RTC for TPS65950

Dang heng

Intellectual 880 points

Hi there,

From the looks of the signals capture for powering on sequence as attached.

It seems like the chip needs a VBKUP before it can do powering up.

VBKUP is the voltage for the RTC which is supplied by a coin cell battery or rechargerable battery.

I have a customer who is thinking of using a Supercap to replace the battery.

Does it means to say that on the very first initial power up, where the supercap have no charge at all, the device will not power up? It will only power up when the cap is charged up to a certain value.

Is there any supercap vaules to recommend?

Thank you in advance.

Adam8468.powering up sequence.doc

over 13 years ago

0 Gandhar Dighe over 13 years ago

TI__Genius 15100 points

Hi,

Backup supply status is not a starting event. Please refer to table 5-11 in the TRM for all starting events.

Based on this you can do not have to be concerned about the initial state of backup supply. You can use a supercap, the value and charge capacity will depend on what the customer requirements are in terms of holding a valid charge on this node.

Hope this helps.

0 Dang heng over 13 years ago in reply to Gandhar Dighe

Intellectual 880 points

Hi Gandhar,

thank you for your reply, so what does the timing signals means attached in my previous message means?

Thank you!

Adam

0 Gandhar Dighe over 13 years ago in reply to Dang heng

TI__Genius 15100 points

I woudl guess it is a copy-paste error. I am not sure myself why this plot will showup on the starting event page/list. To avoid confusion I will take it off. Even if backup is present the user cannot do anything till the device is active.

Power management

Power management forum

RTC for TPS65950