>"Thomas C. Sefranek" wrote: > >> I also am using 10 K resistors to a 1 ufd cap on each analog input. > >10K is specified as the max input impedance for the A2D. Perhaps >lowering this value may improve your readings. The reason 10K is specc'd as maximum is because of the current that is drawn from the pin when the internal s/h cap is charged. Since there is a nice large cap right at the pin, the effective impedance seen by the s/h is essentially zero. I have gotten rated a/d specs with the same setup, except with a 220K resistor and 1 uF cap. Discussions with Mchip's FAE confirmed this. If you monitor the voltage at the pin with a scope (with a 10k series resistor), you will see a small dip when the s/h operates. Otherwise, the input behaves like a standard CMOS input (essentially no loading of the DC input). Like I said, having a large cap right at the pin allows the use of much higher series resistors. dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 15 years of Engineering Innovation (1984 - 1999) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. My posting messages to Usenet neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.