Temperature Problem with STM32F429 BGA Board

[Marc T]

Posted on March 15, 2018 at 16:06

Hello,

we have some temperature problems with STM32F429 (BGA) controller boards. If the temp. exceeds by some boards 40°C, and other boards at 60°C the internal voltage regulator shut down, measured at VCap1 & 2. Every temperature between 35°C and 80°C is possible. The shutdown temperature does not change, it remains fixed. Most controller don't have any problems, they functure with temp. over 80°C.

Any idea? What can I do?

BR Marc

[waclawek.jan]

Posted on March 15, 2018 at 16:41

What code do you run on it? Is there any powerdown mode invoked by the code? If yes, does the problem occur also when running a trivial code without powerdown?

Can't be related to BYPASS_REG's connection? Which BGA in particular?

JW

[Marc T]

Posted on March 15, 2018 at 16:57

Hello Jan,

the controller is in normal mode, without a powerdown function. The software is for every board the same, only some controller boards have the temp. failure. I see that the BYPASS_REG Pin is open

>:(

Could this the reason that some boards don't have any problems, and other make trouble? 

BR Marc

[waclawek.jan]

Posted on March 15, 2018 at 20:43

Certainly yes.

JW

[Marc T]

Posted on March 16, 2018 at 11:40

Hello Jan,

I drill a hole in the backside of the PCB and connect the ball of the BGA with a wire to GND.

That helps, the internal regulator works also with higher temperatures!

Thanks for your help!

BR Marc