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DRV8908-Q1: DRV8908 slew rate control

Scarlett Cao
Expert 3470 points
Part Number: DRV8908-Q1

Hi Team

Could you please kindly help share feedback for below DRV8908-Q1 application questions:

From below datasheet description, slew rate time can be calculated through VOUT voltage change, can we understand that external inductive load turn on time is Tdead+TPD+VM（90%-10%）/SR ?

From below datasheet, can we adjust the MOSFET body diode conduction time through slew rate setting?

Thank you

Scarlett

  • 0
    TI__Guru 54695 points

    Scarlett,

    All of these delays are treated separately and outlined in section 8.3.1.2 of the datasheet.  

    Tdead will be added if the half-bridge is switching (figure 49).  Tprop is added if output is commanded to a different state over SPI (figure 50).  Slew time is shown in figure 47.  Effectively these do add together if the input command is commanding a change in the output.  

    Body diode conduction happens during dead time and before the FET is fully enhanced.  So, diode is conducting during part of the slew time.  For longer slew times, this time would be longer.  Indirectly, you are adjusting the body diode conduction.

    Regards,

    Ryan