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Supply voltage ramp rate of TAS5421

Hello,
We have just found on the TAS5421 datasheet a voltage ramp limitation in the datasheet 15V/m
We didn't understand a such limitation, as this component is build to be connected to vehicle's battery.
 Can you explain us a such limitation
and explain impacts ?
Regards

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  • Hi, Yuan,

    This requirement is for 40V load dump testing (ISO/DIS 7637-2 standard).  With wire/cable resistance and system capacitance the voltage slew rate is quite slow <<15V/ms.

    Thanks,

    Tuan

  • Hello Tuan,

    Thanks to see your reply!

    In fact, the input filter of the audio amplifier is quite the same as the one in datasheet:

    You can see there's a big capacitor(330uF) on the power supply line. And also, we have an MOSFET to control the switch on/off of the power supply(Trace is very short also).

    We have this problem because the audio amplifer can only perform load diagnostic when power on if no failure exist.
    So we should start stop many time in life cycle many time of the audio amplifier even it would be used very occasionally.
    Simulation&Test were done to show we may have the risk of over exceed this limitation in worst case:
    So, do you have any recommendation(what's the possible result and what the solution?)
    Thanks!

    Best wishes, 

    Junwen

  • Hello Tuan,

    Sorry I have made a mistake, for the 330uF input capacitor, we suppose to get a smaller ramp rate.

    If we reduce this capacitor for cost sake, it will surely become harder.

    Anyway, what we care about is just whether the chip will be damaged or malfunction if we get over limitation.

    Best wishes,