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LMR50410-Q1: Please check the LMR50410-Q1 parameter setting

Kygo Cheng
Expert 6830 points
Part Number: LMR50410-Q1
Other Parts Discussed in Thread: LMR50410

Hi Team,

The Tj formula of LMR50410 is currently being calculated, at 85℃

1. Please help confirm the setting of the subscript red box!

2.Does Trise & Tfall refer to Table 7.6 of the datasheet? THX

  • 0
    TI__Mastermind 27030 points

    HI 

    below is the raising and falling time for your refer, tested at 600mA.  The Theta JA at PCB board  will be smaller than JEDEC value, it is around 80deg C/W . we  don't know the Qg value, cause the fet is small, the drive loss will not dominated the power loss, so you value should be fine. 

    Thanks

    Vin

    SW Raising time

    SW Falling time

    12

    5ns

    2ns

    24

    5ns

    2ns

    36

    5ns

    3ns
  • 0 in reply to Daniel Li14
    TI__Expert 6830 points

    Hi Danel,

    Thank you!

    More question,

    What is the Ton_min & Ton _max  in the figure below refers to?

    It seems to be switch on-time too,THX

  • +1 in reply to Kygo Cheng
    TI__Mastermind 27030 points

    Hi 

    LMR50410 have frequency folderback feature, which means when you have like 33V to 3.3V with 2.1Mhz, the on time based on 2.1Mhz will be less than 60ns, then the device will keep working at its min on time and adjust the frequency to make the duty cycle stable. same as min off time, when Vin and Vo is very close, the device will extend the on time and fixed the off time at 110ns(typical) until its ton reach 7.5us, so that the max duty can reach around 98%-99%, but at this time, the frequency will become around 133Khz.