Powering circuit directly from USB while charging li-ion battery side by side
I don't know whether this is a 100% perfect solution as per my requirement or not but seems to be working good and very much similar to the solution I was looking for.

Solution is Load sharing:  charging the battery and have the main circuit run normally

We can use any charge controller ic I am considering here is MCP73831 because of low cost and good features and 5-Pin SOT-23 package, just simple to use.




When USB power is applied this circuit will turn off Q1(P channel
MOSFET), and as long as (Vusb – D1 VF) > (Vbat – Q1 VSD)
then the load will instead use power from USB through D1.
When USB power is applied Q1 will turn off and stop current flowing from the
battery to the load, effectively disconnecting the battery. The load
will then use power from USB through D1.   
The time USB power disconnected, Q1 will turn on and battery will get connected to load.


Will have to test this for charging cycles per day because my requirement is to have low number of charging cycles(as charging/discharging continuously is not preferred and my circuit will be at remote position and will be powered ON 24x7).

For time being this solution looks good to me. 


  References: Thanks Microchip for good explanation on Load sharing concept
  ww1.microchip.com/downloads/en/AppNotes/01149c.pdf
  and a good blog from
  blog.zakkemble.co.uk/a-lithium-battery-charger-with-load-sharing/


as I have lower reputation so cannot share more than two links hence links posted as a string(sorry...)

Please correct me if I am wrong.