338
8271D–AVR–05/11
ATmega48A/PA/88A/PA/168A/PA/328/P
30.1.3
ATmega48A: 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
for other V
CC
and frequency settings than listed in
30.1.3.1
Example
Calculate the expected current consumption in idle mode with TIMER1, ADC, and SPI enabled
at V
CC
= 2.0V and F = 1MHz. From
, third column, we see that we need
to add 11.2% for the TIMER1, 22.1% for the ADC, and 17.6% for the SPI module. Reading from
, we find that the idle current consumption is ~0.028 mA at V
CC
= 2.0V
and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI enabled,
gives:
Table 30-1.
ATmega48PA: 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
2.9uA
20.7uA
97.4uA
PRTWI
6.0uA
44.8uA
219.7uA
PRTIM2
5.0uA
34.5uA
141.3uA
PRTIM1
3.6uA
24.4uA
107.7uA
PRTIM0
1.4uA
9.5uA
38.4uA
PRSPI
5.0uA
38.0uA
190.4uA
PRADC
6.1uA
47.4uA
244.7uA
Table 30-2.
ATmega48PA: 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
1.8%
11.4%
PRTWI
3.9%
20.6%
PRTIM2
2.9%
15.7%
PRTIM1
2.1%
11.2%
PRTIM0
0.8%
4.2%
PRSPI
3.3%
17.6%
PRADC
4.2%
22.1%
I
CC
total
0.028 mA (1 + 0.112 + 0.221 + 0.176)
⋅
0.042 mA
≈
≈