ata6603 ATMEL Corporation, ata6603 Datasheet - Page 55

• Manufacturer Part Number: ata6603
• Description: Microcontroller With Lin Transceiver, 5v Regulator And Watchdog
• Manufacturer: ATMEL Corporation

4.6.6
4921D–AUTO–08/07
Calibrated Internal RC Oscillator
The calibrated internal RC Oscillator by default provides a 8.0 MHz clock. The frequency is nom-
inal value at 3V and 25°C. The device is shipped with the CKDIV8 Fuse programmed. See
“System Clock Prescaler” on page 58
clock by programming the CKSEL Fuses as shown in
no external components. During reset, hardware 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 of 8 MHz ± 1%. The tolerance of the internal RC oscillator remains better than
±10% within the whole automotive temperature and voltage ranges (2.7V to 5.5V, –40°C to
+125°C). The oscillator can be calibrated to any frequency in the range 7.3 - 8.1 MHz within
±1% accuracy, by changing the OSCCAL register. When this Oscillator is used as the chip
clock, the Watchdog 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
on page
Table 4-11.
Notes:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 4-12.
Note:
Power Conditions
BOD enabled
Fast rising power
Slowly rising power
4-12.
1. The device is shipped with this option selected.
2. The frequency ranges are preliminary values. Actual values are TBD.
3. If 8 MHz frequency exceeds the specification of the device (depends on V
1. If the RSTDISBL fuse is programmed, this start-up time will be increased to
2.
302).
Fuse can be programmed in order to divide the internal frequency by 8.
14CK + 4.1 ms to ensure programming mode can be entered.
The device is shipped with this option selected.
Internal Calibrated RC Oscillator Operating Modes
Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
Frequency Range
7.3 - 8.1
Power-down and Power-save
Start-up Time from
(2)
(MHz)
for more details. This clock may be selected as the system
Reserved
6 CK
6 CK
6 CK
Table
ATA6602/ATA6603
4-11. If selected, it will operate with
Additional Delay from
Reset (V
14CK + 65 ms
14CK + 4.1 ms
(1)(3)
14CK
CC
CKSEL3..0
(1)
= 5.0V)
0010
(2)
CC
“Calibration Byte”
), the CKDIV8
SUT1..0
00
01
10
11
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