ATA6612C View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
ATA6612C
Atmel Corporation
'ATA6612C' PDF : 312 Pages View PDF
When this oscillator is selected, start-up times are determined by the SUT fuses as shown in Table 5-12.
Table 5-12. Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
Power Conditions
BOD enabled
Start-up Time from Power-down and
Power-save
6CK
Additional Delay from Reset
(VCC = 5.0V)
14CK(1)
Fast rising power
6CK
14CK + 4.1ms
Slowly rising power
6CK
14CK + 65ms(2)
Note:
Reserved
1. If the RSTDISBL fuse is programmed, this start-up time will be increased to
14CK + 4.1ms to ensure programming mode can be entered.
2. The device is shipped with this option selected.
5.6.6.1 Oscillator Calibration Register – OSCCAL
Bit
Read/Write
Initial Value
7
CAL7
R/W
6
CAL6
R/W
5
4
3
2
CAL5 CAL4 CAL3 CAL2
R/W
R/W
R/W
R/W
Device Specific Calibration Value
1
CAL1
R/W
0
CAL0
R/W
OSCCAL
SUT1..0
00
01
10
11
• Bits 7..0 – CAL7..0: Oscillator Calibration Value
The oscillator calibration register is used to trim the calibrated internal RC oscillator to remove process variations from the
oscillator frequency. The factory-calibrated value is automatically written to this register during chip reset, giving an oscillator
frequency of 8.0MHz at 25°C. The application software can write this register to change the oscillator frequency. The
oscillator can be calibrated to any frequency in the range 7.3 to 8.1MHz within ±1% accuracy. Calibration outside that range
is not guaranteed.
Note that this oscillator is used to time EEPROM and flash write accesses, and these write times will be affected accordingly.
If the EEPROM or flash are written, do not calibrate to more than 8.8MHz. Otherwise, the EEPROM or flash write may fail.
The CAL7 bit determines the range of operation for the oscillator. Setting this bit to 0 gives the lowest frequency range,
setting this bit to 1 gives the highest frequency range. The two frequency ranges are overlapping, in other words a setting of
OSCCAL = 0x7F gives a higher frequency than OSCCAL = 0x80.
The CAL6..0 bits are used to tune the frequency within the selected range. A setting of 0x00 gives the lowest frequency in
that range, and a setting of 0x7F gives the highest frequency in the range. Incrementing CAL6..0 by 1 will give a frequency
increment of less than 2% in the frequency range 7.3 - 8.1MHz.
5.6.7
128kHz Internal Oscillator
The 128kHz internal oscillator is a low power oscillator providing a clock of 128kHz. The frequency is nominal at 3V and
25°C. This clock may be select as the system clock by programming the CKSEL fuses to “11” as shown in Table 5-13.
Table 5-13. 128kHz Internal Oscillator Operating Modes
Note:
Nominal Frequency
128kHz
1. The frequency is preliminary value. Actual value is TBD.
CKSEL3..0
0011
52 ATA6612C/ATA6613C [DATASHEET]
9111L–AUTO–11/14
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