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Original question:

LM61460-Q1: RBOOT sw node rise time

LM61460-Q1: RBOOT internal circuit and principle

Bengi Long
Intellectual 2840 points

Part Number: LM61460-Q1

Hi team,

I want to know the internal circuit for RBOOT and CBOOT part and why increasing RBOOT can decrease SW rise time. Generally, TI parts only have a CPP pin which is 5V above SW node voltage, and we can series a resistor with charge pump capacitor to decrease the SW rise time. What is the principle here?

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  • 0
    TI__Genius 14630 points

    Hi Bengi

    thanks for your message. I will look into it and get back to you

  • 0 in reply to Naresh Adepu
    TI__Genius 14630 points

    Hi Bengi

    Increasing RBOOT slows the charging of the CBOOT capacitor, which supplies the gate drive for the high-side FET. This limits the inrush current to the gate during switching, reducing the dv/dt (slew rate) of the SW node and slowing the rise time. The principle is gate RC charging: higher RBOOT means a slower gate drive, so SW rises more gradually. This method helps control EMI and switching noise by tuning the gate drive speed.

    thanks and regards

    Naresh