Atmel ADC S&H switch on-resistance

Yeh... what part?

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

atmega8 Or any of their 8 bit microcontrollers.. (I think they're all mostly the same ADC-wise)

nevermind, I've found something..

I recall something like 10k + 4pF from the datasheet... good to know someone made their own measurements and found similar results. Thanks,

Tim

..on DuckDuckGo, I did not measure anything myself, just to be clear...

They do have a diagram in their data sheets that gives the resistor as

Oops, wrong. it says 1..100k which is even more off

Atmega 8(L) datasheet Rev. 2486Q-10/06 page 202

That's probably just shitty work on their part, but high ohm silicon paths are notoriously inconsistent; they are matched on chip (hence precise stable ratios, e.g., the R-R-R divider in the '555), but the absolute value has something like 3:1 uncertainty (10k might be 3 or 30k, say).

Tim

For instance, the pull-up resistor is guaranteed 20-50k ohms, which is relatively tight as these things go IIRC. Depends on technique too (long trace vs. pinched trace).

Tim