Datasheet
ATmega164A/PA/324A/PA/644A/PA/1284/P
2018 Microchip Technology Inc. Data Sheet Complete DS40002070A-page 402
30.3.3 Supply current of I/O 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 ”PRR0 – Power Reduction Register 0” on page 56 for details.
It is possible to calculate the typical current consumption based on the numbers from Table 30-8 on page 428
for other V
CC
and frequency settings than listed in Table 30-7 on page 428.
Exam
p
l
e
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 428, third column, we see that we need to add 6.0% for the TIMER1,
14.8% for the ADC, and 10.3% for the SPI module. Reading from Figure 30-153 on page 425, we find that the
idle current consumption is ~0.078mA 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. Additional current consumption for the different I/O modules (absolute values)
PRR bit Typical numbers in
V
CC
= 2V, F = 1MHz V
CC
= 3V, F = 4MHz V
CC
= 5V, F = 8MHz
PRUSART1 3.1µA 21.5µA 100.0µA
PRUSART0 3.0µA 21.0µA 98.2µA
PRTWI 6.4µA 45.7µA 214.5µA
PRTIM2 5.6µA 37.7µA 165.8µA
PRTIM1 3.6µA 24.8µA 107.0µA
PRTIM0 1.7µA 10.4µA 43.2µA
PRADC 11.8µA 59.2µA 257.0µA
PRSPI 5.3µA 40.1µA 206.8µA
Table 30-6. Additional current consumption (percentage) in Active and Idle mode
PRR bit
Additional current consumption
compared to Active with external
clock (see Figure 30-148 on page
423 and Figure 30-149 on page
423)
Additional current consumption
compared to Idle with external
clock (see Figure 30-153 on page
425 and Figure 30-154 on page
426)
PRUSART1 1.4% 5.3%
PRUSART0 1.4% 5.2%
PRTWI 3.0% 11.3%
PRTIM2 2.5% 9.1%
PRTIM1 1.6% 6.0%
PRTIM0 0.7% 2.5%
PRADC 4.2% 14.8%
PRSPI 2.7% 10.3%
ICCtotal 0.078mA (1+ 0.060 + 0.148 + 0.103) 0.102mA