AT90CAN128-16AE ATMEL Corporation, AT90CAN128-16AE Datasheet - Page 39

• Manufacturer Part Number: AT90CAN128-16AE
• Description: 8-bit Avr Microcontroller With 128K Bytes of Isp Flash And CAN Controller.flash (Kbytes) 128 Vcc (V) 2.7-5.5 EEPROM (Kbytes) 4 SRAM (bytes) 4K CAN (mess. Obj.) 15
• Manufacturer: ATMEL Corporation

Calibrated Internal
RC Oscillator
4250C–CAN–03/04
Table 10. Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
Note:
The calibrated internal RC Oscillator provides a fixed 8.0 MHz clock. The frequency is
nominal value at 3V and 25 C. If 8 MHz frequency exceeds the specification of the
device (depends on V
internal frequency by 8 during start-up. The device is shipped with the CKDIV8 Fuse
programmed. See “System Clock Prescaler” on page 42 for more details. This clock
may be selected as the system clock by programming the CKSEL Fuses as shown in
Table 11. If selected, it will operate with no external components. During reset, hard-
ware loads the calibration byte into the OSCCAL Register and thereby automatically
calibrates the RC Oscillator. At 3V and 25 C, this calibration gives a frequency within ±
1% of the nominal frequency. When this Oscillator is used as the chip clock, the Watch-
dog Oscillator will still be used for the Watchdog Timer and for the Reset Time-out. For
more information on the pre-programmed calibration value, see the section “Calibration
Byte” on page 326.
Table 11. Internal Calibrated RC Oscillator Operating Modes
Note:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as
shown in Table 12.
Table 12. Start-up times for the internal calibrated RC Oscillator clock selection
Note:
SUT1..0
CKSEL3..0
10
0100
0110
00
01
11
0101
0111
(1)
(1)
(1)
1. These options should only be used if frequency stability at start-up is not important for
1. The device is shipped with this option selected.
1. The device is shipped with this option selected.
the application
CKSEL3..0
Start-up Time from Power-
down and Power-save
0010
CC
Power-down and Power-save
6 CK
6 CK
6 CK
), the CKDIV8 Fuse must be programmed in order to divide the
Start-up Time from
32K CK
32K CK
1K CK
1K CK
Additional Delay from
Reset (V
Reserved
14CK + 4.1 ms
14CK + 65 ms
14CK
CC
Nominal Frequency
= 5.0V)
8.0 MHz
(1)
Recommended Usage
Stable frequency at start-up
Stable frequency at start-up
AT90CAN128
Recommended Usage
BOD enabled
Fast rising power
Slowly rising power
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