Datasheet

348
8272A–AVR–01/10
164A/164PA/324A/324PA/644A/644PA/1284/1284P
28.1.3 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 28-4
on page 374 for other V
CC
and frequency settings than listed in Table 28-3 on page 374.
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 28-4 on page 374, third column, we see that we need
to add 8.8% for the TIMER1, 20.9% for the ADC, and 13.8% for the SPI module. Reading from
Figure 28-55 on page 371, we find that the idle current consumption is ~0.073 mA at V
CC
= 2.0V
and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI enabled,
gives:
Table 28-1. 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 3.1 µA 20.9 µA 96.7 µA
PRUSART0 2.9 µA 21.6 µA 101 µA
PRTWI 6.1 µA 44 µA 205.8 µA
PRTIM2 5.9 µA 40.1 µA 182 µA
PRTIM1 3.7 µA 26.1 µA 113.2 µA
PRTIM0 1.4 µA 9.4 µA 38.8 µA
PRADC 11.7 µA 55.5 µA 249.5 µA
PRSPI 5.1 µA 37.9 µA 195.5 µA
Table 28-2. Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 28-50 on page
369 and Figure 28-51 on page
369)
Additional Current consumption
compared to Idle with external
clock (see Figure 28-55 on page
371 and Figure 28-56 on page
372)
PRUSART1 1.5
% 7.4%
PRUSART0 1.5% 7.5%
PRTWI 3.2% 15.4%
PRTIM2 2.9% 14.0%
PRTIM1 1.8% 8.8%
PRTIM0 0.7% 3.1%
PRADC 4.4% 20.9%
PRSPI 2.9% 13.8%
ICCtotal 0.073 mA (1+ 0.088 + 0.209 + 0.138)⋅ 0.105 mA≈≈