ATmega48PA/88PA/168PA/328P
29.1.3
ATmega48PA: 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 42 for
details.
Table 29-1. ATmega48PA: Additional Current Consumption for the different I/O modules
(absolute values)
PRR bit
Typical numbers
VCC = 2V, F = 1 MHz
2.9 uA
VCC = 3V, F = 4 MHz
20.7 uA
VCC = 5V, F = 8 MHz
97.4 uA
PRUSART0
PRTWI
6.0 uA
44.8 uA
219.7 uA
PRTIM2
PRTIM1
PRTIM0
PRSPI
5.0 uA
34.5 uA
141.3 uA
3.6 uA
24.4 uA
107.7 uA
1.4 uA
9.5 uA
38.4 uA
5.0 uA
38.0 uA
190.4 uA
PRADC
6.1 uA
47.4 uA
244.7 uA
Table 29-2. ATmega48PA: Additional Current Consumption (percentage) in Active and Idle
mode
Additional Current consumption
compared to Active with external
clock (see Figure 29-1 on page
327 and Figure 29-2 on page 327)
Additional Current consumption
compared to Idle with external
clock (see Figure 29-6 on page
329 and Figure 29-7 on page 330)
PRR bit
PRUSART0
PRTWI
1.8%
3.9%
2.9%
2.1%
0.8%
3.3%
4.2%
11.4%
20.6%
15.7%
11.2%
4.2%
PRTIM2
PRTIM1
PRTIM0
PRSPI
17.6%
22.1%
PRADC
It is possible to calculate the typical current consumption based on the numbers from Table 29-2
on page 332 for other VCC and frequency settings than listed in Table 29-1 on page 332.
Example
Calculate the expected current consumption in idle mode with TIMER1, ADC, and SPI enabled
at VCC = 2.0V and F = 1MHz. From Table 29-2 on page 332, 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
Figure 29-6 on page 329, we find that the idle current consumption is ~0.028 mA at VCC = 2.0V
and F = 1MHz. The total current consumption in idle mode with TIMER1, ADC, and SPI enabled,
gives:
ICCtotal ≈ 0.028 mA ⋅ (1 + 0.112 + 0.221 + 0.176) ≈ 0.042 mA
332
8161D–AVR–10/09
ATMEL [ ATMEL ]
