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TPS2552D: inrush current protection

Jim Tsai
Expert 4470 points
Part Number: TPS2552D
Other Parts Discussed in Thread: TPS2553D

Hi,

I check the datasheet and seems like there's no extra inrush current protection function of the device, right?

The only one current limit protection (included max DC output current and output short circuit) is to design a external resister on ILIM pin and the max value is 1.7A typical.

When overcurrent triggered, the device enter constant-current mode to limit output current but not turn off the internal FET to disable output, right?

  • 0
    TI__Expert 8980 points

    Hi, Jim,

    The datasheet has description of this, the part response differently in below two different condition.

    1. The first condition is when a short circuit or partial short circuit is present when the device is powered-up or enabled. The output voltage is held near zero potential with respect to ground and the TPS2552D and TPS2553D ramps the output current to IOS. The TPS2552D and TPS2553D devices limits the current to IOS until the overload condition is removed or the device begins to thermal cycle. 

    --> It means device enter constant current mode to limit current after enable or powered up.

    2.The second condition is when a short circuit, partial short circuit, or transient overload occurs while the device is enabled and powered on. The device responds to the overcurrent condition within time tIOS (see Figure 21). The current-sense amplifier is overdriven during this time and momentarily disables the internal current-limit MOSFET. The current-sense amplifier recovers and limits the output current to IOS. Similar to the previous case, the TPS2552D and TPS2553D devices limit the current to IOS until the overload condition is removed or the device begins to thermal cycle.

    --> It means device will turn of FET first then turn on into constant current limit mode to limit current.

    The only current limit point is set by external ILIMI resistor. If you want a 75mA current limit, you can connect ILIMIT pin to IN.

    Not sure what do you mean " extra inrush current protection". Above is how TPS2552D/3D do for current limit, I think it helps to avoid the inrush current in first scenario and helps to reduce inrush current in second scenario.

    Regards,

    Bob