Datasheet

176
8006H–AVR–10/09
ATtiny24/44/84
Figure 20-2. Maximum Frequency vs. V
CC
(ATtiny24/44/84)
20.4 Clock Characteristics
20.4.1 Accuracy of Calibrated Internal RC Oscillator
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 21-40 on page 206 and Figure 21-41 on
page 206.
Notes: 1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
2. Voltage range for ATtiny24V/44V/84V.
3. Voltage range for ATtiny24/44/84.
20 MHz
10 MHz
2.7V 4.5V 5.5V
Safe Operating Area
Table 20-2. Calibration Accuracy of Internal RC Oscillator
Calibration
Method Target Frequency V
CC
Temperature
Accuracy at given voltage
& temperature
(1)
Factory
Calibration
8.0 MHz 3V 25°C±10%
User
Calibration
Fixed frequency within:
7.3 – 8.1 MHz
Fixed voltage within:
1.8V – 5.5V
(2)
2.7V – 5.5V
(3)
Fixed temperature
within:
-40°C – 85°C
±1%