Datasheet
452
8272A–AVR–01/10
164A/164PA/324A/324PA/644A/644PA/1284/1284P
28.5.3 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-
12 on page 478 for other V
CC
and frequency settings than listed in Table 28-11 on page 478.
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 28-12 on page 478, 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 28-251 on page 475, 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 28-9. Additional Current Consumption for the different I/O modules (absolute values)
PRR bit Typical numbers in
V
CC
= 2V, F = 1 MHz V
CC
= 3V, F = 4 MHz V
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 28-10. Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 28-246 on page
473 and Figure 28-247 on page
473)
Additional Current consumption
compared to Idle with external
clock (see Figure 28-251 on page
475 and Figure 28-252 on page
476)
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≈≈