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TPS2660: Circuit Breaker

tateo yamashiro
Guru 10890 points
Part Number: TPS2660

Hi,

We got a question from customer about TPS26600.
Could you help us?

[Question]
They would like to make sure the behavior of circuit breaker mode. They are thinking as following. Please let us know if there are misunderstanding.

 - Start-up -
 When the inrush current occurr, inrush lmited to current by R(lim).
 When the short circuit event occur, the fast-trip comparator turns off the internal FET within 250ns.

 - After start-up -
 When the overload condition occurr, the current flow through the device until I(load) < I(fastrip), and if the current flows I(cb) < I(load) < I(fastrip) for 4msec, the device will turn-off.
 If the current falls below I(cb) before the timer exceeds 4msec in overload condition, the timer will be reset.
 When the IC will be restart after retry delay 540ms, the behavior is same as start-up.
 When the short circuit event occur, the fast-trip comparator turns off the internal FET within 250ns.

Best Regards,
tateo

  • 0
    TI__Genius 16305 points
    Hi Tateo,

    Yes customer understanding is correct. Also please note additional information regarding device behaviour in circuit breaker mode.

    Startup:
    Inrush current limited to current set by R(lim) and fault timer starts at inrush. Fault timer expires after 4mS and turns off FETs.
    So if the 4mS time is not sufficient to charge Output capacitor, OUT may not fully charged. R(lim) needs tobe set accordingly.

    When a short circuit event occur during startup (or wakeup the device in OUT short to GND), fast trip comparator turns off internal FET within 250nS and then device enters current limit and stays in current limit for 4mS and turns off. Auto retry variant device (TPS26600 and TPS26602), attempts to restart after 540mS delay. If the short is removed before that device powers up. Latch off variant device (TPS26601) will remain off until reset by toggling SHDN or recycling VIN.

    After startup:
    Short circuit event after fast trip --> behaviour is similar to startup.

    Also in both startup and after start up state, device turns off if Tj > TSD before timer expires.

    Please get back if you need more inputs.

    Regards,
    Kari.