14.6 128kHz Internal Oscillator
The 128kHz internal oscillator is a low power oscillator providing a clock of 128kHz. This clock may be select as the system clock by programming the CKSEL fuses to '0011':
Nominal Frequency(1) | CKSEL[3:0] |
---|---|
128kHz | 0011 |
Note:
- The 128kHz oscillator is a very low power clock source, and is not designed for high accuracy.
When this clock source is selected, startup times are determined by the SUT fuses:
Power Conditions | Startup Time from Power-down and Power-save | Additional Delay from Reset | SUT[1:0] |
---|---|---|---|
BOD enabled | 6 CK | 19CK(1) | 00 |
Fast rising power | 6 CK | 19CK + 4ms | 01 |
Slowly rising power | 6 CK | 19CK + 65ms | 10 |
Reserved | 11 |
Note:
- If the RSTDISBL fuse is programmed, this startup time will be increased to 19CK + 4ms to ensure programming mode can be entered.