Datasheet

393
8011O–AVR–07/10
ATmega164P/324P/644P
26.3.3 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 26-6
on page 393 for other V
CC
and frequency settings than listed in Table 26-5 on page 393.
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 26-6 on page 393, 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 26-100 on page 390, 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 26-5. 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 26-6. Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 26-95 on page
388 and Figure 26-96 on page
388)
Additional Current consumption
compared to Idle with external
clock (see Figure 26-100 on page
390 and Figure 26-101 on page
391)
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≈≈