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LMR23630: request LMR23630 bypass Capacitor selection guide for Internal LDO

user5313791
Prodigy 30 points
Part Number: LMR23630

I will use LMR23630 at my project.

I have a question while reading LMR23630 datasheet.

(that about iternal LDO of LMR23630 for operting internal contorol block and fet driver.)

teaching to me on datasheet that "Place a high-quality ceramic capacitor with a value of 2.2 μF to 10 μF, 16 V or higher rated voltage as close as possible to VCC and grounded to the exposed PAD and ground pins"

but i want to use 6.5V MLCC.

it is possibel or impassible?

I want to know, why rating voltage of MLCC is 16V? (Input voltage is maximum 38.0V)

  • 0
    TI__Mastermind 35210 points

    Hi,

    We recommend a 16V capacitor due to capacitor's capacitance derating (decreasing in value) as ambient temperature increases, as well DC voltage applied. I would recommend using a X7R and a value in that range where you can fit into a smaller package, than say a 10uF, such that you place the VCC cap as close as possible to the converter.

    Hopefully this answers your question.

  • 0 in reply to Marshall_Beck
    Prodigy 30 points

    Hi marshall.

    and thank you but i don't know.

    for example 

    10uF 6.3V is OK? or NO? - TDK   CGA3E1X7R0J225K080AC (cf. https://www.digikey.com/product-detail/en/tdk-corporation/CGA3E1X7R0J225K080AC/445-6933-1-ND/2672951

    I will use MLCC range of 2.2uF ~ 10uF . but rating voltage is 6.3V.

  • 0 in reply to user5313791
    TI__Mastermind 35210 points

    Sorry I was not clear in my last post, let me summarize my thoughts and then I will give you my suggestion.

    1. Capacitance decreases at elevated temperatures

    2. Capacitance decreases as applied DC voltage is increased

    We specify in the datasheet that we recommend at least a 2.2uF, 16V, X7R capacitor to ensure stability of the converter. Following this suggestion, you would ensure that your capacitor does not derate too much from its nominal value, as a higher DC voltage rating cap will derate less with a lower applied DC voltage (if your interested in me explaining further I have a few good resources that I can find for you). 

    I can not recommend using a 6.3V capacitor as that disagrees with the datasheet. I recommend you choosing a 2.2uF, 16V capacitor. 

    If you would like me to review your schematic, feel free to start a new thread and I will be willing to provide you with some feedback! 

  • 0 in reply to Marshall_Beck
    Prodigy 30 points

    OK!. I got it.

    thank you for your help. ;)