Re: Digital potmeter with on/off switch?

Hello Frank,


Well, all the digital potmeters I've seen had a i2c or SPI or up/dn
control inputs, not suitable for direct pushbutton connections. I'm
afraid you will need a small uC anyway. Maxim has plenty of choice
for digital pots.


Dallas has some that support direct button connections. They have de-bounce on board. I have no clue why AD didn't think of that with some of their digipots.


I suppose you could make a FF from two cmos nand gates, and power
the uC/pot circuit from one of the outputs, to get that 'few uA when off'.
The 'up' button would always set the FF. The uC can reset the FF,
once the 'down' button has steered the wiper all the way down, and
putting everything to sleep.


Currently there is no uC, it's just for a few demo models. I am afraid I'll have to cook up some logic like usual. I wonder why there is no product for the typical scenario: Dormant upon power-up, wiper at bottom and not in the middle like most of them. Hit UP button, unit turns on or a logic output goes high. Hit UP some more and pot wiper goes upwards. All that's needed would be a logic output, the rest could be done with FETs and stuff. Holding the DOWN button long enough would turn it all off again.

Regards, Joerg

http://www.analogconsultants.com
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