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TPS2597: TPS25970A Active Current limit Level vs Short Circuit

Arief Hernadi
Mastermind 23845 points
Part Number: TPS2597

Tool/software:

Hi, 

I am currently evaluating TPS2597 using the EVM for my customer. I set my active current limiting value of ILIM to be at 6.3A. 

When i ran the test, i verify if i slowly ramp the current limit using electronic load, the protection will be engaged at 6.3A which match the design target. 

But when i do a short circuit test, i can see that after the initial current spike, the current limit level is only ~4.8A instead of the ILIM set of 6.3A. 

Is this a normal operation for the part? If yes, do you know how the 4.8A value is derived from?

I attached the schematic and the scope shot below

Short Circuit Current limit test

Normal Active Current limiting

Thanks

-Arief

  • +1
    TI__Mastermind 38335 points

    Hi Arief,

    In our devices, we have current foldback when the Vout is low (Vout < VFB). During this current foldback, the current limit is expected to be lower than the ILIM value set by the external resistor. The VFB is given in the datasheet. The typical value of VFB is 1.88V for this device. 

    Arief Hernadi said:
    Is this a normal operation for the part? If yes, do you know how the 4.8A value is derived from?

    Current limiting during foldback is around 50-70% of the ILIM but may have even wider range.

    Please let me know if you have any other follow up questions on this.

    Best Regards,
    Arush