Datasheet

396
8011Q–AVR–02/2013
ATmega164P/324P/644P
27.3.3 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 48 for details.
It is possible to calculate the typical current consumption based on the numbers from Table 27-6
on page 396 for other V
CC
and frequency settings than listed in Table 27-5 on page 396.
Example Calculate the expected current consumption in idle mode with TIMER1, ADC, and SPI enabled
at V
CC
= 2.0V and F = 1 MHz. From Table 27-6 on page 396, third column, we see that we need
to add 8.9% for the TIMER1, 17.2% for the ADC, and 12.3% for the SPI module. Reading from
Figure 27-100 on page 393, we find that the idle current consumption is ~0.1 mA at V
CC
= 2.0V
and F = 1 MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI
enabled, gives:
Table 27-5. Additional Current Consumption for the different I/O modules (absolute values)
PRR bit Typical numbers
V
CC
= 2V, F = 1 MHz V
CC
= 3V, F = 4 MHz V
CC
= 5V, F = 8 MHz
PRUSART1 5.8 µA 37.7 µA 152.0 µA
PRUSART0 6.5 µA 40.5 µA 154.8 µA
PRTWI 9.4 µA 59.7 µA 239.3 µA
PRTIM2 11.5 µA 75.0 µA 297.0 µA
PRTIM1 5.9 µA 41.5 µA 171.8 µA
PRTIM0 3.3 µA 19.7 µA 78.3 µA
PRADC 14.5 µA 73.8 µA 302.7 µA
PRSPI 8.9 µA 56.7 µA 226.0 µA
Table 27-6. Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 27-95 on page
391 and Figure 27-96 on page
391)
Additional Current consumption
compared to Idle with external
clock (see Figure 27-100 on page
393 and Figure 27-101 on page
394)
PRUSART1 1.6% 8.1%
PRUSART0 1.8% 8.7%
PRTWI 2.6% 13.0%
PRTIM2 3.3% 16.1%
PRTIM1 1.8% 8.9%
PRTIM0 0.9% 4.0%
PRADC 3.5% 17.2%
PRSPI 2.5% 12.3%
ICCtotal 0.1 mA (1 + 0.089 + 0.172 + 0.123) 0.138 mA