Nominal Animal
Well-known member
I'm considering using a TI TLV2372 rail-to-rail I/O (dual) opamp to buffer certain signals to Teensy 3.2 ADC.
As suggested here by Paul, I'd use a resistor between the opamp output and the analog input pin, and a 10 nF capacitor from the analog input pin to ground to act as a reservoir for the ADC, to avoid ringing.
Paul suggested using an 1 kΩ resistor, but I'm hoping to keep the bandwidth relatively high, say 50 kHz or better, so a much smaller resistance is needed. (I'm hoping to catch transients; with one half of the dual opamp a buffer after a voltage divider, and the other half in an instrumentation amplifier configuration over a current sense resistor, to monitor both voltage and current to an Odroid HC1 single-board computer. Or any other 5V device consuming up to 8A, I guess. Full schematics are here.)
Now, the TLV2372 datasheet claims that "a minimum value of 20 Ω should work well for most applications", "for capacitive loads of greater than 10 pF". I'm considering something like a 20 Ω to 47 Ω resistor.
Unfortunately, I dont have the test equipment to verify that has any hope of working at all in practice. In particular, I don't have an oscilloscope or a signal generator, which makes investigating this .. difficult.
Does anyone have practical experience using such buffering with a Teensy 3.2, targeting say 50 - 150 kSamples/sec?
As suggested here by Paul, I'd use a resistor between the opamp output and the analog input pin, and a 10 nF capacitor from the analog input pin to ground to act as a reservoir for the ADC, to avoid ringing.
Paul suggested using an 1 kΩ resistor, but I'm hoping to keep the bandwidth relatively high, say 50 kHz or better, so a much smaller resistance is needed. (I'm hoping to catch transients; with one half of the dual opamp a buffer after a voltage divider, and the other half in an instrumentation amplifier configuration over a current sense resistor, to monitor both voltage and current to an Odroid HC1 single-board computer. Or any other 5V device consuming up to 8A, I guess. Full schematics are here.)
Now, the TLV2372 datasheet claims that "a minimum value of 20 Ω should work well for most applications", "for capacitive loads of greater than 10 pF". I'm considering something like a 20 Ω to 47 Ω resistor.
Unfortunately, I dont have the test equipment to verify that has any hope of working at all in practice. In particular, I don't have an oscilloscope or a signal generator, which makes investigating this .. difficult.
Does anyone have practical experience using such buffering with a Teensy 3.2, targeting say 50 - 150 kSamples/sec?