ATmega644PA datasheet(397/468 Pages) ATMEL

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397

8152G–AVR–11/09

ATmega164PA/324PA/644PA/1284P

28.3.3

Supply Current of I/O modules

The tables and formulas below can be used to calculate the additional current consumption for

the different I/O modules in Active and Idle mode. The enabling or disabling of the I/O modules

are controlled by the Power Reduction Register. See ”PRR – Power Reduction Register” on

page 49 for details.

It is possible to calculate the typical current consumption based on the numbers from Table 28-6

on page 397 for other V

CC and frequency settings than listed in Table 28-5 on page 397.

Example

Calculate the expected current consumption in idle mode with TIMER1, ADC, and SPI enabled

at V

CC = 2.0V and F = 1MHz. From Table 28-6 on page 397, third column, we see that we need

to add 9.1% for the TIMER1, 17.9% for the ADC, and 12.4% for the SPI module. Reading from

Figure 28-100 on page 394, we find that the idle current consumption is ~0.078 mA at V

CC =

2.0V and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI

enabled, gives:

Table 28-5.

Additional Current Consumption for the different I/O modules (absolute values)

PRR bit

Typical numbers in

CC = 2V, F = 1 MHz

CC = 3V, F = 4 MHz

CC = 5V, F = 8 MHz

PRUSART1

5.9 µA

37.3 µA

149 µA

PRUSART0

6.7 µA

40 µA

157.1 µA

PRTWI

9.5 µA

58.9 µA

239.5 µA

PRTIM2

12 µA

74.3 µA

297.6 µA

PRTIM1

6.6 µA

41.4 µA

170.3 µA

PRTIM0

3.1 µA

19.5 µA

78.6 µA

PRADC

16.2 µA

75.4 µA

301.4 µA

PRSPI

9.3 µA

56.6 µA

226.3 µA

Table 28-6.

Additional Current Consumption (percentage) in Active and Idle mode

PRR bit

Additional Current consumption

compared to Active with external

clock (see Figure 28-95 on page

392 and Figure 28-96 on page

392)

Additional Current consumption

compared to Idle with external

clock (see Figure 28-100 on page

394 and Figure 28-101 on page

395)

PRUSART1

1.6%

8.1%

PRUSART0

1.8%

8.8%

PRTWI

2.6%

12.9%

PRTIM2

3.3%

16.3%

PRTIM1

1.9%

9.1%

PRTIM0

0.9%

4.3%

PRADC

3.65%

17.9%

PRSPI

2.5%

12.4%

ICCtotal

0.070 mA (1+ 0.091 + 0.179 + 0.124)

⋅

0.091 mA

≈≈

ATmega644PA Datasheet(PDF) 397 Page - ATMEL Corporation

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