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TPS61040 inrush current question.

Chen Bogey8
Mastermind 9990 points
Other Parts Discussed in Thread: TPS61040

Dear Sir 

As i understand from P10 8.3.2, the TPS61040 inrush current should be limit in ILIM/4 in first step and ILIM/2 in next step.

but from Figure 15. Start-Up Behavior, it first inrush current 50mA/div * 4.5DIV = 225mA > 450mA/4 = 112.5mA.

Is i understand wrong or how to calculate inrush current?

                                                                Best regards,

                                                                              Bogey

  • 0
    TI__Mastermind 40080 points
    Bogey,
    what you mentioned is not the inrush current. Usually, the first peak current is determined by the input capacitor, not the converter. The bigger the input capacitor, the higher the first current peak. So please don't take the current waveform with in 100us after start-up as the inrush current.
    If we look at the first step and second step (ingore the first current peak), it is about ILIM/4 in first step and ILIM/2 in next step.
    Please click answered if you satisfied with the answer :)BR,Helen
  • 0 in reply to Helen chen
    Mastermind 9990 points

    Dear Sir

     My customer main concern is if TPS61040 will go to shut down due to inrush current(if first inrush current over ILIM)?

                                                                       Best regards,

                                                                                        Bogey

     

     

  • 0 in reply to Chen Bogey8
    TI__Mastermind 40080 points
    Hi Bogey,
    The TPS61040 will not enter into shut down because of the first inrush, the first sharp inrush current flow into the input capacitor instead of the TPS61040.
    Could you please share the detailed application information for us? Like what kind of equipment? Volume? MP schdule?You can send the information to me by email, my email address is helen-chen@ti.com
    BR,Helen