Author Topic: Digital Potentiometer DS1802 - limit upper range  (Read 1150 times)

0 Members and 1 Guest are viewing this topic.

Offline irq99Topic starter

  • Newbie
  • Posts: 1
  • Country: de
Digital Potentiometer DS1802 - limit upper range
« on: September 15, 2017, 11:49:48 am »
Hi,

maybe someone can give me an hint with this problem.

Since there seem to be nearly no 5k digipots with pushbutton control available i am curious if i can use a DS1802 (10k) and limit its upper range somehow? The Datasheets dont really provide any useful information about this (at least for me).

Can i just parallel 2 of those to half its Range?

https://datasheets.maximintegrated.com/en/ds/DS1802.pdf

Thanks!

Juergen
 

Offline danadak

  • Super Contributor
  • ***
  • Posts: 1875
  • Country: us
  • Reactor Operator SSN-583, Retired EE
Re: Digital Potentiometer DS1802 - limit upper range
« Reply #1 on: September 15, 2017, 02:18:15 pm »
Paralleling not a good idea. First the chip to chip ladder variation is quite
large. Second its log so variation effect is aggravated by curvature of response.



Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 19345
  • Country: gb
  • 0999
Re: Digital Potentiometer DS1802 - limit upper range
« Reply #2 on: September 16, 2017, 07:32:59 pm »
If the potentiometers are both on the same IC, then I would have thought they'd be fairly closely matched.

Why does it need to be 5k? Can't you modify the circuit so it works with a 10k potentiometer? Please post a schematic.
 

Offline danadak

  • Super Contributor
  • ***
  • Posts: 1875
  • Country: us
  • Reactor Operator SSN-583, Retired EE
Re: Digital Potentiometer DS1802 - limit upper range
« Reply #3 on: September 16, 2017, 11:36:49 pm »
Actually that is a good point, there is an inter channel matching spec,
but not a spec on absolute ladder R matching. Eg. the matching is
in db attenuation, a ratiometric spec. But maybe all things being equal
the ladders themselves are also matched.

Contact Maxim and pose the question and ask if the ladders will meet
your requirement.


Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf