JAGXi RTC recharge battery

[AmyChen]

Hello
Due to the consumption of RTC when the Vin is off is very high in the JAGXi.
I want to use a rechargeable coin cell LIR2032.
I know there is a charging circuit in the JAGXi SOM, but I can’t find any documentation describing the internal diagram in detail.
May I know what circuit can I refer to?
Or do I just need to connect a rechargeable battery on the VCC_RTC pin? Is a current limiting resistor required in the path? I don’t think I need a diode, that would block the current from charging the battery in reverse, right?
Can you draw me a simple circuit diagram?
Thank you.

[Trumany]

Just need to add a battery to the pin as listed in P2822 schematic: http://developer.nvidia.com/embedded/dlc/jetson-xavier-developer-kit-carrier-board-design-files-b03

[AmyChen]

Hi Trumany

Thanks for the reply.
But I can’t download anything from the link.
Possibly an invalid link?
I just want to know if there is a current limiting resistor in series in the path?
Thank you.

[Trumany]

You can search that in DLC: https://developer.nvidia.com/embedded/downloads

[AmyChen]

Hi Trumany

Thanks a lot.
Another thing, I am using a 3.6 volt LIR2032 rechageable coin battery. Is the voltage suitable for application?

What is the maximum charging voltage that can be set?
I can now set the voltage from 1.2V to 3.5V to charge the battery.
I found that I couldn’t set the voltage higher than 3.5V.
Even though I set it to 3.7V it was still 3.4V which I measured.

Thank you.

[Trumany]

As you can see in datasheet: The backup cells must provide a voltage in the range 2.5V to 3.5V. These will be charged with a constant current, and a constant voltage charger that can be configured between 2.5V and 3.5V (constant voltage) output and 50 uA to 800 uA
(constant current).