Power supply design with charging circuit
https://robu.in/product/micro-usb-5v-1a-18650-lithium-battery-charger-module/


This is TP4056 based 1-cell lithium ion battery charging circuit supports up to 1A with battery protection using (DW01A + FS8205).


  Can I give 5V supply at the input at this circuit and connect battery at the battery terminals?


Yes you can.


  Can I draw supply from the output terminals of the circuit infinitely?


You don't have to do this, since the module will shutdown its output once the battery gets to its full capacity.

once its shutdown the load draws power from battery again the output will be enabled once the battery voltage just drops below its maximum voltage... this cycle goes on repeating.

i am not saying it will not work. It will work but that is not a good approach.

So better go for some intelligent design to avoid the above case.


  The power adapter at the input will be connected forever and this is in turn connected to UPS. The battery is only for the unforeseen event when UPS also goes down. Will the circuit above work OK for an extended period application?


Yeh it will sustain.