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TPL7407L: TPL7407L

Daniel Adolf
Prodigy 20 points
Part Number: TPL7407L

Part TPLD740LD will be destroyed in a series ( White goods project) and I can´t find the root cause

Schematic

Connected are only 2 Outputs (Nozzle Heater 1,9W + FAN 1,2W)

Controller Voltage is 3V3. The 3V3 are generated via a DC/DC buck

The destroyed parts look like this

The LDO and the uC are getting very warm

My first thought was a shortcut of one Output, but with this I was not able to reproduce the failure,

The next thought is a possible damage of the internal LDO, but what could be the reason for this or how can a reproduce the failure?

Thanks in advance for your support

  • 0
    TI__Mastermind 32650 points

    Hi Daniel,

    Looking at your power figures and operating voltage, I think that your max current through the channel (for the 1.9W system) is around 160mA. I think the current flowing through the device should be acceptable. These devices have no internal protection features like thermal shutdown.

    Could you replace the device with a TPL7407LA and retest? This is a more robust version of TPL7407L but is only rated to 30V. For your system, I think this should still be acceptable. This is a pin to pin replacement so no change to the PCB is necessary.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    Prodigy 20 points

    Hi Shreyas,

    thanks for your Feedback and I will try this.
    From you Point of view what could be the rootcause of this failure? A short cut on the Output or a Damage of the uC?

    The part is alwas destroyed at the same Position (left Picture) Another assuption from my side is when both Output were enabled at the same time. Could this lead to the failure?

    Would it be possible for you to deeply analyse the IC and see what has happenend in the inside?  

    Best regards

    Daniel

  • 0 in reply to Daniel Adolf
    TI__Mastermind 32650 points

    Hi Daniel,

    I believe you can submit a formal failure analysis request through the customer service portal but when the damage is gross and over a large area, further failure analysis is limited. Another option to get a failure analysis performed is to contact your TI sales rep who will be able to handle this request internally.

    In my opinion, I think a short current is possible but the devices could have been damaged during installation which could explain why you weren't able to replicate the failure with a short to GND event. Another cause could be that the internal diode is insufficient to handle the inductive kickback of your fan load. If damaged, this could provide a high current path through the system. Without a waveform of the specific failure, it will be tough to pinpoint this as this device has no protection features. 

    Thanks,

    Shreyas