323
2545M–AVR–09/07
ATmega48/88/168
It is possible to calculate the typical current consumption based on the numbers from Table 2 for
other V
CC
and frequency settings than listed in Table 1.
29.3.0.1 Example 1
Calculate the expected current consumption in idle mode with USART0, TIMER1, and TWI
enabled at V
CC
= 3.0V and F = 1MHz. From Table 2, third column, we see that we need to add
18% for the USART0, 26% for the TWI, and 11% for the TIMER1 module. Reading from Figure
3, we find that the idle current consumption is ~0,075mA at V
CC
= 3.0V and F = 1MHz. The total
current consumption in idle mode with USART0, TIMER1, and TWI enabled, gives:
29.3.0.2 Example 2
Same conditions as in example 1, but in active mode instead. From Table 2, second column we
see that we need to add 3.3% for the USART0, 4.8% for the TWI, and 2.0% for the TIMER1
module. Reading from Figure 1, we find that the active current consumption is ~0,42mA at V
CC
=
3.0V and F = 1MHz. The total current consumption in idle mode with USART0, TIMER1, and
TWI enabled, gives:
29.3.0.3 Example 3
All I/O modules should be enabled. Calculate the expected current consumption in active mode
at V
CC
= 3.6V and F = 10MHz. We find the active current consumption without the I/O modules
to be ~ 4.0mA (from Figure 2). Then, by using the numbers from Table 2 - second column, we
find the total current consumption:
Table 29-2. Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock
(see Figure 29-1 and Figure 29-2)
Additional Current consumption
compared to Idle with external clock
(see Figure 29-7 and Figure 29-8)
PRUSART0 3.3% 18%
PRTWI 4.8% 26%
PRTIM2 4.7% 25%
PRTIM1 2.0% 11%
PRTIM0 1.6% 8.5%
PRSPI 6.1% 33%
PRADC 4.9% 26%
ICCtotal
mA
()•
mA≈≈
I
CCtotal
mA
()•
mA≈≈
I
CCtotal
mA
1 0,033 0,048 0,047 0,02 0,016 0,061 0,049+++++++
()•
mA≈≈
