Dear all!
Soon I'm going to get some special Netsys NS-280FX SFP switches on my repair desk.
Models which have been manufactured before 2023 will die in the field due to a bad PCB design.
Attached a picture of the PCB. This one has been repaired aready but you can see the baked PCB from the previous regulator
This is a small QFN-14 case and I seek for advice about how to cool that thing properly.
It's sitting in the airflow of a fan and maybe a simple yet small glue-on heatsink will do the trick.
Any product advice or real life trick?
Background:
The switching regulator MP8712GL-P has been used in this design to convert the 12V from the main PSU to 3.3V for all SFP modules.
Fully equipped with VDSL modems, the switch will draw significant current on the 3.3V rail.
Unfortunately the designer of the PCB was obviously skipping the "thermal design" section of the datasheet.
This will cause the poor regulator to operate at the upper thermal limit, bake & break with time and sometimes even switching off during operation.
Customer unhappy, public transport agency unhappy, travellers unhappy due to train departure terminals going offline...
Have a great week-end!
Cheers,
Bernhard