Alternative to the AD5292 Digipot?

[MattHelm]

Ok, I am wanting to design an adjustable power supply. Woohoo, whatever.

The rough specs are something like 1.2VDC - 30VDC @ 4A.

I am thinking about using the LM2679 (a simple switching regulator), Adjustment is fairly trivial by using a voltage divider to drive the feedback input.

So far, so good, nothing too exciting.

Now, the fun part. I want to control the voltage divider using a Pic or other uC. The first thought that came to mind was "A digipot! No problem."

Then I started thinking about the voltage divider... It feeds straight from the regulator's output (after some filtering). The digipot will see 30VDC on it's virtual wiper. That severely limits my digipot choices. The AD5292 will handle that as long as you supply it with a Vdd of greater than the V on the virtual contacts (with a max Vdd of 35V).

Any other digipots that I don't know about that will handle those voltage levels?

PS: I suppose I could use a DAC and a MOSFET, but at first blush the digipot route seems simpler.

[migsantiago]

I also want to build an adjustable power supply and use a digital pot. I will use a Microchip digipot that only works from 0V to 5.5V, and then connect an opamp and amplify it's voltage output.

I didn't know that there were digipots which could take voltages up to 35V. If there's one, please let us know. 

[MattHelm]

As noted above. the the AD5292 reportedly will. Unless I am misreading the specs. My eyes are trashed today.

The product page: http://www.analog.com/en/digital-to-analog-converters/digital-potentiometers/ad5292/products/product.html

Actually, although Vdd max is 35V, recommended single supply max is 33V.


ETA: I suppose I could use a lower rated digipot and an opamp as well. I will have to think about it in more detail. The essence is that the regulator will try to do what ever it takes to see 1.2V on it's feedback input. Using an opamp means an additional component and breaking up the feedback loop a bit. But it saves having to power the digipot with 33V.  I'm starting to like it, thanks!