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Electronics => Beginners => Topic started by: irq99 on September 15, 2017, 11:49:48 am

Title: Digital Potentiometer DS1802 - limit upper range
Post by: irq99 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

Title: Re: Digital Potentiometer DS1802 - limit upper range
Post by: danadak 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.

Title: Re: Digital Potentiometer DS1802 - limit upper range
Post by: Zero999 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.

Title: Re: Digital Potentiometer DS1802 - limit upper range
Post by: danadak 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.