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LME49810 Issues - design flaws?

Stuart Ralston
Prodigy 40 points

I have noticed a potentially big issue with LME49810!

When the LME overheats, it seems to lock the output at the negative power rail. 

According to the datasheet, it goes into thermal shut-down at 150 degrees C and comes back out at 145 degrees C.

By purposely heating the chip up with a hot air gun, the output locks at the negative rail and does not unlock even if the chip cools down. It needs to be heated to about 150 degrees C for this to happen. When "locked" the chip seems to generate a lot more heat than normal and tends to stay around 90 degrees C.

Happens in mute mode and in play mode.

Anyone noticed this?

Could this be a design flaw?

  • TI__Guru** 109695 points
    Hi Stuart,

    First of all sorry for the delay.

    As you say this device has a thermal protection that locks the output when the temperature reaches the 150 degrees C.
    What may be happening with your device is that the overheat condition lasts a long time and the device cycles between the thermal shutdown temperature limits, this is also stated in the datasheet.

    Let me ask, if you reset the device after letting it to cool down, does it work fine?

    Best regards,

    Iván Salazar
  • in reply to Ivan Salazar
    Prodigy 40 points
    Hi Ivan,

    Thanks for the reply.

    I am finding that the output stays locked, even when the chip cools down. It does not seem to cycle in and out. But more to the point, it should not lock at VEE!

    After a power cycle, the device does reset and does work fine.

    Thoughts?

    Cheers,

    Stuart