Infineon SAB 80C517A, SAB 83C517A-5 User's Manual ... - Keil
Infineon SAB 80C517A, SAB 83C517A-5 User's Manual ... - Keil
Infineon SAB 80C517A, SAB 83C517A-5 User's Manual ... - Keil
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After the on-chip oscillator finally has started, the oscillator watchdog detects the correct function;<br />
then the watchdog still holds the reset active for a time period of 768 cycles of the RC oscillator in<br />
order to allow the oscillation of the on-chip oscillator to stabilize (figure 4-4, II). Subsequently the<br />
clock is supplied by the on-chip oscillator and the oscillator watchdog’s reset request is released<br />
(figure 4-4, III). However, an externally applied reset still remains (figure 4-4, IV) active and the<br />
device does not start program execution (figure 4-4, V) before the external reset is also released.<br />
Although the oscillator watchdog provides a fast internal reset it is additionally necessary to apply<br />
the external reset signal when powering up. The reasons are as follows:<br />
– Termination of Hardware Power Down Mode (a HWPD signal is overridden<br />
by reset)<br />
– Termination of Software Power Down Mode<br />
– Reset of the status flag OWDS that is set by the oscillator watchdog during the<br />
power up sequence.<br />
The external reset signal must be hold active at least until the on-chip oscillator has started and the<br />
internal watchdog reset phase is completed. An external reset time of more than 5 ms should be<br />
sufficient in typical applications. If only a capacitor at pin Reset is used a value of 100 nF provides<br />
the desired reset time.<br />
Semiconductor Group 4 - 9<br />
System Reset