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TPS7H2201-SP: Current limit setting accuracy

Part Number: TPS7H2201-SP

We want to use device TPS7H2201-SP to limit the current to 2.5A. In page 9 of datasheet, it is recommended to set limit to 3.5A (IOUT + 1A). Does this mean current limit will be triggered at 3.5A? Can this be reduced to 3A cut off?

Regards,

Sachin

ftscentre@corpbank.co.in

  • Hi Sachin,

     

    If Iout=2.5A then yes, the lowest value the current limit can be set to is 3.5A. Due to the accuracy of the current limit, it will be triggered within +/-20% of the value it is set to.

    If you want to ensure that the device doesn’t exceed 2.5A, then Iout will need to be lowered to 1.083A so that the current limit can be set to 2.083A. 

     

    Thanks,

    Sarah

  • Hi Sarah,

      

         If i set the IOUT to 1.083A & current limit to 2.083 A to ensure that the device doesn't exceed 2.5A, does this mean that the current cut-off from the device will be triggered only at 2.5A but not before that (means with load of less than 2.5A)?

    Thanks,

    Sachin

  • Hi Sachin,

    Because the current limit is not perfectly accurate, there are a range of loads that may trigger it instead of an exact load value. If the current limit is set to 2.083A, this means that the current limit will be triggered when the load reaches a value somewhere in the range of 20% lower (1.67A) to 20% greater (2.5A) than the set value. 

    IL*1.2 = Largest possible current limit trigger

    IL*0.8 = Lowest possible current limit trigger

    If you want to make sure the current limit is not triggered before 2.5A, you will need to set the current limit to at least 3.125A. However, you also need to make sure the current limit is not set below the minimum value from page 9 of the datasheet. 

    Let us know if you would like further clarification.

    Thanks,

    Sarah