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DRV8871: Wait Time when switching the control input (IN1, IN2) of the DC motor

Motoyasu Hattori
Genius 11065 points
Part Number: DRV8871

Hi,
My customer has the following questions of DRV8871.

*1. Could you please let us know the restrictions on Wait Time when switching the control input (IN1, IN2) of the DC motor?   Is it no issues on the case that the tPD + tR + tDEAD shown in Figure 6 on the datasheet P.9 is fully satisfied?  Please advise us.

*2. Could you please let us know any concerns on shortening the Wait Time?

Thanks and best regards,
M.HATTORI.

  • 0
    TI__Mastermind 37683 points

    Hi Motoyasu,

    Below are the answer to your questions:

    1. The minimum control input drive time (ON time) is tPD+tR+tDEAD as shown in Figure 6 of the datasheet. Switching the control inputs at a lower ON timer may lead to improper operation. If the dead time has not expired before the control outputs are switched, the outputs will remain at a High-Z state.
    2. One concern, as I mention in (1), is that the driver may not be able to drive the load since the outputs will remain in High-Z state. Another concern is shoot-through. tDEAD is added to ensure that the High-side and Low-side FETs on one half-bridge are not enabled at the same time which will cause shoot-through.

    I hope this answers the customer questions.