User Manual

374
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
8271E–AVR–07/2012
30.3.3 ATmega88A: 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 30-8 on page 399 for
other V
CC
and frequency settings than listed in Table 30-7 on page 399.
30.3.3.1 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 30-8 on page 399, third column, we see that we need to add 13.6% for the TIMER1, 26.3%
for the ADC, and 21.5% for the SPI module. Reading from Figure 30-147 on page 396, 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 30-5. ATmega88PA: 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 3.0uA 21.3uA 97.9uA
PRTWI 6.1uA 45.4uA 219.0uA
PRTIM2 5.2uA 35.2uA 149.5uA
PRTIM1 3.8uA 25.6uA 110.0uA
PRTIM0 1.5uA 9.8uA 39.6uA
PRSPI 5.2uA 40.0uA 199.6uA
PRADC 6.3uA 48.7uA 247.0uA
Table 30-6. ATmega88PA: Additional Current Consumption (percentage) in Active and Idle mode
PRR bit
Additional Current consumption
compared to Active with external
clock (see Figure 30-142 on page
393 and Figure 30-143 on page
394)
Additional Current consumption
compared to Idle with external
clock (see Figure 30-147 on page
396 and Figure 30-148 on page
396)
PRUSART0 1.8% 11.4%
PRTWI 3.9% 24.4%
PRTIM2 2.9% 18.6%
PRTIM1 2.1% 13.6%
PRTIM0 0.8% 5.2%
PRSPI 3.5% 21.5%
PRADC 4.2% 26.3%
ICCtotal 0.027 mA (1 + 0.136 + 0.263 + 0.215) 0.043 mA