Datasheet

200
8246B–AVR–09/11
ATtiny2313A/4313
22.3 Speed
The maximum operating frequency of the device is dependent on supply voltage, V
CC
. The rela-
tionship between supply voltage and maximum operating frequency is piecewise linear, as
shown in Figure 22-1.
Figure 22-1. Maximum Frequency vs. V
CC
22.4 Clock Characteristics
22.4.1 Calibrated Internal RC Oscillator Accuracy
It is possible to manually calibrate the internal oscillator to be more accurate than default factory
calibration. Note that the oscillator frequency depends on temperature and voltage. Voltage and
temperature characteristics can be found in Figure 23-46 on page 229, and Figure 23-47 on
page 230.
Notes: 1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
4 MHz
1.8V 5.5V
4.5V
20 MHz
2.7V
10 MHz
Table 22-1. Calibration Accuracy of Internal RC Oscillator
Calibration
Method Target Frequency V
CC
Temperature
Accuracy at given Voltage
& Temperature
(1)
Factory
Calibration
4.0 / 8.0MHz 3V 25°C±10%
User
Calibration
Fixed frequency within:
3.1 – 4.7 MHz /
7.3 – 9.1MHz
Fixed voltage within:
1.8V – 5.5V
Fixed temperature
within:
-40°C – 85°C
±2%