Precision Current Limiting with the LMP8646 and LP38501

The LMP8646 is a precision current limiter used to improve the current limit accuracy of any switching or linear regulator with an available feedback node. Many regulators might have an internal current limiter, but its output accuracy is often as high as 30%. The output accuracy of the LMP8646 can be as low as 3%, making it a preferred current limiter for many regulator applications. In this app note, we will discuss how to design the LMP8646 with the LP38501 voltage regulator and a resistive load application, as seen in Figure 1.

For this example, we will let the open-loop current to be 1.25A and the close-loop current, ILIMIT, to be 1A. An open-loop occurs when the LMP8646's output is not connected to the LP38501's ADJ pin; whereas, a close-loop scenario is when the LMP8646's output is connected to the LP38051's ADJ pin.

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