LT3966 Shorting and Idle heat

Hi Team,

I have built up about 20 boards using PN: LT3966.

There are 2 questions. I'm using the "100W Buck Mode LED Driver with I2C Dimming" configuration shown on the first page of the datasheet. Shown below is the current schematic that is used.

1) Upon power-up some boards and sitting idle for a couple of minutes, net "VIN" and net "INTVCC" become shorted to ground about 1.7Ohm. I have about 5 boards that have done this and subsequently I replace the part with a new one and everything is fine. What could be the possible reason for the LT3966 part to fail in a couple of minutes? (VIN = 52V. No load on any LED channels.)

2) The LT3966 get noticeably warm when no channels are connected to a load. Is there any settings in software that would cause excessive current draw even with no loaded channels? Or is something in my schematic connected wrong or wrong part value? 

Thank you for reading this and for your time. Much appreciated.


  • 0
    •  Analog Employees 
    on Oct 7, 2021 1:01 AM

    Hi Kevin,

    If you have built around 20 boards of this and only 5 are not working, we think it might be a manufacturability issue especially since replacing the IC with a new one fixes it. You may be getting boards with poorly soldered components which could also be a reason for heating. You may also check the parts if they're the same or if they came from a reliable source.