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LM5149-Q1: LM5149 deadtime spec

Scarlett Cao
Expert 3830 points
Part Number: LM5149-Q1
Other Parts Discussed in Thread: LM5149

Hi team,

Could you please help share how the LM5149 20ns typ dead time is defined? Take LO off to HO on deadtime as example, is it counted from LO decreasing moment, or from LO dropping below the 2V threshold voltage?

Also customer would like to know if the deadtime is adjustable. 

They need to understand this to consider the  deadtime headroom with different gate resistor and gate cap. 

Thank you

Scarlett

  • 0
    TI__Mastermind 22299 points

    Hi Scarlett,

    The 20ns deadtime measurement is measured from command to command.

    For example, it is when LO starts falling to when HO starts rising.

    This will include the 7ns LO fall time in the datasheet.

    The dead time will increase if the fall-time increases, with larger gate capacitances.

    Hope this helps,

    -Orlando

  • 0 in reply to Orlando Murray
    Prodigy 30 points

    Thanks!

    "The dead time will increase if the fall-time increases, with larger gate capacitances." 

    It seems there are some detection modules/methods to monitor the LO falling and HO rising behavior to prevent cross conduction? can you share the details?

    Thanks!

  • 0 in reply to Cheng Hui
    TI__Mastermind 22299 points

    Hi,

    Correct, with adaptive deadtime, we wait for HO and LO to fall below 2V before turning on the other FET.

    -Orlando