Digital Pot - 3 joined to double resolution


I have been doing some reading about the AD5171 (i2c 6bit digital pot) chips, and in the datasheet it states the following ( page 20:

RESOLUTION ENHANCEMENT The resolution can be doubled in the potentiometer mode of operation by using three digital potentiometers. Borrowed from ADI's patented RDAC segmentation technique, users can con-figure three AD5171s (Figure 46) to double the resolution. First, U3 must be parallel with a discrete resistor, RP, which is chosen to be equal to a step resistance (RP = RAB/64). Adjusting U1 and U2 together forms the coarse 6-bit adjustment, and adjusting U3 alone forms the finer 6-bit adjustment. As a result, the effective resolution becomes 12-bit.

That sounds great, but the chips are only available in small SMT packages, and I really want to prototype with DIP. There are various SPI chips in DIP format that are cheap, and I was wondering if anyone sees anything wrong with putting 3 of these as described in the AD5171 description, in order to get a higher resolution?


Yes that technique will work with any digital pot that has independent ends. That is nether end of the digital pot should be tied to ground, this is not always the case with digital pots.

You could also try these guys for surface mount to dip adapters.

We have successfully hand soldered parts wth 0.025" spacing onto a DIP adapter (with the standard 0.1" spacing). Parts with leads that are 0.05" seemed easy after that!

I was just watching videos at for mounting surface mount parts also. They have a products intended to make surface mount parts user friendly. Haven’t looked at their prices.

Thanks Mike, good info there.

Thanks CrossRoads - I will have a good look at that site, could be useful. That smt video site sounds great too.