SAB80C517 Datasheet, PDF (43/61 Pages) Siemens Semiconductor Group – 8-Bit CMOS Single-Chip Microcontroller

SAB 80C517/80C537
Figure 11
Block Diagram of the Programmable Watchdog Timer
Oscillator Watchdog
The oscillator watchdog monitors the on-chip quartz oscillator. A detected oscillator failure
(f _OSC < appr. 300 kHz) causes a hardware reset. The reset state is held until the on-chip
oscillator is working again. The oscillator watchdog feature is enabled by a high level at pin
OWE (pin 69). An oscillator watchdog reset sets status flag OWDS which can be examined and
modified by software. Figure 12 shows a block diagram of the oscillator watchdog.
Figure 12
Functional Block Diagram of the Oscillator Watchdog
Semiconductor Group
42