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TPS61240: Start up issues into 18ohm static load

Part Number: TPS61240

I'm wondering if the device can startup with a 18R load on it?


There is a Figure 18 in the datasheet which is referenced as "Startup after Enable, Vin = 3.6 V, Vout = 5 V, Load = 16.5 Ω".  Based on that, 5V/16.5R = 300mA , but the graph itself has "Iout=150mA" on it.  Same as Figure 19.    Our design is very similar to this: We're supplying 4.2V (better than 3.6V) , 18R instead of 16.5R , and therefore 280mA load. However, the output is only reaching around 3.9V  - it seems to have reached a current limit and the output is folding back. However, the boost is spec'd to 500mA, and if we enable it with no load attached, we can load it to >400mA with no problem. Even as a step response from a few mA to 400mA its fine (But has to be after startup).


I wonder if you could help with these questions:


1/ Please check and confirm the details around Figure 18. Is it startup with load of 150mA or 300mA?


2/ What is the maximum current load permissible to startup with?  


3/ What are the limitations around that?