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DRV8412: Understanding the section 7.3.2.2 of data sheet

Jonathan Geronga
Expert 7930 points
Part Number: DRV8412

Hi Team, 

I am posting this inquiry in behalf of our customer:

I am working with the DRV8412 part and need assistance understanding the section 7.3.2.2. Does the part guard itself against shoot thru due to improper high and low side drive FET timing? My circuit has > 10micro-henrys of inductance on the output filter so I believe it has enough output inductance to protect against a short in the actuator coil.

Thanks!

Jonathan

  • 0
    TI__Guru** 114905 points
    Hi Jonathan,

    First the DRV8412 has internal shoot through protection. There is internal circuitry that monitors the low and high side FETs to ensure the opposite side is off before turning on the desired FET.


    I am assuming the reset of the thread is regarding the paragraphs above and below the one quoted below:

    "However during a short condition, the motor (or other load) is shorted, so the load inductance is not present in
    the system anymore; the current in the device can reach such a high level that may exceed the abs max current
    rating due to extremely low impendence in the short circuit path and high di/dt before oc detection circuit kicks in.
    So a ferrite bead or inductor is recommended to use the short-circuit protection feature in DRV841x2. With an
    external inductance or ferrite bead, the current will rise at a much slower rate and reach a lower current level
    before oc protection starts. The device will then either operate CBC current limit or OC shut down automatically
    (when current is well above the current limit threshold) to protect the system."

    These paragraphs assume something has damaged the load and there is little or no inductance seen at the outputs. If this occurs, the current can rise very quickly and exceed the abs max current rating. That is why the ferrite bead or inductor is recommended.