Thermal Shutdown problem

Posted by: pentaindustrial on 03/25/2011

I have an over-temperature shutdown problem with some parts from the LOT Number J508 TOP247Y 32952A. Of 42 parts I´ve bought, 18 of them had thermal shutdown problem around 42 degrees. It means that parts shuts off when the CASE Temperature(I used and IR Thermometer and an contact thermometer) arises over aproximately 42degrees Celcius.

I´m going to attach the project pictures.

How can I proceed?
Thanks
Eduardo

Files

Top_Dsc06242.jpg (148.57 KB)

Bottom_Dsc06243.jpg (401.63 KB)

Schematic_0.gif (25.35 KB)

sep_IT_fonte.bom_.xls (21 KB)

Waves_0.pdf (72.17 KB)

Comments

Hi,

Were the thermal tests done with the shunt in place? Also where was the shunt placed? It is very important that it was placed in series with the Drain and NOT the source as the source is the internal ground for the MOSFET and controller and placing a resistance in series with the source will cause a ground reference shift between the controller and the external components!

We do not recommend making drain current measurements in this manner. If you must do so, as said above, make sure to place the shunt in series with the drain.

Also do you have any photos of how the thermal measurements were made? Please let me know!

Thanks!

-Wesley

Dear MR. Wesley

About the shunt current tests, I did them with a low shunt resistor in series with the drain. I measured the shunt voltage, that is proportional to the current(Of course, I not put the shunt resistor through the source tab).

I have no photos about the thermal tests, but I can explain you how I did.
*I measured the temperature using a multimeter temperature sensor glued with thermal paste at the TOP247Y Metal Tab(the same place where was the screw).
*The IR thermometer test I did it putting the IR phototransistor lens as near as possible to the TOP247Y Metal Tab.

ps: I did the thermal tests separately of the current tests, but with same component.

Thanks
Eduardo

Dear. Mr. Wesley.

Can you help me about that problem? Are there some althernative?

Thanks
Eduardo

I contacted PI official distributor in Brazil. Then, they send me some samples and ALL OF THEM WORKED VERY WELL, even in high temperature as 70degree.

So, I understand that the problem can be with some parts of the Lot I´ve mentioned.

Thanks for all assistance.
Sincerely
Eduardo