My stm32 opamp characteristics understanding is that
- max output current 500µA in normal mode, stand-alone
- min output impedance 4kR in normal mode, stand-alone.
This last value fairly aligns to considering a serviceable output impedance corresponding to 3.6V/2 / 500µA.
As a consequence, when one routes opamp output (standalone+normal mode) into ADC input, it means that sample rate should a Rain above 4k. Do i get it right?
For example, for ADC running at 80MHz and 12 bit resolution :
- (fast channel) min usable Rain_max = 4,7k
Corresponds to selecting min 92.5 sampling cycles
Results in anti-aliasing required cut-off at Fs/2 = ~380kHz max
- (slow channel) min usable Rain_max = 10k
Corresponds to selecting min 247.5 sampling cycles
Results in anti-aliasing required cut-off at Fs/2 = ~154kHz max