Mike,

Check the frequency response specification of the digital pot. If I
recall correctly (and I haven't looked recently), most digital pots
don't have a frequency response much above a few 100KHz. Also, check on
the settling time from when you give a digital control input until the
pot value settles to it's final value. I think these parameters are
going to be your limiting factors concerning speed.

A better way to do it might be to use a D/A converter in the PS
feedback loop if you want to adjust output voltage/current at a fast
rate.

Matt Pobursky
Maximum Performance Systems

On Sat, 3 Aug 2002 00:32:18 +0300, Mike Singer wrote:
>Has anybody any suggestions of max regulated frequency?
>If I replace bottom resistor of feedback chain by digital
>potentiometer and reduce output capacitor, what "max frequency" very
>aprox could I send to digital potentiometer, aiming at microstepping
>motor applications?
>LM3485 can work at >1mhz.

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