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Original question:

UCC27517: Input capacitance

UCC27517: Input capacitance

Hideki Hayashi1
Expert 8390 points
Part Number: UCC27517
Other Parts Discussed in Thread: LM5155,

Tool/software:

Hi team,

Is it able to provide the input capacitance between IN+ and IN- pin?

This is needed to check the system work because the input is LM5155 (boost controller) and there is a limitation of Qg@Vcc * Fsw <35mA.

They uses UCC27517 between LM5155 and MOSFET to configure boost converter. If capacitance is not able to be provided, please check if it is ok.

Regards,

Hayashi

  • +1
    TI__Genius 14145 points

    Hey Hayashi,

    Thank you for reaching out with your questions regarding the UCC27517.

    There is not an input capacitance that we are able to provide for the input pins. They do have pullup/pulldown resistances as shown in the block diagram.

    While I am not the expert for the LM5155, it is designed for driving a MOSFET and the input requirements of the UCC27517 gate driver are much less than that of a MOSFET. So with the output of the LM5155 connected to the inputs of the UCC27517, I see no concern with regards to the average current sourcing ability of the LM5155 being less than 35mA. The inputs of the UCC27517 gate driver are configured to be compatible with MCUs and therefore do not require a large amount of current.

    Let me know if there are any further questions.

    Thank you,

    William Moore