We have a few of the modules in our multi PCB assembly stack . 2 modules ( MPM3632CGQV ) designed
for Vin = 8V
to Vout =3.3V ;
Testing under heated conditions for several weeks appears to have may stressed the devices
or possibly a more improved design.
Some recommendations would be helpful…thank you.
I am assuming that your circuit is properly functioning at room temperature. It is very important to ensure that the temperature of your device does not increase the rated temperature. Do you have a way of measuring the device temperature? Despite the controlled oven temperature, it is possible that the dissipated heat by the device and the ambient temperature are compounding.
I would recommend taking measures to dissipate heat as much as possible. Such as using heat sinks wider traces etc. You could also try placing components far apart to reduce thermal coupling.
I hope this helps.
Thank you for your expeditious response…
The module appears to be pulling less than 300 mA. Clearly well below the rating but very inefficient.
If you can review the layout and provide your additional thoughts:
best , adam
Are those your expected load specs for your application? You are right the device is inefficient at 300mA and probably why it is failing. Probably because the device is trying to dissipate the lost energy in the form of heat. See chart below:
You could try increasing the load current to increase the efficiency. If your requirement is to operate the device at a lower current you can try using MPM3804.
With regard to your layout, I don’t think your current board state should have a huge impact on the issues you are facing. But you can make a few improvements by reducing the size of your feedback loop. Please refer to the datasheet for best layout practices.
You can also refer to the Evaluation board datasheet for MPM3632C for more information.
Hope this helps!
In regard to your last comment:
" You are right the device is inefficient at 300mA and probably why it is failing. Probably because the device is trying to dissipate the lost energy in the form of heat. "
Because of the inefficiency, are you suggesting that the device may be overheating past the Thermal requirements and damaging the device?
If so, it appears a temperature probe on the device would be helpful for more understanding.
We did some further testing to evaluate the case/package temperature at the 300 mA load previously described … The temperature was approximately 85C +/- 2 C.
Can you please confirm during the MFG and testing process that the device goes through a temperature 'hardening/baking ’ process and if so, can you please share the temperature profile.