ATmega48/88/168
Table 137.
Additional Current Consumption (percentage) in Active and Idle mode (Continued)
Additional Current consumption
compared to Active with external
clock
Additional Current consumption
compared to Idle with external
clock
PRR bit
PRTIM1
PRTIM0
PRSPI
(see Figure 136 and Figure 137)
(see Figure 142 and Figure 143)
2.0ꢀ
1.6ꢀ
6.1ꢀ
4.9ꢀ
11ꢀ
8.5ꢀ
33ꢀ
26ꢀ
PRADC
It is possible to calculate the typical current consumption based on the numbers from
Table 2 for other VCC and frequency settings than listed in Table 1.
Example 1
Calculate the expected current consumption in idle mode with USART0, TIMER1, and
TWI enabled at VCC = 3.0V and F = 1MHz. From Table 2, third column, we see that we
need to add 18ꢀ for the USART0, 26ꢀ for the TWI, and 11ꢀ for the TIMER1 module.
Reading from Figure 3, we find that the idle current consumption is ~0,075mA at VCC
=
3.0V and F = 1MHz. The total current consumption in idle mode with USART0, TIMER1,
and TWI enabled, gives:
ICCtotal ≈ 0.075mA • (1 + 0.18 + 0.26 + 0.11) ≈ 0.116mA
Example 2
Example 3
Same conditions as in example 1, but in active mode instead. From Table 2, second col-
umn we see that we need to add 3.3ꢀ for the USART0, 4.8ꢀ for the TWI, and 2.0ꢀ for
the TIMER1 module. Reading from Figure 1, we find that the active current consumption
is ~0,42mA at VCC = 3.0V and F = 1MHz. The total current consumption in idle mode
with USART0, TIMER1, and TWI enabled, gives:
ICCtotal ≈ 0.42mA • (1 + 0.033 + 0.048 + 0.02) ≈ 0.46mA
All I/O modules should be enabled. Calculate the expected current consumption in
active mode at VCC = 3.6V and F = 10MHz. We find the active current consumption with-
out 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:
ICCtotal ≈ 4.0mA • (1 + 0.033 + 0.048 + 0.047 + 0.02 + 0.016 + 0.061 + 0.049) ≈ 5.1mA
305
2545D–AVR–07/04
ATMEL [ ATMEL ]
