googling gives me too many options, but I don't know what I should choose. I am looking for a 1k digital potentiometer to drive with the PWM signal from the arduino. 1k is a must as I am replacing a mechanical potentiometer and trailfitting some higher value messed up the item. I found some 100-step ones, 256 step versions only for higher resistance values. I would really like more steps, low tollerance on the value and the 1k is as I said a must.
First of all, digital pots are not controlled with PWM, but rather with data communications (i.e. TWI, SPI or even parallel).
Also, digital pots are not like mechanical pots in that you cannot have the element and wiper at any arbitrary voltage relative to ground. Usually all 3 pins of the "pot" must remain within Vdd and Vss.
If, as I'm guessing, you are trying to build a digitally controlled power supply, all I can say is "been there, done that" and I've got many more gray hairs to prove it.
I tried digital pots, I tried 10 turn ANALOG pots rotated by a stepper motor, I tried PWM and DAC's (trying to control an LM-317 with a big pass transistor current booster).
Nothing but grief.
I finally got myself a 3 to 24 volt remote adjustable switcher supply that takes a 0 to 5 volt signal to control the output from 3 to 24 volts at 10 amperes, controlled with a 328P (think UNO) and two 8 bit R-2R networks wired up as a single 16 bit DAC.
Now it's perfect. Simple, stable, reliable.
If you're NOT building a power supply, then....... nevermind...