ADC input maximum voltage

[normanfust]

I have a sensor which has output in the range of 0-5V. I want to connect it to an nrf51822 GPIO pin and to be able to read the value via it's 10 bit ADC. Is there any guide on how to select the voltage divider values, prescaler etc??

[Turbo J]

That won't fly, you cannot exeed VDD+0.3V on any GPIO input.

And since you need a divider anyway you can now design it to fit your selected reference voltage.

Not more help possible at this point- as the OP did not provide the needed infos (impedance, accuracy).

[normanfust]

I am aware of that 5V would potentially harm the GPIO so that I asked for some guidance in order to avoid such a situation. What parameters are essential to calculate a circuit that will drive the sensor to the ADC?

[Jørn]

You can find recommendations on how to design the voltage divider in the nRF51 reference manual, section 31.1.5, page 165. sections 31.1.4 Input voltage range and 31.1.6 Input impedance can also be of interest. You can find the nRF51 reference manual here. infocenter.nordicsemi.com/.../nRF51_RM_v3.0.1.pdf

[normanfust]

@Jorn according to my calculations I should use R2 - 1kOhm, R1 - 7.3kOhm for the voltage divider. What is the formula to calculate the capacitance? Is there a schematic on how to connect the FET? When using these values should I adjust the prescaling of ADC as well??