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LMZM33603: About Inverting circuit

Part Number: LMZM33603
Other Parts Discussed in Thread: LMZ14203H, LMZ14203, LMZ34002


Customer wants to use LMZM33603 under the following conditions:
・Vin=24V (AC adapter 24V±10%)

I have two questions.
1.Customers want to use ACadapter with 10% accuracy.
  Therefore, customers want to allow an input voltage of 26.4V.
  Is this usage condition acceptable?
  And Is it acceptable depending on the load current?

2.About Switching Frequency vs Output Voltage 
  Customers want a table of Inverting circuit versions.
  Can you provide that information?


Best Regards,

  • Hello Yusuke-san,

    26.4Vin to -12Vout will apply 38.4V across the LMZM33603 device, which is more than the recommended maximum operating input voltage for the part. Abs max is at 42V, so the part will likely survive but it is not recommended.

    I think it would be better to use the LMZ14203H, which is a 42V maximum operating part.

    You can use the typical application components for 12V output on page 16 of the datasheet.

    In terms of configuring the part, you can use the inverting application note for LMZ14203 (which is pin-to-pin to the "H" version of the part).


  • Denislav-san,

    Thank you for your kind support.
    I understand your explanation.
    Thank you for introducing LMZ14203.
    However, customers want to consider LMZM33603 with PKG size and function.

    When using at least 24V AC adapter,
    Recommended input voltage value of ± 5% (25.2V) is required.
    Do you have any solutions?

    And, Do you have "Switching Frequency vs negative output voltage" data? 

    Best Regards,

  • Hello Yusuke-san,

    For switching frequency guidance, I would suggest using the recommendations for VOUT = 12V (positive) and the maximum seen input voltage (e.g. 36V).  

    But anyway, it looks like they will need higher voltage rated part so we have to consider another option. 

    Please consider the LMZ34002 (datasheet link), which comes in a QFN package as well. It looks like it should fit their requirements.

    Here is the LMZ34002 output current capability vs VIN and VOUT:


  • Denislav-san,

    Thank you for your kind support.
    I understand your information.

    Could you do me one more favor?
    I don't get replies for the following threads.

    Best Regards,

  • Hi Yusuke-san,

    Sorry for the late reply. I've replied back to your message yesterday and am waiting on your comments of my questions.

    Please let us continue the discussion on the other thread. I will be closing this thread. 

    Thank you,