The Analog-to-Digital Converter (ADC) peripheral is a 12-bit differential and single-ended ADC, with a Programmable Gain Amplifier (PGA), and a conversion rate up to 375 ksps at 12-bit resolution. The ADC is connected to an analog input multiplexer for selection between multiple single-ended or differential inputs. In single-ended conversions, the ADC measures the voltage between the selected input and 0V (GND). In differential conversions, the ADC measures the voltage between two selected inputs. The ADC inputs can be either internal (for example, a voltage reference) or external 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. This makes it possible to sample input signals periodically, trigger an ADC conversion on a special condition, and also trigger ADC conversions in Standby sleep mode. A digital window compare feature is available for monitoring the input signal and can be configured to trigger an interrupt if the sample is under or over a user-defined threshold, or inside or outside a user-defined window, with minimum software intervention required.
The ADC input signal is fed through a sample-and-hold circuit that ensures the input voltage to the ADC is held at a constant level during the conversion.
The ADC supports sampling in bursts where a configurable number of samples are accumulated into a single ADC result (Sample Accumulation).
The ADC reference voltage can be either internal or supplied from the external analog reference pin (VREFA).