I am working with the PIC16C710. I am using its A/D module in a design. It states in the databook that the minimium TAD time needs to be 1.6us. I am using a 20mhz crystal and the choices I have through ADCON0 are 2*TOSC, 8*TOSC and 32*TOSC. for a 20mhz crystal, TOSC = 50ns. So: IF TAD = 2*TOSC = 100ns (illegal TAD) TAD = 8*TOSC = 400ns (illegal TAD) TAD = 32*TOSC = 1.6ns (legal TAD) The funny thing is that the A/D was inaccurate if I set it to 32*TOSC, but was perfect with 8*TOSC which according to the data book is in voilation. 2*TOSC was inaccurate, but that certainly makes sense. Why would a slower clock give worse results, especially when the faster one was in violation!! I repeated this experiment with different oscillators and also tried it with a PIC16C77. Same thing!! Perhaps someone has run across the same anamoly and has some kind of explanation for it. I really should not complain, since the faster A/D conversion is nice. But since this design will be part of a product, I am concerned about pushing any spec, even though it works better in the lab. Thanks ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com