atam894 ATMEL Corporation, atam894 Datasheet - Page 19

• Manufacturer Part Number: atam894
• Description: Atam894 8k-flash Microcontroller
• Manufacturer: ATMEL Corporation

5.5.2.5
5.5.3
4679D–4BMCU–05/05
Clock Management
32-kHz Oscillator
Figure 5-17. Ceramic Resonator
Note:
Some applications require long-term time keeping or low resolution timing. In this case, an
on-chip, low power 32-kHz crystal oscillator can be used to generate both the SUBCL and the
SYSCL. In this mode, power consumption is greatly reduced. The 32-kHz crystal oscillator can
not be stopped while the power-down mode is in operation.
Figure 5-18. 32-kHz Crystal Oscillator
Note:
The clock management register controls the system clock divider and synchronization stage.
Writing to this register triggers the synchronization cycle.
Both, the 4-MHz and the 32-kHz crystal oscillator, use an integrated 14 stage divider circuit to sta-
bilize oscillation before the oscillator output is used as system clock. This results in an additional
delay of about 4 ms for the 4-MHz crystal and about 500 ms for the 32-kHz crystal.
Both, the 4-MHz and the 32-kHz crystal oscillator, use an integrated 14 stage divider circuit to sta-
bilize oscillation before the oscillator output is used as system clock. This results in an additional
delay of about 4 ms for the 4-MHz crystal and about 500 ms for the 32-kHz crystal.
configurable
C
C
*
configurable
3
4
32 kHz
XTAL
OSC1
OSC2
*
OSC1
OSC2
Cer.
Res
*
C
*
C
1
2
Oscin
Oscout
*
C
*
C
1
2
oscillator
32-kHz
Oscin
Oscout
oscillator
4-MHz
32Out
4Out
Stop
Osc-Stop
32Out
4Out
ATAM894
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