MODM7AE70 ADC VREF pin

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rdabney
Posts: 1
Joined: Thu Jun 06, 2024 5:56 am

MODM7AE70 ADC VREF pin

Post by rdabney »

I am updating a system from a MOD5234 to a MODM7AE70. These boards plug into a motherboard in a larger system, all of the pins are backwards compatible (most are just GPIO) except one. Pin P2:5 is a GPIO on the MOD5234 and used as ADC VREF on the MODM7AE70. In our design this is used for a selector knob: either pulled high (3.3V) or active low (GND).

To avoid having to update the motherboard I would like to simply jump P2:5 to a different unused GPIO pin. This would mean that the ADC VREF is being changed somewhat frequently. My question is would this cause any issues like frying the ADC or is there any sort of internal pull down resistor or is this pin driven internally somehow? We are not using the ADC on this project, so I don't care if the ADC doesn't work, just don't want any damage and want to make sure the signal can pass through untouched via that pin.

As far as I can tell it should work, but I am not confident about whether this pin can be driven or affected by something internal to the MODM7AE70.

Thanks
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pbreed
Posts: 1086
Joined: Thu Apr 24, 2008 3:58 pm

Re: MODM7AE70 ADC VREF pin

Post by pbreed »

Have not tried this.
I don't think your using the A/D so messing up Vref should be fine.
Looking at the data sheet I could find a minimum operational vvalue of 1.7V, but could not find anything on vref in the datasheet maximum table.

I think it should be fine.
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