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LMQ66430-Q1: External CBOOT

Masatoshi Oguri
Expert 4780 points
Part Number: LMQ66430-Q1

Hello,

In the “9.2.1.2.6 CBOOT” in p.30 of the datasheet, it is implied there might be a case that requires an external CBOOT. In what situation an external CBOOT comes necessary? What improvement will it provide?

Thank you.

Regards,

Oguri (TIJ automotive FAE)

  • +1
    TI__Genius 13210 points

    Hi Oguri,

    The driver of the high-side (HS) switch requires bias higher than VIN. The capacitor, CBOOT, connected between CBOOT and SW, works as a charge pump to boost voltage on the CBOOT pin to SW + VCC. The LMQ66430-Q1 has an integrated bootstrap 0.1-μF capacitor connected internally between the BOOT pin and the SW pin. This capacitance value is also the recommended value of CBOOT. Suitable under almost all normal operating conditions. However, if the customer thinks that the CBOOT capacity is not enough during the actual test and wants to enlarge it, it can be added appropriately.

    Aurora