Periodic Wakeup From Power Down Without An External Oscillator - Philips P89LPC902 User Manual

Philips Semiconductors User's Manual - Preliminary -
WATCHDOG TIMER
P89LPC901/902/903

Periodic wakeup from Power down without an external oscillator

Without using an external oscillator source, the power consumption required in order to have a periodic wakeup is determined
by the power consumption of the internal oscillator source used to produce the wakeup.The Real-time clock running from the
internal RC oscillator can be used. The power consumption of this oscillator is approximately 300uA. Instead, if the WDT is used
to generate interrupts the current is reduced to approximately 50uA. Whenever the WDT underflows, the device will wake up.
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2003 Dec 8