ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 29

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

9223B–AVR–09/11
The Low Power Oscillator can operate in three different modes, each optimized for a specific
frequency range. The operating mode is selected by the fuses CKSEL3...1 as shown in
9-3 on page
Table 9-3.
The CKSEL0 Fuse together with the SUT1...0 Fuses select the start-up times as shown in
Table
Table 9-4.
Notes:
Oscillator Source / Power
Conditions
Ceramic resonator, fast
rising power
Ceramic resonator, slowly
rising power
Ceramic resonator, BOD
enabled
Ceramic resonator, fast
rising power
Ceramic resonator, slowly
rising power
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
Notes:
Atmel ATmega48PA/88PA/168PA [Preliminary]
Frequency Range
9-4.
8.0 - 16.0
1. This is the recommended CKSEL settings for the difference frequency ranges.
2. This option should not be used with crystals, only with ceramic resonators.
3. If the crystal frequency exceeds the specification of the device (depends on V
1. These options should only be used when not operating close to the maximum frequency of
2. These options are intended for use with ceramic resonators and will ensure frequency sta-
0.4 - 0.9
0.9 - 3.0
3.0 - 8.0
(MHz)
CKDIV8 Fuse can be programmed in order to divide the internal frequency by 8. It must be
ensured that the resulting divided clock meets the frequency specification of the device.
the device, and only if frequency stability at start-up is not important for the application.
These options are not suitable for crystals.
bility at start-up. They can also be used with crystals when not operating close to the
maximum frequency of the device, and if frequency stability at start-up is not important for
the application.
29.
Low Power Crystal Oscillator Operating Modes
Start-up Times for the Low Power Crystal Oscillator Clock Selection
Start-up Time from
Power-down and
Power-save
16K CK
16K CK
16K CK
258 CK
258 CK
1K CK
1K CK
1K CK
Capacitors C1 and C2 (pF)
Recommended Range for
12 - 22
12 - 22
12 - 22
–
Additional Delay from
14CK + 4.1ms
14CK + 4.1ms
14CK + 65ms
14CK + 65ms
14CK + 4.1ms
14CK + 65ms
(V
CC
14CK
Reset
14CK
= 5.0V)
(3)
(2)
(1)
(2)
(1)
(2)
CKSEL0
CKSEL3...1
0
0
0
0
1
1
1
1
100
101
110
111
CC
(2)
), the
SUT1...0
(1)
00
01
10
11
00
01
10
11
Table
29