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BQ24074: Could you review BQ24074 SCH.

Downey Kim
Expert 2675 points
Part Number: BQ24074
Other Parts Discussed in Thread: BQ24073

Hi TI experts,

My customer is mass producing boards with BQ24074 applied.

The BQ24073 burnout or no output symptom occurred in 300 out of a total of 6000 products.

The circuit setting is as follows.

1. Vin : 5V

2. Iset : Around 1.3A

3. symptom : Device Burn-out or no Output.

Please review for any problems.

Thanks & Regards,

Downey Kim.

  • 0
    TI__Mastermind 23410 points

    Hi Downey,

    Looking at the schematic, I do not see any major issues. I would like to clarify the resistor valueon the ISET pin. Is 680k on the ISET pin correct? A 680k resistor will charge with 1mA. Is it intended for this resistor to be 680-Ohm? 

    I do not see any other issues. 

    Can you provide information on the situation at which the burnout or no output occurs? 

  • 0 in reply to Anthony P Pham
    Expert 2675 points

    Hi Anthony,

    IC burning occurs during charging.

    There is one suspicious thing. The customer separated the thermal pad from GND with a bead.

    There seems to be a problem with the heat dissipation. However, the BQ24074 has a temp protection function.

    Are there scenarios when temp protection doesn't work?

    Thanks.

  • 0 in reply to Downey Kim
    TI__Mastermind 23410 points

    Hi Downey,

    As the BQ24074 is a linear charger, the temp function is important but I suspect as the device is "burning" during charging this may be the case. Is the customer able to compare one unit with the thermal pad shorted to GND directly instead of through the bead? It sounds like for the other units that have no output, this may be the case.

    Is there a particular concern for the customer to be using a ferrite bead? It'd be interesting to know what the reason was for including it.

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Expert 2675 points

    Hi Anthony,

    It was short with GND instead of Bead, but the same defect occurred.

    If it's a problem with temperature, Charger IC should active thermal protection.

    We can't test it because we don't have a customer board. If I get B'D, I will ask you again after the test.

    Please check if IC failure can occur due to PCB design for Thermal pad.

    Thanks.

  • 0 in reply to Downey Kim
    TI__Mastermind 23410 points

    Hi Downey,

    Is it possible to get voltage waveforms of the input, battery, and output? Would also be helpful if there are current waveforms of IN, BAT, and OUT as well. 

    Best Regards,

    Anthony Pham