Question about AD conversion

Discussion in 'Embedded Systems and Microcontrollers' started by picpic, Feb 1, 2012.

  1. picpic

    Thread Starter New Member

    Apr 29, 2011
    Hi. When I use PIC18F I usually use a 10k pot when I want to read a pot value. But now I am using a dspic33f microcontroller and the input impedance is much smaller - 2.5kOhms is maximum recommended for PIC18F, but for the dspic the maximum is only 200ohms! (To minimize the effects of pin leakage currents, it says). I have 6 pots Id like to read, but don't want to consume too much current. Has anyone got any recommendations?

  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Well it seems you don't want to use six 200 ohm pots.

    Only other choice I can see is to keep the higher value pots and add an op amp to each as a unity gain buffer. A low bandwith CMOS type amp should work nice and take a lot less current. Microchip actually makes some of these, I used one in a commercial product with good success.