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LM5105 MDT seems not to met the spec

na na78
Guru 16770 points
Other Parts Discussed in Thread: LM5105

Hi

We are evaluating LM5105SDX/NOPB and we are facing the problem that the datatime DT1 and DT2 are not the same.

We attached the image.

LM5105_DeadTime.ppt

According to tha datasheet, MDT is 50ns(typ) but measured value is 300ns.

What is the cause? Do you have idea?


BestRegards

  • 0
    TI__Mastermind 31580 points
    Hi

    I have asked one of the drivers application engineers to respond to your post. You should see a response soon.

    Regards

    Peter
  • 0
    TI__Mastermind 21685 points

    Hello,

    We regret you are seeing some issues with the LM5105. Induced noise from the layout can cause inconsistency in the dead time.

    For the dead time circuit, it is important in the board layout to have the resistor as close to the DT pin as possible and connected to a low impedance ground connection with short traces. Make sure the resistor ground connection is kelvin referenced to the VDD cap, ideally with a small ground plane. 

     The dead time resistance of 91k looks like it may be a little high for a 500ns target, referring to the Figure 17 curve in the datasheet.