MA12040 - Sensitivity to Failure

[mattw2727]

We are currently experiencing a high failure rate among the MA12040 amp ics used in the following circuit:

We are currently configured for a full bridge tied load (R45 and R44 are populated and L3 and L4 are not) - all output is going to J8.  PVDD is between 12V and 18V.

This design is producing subjectively good audio output results - but it seems highly sensitive to electrical failure.  We're seeing amp ics fail from time to time with no obvious cause.   There have been a couple which failed due to shorts between a pair of adjacent capacitors (C42 - C46) -- but even when no obvious stress occurred we're getting a number of failures with similar outcomes (IC internally shorted).

A couple questions: is there anything about this design that could explain this sensitivity  - and/or should be remedied to improve performance?  Is there anything about the new MA12070 amp IC that will improve this issue?

Thanks very much for any insights / input.

[amusz]

Hello @mattw2727 ,

This might be related to item 1.3 in the errata sheet. The PVDD rump up speed should be always lower than 0.25V/uS. This can be easily solved with a series 100mOhm/200mOhm resistor between P18V0 and C47 to build an RC constant when PVDD goes up. 

On a separate note, for 18V products we strongly recommend MA2304DNS or MA2304PNS as MA12040P is not recommended for new designs, unless the analog input is needed.

Best regards

[mattw2727]

Thanks for this initial response  - we are moving to the MA12070 part - is there any caution there?  Or would you recommend it as well (in addition to the MA2304DNS and MA2304PNS parts you mentioned)?

[amusz · Accepted solution]

Hi  @mattw2727 ,

The errata sheet items apply for both MA12040 and MA12070. If the application does not require higher supply voltages than 18V DC (+ it's ripple, for instance max 20V) we still recommend MA2304DNS or MA2304PNS as it has better performance as well in terms of efficiency, idle power consumption, residual noise, etc...

Best regards