Datasheet

197
8197C–AVR–05/11
ATtiny261A/461A/861A
20. Typical Characteristics
The data contained in this section is largely based on simulations and characterization of similar
devices in the same process and design methods. Thus, the data should be treated as indica-
tions of how the part will behave.
The following charts show typical behavior. These figures are not tested during manufacturing.
During characterisation devices are operated at frequencies higher than test limits but they are
not guaranteed to function properly at frequencies higher than the ordering code indicates.
All current consumption measurements are performed with all I/O pins configured as inputs and
with internal pull-ups enabled. Current consumption is a function of several factors such as oper-
ating voltage, operating frequency, loading of I/O pins, switching rate of I/O pins, code executed
and ambient temperature. The dominating factors are operating voltage and frequency.
A sine wave generator with rail-to-rail output is used as clock source but current consumption in
Power-Down mode is independent of clock selection. The difference between current consump-
tion in Power-Down mode with Watchdog Timer enabled and Power-Down mode with Watchdog
Timer disabled represents the differential current drawn by the Watchdog Timer.
The current drawn from pins with a capacitive load may be estimated (for one pin) as follows:
where V
CC
= operating voltage, C
L
= load capacitance and f
SW
= average switching frequency of
I/O pin.
20.1 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 “PRR – Power Reduction Register” on
page 39 for details.
Table 20-2 below can be used for calculating typical current consumption for other supply volt-
ages and frequencies than those mentioned in Table 20-1 above.
I
CP
V
CC
C
L
f××
SW
≈
Table 20-1. 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
PRTIM1 35 µA 200 µA 900 µA
PRTIM0 5 µA 25 µA 100 µA
PRUSI 5 µA 25 µA 450 µA
PRADC 200 µA 280 µA 550 µA