I amm trying to drive a CREE LED rated for 36v / 50 watts. I used TI Power Bench app to come up with the circuit using TPS40210, and someone else had pointed me to QX9920 for current control. The power supply for this project is a 360W 12V power supply. The TPS40210 is set to put out 42V, and the QX9920 is set to draw 1.36A of current. However it is only drawing about 170mA, the voltage supply circuit is supplying 42V, however its extremely noisy.
This is actually the second version of this board I did, I respun in to add a bunch of caps and a common mode choke on the 3.3V and 5V rails. Attached are schematics for the QX9920 and TPS40210 circuits, as well as various measurements of the 5V rail, 12V rail, QX9920 current sense, and mosfet drive pin for the QX9920.
Any help possible in getting this circuit to work is GREATLY appreciated. Any additional info needed and I will gladly post.