John Pizzuto

Vref+ impedance on 9S12

Discussion created by John Pizzuto on May 11, 2007
Latest reply on May 11, 2007 by bigmac
In my application, I set Vref+ to 2.55v from the wiper of a 10k pot, resulting in 10mv per bit.

In my HC11 designs, I padded the pot with 3.6k resistors in each leg.

I changed these to 51k in my S12 based design, and find that Vref+ is being pulled by the chip to about 1.3v.

Things work normally again when I change back to 3.6k resistors, but of course Vref is harder to set. Will buffer it in the next revision.