I'm converting ~55V to 5V through a LM5116. When things start up, it can be presented with a very low load, perhaps 12-20mA. It seems that when this occurs that the device does not regulate very well, and goes under voltage.
when i put a bigger load on the device ( putting some 10R/10W resistors across the output ), the device operates normally.
Normal operation will se loads of between 0.2 an 2.5A on the device and in that range it seems to be ok. Its just at start up.
I'm sure i've read somewhere about not having enough load to make it work.