[sdiy] nice Digi Pot

[Vladimir Pantelic]

"This SPI Interface does NOT support daisy chaining."

:(( why Microchip, oh why....


On 27.06.2016 19:06, sleepy_dog at gmx.de wrote:
>
> Reading the thread "non-mechanical switching solutions",
> I just remembered a nice series of digital potentiometers which I discovered
> some months ago,
> which are SDIY friendly ( for those not afraid of TSSOP ;) ), as they
> - support +/- 18V dual rails
> - digital voltage: 2.7 ... 5.5V (or even 1.8V)
> - cost less than 2 bucks
>
> I have used, as an experiment, digi pots in some VCFs to easily control
> resonance from an MCU, but before I found those here, I only knew similar
> products in a price range of 8...12 US$ or something like that.
>
> So I just thought, I'll throw that in here, maybe someone else also only knew
> the expensive ones.
>
> MCP41HVx1 series, where
> http://www.tme.eu/de/details/mcp41hv31-503e_st/digitalpotentiometer/microchip-technology/
>
>
> available in 5k, 10k, 50k, 100k
>
> datasheet
> http://www.tme.eu/de/Document/8b361619149495099964ddab197bebfe/mcp41xvx1.pdf
>
>
> regards,
> Steve
>
>
> Am 27.06.2016 um 16:27 schrieb Vladimir Pantelic:
>> On 27.06.2016 16:15, Pete Hartman wrote:
>>
>>> First thought: CD4052, but that doesn't work well in practice at all.
>>>
>>> Second thought: DG409, better characteristics, but that still doesn't
>>> work sufficiently well.
>>>
>>> Dig around a while for why.... aha, the on resistance for both is
>>> significant, especially for the capacitive stages of a ladder filter.
>>> The DG409 has on the order of 100R - 120R.  Too much, and confirmed to
>>> be the issue by comparing physical connections with wire to physical
>>> connections with 100R resistors.
>> ADG1414, R_on = 9.5R and 8 switches inside one package - but needs SPI
>> so you need to add a 50¢ uC to control it
>>
>>
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