
208
8008H–AVR–04/11
ATtiny48/88
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
CC curve is linear between 1.8V < VCC <
4.5V.
Figure 22-1. Maximum Operating Frequency vs. Supply Voltage
22.4
Clock Characterizations
22.4.1
Calibrated Internal Oscillator Accuracy
It is possible to manually calibrate the internal oscillator to be more accurate than default factory
calibration. Please note that the oscillator frequency depends on temperature and voltage. Volt-
Notes:
1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
4 MHz
1.8V
5.5V
4.5V
12 MHz
2.7V
8 MHz
Table 22-1.
Calibration Accuracy of Internal Oscillator
Calibration
Method
Target Frequency
VCC
Temperature
Accuracy at given
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
Fixed temperature within:
-40
°C to +85°C
±1%