SAK-C505L Infineon Technologies AG, SAK-C505L Datasheet - Page 50

• Manufacturer Part Number: SAK-C505L
• Description: 8-bit CMOS Microcontroller
• Manufacturer: Infineon Technologies AG

Oscillator Watchdog
The oscillator watchdog unit serves for four functions:
Data Sheet
– Monitoring of the on-chip oscillator’s function
– Fast internal reset after power-on
– Control of wake-up from software power-down mode
Note: The oscillator watchdog unit is always enabled.
The watchdog supervises the on-chip oscillator’s frequency; if it is lower than the frequency
of the auxiliary RC oscillator in the watchdog unit, the internal clock is supplied by the RC
oscillator and the device is brought into reset; if the failure condition disappears (i.e. the on-
chip oscillator has a higher frequency than the RC oscillator), the part executes a final reset
phase of typ. 1 ms in order to allow the oscillator to stabilize; then the oscillator watchdog reset
is released and the part starts program execution again.
The oscillator watchdog unit provides a clock supply for the reset before the on-chip oscillator
has started. The oscillator watchdog unit also works identically to the monitoring function.
When the software power-down mode is left by a low level at the P3.2/INT0 pin or an active
Real-Time Clock Interrupt Request flag IRTC, the oscillator watchdog unit assures that the
microcontroller resumes operation (execution of the power-down wake-up interrupt) with the
nominal clock rate. In the power-down mode the RC oscillator and the on-chip oscillator are
stopped. Both oscillators are started again when power-down mode is released. When the on-
chip oscillator has a higher frequency than the RC oscillator, the microcontroller starts
operation after a final delay of typ. 1 ms in order to allow the on-chip oscillator to stabilize.
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C505L
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