ATAM894X-TNQY ATMEL [ATMEL Corporation], ATAM894X-TNQY Datasheet - Page 17

• Manufacturer Part Number: ATAM894X-TNQY
• Description: 8k-flash Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

5.5.2
5.5.2.1
5.5.2.2
4679D–4BMCU–05/05
Oscillator Circuits and External Clock Input Stage
RC-oscillator 1 Fully Integrated
External Input Clock
The ATAM894 series consists of four different internal oscillators: two RC-oscillators, one 4-MHz
crystal oscillator, one 32-kHz crystal oscillator and one external clock input stage.
For timing insensitive applications, it is possible to use the fully integrated RC-oscillator 1. It
operates without any external components and saves additional costs. The RC-oscillator 1 cen-
ter frequency tolerance is better than ±50% over the full temperature and voltage range. The
basic center frequency of the RC-oscillator 1 is f
default after power-on reset.
Figure 5-13. RC-oscillator 1
The OSC1 or OSC2 can be driven by an external clock source provided it meets the specified
duty cycle, rise and fall times and input levels. Additionally, the external clock stage contains a
supervisory circuit for the input clock. The supervisor function is controlled via the OS1, OS0 bit
in the SC register and the CCS bit in the CM register. If the external input clock is missing for
more than 1 ms and CCS = 0 is set in the CM register, the supervisory circuit generates a hard-
ware reset.
Figure 5-14. External Input Clock
Clock
Clock
Ext.
Ext.
or
OSC1
OSC2
RC-oscillator 1
Control
Ext. input clock
ExIn
Clock monitor
RcOut1
Stop
O
ExOut
Stop
4.0 MHz. The RC-oscillator 1 is selected by
Osc-Stop
RcOut1
Osc-Stop
RcOut1
CCS
Res
ATAM894
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