Reference

nRF5340 Product Specification

The ADC can use the following two references, controlled in the REFSEL field of the CH[n].CONFIG register.

  • Internal reference
  • VDD as reference

The internal reference results in an input range of ±0.6 V on the ADC core. VDD as reference results in an input range of ±VDD/4 on the ADC core. The gain block can be used to change the effective input range of the ADC. 

Input range = (+- 0.6 V or +-VDD/4)/Gain

For example, choosing VDD as reference, single ended input (grounded negative input), and a gain of 1/4 the input range is the following: 

Input range = (VDD/4)/(1/4) = VDD

With internal reference, single ended input (grounded negative input), and a gain of 1/6 the input range is the following: 

Input range = (0.6 V)/(1/6) = 3.6 V

The AIN0 - AIN7 inputs cannot exceed VDD, or be lower than VSS.