>> Hello everyone!
>> I am using the 5 channel A/D on the PIC16C73A running at 5V.  I am
using
>> an external voltage reference of 2.5V on pin RA3/AN3/Vref.  My
question
>> is: Should I use a zener diode, etc. to protect the port from
voltages
>> from 2.5V to Vdd+.6 or will this just give me a full scale reading?
Are
>> there any other thought on protecting A/D inputs?  Thanks in advance.
>> Steve McAlonan
> I'm sorry, but all I can add to this one is more questions.  I am
using
>the '72 part with 5 channel A/D's also.  I have the Vref from Vdd
(+5V).
>I seem to have problems if I don't tie the unused channels to ground.
I
>remember CMOS parts needing unused inputs tied to Vcc or Vdd.  Is this
>true for ALL pins on the PIC (I believe I can clear unused I/O pins to
>outputs, and forget about making sure they are grounded)?
>
>Thank you,               6500
>                              7000
>Dave Celsnak                    ___7500

Dave,

Setting all unused pins on your '72 to outputs prevents harmful
oscillations on those pins.  Besides increasing power consumption that
may be affecting your A/D readings.

-Steve

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