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LMR14006: Maximum and minimum voltage at Pin CB

vaibhav waman
Intellectual 270 points
Part Number: LMR14006

Hello Team,

we need bootstrap voltage for our MOSFET drive purpose. As we are already using LMR14006XDDCR in same circuit, can we use charge from CB capacitor ?

In that case what is the maximum and minimum voltage can appear on the boot capacitor ? Does TI recommend such application ? 

Currently I have observed ~19V at pin CB when input is at 12V and output at 5V.

  • 0
    TI__Genius 14350 points

    Hi,

    The CB capacitor is used to provide bootstrap voltage for high-side mosfet. You can find the maximum and minimum voltage at CB pin in datasheet.

    The Cboot capacitor added between CB pin and SW pin, so the maximum voltage of this capacitor is less than 10V.

    Best Regard,

    Aurora

  • 0 in reply to Aurora Tie
    Intellectual 270 points

    Thank you.

    datasheet says it will be at maximum 6V. but you mentioned 10V, so did you conisder additional voltage from SW pin ? 

    Also if difference betwwen input and output voltage of buck is very less then high side MOSFET operate at 100% duty cycle, In that case as per datasheet this CB to SW voltage can drop till 3V and then low side diode will refresh it ? Is my understanding correct ?

  • +1
    TI__Genius 14350 points

    Hi,

    Thanks for your feedback. The 10V I mentioned means that the CB capacitor can choose 10V withstand voltage, not means there are some addition voltage. For your second question, your understanding is correct.

    Best Regard,

    Aurora