TPA3156D2: thermal runaway failure(catastrophic) when pushed beyond low output levels

Hello Ray,

Can you provide your schematic, also what output power are you encountering thermal runaway?

best regards,

Luis

Please note: the inputs are currently differential but single ended input has the same problem. The indicated 26V supply is set to 24 VDC for operation. C28 and C35 are 1206 NPO Caps on the bottom layer bonded to the ground plane between the two  sets of power pins directly underneath the chip. The two 220uF caps are located close to the power pins of the chip.

also it starts having issues with output around 12V RMS output across 4 ohm load

Hi Ray,

What's the issue with 12V RMS output across 4 ohm load? Is the fault triggered?

What's Isat of output inductor?

You said when increase output power there will have thermal issue, did you use fan to decrease temperature to double check? Was any fault triggered?

Regards,

Derek

https://www.mouser.com/datasheet/2/643/ds-ST-P177-SCIHP1367-1661426.pdf

The thermal issue is thermal runaway..which is to say something in the chip fails and then it  literally burns up; physically destroying the chip and the pad. The fault will trigger sometimes then it will sound choppy as it faults and resets but will ultimately fail. I have had one just fail abruptly with no fault having time to trigger. I know its something I am doing incorrectly but it is confusing because I can drive a TPA3116 at 25 VDC to the point of clipping  on the same pcb..with no trouble at all. This is at about 17volts RMS into a 4 ohm load. I have been using a ceramic heat sink with thermal tape..so the top heatsink pad does not end up bonded to ground. It works fine with the TPA3116 this way.

Hello Ray, 

For the damage devices are certain pins burned up? Do you have a image of the damaged devices on the board. Additionally can you provide of picture of your heatsink connection.

best regards,

Luis