Datasheet

481
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
29.6.3 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 ”PRR0 – Power Reduction Register 0” on
page 48 for details.
It is possible to calculate the typical current consumption based on the numbers from Table 29-
12 on page 481 for other V
CC
and frequency settings than listed in Table 29-11 on page 481.
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 29-12 on page 481, 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 29-251 on page 478, we find that the idle current consumption is ~0.078mA at V
CC
= 2.0V
and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI enabled,
gives:
Table 29-11. Additional current consumption for the different I/O modules (absolute values).
PRR bit Typical numbers in
V
CC
= 2V, F = 1MHz V
CC
= 3V, F = 4MHz V
CC
= 5V, F = 8MHz
PRUSART1 5.9µA 37.3µA 149µA
PRUSART0 6.7µA 40µA 157.1µA
PRTWI 9.5µA 58.9µA 239.5µA
PRTIM2 12µA 74.3µA 297.6µA
PRTIM1 6.6µA 41.4µA 170.3µA
PRTIM0 3.1µA 19.5µA 78.6µA
PRADC 16.2µA 75.4µA 301.4µA
PRSPI 9.3µA 56.6µA 226.3µA
Table 29-12. Additional current consumption (percentage) in Active and Idle mode.
PRR bit
Additional current consumption
compared to Active with external
clock (see Figure 29-246 on page
476 and Figure 29-247 on page
476)
Additional current consumption
compared to Idle with external
clock (see Figure 29-251 on page
478 and Figure 29-252 on page
479)
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 0.070mA (1+ 0.091 + 0.179 + 0.124) 0.091mA