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LM5035x / SR State in UVLO Shutdown and Hiccup Current Limit

K.Yaita
Guru 29720 points
Other Parts Discussed in Thread: LM5025, LM5025A, LM5025B, LM5025C

Hi Team,

I would like to ask about "SR State in UVLO Shutdown and Hiccup Current Limit" of LM5035x.



Does "High" indicate the following MOSFETs to "ON/ON" and "Low" indicate "OFF/OFF" in UVLO shutdown and hiccup current limit?
I would also like to know background of having this selection. 



Best Regards,
Yaita / Japan disty

  • 0
    TI__Genius 9130 points
    Kensuke-san,

    This is my understanding of the behaviour/differences, but I will double-check internally and confirm.

    For the LM5025/LM5025A/LM5025A-1, the SR1/2 signals are actively driven as the complement (i.e. inverse) of HO/LO, with dead-time between them, even during soft-stop, shutdown and hiccup-mode. In these modes, the SR1/2 outputs to will stay high (i.e. SR's on) as long as VCC & REF pin levels are greater than their internal UV levels.

    For the LM5025B, only the HO/LO signals ramp down during soft-stop, the SR1/2 signals will always be low (SR's off) during soft-stop, shutdown and hiccup modes.

    For the LM5025C, there is not soft-stop function, the SR1/2 signals will always be low (SR's off) during soft-stop, shutdown and hiccup modes.


    Thanks,
    Bernard
  • 0 in reply to Bernard Keogh
    Guru 29720 points

    Hi Bernard-san,

    Thank you for your support.
    I will wait for your feedback.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Guru 29720 points

    Hi Bernard-san,

    Is there any update for your confirmation?

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Intellectual 2230 points
    Hi Kensuke-san,

    Bernard's interpretation is absolutely right. One thing should be noticed is that shutdown means UVLO below 1.25V but above 0.4V threshold. The controller is in standby mode at this condition, when UVLO<0.4V the controller is in a low current shutdown mode and all the PWM output will be disabled(output low).

    Best Regards
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