LM3406 LED Driver Board

LM3406 LED driver

I was given a bunch of LM3406 1.5A switching buck converter led driver chips for evaluation purposes the other day. These chips make very powerful and efficient LED/laser diode drivers when used properly.
In order to make them useful a PCB had to be designed again, because the TSSOP14 package is too fine-pitched to prototype on a perfboard (as opposed to SOIC8). So I made an adjustable version with selectable output currents and had it manufactured by OSH Park.

LM3406 LED Driver Schematic

The trick behind the current adjustment is to have several sense resistors in parallel out of which certain ones can be added to or removed from the circuit via jumpers. The board is pretty versatile since you can add the appropriate resistors for currents you need and parallel them up if you are not able to find the right values. You don’t need to populate the entire row of resistors when a single fixed LED current is needed. Check out the data sheet for more information on sense resistor values.

In my current configuration you can select 300mA (no jumper), 700mA (only jumper in the middle populated) and 1000mA (all jumpers populated) and also some more exotic settings if you combine the jumpers differently.

Eagle board files:

LM3406 led driver

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