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TPS54335A: Bootstrap capacitor charging time

Shota Mago
Expert 8160 points
Part Number: TPS54335A

Hi team,

My customer has been using TPS54335A and provided some questions as follows.

  1. The datasheet says that minimum off time is 0% under condition that Vboot-ph>3V in section 6.7.
    Does this mean the device can work at 100% duty cycle as long as Vboot-ph keeps above 3V?
  2. The datasheet says that "When the voltage between BOOT and PH pins drops below the BOOT-PH UVLO threshold, which is 2.1 V (typical), the high-side MOSFET turns off and the low-side MOSFET turns on, allowing the boot capacitor to recharge" in section 7.3.9.
    How long time does it take for recharge when Vboot-ph drops below BOOT-PH UVLO threshold?
  3. Refering to equation (2), when the customer set Vstart is lower than target output voltage, does device work correctly?
    e.g. Vstart=7.5V, target Vout=9V
  4. Under condition that target output voltage is higher than input voltage, does device work correctly at 100% duty cycle?
    (Except for recharge time for bootstrap capacitor.)

I'm looking forward to hearing back from you.

Best regards,

Shota Mago