We made a following schematic. On giving Vin = 4V using battery, Vout was 5.06V as expected. Load is very light and should be in few mA. We are just powering MCU.
Now the Vout is at~ 1V. What could be caused ?
We didn't touch anything in schematic. All we remember we disconnect/connect few times Vin supply coming from Lithium battery.
Thanks
We changed the IC and put 470uf/25V Electrolytic at I/P. IC seems to be working fine now. We toggle on/off many times and no issue now.. IC is working fine.
Anyway, earlier We had long wires coming from battery. Also we realized the layout is not good. Our pcb designer didn't pay attention to layout guideline document.
Below are waveform at SW and Vo captured with AC coupling. Yellow one is Vout. There is ringing in SW. Please let know your comments. 
Hi Nick,
SW ringing is normal for switching regulators and the IC will be fine as long as your SW spike is below our maximum ratings:
We advise measuring the SW spike under your maximum inductor current because the SW spike gets worse when heavy load is applied.
Best Regards,
Travis
