If you want to use a high value pot to minimise power consumption you can often satisfy the ADC maximum impedance requirements by putting a capacitor to ground from the pot wiper if the resistance is high,
Keith
hi prmurthy....Hi all
One clarification is required. Does PIC controller accepts above 10K for ADC. I think PIC does make any differnce above 10K. Please correct me if I am wrong and also weather it depends on different controllers like ATMEL, TI etc
Thankyou
hi prmurthy....
I think there is no relationship between potmeter value vs Mc ADC.... (Particularly ADC potmeters). You can use any value for any microcontroller.
Potentiometer may get saturated and show no variation after certain value.. So a 10k Is usually used.. you need to find out the saturation value and use a proper value pot.....
If you want to use a high value pot to minimise power consumption you can often satisfy the ADC maximum impedance requirements by putting a capacitor to ground from the pot wiper if the resistance is high,
Keith
Thanks for your valuable comment mr.alex. Now only i hered this news about AVR thanks....I have to dissagree on that, for example the AVR datasheet says in the ADC section
"The ADC is optimized for analog signals with an output impedance of approximately
10 kΩ or less. If such a source is used, the sampling time will be negligible. If a source
with higher impedance is used, the sampling time will depend on how long time the
source needs to charge the S/H capacitor, with can vary widely. The user is recom-
mended to only use low impedance sources with slowly varying signals, since this
minimizes the required charge transfer to the S/H capacitor."
Alex
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