29
8006K–AVR–10/10
ATtiny24/44/84
Notes:
1. This option should not be used with crystals, only with ceramic resonators.
The Oscillator can operate in three different modes, each optimized for a specific frequency
range. The operating mode is selected by fuses CKSEL3:1 as shown in
Table 6-9.
The CKSEL0 Fuse together with the SUT1:0 Fuses select the start-up times as shown in
TableNotes:
1. When the BOD has been disabled by software, the wake-up time from sleep mode will be
approximately 60s to ensure that the BOD is working correctly before the MCU continues
executing code.
2. These options should only be used when not operating close to the maximum frequency of the
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
3. These options are intended for use with ceramic resonators and will ensure frequency stability
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
Table 6-9.
Crystal Oscillator Operating Modes
CKSEL3:1
Frequency Range (MHz)
Recommended C1 and C2 Value (pF)
0.4 - 0.9
–
101
0.9 - 3.0
12 - 22
110
3.0 - 8.0
12 - 22
111
8.0 -
12 - 22
Table 6-10.
Start-up Times for the Crystal Oscillator Clock Selection
CKSEL0
SUT1:0
Start-up Time from
Additional Delay
from Reset
Recommended Usage
0
00
14CK + 4 ms
Ceramic resonator,
fast rising power
0
01
14CK + 64 ms
Ceramic resonator,
slowly rising power
010
14CK
Ceramic resonator,
BOD enabled
011
14CK + 4 ms
Ceramic resonator,
fast rising power
100
14CK + 64 ms
Ceramic resonator,
slowly rising power
1
01
16K CK
14CK
Crystal Oscillator,
BOD enabled
1
10
16K CK
14CK + 4 ms
Crystal Oscillator,
fast rising power
1
11
16K CK
14CK + 64 ms
Crystal Oscillator,
slowly rising power