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TPS56339: Rboot

Julian Chen
Expert 2550 points
Part Number: TPS56339
Other Parts Discussed in Thread: TPS563249

Hi E2E,

I find the reference design of datasheet which R3 is 20R. (P.14)

Is  resistance value  too large? I concern that had short circuit issue.

(BTW, TPS563249 datasheet 1st version, reference design of datasheet which Rboot is 20R, But it modify to 0R from 2nd version) 

  • 0
    TI__Expert 4035 points

    Hi Julian,

    The bootstrap resistor is used to slow down the turn-on slew rate of the high-side MOSFET. Some customer required no damage with the ABS input voltage when doing the hard short test even though the real input voltage was much lower than the VIN ABS voltage., that's why the Rboot=20R was recommended in the datasheet. If no above requirement, and the real input voltage is much lower than 26V, a lower value of resistor is ok, even down to zero. In fact, we found no obvious difference in efficiency with Rboot=0R, 10R, 20R and 30R. So in the final version datasheet, we might use Rboot=30R as the default value.

    BRs,

    Ryan