ATMEGA640 datasheet(265/436 Pages) MICROCHIP

265 / 436 page

265

ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

25. AC – Analog Comparator

The Analog Comparator compares the input values on the positive pin AIN0 and negative pin AIN1. When the volt-

age 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 diagram of the comparator and its surrounding logic is

shown in Figure 25-1.

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 25-1. Analog Comparator Block Diagram(2)

Note:

1. See Table 25-1.

2. Refer to Figure 1-1 on page 2 and Table 13-5 on page 76 for Analog Comparator pin placement.

25.1 Analog Comparator Multiplexed Input

It is possible to select any of the ADC15:0 pins to replace the negative input to the Analog Comparator. 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 and MUX2:0 in ADMUX select the input pin to replace the negative input to the Analog

Comparator, as shown in Table 25-1. 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 25-1.

Analog Comparator Mulitiplexed Input

ACME

ADEN

MUX5

MUX2:0

Analog Comparator Negative Input

xxx

AIN1

xxx

AIN1

100

000

ADC0

100

001

ADC1

100

010

ADC2

100

011

ADC3

ATMEGA640 Datasheet(PDF) 265 Page - Microchip Technology

ATMEGA640 Datasheet(HTML) 265 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL