Datasheet

275
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
AC – Analog Comparator
The Analog Comparator compares the input values on the positive pin AIN0 and nega-
tive pin AIN1. When the voltage on the positive pin AIN0 is higher than the voltage on
the negative pin AIN1, the Analog Comparator output, ACO, is set. The comparator’s
output can be set to trigger the Timer/Counter1 Input Capture function. In addition, the
comparator can trigger a separate interrupt, exclusive to the Analog Comparator. The
user can select Interrupt triggering on comparator output rise, fall or toggle. A block dia-
gram of the comparator and its surrounding logic is shown in Figure 112.
The Power Reduction ADC bit, PRADC, in “PRR0 – Power Reduction Register 0” on
page 55 must be disabled by writing a logical zero to be able to use the ADC input MUX.
Figure 112. Analog Comparator Block Diagram
(2)
Notes: 1. See Table 124 on page 276.
2. Refer to Figure 1 on page 2 and Table 41 on page 92 for Analog Comparator pin
placement.
ACBG
BANDGAP
REFERENCE
ADC MULTIPLEXER
OUTPUT
ACME
ADEN
(1)