438
8271D–AVR–05/11
ATmega48A/PA/88A/PA/168A/PA/328/P
30.5.3
ATmega168A Supply Current of IO 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
”Power Reduction Register” on page 43
for
details.
It is possible to calculate the typical current consumption based on the numbers from
CC
and frequency settings than listed in
.
30.5.3.1
Example
Calculate the expected current consumption in idle mode with TIMER1, ADC, and SPI enabled
at V
CC
, third column, we see that we need
to add 10.3% for the TIMER1, 20.3% for the ADC, and 17.1% for the SPI module. Reading from
, we find that the idle current consumption is ~0.027 mA at V
CC
=
2.0V and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI
enabled, gives:
Table 30-9.
ATmega168A: Additional Current Consumption for the different I/O modules
(absolute values)
PRR bit
Typical numbers
V
CC
= 2V, F = 1MHz
V
CC
= 3V, F = 4MHz
V
CC
= 5V, F = 8MHz
PRUSART0
2.86uA
20.3uA
52.2uA
PRTWI
6.00uA
44.1uA
122.0uA
PRTIM2
4.97uA
33.2uA
79.8uA
PRTIM1
3.50uA
23.0uA
55.3uA
PRTIM0
1.43uA
9.2uA
21.4uA
PRSPI
5.01uA
38.6uA
111.4uA
PRADC
6.34uA
45.7uA
123.6uA
Table 30-10.
ATmega168A: Additional Current Consumption (percentage) in Active and Idle
mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see
and
)
Additional Current consumption
compared to Idle with external
clock (see
PRUSART0
1.5%
8.9%
PRTWI
3.2%
19.5%
PRTIM2
2.4%
14.8%
PRTIM1
1.7%
10.3%
PRTIM0
0.7%
4.1%
PRSPI
2.9%
17.1%
PRADC
3.4%
20.3%
I
CC
total
0.027 mA (1 + 0.103 + 0.203 + 0.171)
⋅
0.040 mA
≈
≈