CHR-IN restriction



I am using a Q2686 module, and I need a battery for backup.
My solution is, a step-down from 12V input to Vout=5V Iout=500mA, to the CHG-IN pin, and in Vbatt pin a 1 cell Li-ion battery.

I would like to know how restrictive is this CHG-IN input, I need other type of protection a part of the step down?. It can be another type of step-down. Is Q2686 controlling the current in this input signal.

Thank you.