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Original question:

TPS2561: TPS2561 FAULT pin internal resistance

TPS2561: Confuse about the picture of fig 7-3: Full-Load to Short-Circuit Transient Response

Jason Shen
Intellectual 1945 points
Part Number: TPS2561

Dear experts

My customer have some confuse about the device behavior with the condition of Full-Load to Short-Circuit Transient Response.

From the picture, when a short condition happened, there have a current spike, and then seemed one channel have shutdown, and then the device ramp the current back to Ios.

The first confuse is why the channel will turn off after short?  And the second one is about the current spike peak(fig8-2. Response Time to Short Circuit Waveform), is this related with some parameters?

Thanks

Jun Shen

  • 0
    TI__Expert 8980 points

    Hi, Jun,

    Thanks for reaching out. Below are my comments to your questions.

    Q:The first confuse is why the channel will turn off after short?

    A: TPS2561 has very fast response time, which is 3.5us. To achieve this fast response time, the part need to pull down the gate of power FET very fast, so the FET is turned off. It's hard to achieve so fast response time and limit it to Ios without shutoff power FET. 

    Q:And the second one is about the current spike peak(fig8-2. Response Time to Short Circuit Waveform), is this related with some parameters?

    A: The current peak is related to VIN voltage and input cap slightly. Higher VIN voltage and input caps usually will cause higher current peak and faster response time.