31.2 Overview

The Analog-to-Digital Converter (ADC) peripheral features a 10-bit Successive Approximation ADC (SAR), with a sampling rate up to 115 ksps at 10-bit resolution (150 ksps at 8-bit). The ADC is connected to a 12-channel analog multiplexer, which allows twelve single-ended voltage inputs. The single-ended voltage inputs refer to 0V (GND). The ADC input channel can either be internal (e.g. a voltage reference) or external through the analog input pins.

An ADC conversion can be started by software or by using the Event System (EVSYS) to route an event from other peripherals, making it possible to do a periodic sampling of input signals, trigger an ADC conversion on a special condition, or trigger an ADC conversion in Standby Sleep mode. A window compare feature is available for monitoring the input signal and can be configured to only trigger an interrupt on user-defined thresholds for under, over, inside, or outside a window, with minimum software intervention required.

The ADC input signal is fed through a sample-and-hold circuit that ensures that the input voltage to the ADC is held at a constant level during sampling.

The ADC supports sampling in bursts where a configurable number of conversion results are accumulated into a single ADC result (Sample Accumulation). Further, a sample delay can be configured to tune the ADC sampling frequency associated with a single burst. This is to tune the sampling frequency away from any harmonic noise aliased with the ADC sampling frequency (within the burst) from the sampled signal. An automatic sampling delay variation feature can be used to randomize this delay to slightly change the time between samples.

Selectable voltage references from the internal Voltage Reference (VREF) peripheral, V_DD supply voltage, or external VREF pin (VREFA).

This device has two instances of the ADC; ADC0 and ADC1.

When the Peripheral Touch Controller (PTC) is enabled, ADC0 is fully controlled by the PTC peripheral.