S42 Hardware User Guide
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Page 40 of 62
5.4.3
Analog Digital Converter (ADC)
5.4.3.1
Input Voltage Range
It is very important to configure the ADC, so the input voltage range and the ADC voltage
range are matching.
•
If the input voltage range is lower than the ADC voltage range, the resolution will not
be fully utilized.
•
If the input voltage range is higher than the ADC voltage range, all values above the
maximum ADC voltage range will be limited to the maximum value, also called the
saturation point.
Input voltage range and saturation point depend on the configured ADC reference voltage
(see 5.4.4) and the chosen prescaling.
Input Voltage Range = ADC Reference Voltage / Prescaler
Limitation for maximum input voltage is described in 5.4.5
5.4.4
ADC Reference Voltage
ADC Reference voltage can be obtained from:
•
Internal band gap reference: 1,2V ± 1,5%
or
•
External reference pin AREF: min. 0,83V typ. 1,2V max. 1,3V
Source Impedance: <5k
Ω