Hi Circuiteers.
I want to measure a low impedance voltage source using the ADC when the source is in the ~1V range. However it can also go up to ~50V so I need to protect the PIC. Would a ~100k resistor suffice? This would limit the current to ~0.5mA at 50V but will PIC24FV tolerate this? The datasheet specifies the limit in voltage space ie. Vdd+0.3V, rather than current space.
I'm not worried about a little imprecision due to the leakage current through the large resistor. The RC with the 30pF ADC input cap will be 3us, which is also ok for my application. I just want to avoid using a potential divider or a zener diode to gnd or a schottky to Vdd.
I want to measure a low impedance voltage source using the ADC when the source is in the ~1V range. However it can also go up to ~50V so I need to protect the PIC. Would a ~100k resistor suffice? This would limit the current to ~0.5mA at 50V but will PIC24FV tolerate this? The datasheet specifies the limit in voltage space ie. Vdd+0.3V, rather than current space.
I'm not worried about a little imprecision due to the leakage current through the large resistor. The RC with the 30pF ADC input cap will be 3us, which is also ok for my application. I just want to avoid using a potential divider or a zener diode to gnd or a schottky to Vdd.