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LM5022-Q1: SEPIC Design

Part Number: LM5022-Q1
Other Parts Discussed in Thread: PMP20128, LM5022, PMP

Hi team,

My customer need a DCDC to support 6-16Vin, 9.6Vout, 1.5A output current, we are thinking about using LM5022-Q1 and follow this reference design http://www.ti.com/tool/PMP20128 

  • Hi team,

    My customer need a DCDC to support 6-16Vin, 9.6Vout, 1.5A output current, we are thinking about using LM5022-Q1 and follow this reference design PMP20128

    attached is the draft schematic, would you please help to review and suggest on component parameter requirement like inductor/diode/etc? 

    Kevin

  • Hi Kevin,

    Thank you promoting the device but I am afraid your customer referenced to a wrong circuit. The PMP20128 is a SEPIC with two outputs, of which one is obtained with charge pump. You just have one output, and the charge pump circuit can be saved. Namely, delete D1, D2, D4, D5 and C3 and C5. Besides, the way that you feed the charge pump output voltage to VCC would blow up the IC because it would exceed the 14V rating.

    You may reuse the PMP20128 coupled inductor, but you don't need 100V rated MOSFET and 60V rated diode. Chose 40V rated FET in the same size, MOSFET, and 40V rated diode. All the output capacitors 16V rated. Your 25V selection is not wrong, though. I don't think you need all three of C4, C6 and C7. Delete C7 and reserve C6, and just populate C4, to save board space and BOM cost.

    Hope these help.

    Thanks,
    Youhao Xi, Applications Engineering
  • Hi Youhao,

    would you please give us a example circuit of LM5022 SEPIC design? there is no SEPIC example circuit in the datasheet and WEBENCH is also not working for this design. thanks.

    Kevin
  • Hi Kevin,

    There are a few PMP ref designs of LM5022 SEPIC, which you can find on TI LM5022 web page, under the Tools and Software tag. I think the PMP7305 is close to your application:

    http://www.ti.com/tool/pmp7305

    Thanks,
    Youhao