Different RC oscillators have been utilized in the AVR microcontroller throughout its history. An overview of the RC oscillators with device examples is provided in the table below. The list is sorted by oscillator type, which is also roughly equivalent to sorting by release date. Only tunable oscillators are listed in the table. For oscillator details on a specific device, refer to the device datasheet.
| Oscillator version | Example device | RC oscillator frequency [MHz] | CKDIV | PRSCK |
|---|---|---|---|---|
| 1.1 | ATtiny12 | 1.2 | - | - |
| 1.2 | ATtiny15 | 1.6 | - | - |
| 2.0 | ATmega163 | 1.0 | - | - |
| 3.0 | ATmega16 | 1.0, 2.0, 4.0, and 8.0 | - | - |
| 3.1 | ATmega128 | 1.0, 2.0, 4.0, and 8.0 | XDIV (1) | - |
| 4.0 | ATmega169 (2) | 8.0 | Yes | Yes |
| 4.1 | ATtiny13 | 4.8 and 9.6 | Yes | Yes |
| 4.2 | ATtiny2313 | 4.8 and 9.6 | Yes | Yes |
| 5.0 | ATmega169P (2) | 8.0 | Yes | Yes |