- Tue Jan 31, 2017 2:32 am
#61803
Yes, ADAFruit has not added a resistance divider do direct ADC input. The input leakage current of 50nA sounds correct so 20Mohms can't be far out.
- Tue Jan 31, 2017 12:37 pm
#61825
regarding the impedance of Tout:
http://bbs.espressif.com/viewtopic.php? ... ance#p3135
that is the only "official" statement I ever saw.
but you could check for yourself: just take a stable voltage source (<=1V) with low impedance and connect it via trim-pot (~2MOhm) to Tout.
Start with a setting of 0Ohm and get an averaged stable reading, then increase the value until your get half of your first reading. Now the set resistance correlates to the input impedance of the adc.
http://bbs.espressif.com/viewtopic.php? ... ance#p3135
that is the only "official" statement I ever saw.
but you could check for yourself: just take a stable voltage source (<=1V) with low impedance and connect it via trim-pot (~2MOhm) to Tout.
Start with a setting of 0Ohm and get an averaged stable reading, then increase the value until your get half of your first reading. Now the set resistance correlates to the input impedance of the adc.
- Tue Apr 18, 2017 2:33 pm
#65056
> The input impedance of the ADC is very high, in the range of 1MΩ.
Source: http://bbs.espressif.com/viewtopic.php?t=909
cerebrate wrote:Quick question, if I may - is the input impedance, or maximum input current, of the ESP8266-12 ADC pin documented anywhere? I haven't been able to find it in any of the spec sheets I've dug up.
Thanks in advance,
-c
> The input impedance of the ADC is very high, in the range of 1MΩ.
Source: http://bbs.espressif.com/viewtopic.php?t=909
- Thu Apr 20, 2017 2:21 am
#65086
Thanks, much appreciated!
-c
temoto wrote:> The input impedance of the ADC is very high, in the range of 1MΩ.
Source: http://bbs.espressif.com/viewtopic.php?t=909
Thanks, much appreciated!
-c
