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LM27222: Max Duty Cycle

Naizeng Wang
Expert 4100 points
Part Number: LM27222
Other Parts Discussed in Thread: UCC27282

Hi team,

What's the max duty cycle of LM27222? If the duty cycle is too large, there may be problems with the bootstrap circuit.

Best regards,

Nison

  • 0
    TI__Genius 13445 points

    Hi Nilson,

    Thanks for reaching out. 

    You're correct, LM27222 uses bootstrap circuitry to provide bias to the high-side gate therefore the duty cycle will be restricted to allow sufficient time for the boot cap to fully charge the high-side gate but also adequate time to replenish. 

    If your application requires high duty cycle operation, you might consider implement an isolated bias to provide constant bias on the CB-SW node to maintain above the high-side gate thresholds. 

    THe link below discusses this further:

    https://e2e.ti.com/support/power-management/f/196/t/756946

    An example topology for high duty cycle is shown below using UCC27282 (an optimized version of LM device).

     

    Please let us know if you have additional questions or press the green button if this addressed your inquiry.

    Regards,

    -Mamadou