...from what I know...and been told by the factory....the analog >inputs do NOT have the clamping function, so driving in past the reference >can possible damage the input to the PIC. In fact....I've seen it.... Do you think the protection diodes (the one to Vss is a parasitic diode due to the isolation diffusion) somehow disappear when you change the relevant SFR to make a digital input analog? Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com ->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --------------------------------- Yahoo! FareChase - Search multiple travel sites in one click. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist