On Fri, 5 Dec 1997, stephen mcalonan wrote:

> 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
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