ATtiny261A datasheet(135/292 Pages) ATMEL

135 / 292 page

135

8197A–AVR–10/09

ATtiny261A/461A/861A

14. AC – Analog Comparator

The analog comparator compares the input values on the selectable positive pin (AIN0, AIN1 or

AIN2) and selectable negative pin (AIN0, AIN1 or AIN2). When the voltage on the positive pin is

higher than the voltage on the negative pin, the Analog Comparator Output, ACO, is set. 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 diagram of the com-

parator and its surrounding logic is shown in Figure 14-1.

Figure 14-1. Analog Comparator Block Diagram

Notes: 1. See Table 14-1 on page 135.

See Figure 1-1 on page 2 and Table 10-3 on page 61 for Analog Comparator pin placement.

14.1 Analog Comparator Multiplexed Input

When the Analog to Digital Converter (ADC) is configurated as single ended input channel, it is

possible to select any of the ADC10:0 pins to replace the negative input to the analog compara-

tor. The ADC multiplexer is used to select this input, and consequently, the ADC must be

switched off to utilize this feature. If the Analog Comparator Multiplexer Enable bit (ACME in

ADCSRB) is set and the ADC is switched off (ADEN in ADCSRA is zero), MUX5:0 in ADMUX

select the input pin to replace the negative input to the analog comparator, as shown in Table

14-1. If ACME is cleared or ADEN is set, either AIN0, AIN1 or AIN2 is applied to the negative

input to the analog comparator.

ACBG

BANDGAP

REFERENCE

ADC MULTIPLEXER

OUTPUT

ACME

ADEN

(1)

MUX

AIN0

AIN1

AIN2

ACM2..1

Table 14-1.

Analog Comparator Multiplexed Input

ACME

ADEN

MUX5:0

ACM2:0

Positive Input

Negative Input

xxxxxx

000

AIN0

AIN1

xxxxxx

001

AIN0

AIN2

xxxxxx

010

AIN1

AIN0

xxxxxx

011

AIN1

AIN2

ATtiny261A Datasheet(PDF) 135 Page - ATMEL Corporation

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