50
XMEGA A3U [DATASHEET]
Atmel-8386D-AVR-ATxmega64A3U-128A3U-192A3U-256A3U–03/2014
30.
AC – Analog Comparator
30.1
Features
Selectable propagation delay versus current consumption
Selectable hysteresis
No
Small
Large
Analog comparator output available on pin
Flexible input selection
All pins on the port
Output from the DAC
Bandgap reference voltage
A 64-level programmable voltage scaler of the internal VCC voltage
Interrupt and event generation on:
Rising edge
Falling edge
Toggle
Window function interrupt and event generation on:
Signal above window
Signal inside window
Signal below window
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 and PORTB each has one AC pair. Notations are ACA and ACB, respectively.