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TDA2SX: Power down sequence

user4941165
Prodigy 30 points
Part Number: TDA2SX


In our design, the power supply scheme is 12V->5V& 3.3v -> PMIC TPS659039-> TDA2SX. When the system is shut down, the 12V input power will be disconnected directly, thus causing TDA2SX to fail to meet the power down sequence. My question is, what are the consequences of this,and what's the good solution, or can we ignore this problem?

Thanks!

  • 0
    TI__Mastermind 19560 points

    Hi,

    Please don't ignore the power-down sequence. It can lead to reliability issues.

    First solution I recall is to use one always-on 12-V supply, and one power-on/off signal such as car's ignition-on/off. The PMIC leakage is minimal therefore it should not drain car's battery.

    If you use a single 12-V supply, given you have large enough bulk filter capacitor,  you can detect the 12-V ramp down , and then issue a  power-off command  to PMIC. System would be powered by the discharging bulk capacitor during the power-off sequence. This however is a subject of further research and design and may not be as reliable as the first solution.

    Regards,

    Stan

  • 0 in reply to Stanislav Stilyanov
    Prodigy 30 points

    Since TDA2SX has a lot of power, it's hard to guarantee that all of them will be able to meet the power down sequence.If we can't fully meet, what are the things that must be met, and what can we ignore?

    Thanks!

  • 0 in reply to user4941165
    TI__Mastermind 19560 points
    "Since TDA2SX has a lot of power, it's hard to guarantee that all of them will be able to meet the power down sequence."
    - It is very hard to me to understand your concern.

    "If we can't fully meet, what are the things that must be met, and what can we ignore?"
    - The power-down sequence must be fully met. The sequence is pre-programmed in the PMIC. Again, I don't understand your concern. Most important point is to provide sufficient power during the power-down. I can't see other issues.