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How to select Vref?

Discussion in 'Microcontrollers, Programming and IoT' started by sid2286, Sep 24, 2012.

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  1. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    Hi,

    I'm using PIC18F4520 for my project. my input for ADC is 200mV to 1.2V.
    now i want to give vref to my microcontroller. It has to pin RA3/AN3/
    VREF+ and RA2/AN2/VREF-/CVREF pins.

    So how do i give Vref? should i apply 1.5v to only VREF+ and keep open VREF- or should i ground the Vref- pin??

    Please help.

    Rgds,
    Sid
     
  2. GreenGiant

    GreenGiant

    842
    6
    Feb 9, 2012
    it should be you only have to connect the 1.5 to the +Vref but connecting ground to the -Vref should not have any negative affects, this is drawing from experience with Arduino's NOT PIC's so I'm not 100% sure if they work the same
     
  3. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    In PICs you can separately specify whether Vref+ and Vref- are internal or external. You would leave the Vref- internal, which connects it to ground and frees that pin for other uses. Also check the datasheet for the minimum Vref. I think 1.5V is going to be too low.

    Bob
     
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