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LM53600-Q1: 8V output voltage

tateo yamashiro
Guru 10890 points
Part Number: LM53600-Q1

Hi,

We got a question from the customer about LM53600-Q1.
Could you help us?

[Question]
They are considering using LM53600-Q1 for 8V output voltage. The IC is recommended to contact you for using out of recommended range. Are there any concerns for this usage?

 - Condition -
 Vin=15V
 Vout=8V
 Iout=8V
 Spread spectrum option

Best Regards,
tateo

  • 0
    TI__Guru 74402 points
    Hi Tateo,

    Let me contact the apps expert for this part. We'll get back to you shortly.

    Regards,
    Tim
  • 0 in reply to Timothy Hegarty
    TI__Expert 6245 points
    Hello Tateo,

    The adjustable version of the LM53600-Q1 is able to output 8 V. We recommend using an inductor of 8.2 or 10 uH, depending on output current. Also, at least 40 uF output capacitance, 60 uF preferred. Note that frequency fold back will start at an input voltage of approximately 20 V since frequency fold back for this device is independent of on-time. See curves for the 5 V output example in the applications section of the LM53600-Q1’s datasheet.

    If you would like more exact advice, please post your output current and step load response needed.
  • 0 in reply to Robert Blattner
    Guru 10890 points

    Hi, Thank your for your reply.

    Let me confirm one thing. I think the frequency foldback will start due to the minimum on time. According figure 21 in datasheet, it starts at approximately 100nsec on time. Therefore I assume even if the input voltage was 36V, the IC would not enter the frequency foldback. Is this my understanding correct?

    Best Regards,
    tateo

  • 0 in reply to tateo yamashiro
    TI__Expert 6245 points
    Hello Tateo-San

    This IC uses a circuit which senses input voltage to control frequency fold back. It will fold frequency at the same input voltage as the 5 V circuit in the datasheet. The actual minimum on time for this IC is less than 70 ns. The input voltage controlled fold back scheme that this IC uses allows the IC to run in current mode control even when in fold back.