ATtiny13A datasheet(79/174 Pages) ATMEL

79 / 174 page

8126D–AVR–11/09

ATtiny13A

13. Analog Comparator

The Analog Comparator compares the input values on the positive pin AIN0 and negative 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 can trigger a separate inter-

rupt, exclusive to the Analog Comparator. The user can select Interrupt triggering on comparator

output rise, fall or toggle. A block diagram of the comparator and its surrounding logic is shown

in Figure 13-1 on page 79.

Figure 13-1. Analog Comparator Block Diagram

See Figure 1-1 on page 2, Table 10-5 on page 57, and Table 13-2 on page 81 for Analog Compar-

ator pin placement.

13.1 Analog Comparator Multiplexed Input

It is possible to select any of the ADC3..0 pins to replace the negative input to the Analog Com-

parator. 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), MUX1:0 in ADMUX

select the input pin to replace the negative input to the Analog Comparator, as shown in Table

13-1. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to the Analog

Comparator.

ACBG

BANDGAP

REFERENCE

ADC MULTIPLEXER

OUTPUT

ACME

ADEN

(1)

Table 13-1.

Analog Comparator Multiplexed Input

ACME

ADEN

MUX1..0

Analog Comparator Negative Input

AIN1

ADC0

ADC1

ADC2

ADC3

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