ATXMEGA128B1_14 Datasheet, PDF (51/142 Pages) ATMEL Corporation – 8/16-bit Atmel XMEGA B1 Microcontroller

30. AC – Analog Comparator
30.1
Features
 Four Analog Comparators (AC)
 Selectable hysteresis
 No
 Small
 Large
 Analog comparator output available on pin
 Flexible input selection
 All pins on the port
 Bandgap reference voltage
 A 64-level programmable voltage scaler of the internal V_CC 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.
One important property of the analog comparator’s dynamic behavior is the hysteresis. This parameter 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.
XMEGA B1 [DATASHEET] 51
Atmel-8330F-AVR-ATxmega64B1-128B1_datasheet–02/2014