SDG #165 Designing some panelised PCBs for high power LEDs (Cree XHP 50.2)

This episode is a design walkthrough rather than a product test, covering the layout of small carrier boards for the Cree XHP 50.2 emitter, one of the higher output single die LEDs in the XLamp family and a part that demands serious attention to heat removal and current control.

The practical focus is on the details that trip people up when they first move from indicator LEDs to multi amp emitters. The XHP 50.2 sits on a thermal pad that has to be soldered properly, so the footprint needs generous copper, thermal vias or a metal substrate, and reflow or hot air rather than an iron. Forward voltage also matters: the part is available in 6V and 12V configurations, which changes the driver topology and the current headroom you can expect from a given supply.

Equally important is the choice to panelise. Breakout boards this small are wasteful to order individually and awkward to handle during assembly, so grouping several on a single panel with tabs or mouse bite perforations keeps the unit cost down, makes stencil printing practical, and gives you spares when an emitter is inevitably cooked during testing. The video also touches on the constant current requirement, since driving these emitters from a fixed voltage supply with a series resistor is a fast route to thermal runaway.

For anyone planning a torch, bike light or machine vision illuminator, the takeaway is that the PCB is part of the heatsink, and the design should be treated accordingly before any current is applied.