User Manual

498
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
8271E–AVR–07/2012
30.8.3 ATmega328P 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 Reduc-
tion Register. See ”Power Reduction Register” on page 41 for details.
It is possible to calculate the typical current consumption based on the numbers from Table 30-15 for other V
CC
and frequency settings than listed in Table 30-16.
30.8.3.1 Example
Calculate the expected current consumption in idle mode with TIMER1, ADC, and SPI enabled at V
CC
= 2.0V and
F = 1MHz. From Table 30-16, third column, we see that we need to add 14.5% for the TIMER1, 22.1% for the ADC,
and 15.7% for the SPI module. Reading from Figure 30-336 on page 496, we find that the idle current consumption
is ~0.055 mA at V
CC
= 2.0V and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI
enabled, gives:
Table 30-15. ATmega328P: 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 3.20 µA 22.17 µA 100.25 µA
PRTWI 7.34 µA 46.55 µA 199.25 µA
PRTIM2 7.34 µA 50.79 µA 224.25 µA
PRTIM1 6.19 µA 41.25 µA 176.25 µA
PRTIM0 1.89 µA 14.28 µA 61.13 µA
PRSPI 6.94 µA 43.84 µA 186.50 µA
PRADC 8.66 µA 61.80 µA 295.38 µA
Table 30-16. ATmega328P: Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 30-330 on page
493 and Figure 30-331 on page
493)
Additional Current consumption
compared to Idle with external
clock (see Figure 30-335 on page
495 and Figure 30-336 on page
496)
PRUSART0 1.4% 7.8%
PRTWI 3.0% 16.6%
PRTIM2 3.3% 17.8%
PRTIM1 2.7% 14.5%
PRTIM0 0.9% 4.8%
PRSPI 2.9% 15.7%
PRADC 4.1% 22.1%
ICCtotal 0.045 mA (1 + 0.145 + 0.221 + 0.157) 0.069 mA