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# TPS25921A: Tolerance of ILIM in Design Calculation

Part Number: TPS25921A
Other Parts Discussed in Thread: TPS25921EVM-637, TPS2596

Dear all

The values of the following items (red frame) of "TPS25921EVM-637 Design Calculator Tool" are as follows.
① The items in the red frame are calculated from the tolerance of RLIM, but if you check the Excel formula, the square root of the sum of the square of the tolerance of RLIM and the square of 0.08 is calculated. . What factor does 0.08 (8%) mean here?

(2) Check the min, typ, and max values of ILIM in the data sheet, and the min and max values are specified at about ± 20% of the typ value. On the other hand, the tolerance of the above red frame is 8.1%. Which value is the correct current limit error?

Best Regards,

Y.Ottey

• Hi Ottey,

I will get back to you on this by end of day.

• Hi Ottey,

The '0.08' term in the SQRT(0.08^2+F32^2) is the current limit accuracy considering the entire current limit range.

For more accurate calculations, consider the current limit accuracy for the respective current limit from the graph below instead of 0.08 in the equation.

You can consider using our latest device TPS2596 instead of TPS25921 which is pin-to-pin replacement and also has better current limit accuracy.