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The LM3485 is a high-efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, low-cost, switching buck regulator for a wide range of applications. The hysteretic control architecture provides for simple design without any control-loop stability concerns using a wide variety of external components. The PFET architecture also allows for low component count as well as ultralow dropout, 100% duty cycle operation. Another benefit is high efficiency operation at light loads without an increase in output ripple.

Current limit protection is provided by measuring the voltage across the R_DS(ON) of the PFET, thus eliminating the need for a sense resistor. The cycle-by-cycle current limit can be adjusted with a single resistor, ensuring safe operation over a range of output currents.