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LM5101C: About timing specification

Part Number: LM5101C


I have a question about the LM5101C.

For details, please see the attached document.

Thank you.


  • Hello Masazumi,

    Thank you for the interest in the LM5101C. I support this device and will work to answer your questions.

    From the attached file I see you are asking what is the minimum value for the LO and HO turn on and turn off propagation delay.

    We will not be able to provide a guaranteed minimum specification, as this parameter minimum value was not determined before the device release.

    I have a question regarding why this value is a concern. In most applications the maximum propagation delays and the delay matching, tMON and tMOFF, are the concerns for driver timing in the application. Why are you concerned if the propagation delay is less than the typical, if the delay matching is guaranteed in the datasheet?

    I will research data that I can provide propagation delay lower values that can be expected in the device. These would not be guaranteed parameters however.


    Richard Herring

  • Hello,

    Thank you for your reply.

    The reason is necessary to adjust the dead time in detail to raise the efficiency and prevent through current.

    Thank you.

  • Hello Masazumi,
    If the concern is the propagation delay difference of the high side driver and the low side driver, for purposes of setting dead time, the parameters to pay attention is the TMON and TMOFF parameters in the datasheet.
    For the LM5101C the TMON which is the LO on and HO off delay matching is 4ns typical and 10ns max, the TMOFF is the LO off and HO on delay matching which is also 4ns typical and 10ns maximum.
    For dead time considerations if you have the typical 4ns dead time matching, and can have a maximum of 10ns you should add 6ns to the dead time above what you observe to be an optimum setting on a typical system. If you want to be conservative, and assume there may be perfect matching (0ns) on the converter in evaluation, and there can be a maximum of 10ns delay matching, you would add 10ns to the dead time over the observed optimum dead time.
    If there is concern from device to device, I will need to continue to research test data for expected minimum dead times.
    Please confirm if this answers your question, or need further information.

    Richard Herring