Datasheet

426
8272A–AVR–01/10
164A/164PA/324A/324PA/644A/644PA/1284/1284P
28.4.3 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 28-8
on page 426 for other V
CC
and frequency settings than listed in Table 28-7 on page 426.
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 28-8 on page 426, third column, we see that we need
to add 6.0% for the TIMER1, 14.8% for the ADC, and 10.3% for the SPI module. Reading from
Figure 28-153 on page 423, 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 28-7. 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 3.1 µA 21.5 µA 100.0 µA
PRUSART0 3.0 µA 21.0 µA 98.2 µA
PRTWI 6.4 µA 45.7 µA 214.5 µA
PRTIM2 5.6 µA 37.7 µA 165.8 µA
PRTIM1 3.6 µA 24.8 µA 107.0 µA
PRTIM0 1.7 µA 10.4 µA 43.2 µA
PRADC 11.8 µA 59.2 µA 257.0 µA
PRSPI 5.3 µA 40.1 µA 206.8 µA
Table 28-8. Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 28-148 on page
421 and Figure 28-149 on page
421)
Additional Current consumption
compared to Idle with external
clock (see Figure 28-153 on page
423 and Figure 28-154 on page
424)
PRUSART1 1.4% 5.3%
PRUSART0 1.4% 5.2%
PRTWI 3.0% 11.3%
PRTIM2 2.5% 9.1%
PRTIM1 1.6% 6.0%
PRTIM0 0.7% 2.5%
PRADC 4.2% 14.8%
PRSPI 2.7% 10.3%
ICCtotal 0.078 mA (1+ 0.060 + 0.148 + 0.103)⋅ 0.102 mA≈≈