Can the RTC in BCM20737S works with external 32k LPO to wake up longer than 144 hours?

[Anonymous]

Hi,

I am using RTC function in BCM20737S to do a wakeup call in my design to activate some activities and then goes back to deep sleep again.

I use an external 32K LPO, that allows the RTC can wake up at anytime from 128ms to approx 144 hours.

However the sleep time of my design will be longer than 144 hours, that means once the device goes to deep sleep, it could wake up at a time that is longer than 144 hours.

How can I make the wake up time longer than 144 hours without wake up the device at every144 hours, say, to reload the RTC clock to run again.

If I do that, the device will need to wakeup every 144 hours elapsed for any longer sleep time than 144 hours though.

Please advise.

Alex

[JacobT_81]

Unfortunately, no, the RTC cannot be used for a timed-wake of longer than approximately 144 hours.

Jacob

[Anonymous · Accepted solution]

Thanks Jacob,

Then what I need is to wake up the BLE device at say 120 hours to do reload RTC again to then back to deep sleep mode.

This is proved to work on my design.

Thanks again.

Alex