I developing an application where I need to current share a couple of external, stand-alone DC switch mode power supplies. I'm planning to use TI UC2907 as a load share controller. There aren't any application notes specifically on this chip, but there is a note on UC3907 with an approach that I want to use. It looks like it ties into the sense feedback lines to drive/share the current between the supplies.
In the application note it shows a rough schematic of the approach (see the attached image), but I'm a little confused what the highlighted portion is doing. It looks like it's clamping the emitter of the transistor at the chip's reference voltage but I don't really understand why. Does anyone have any idea what this portion of the circuit is doing?