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TPS61086 the current limit delay time

tateo yamashiro
Guru 10890 points
Other Parts Discussed in Thread: TPS61086

Hi,

My customer has question about TPS61086.
Could you tell us about question?

[Question]
 My customer is worried about during a transient short circuit event.
 The current through the device increases very rapidly. So the IC can't respond quickly to current limit.
 How much is the current limit delay time?

Best Regards,
tateo

  • 0
    TI__Mastermind 40080 points
    Hi Tateo,
    TPS61086 doesn't have short circuit protection, because even we disable the IC, there still exist a current path from the input--inductor--output diode-output.This IC has current limit function when Vo is higher than Vin, but when there is a short circuit at the output side, which let the Vo even lower than Vin, all the current will flow through the output diode, then current limit function can't limit the current through the diode as the this function only detect the peak current in the low side MOSFET. So the current through the output diode will be very big.
    And when the output current is higher than the maximum output capability and the converter work in the current limit mode, the transition time from normal operation to current limit is depend on the reponse of EA. which is about 100us or more.
    Could you share the detailed application information with me. My email address is Helen-chen@ti.com.
    Please click answered if you satisfied with the answer :)BR,Helen
  • 0 in reply to Helen chen
    Guru 10890 points

    Thank you for your reply.

    We understand your suggestion.

    > the response of EA. which is about 100us or more.

     -> I think, 100us is long time. Is it correct?

    Best Regards,

    tateo

  • 0 in reply to tateo yamashiro
    TI__Mastermind 40080 points
    Because for the Boost converter, the cross over frequency fc is limited by its right half-plane zero, usually the fc is <20KHz, which may be about 10KHz, so the response is about 100us, if fc is lower than 10KHz, then the response time will be higher than 100us.
    The above analysis only for a current limit condition, in the short circuit condition, the current limit circuit can't take action. So the current limit response time is meaningless in the short circuir condition.