I need to replace a 5k mechanical potentiometer with a digital one. The hang up is that it will have a maximum of 14V across it. That's too high for most digital pots on the market. The max current should be less than 10mA, so that's not an issue.
These are the main three parts I've narrowed it down to:
- AD7376 - 128 positions, volatile, 10k, 28V range, TSSOP $2.86
- AD5290 - 256 positions, volatile, 10k, 30V range, MSOP $1.92
- AD5292 - 1024 positions, non-volatile, 20k, 33V range, TSSOP $2.62
I think it would be helpful to have it be non-volatile, but it seems like it would be able to initialize to the correct value pretty quickly after initialization, so I don't know if that's too important.
My main question is related to the size. The 7376 has 10k/128 = 78 ohms/tick precision. The 5290 is slightly better at 39 ohms/tick. Finally, the 5292 has 19 ohms/tick.
I'd like to have it be as smooth as possible, so it seems like the 1024 position one would be a good choice. Is there any disadvantage I'm missing with going with a 20k pot when I'm only ever going to use it from 0 to 5k?