Rainbow Electronics ATmega64M1 - Manual (Page 30)

30
8209A–AVR–08/09
ATmega16M1/32M1/64M1
Notes: 1. The frequency ranges are preliminary values. Actual values are TBD.
2. This option should not be used with crystals, only with ceramic resonators.
The CKSEL0 Fuse together with the SUT1..0 Fuses select the start-up times as shown in Table
9-4 .
Notes: 1. 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.
2. 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 9-3. Crystal Oscillator Operating Modes
CKSEL3..1 Frequency Range (1) (MHz)
Recommended Range for Capacitors C1 and
C2 for Use with Crystals (pF)
100 (2) 0.4 - 0.9 –
101 0.9 - 3.0 12 - 22
110 3.0 - 8.0 12 - 22
111 8.0 -16.0 12 - 22
Table 9-4. Start-up Times for the Oscillator Clock Selection
CKSEL0 SUT1..0
Start-up Time from
Power-down and
Power-save
Additional Delay
from Reset
(V
CC
= 5.0V) Recommended Usage
0 00 258 CK (1) 14CK + 4.1 ms
Ceramic resonator, fast
rising power
0 01 258 CK (1) 14CK + 65 ms
Ceramic resonator, slowly
rising power
0 10 1K CK (2) 14CK
Ceramic resonator, BOD
enabled
0 11 1K CK (2) 14CK + 4.1 ms
Ceramic resonator, fast
rising power
1 00 1K CK (2) 14CK + 65 ms
Ceramic resonator, slowly
rising power
1 01 16K CK 14CK
Crystal Oscillator, BOD
enabled
1 10 16K CK 14CK + 4.1 ms
Crystal Oscillator, fast
rising power
1 11 16K CK 14CK + 65 ms
Crystal Oscillator, slowly
rising power