Datasheet

322
2545T–AVR–05/11
ATmega48/88/168
It is possible to calculate the typical current consumption based on the numbers from Table 30-2
on page 321 for other V
CC
and frequency settings than listed in Table 30-1 on page 321.
30.3.0.1 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 30-2 on page 321, third column, we see that
we need to add 18% for the USART0, 26% for the TWI, and 11% for the TIMER1 module. Read-
ing from Figure 30-7 on page 318, 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:
30.3.0.2 Example 2
Same conditions as in example 1, but in active mode instead. From Table 30-2 on page 321,
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 30-1 on page 315, 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:
30.3.0.3 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 30-2 on page 316). Then, by using the numbers from Table 30-2 on
page 321 - second column, we find the total current consumption:
PRTIM1 2.0% 11%
PRTIM0 1.6% 8.5%
PRSPI 6.1% 33%
PRADC 4.9% 26%
Table 30-2. Additional current consumption (percentage) in active and idle mode. (Continued)
PRR bit
Additional current consumption
compared to active with external clock
(see Figure 30-1 on page 315 and
Figure 30-2 on page 316)
Additional current consumption
compared to Idle with external clock
(see Figure 30-7 on page 318 and
Figure 30-8 on page 319)
ICCtotal 0.075mA 10.180.260.11+++()• 0.116mA≈≈
ICCtotal 0.42mA 1 0.033 0.048 0.02+++()• 0.46mA≈≈
ICCtotal 4.0mA 1 0.033 0.048 0.047 0.02 0.016 0.061 0.049+++++++()• 5.1mA≈≈