I recently designed my first PCB, which houses LED driver circuitry for some custom lighting. I fastidiously followed the driver's datasheet (Diodes Inc AL8862QSP-13) in designing the circuit: making sure the inductor, capacitor, current sense resistor, and freewheel diode were suitable, and particularly ensuring input and output voltages (48v and 18-25v, respectively) were within spec.
I plugged it in and the LEDs lit briefly before tripping the power supply's overcurrent protection. I should have stopped here to think, but I instead connected it to a larger power supply (same voltage). Pop! All three drivers went up in smoke.
I've carefully reread the driver datasheet and scrutinized my design, and I am completely at a loss what might be wrong. My circuit is laid out exactly like the typical circuit in the datasheet.
The drivers are supposed to have overcurrent protection, so I'm not sure how they would have immediately blown up like that. This is only my second time doing SMD soldering (and I did it in a toaster oven), so that's a possible failure point, but the fact that 3 out of 3 drivers failed makes me think it's something other than that. Unless I possibly overheated the ICs in the toaster oven? I've also realized the exposed pad (EP) should be connected to ground, whereas I had it floating, but I don't think that's a major problem.
Can anyone provide suggestions? I've included a screenshot showing the schematic, pictures of the final product, and the KiCad PCB design (note that copper pours are not shown to make it easier to see the tracks). Inductor is 330uH (Bourns PM5022-331M-RC); capacitor is 10uF (Samsung CL31B106KBHNNNE); resistor is 100mOhm (Stackpole CSRN2512FTR100); freewheel diode is SMC DSS15U.
I have verified that the wire connections from J1 to the LEDs are in the correct order.
Track width was based on IPC-2152, which indicates that TINY (0.06mm) traces are sufficient for 40C rise with copper pour and 1oz copper. For safety, I increased this to 0.5mm. This board is also actively cooled with a fan. I've checked and double-checked to ensure the components are oriented properly.