Accuracy of Calibrated Internal 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 3 and Figure 4

Table 1. Calibration Accuracy of Internal RC Oscillator
Calibration
Method Target Frequency VCC 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 Fixed temp. within:
-40°C - 85°C ±1%
Note:
  1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
Parent topic: Clock Characteristics