[SOLVED] Digital potentiometers in parallel?

[SparkyBoy]

Hi,

I want to simulate a Ni1000 temperature sensor, effectively a variable resistor that changes by approx. 5.5Ohms/°C. This is easily achieved using a manual precision turn potentiometer of suitable range, but I would like a digital method as pots are bulky and tend to take up a lot of space and wiring etc.

I know digital pots exist, 1kOhm with 256 taps, approx. 3.9Ohms per tap, but to achieve a usuable temperature resolution I need finer control per tap.

A device measuring the resistance pulses 1.5-2mA through the resistance, measuring the volt drop and calculating the temperature using the Ni1000 characteristic curve.

So the question is can I take a dig. pot IC with say dual or quad pots per IC and connect them in parallel, just like resistors in parallel, to achieve a lower effective resistance?

Regards

Mark.

 

[crutschow]

I see no reason that you can't. Just be aware that the resistance tolerance of most digital pots is fairly wide, so you would likely have to calibrate the setup with some trimpots to get the precision/accuracy you need.

 

[tpetar]

1024 taps digital pot :

MAX5494, MAX5495, MAX5496, MAX5497, MAX5498, MAX5499
10-Bit, Dual, Nonvolatile, Linear-Taper Digital Potentiometers
https://www.maximintegrated.com/datasheet/index.mvp/id/4636


Best regards,
Peter

:wink:

 

[SparkyBoy]

Thanks for your replies guys.

I have actually found an application note: https://www.analog.com/static/imported-files/application_notes/AN-582.pdf which looks very interesting.

Regards

Mark.