• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 567 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM3481: Schematic validation for the LM3481

Julien Riou17
Prodigy 160 points
Part Number: LM3481

Hello,

I am finalizing my design of a SEPIC supply based on LM3481, and I would like that some TI engineer validate my schematic, please.

Vin = 23.5 to 28V 

VUSB = 5V 

BATT_LIION_OUT = 3.2 to 4.2V

Iout = 220 mA / 1 A peak

T° range : 5°C to 70°C

Regards,

  • 0
    TI__Guru* 78080 points
    Hi Julien,

    Thank you for considering the LM3481 in your design. The schematic basically looks okay.
    (1) Just wondering why you use a TVS on UVLP pin. Shouldn't it be a Zener other than the TVS? Anyway, you may increase R58 to reduce the power loss in the voltage clamp device when VIn=28V.
    (2) BATT_LIION_OUT may not work, because the LM3481 requires a min input voltage of 2.97V. The forward voltage drop of D1 will reduce your 3.2V to below 2.97V.

    Thanks,
    Youhao Xi
  • 0 in reply to Youhao Xi
    Prodigy 160 points

    Hello Youhao,

    Thank you for your reply.

    1) I have put a TVS instead of a zener because I already had it in my BOM, whereas I hadn't any Zener. I will put a Zener and increase  the value of R58 as you suggest.

    2) If the systems stops when BATT_LIION_OUT reaches 3.3V it is not so important, as it is a secondary supply, used only in emergency cases.

    Have a nice day

    Julien Riou.