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# TPS25831-Q1: Current Limit Accuracy

Part Number: TPS25831-Q1

Hello,

My customer is using TPS25831-Q1 for their design.

They have a question about current limit accuracy.

They are adopting “Buck average current limit.
According to the datasheet, Rsns=15mohms, Rset=300ohms and Rlimit=11.8Kohms are recommended for ILIMIT=3.3A.
If all Rsns, Rset and Rlimit are very accurate (no error at all), as a rule of thumb, how much could the ILIMIT vary under all over PVT variations?

Best regards,

K.Hirano

• Hi, Hirano,

There are not current limit data of RILIM=11.8k in datasheet EC table. But we can calculate the variation from the data of RLIMI=13k and RILIM=26.1k below.

From the table below, we can know the CSP-CSN variation (offset of amplifier) is 2.5mV (-40C<=Tj<=125C).

So when RILIM=11.8k, we can know the typical CSP-CSN=(1/11.8k)*2*300=50.85mV. Considering the offset, then CSP-CSN max will be 50.85+2.5mV, min will be 50.85-2.5mV, which corresponds to 3.557A and 3.223A.

Bob