#1669 MCP4131 Serial Interface Programmable Potentiometer

Episode 1669 chip of the day
serial interface programmable potentiometer
Board from ideaspark. search for 'Nano V3 Board ATmega328P CH340 Controller with 0.91'' OLED Display for Arduino'

[MickHealey]

Nice video, thanks. At 2:18 you mentioned that you were not sure how they accomplish the potentiometer functionality inside a chip. Having used these before, I can tell you that there are 256 resistors in series (for the 8 bit version) strung between the pot ends P0A and P0B. This gives you 257 possible voltage levels (both ends + 255 junctions along the string). As you suspected, FETs are used to tap off the appropriate resistor in the string to give the wiper voltage at P0W. These are great little chips. I used the dual version to design some test equipment for the radiotherapy company I worked for, using Arduino as the controller. This won me my one and only patent. So, I love this chip 🙂

[rhp]

We do really love Chip Of The Day!
Amazing video series you have going!

[matteo]

I use a similar digipot to do the auto-ranging feature for the input of an ADC on a bed-of-nails test fixture at work. Linearity isn't the greatest, especially with temperature changes, but still a nice IC!

[brianbrumfield]

The biggest problem with the digital pots is the limited voltage on the resistor pins.

[stefflus]

I've smoked some digital pot in my days

[WRMD]

Thanks for showing. Have a great day and weekend.

[RonDogInTheHouse]

Been using the digi-pots for some time now. What I didn't know was the Nano with OLED, need to get me some of them, they'll make prototyping easier. Thanks

[fer_fdi]

Very cool. And what a beautiful HP meter!!! : )

[danielmantione]

It is a nice chip, but you may want take a look at the SLG47004. For a lower price than the MCP4131 you get two digital rheostats that can be serially programmed, and there are a hell of a lot more interresting function blocks on that chip. The price that Microchip asks seems fair for the functionality, but, compared to the SLG47004, it suddenly is way to costly.

[Enigma]

I think the digi-pots have limited application compared to "physical" pots since they typically can only handle a few mA.

[christopherjackson]

Oh neat ive never seen a digital pot. That could certainly come in useful

[MAVNX]

Love these for the 2.5mA current limit😢

[aduedc]

I guess with dual pot of this chip, one can use Wien Bridge Oscillator topology and make Digital Controlled Oscillator (DCO) at low frequencies. As you know making low phase noise VCO at low frequencies is difficult.

[barrybogart]

That's pretty cool. I'm still trying to get my old head around passive components imbedded (simulated?) in IC packages. Can they do dual gang nonlinear variable caps and ferrite slug variable inductors?

[hayleyxyz]

Really cool chip. I'd be interested in how they implemented this in silicon. Since it's only 8 bit, maybe a huge voltage divider and the logic just chooses which route to take? Thanks for sharing

[simontay]

Is this Arduino board with the OLED display compatible with LCD smartie? LCD Smartie is open-source software for Microsoft Windows which allows a character LCD to be used as an auxiliary display device for a PC.

[lahtinenk]

I have wondered if this is suitable for audio volume control or mixers?

[pauldery]

Can this be used as an electronic volume control?

[bayareapianist]

If there is a DAC in your arduino chip, why would you want to do this?

[ИпполитМатвеевичВоробьянин-тп]

Do I understand correctly that one chip costs about $5?