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LM5088: Usage as Negative Boost Converter

Kuramochi Tadahiko
Guru 28715 points
Part Number: LM5088
Other Parts Discussed in Thread: LM5022, TPS40200

Hi,

My customer is considering to use LM5088 on following condition.

VIN=-28V, VOUT=-48V, Iout=2.5A

Is there any specific caution point by using LM5088?

We read below application note.

www.ti.com/.../slyt516.pdf

Best Regards,

Kuramochi

  • 0
    TI__Mastermind 33090 points

    Hello Kuramoci san,

    From your specification it appears you need a negative to negative boost?  and you need the negative output voltage referenced to Gnd?

    If this is the case, you will need to use a Boost device.  From your specification, suggest using the LM5022.  See attached concept with the conceptual feedback level shift circuit.

    I hope this helps?

    David.

  • 0 in reply to David Baba
    Guru 28715 points
    Hi David-san,

    Thank you for your advice.

    However I'm confusing because I found following reference design.
    http://www.ti.com/tool/PMP4589
    This circuit consists of buck converter IC(TPS40200).

    Can both Buck and Boost use as negative boost converter?

    Best Regards,
    KUramochi
  • 0 in reply to Kuramochi Tadahiko
    TI__Mastermind 33090 points
    Hello Kuramochi san,

    Sorry for my confusion. After deeper analysis, I confirm you are correct and I need to clean this thread up by stating the following.

    1. if you there is a negative input and you need a more negative output, you can use a buck converter as a negative boost [as shown by PMP4589].
    2. if you have a negative input and you need a less negative output, you can use a boost converter as a negative buck [as I shown in the thread above].

    Back to the negative boost using the LM5088.

    I dont see any issues with using the LM5088 in this case.

    Hope this helps?