Datasheet

53
XMEGA A4U [DATASHEET]
Atmel-8387H-AVR-ATxmega16A4U-34A4U-64A4U-128A4U-Datasheet_09/2014
30. AC – Analog Comparator
30.1 Features
z Two Analog Comparators (ACs)
z Selectable propagation delay versus current consumption
z Selectable hysteresis
z No
z Small
z Large
z Analog comparator output available on pin
z Flexible input selection
z All pins on the port
z Output from the DAC
z Bandgap reference voltage
z A 64-level programmable voltage scaler of the internal AV
CC
voltage
z Interrupt and event generation on:
z Rising edge
z Falling edge
z Toggle
z Window function interrupt and event generation on:
z Signal above window
z Signal inside window
z Signal below window
z Constant current source with configurable output pin selection
30.2 Overview
The analog comparator (AC) compares the voltage levels on two inputs and gives a digital output based on this
comparison. The analog comparator may be configured to generate interrupt requests and/or events upon several
different combinations of input change.
Two important properties of the analog comparator’s dynamic behavior are: hysteresis and propagation delay. Both of
these parameters may be adjusted in order to achieve the optimal operation for each application.
The input selection includes analog port pins, several internal signals, and a 64-level programmable voltage scaler.
The analog comparator output state can also be output on a pin for use by external devices.
A constant current source can be enabled and output on a selectable pin. This can be used to replace, for example,
external resistors used to charge capacitors in capacitive touch sensing applications.
The analog comparators are always grouped in pairs on each port. These are called analog comparator 0 (AC0) and
analog comparator 1 (AC1). They have identical behavior, but separate control registers. Used as pair, they can be
set in window mode to compare a signal to a voltage range instead of a voltage level.
PORTA has one AC pair. Notation is ACA.