The LT3971A is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 38V. Low quiescent current design consumes only 2.8μA of supply current while regulating with no load. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mV in a typical application. An internally compensated current mode topology is used for fast transient response and good loop stability. A high efficiency 0.33Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control and logic circuitry. An accurate 1V threshold enable pin can be used to shut down the LT3971A, reducing the input supply current to 700nA. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUTreaches 91% of the programmed output voltage. The LT3971A is available in a small 10-lead MSOP package with an exposed pad for low thermal resistance.The LT3971A and LT3971A-5 have a more accurate reference voltage compared to the LT3971 and LT3971-5. The LT3971A-5 also has specified VOUTpin current and ABSMAX current. These characteristics are important for USB applications.VOUTIOUTVREFAccuracyLT3971Adj1.2A2.5%LT3971-3.33.3V1.2A2.5%LT3971-55V1.2A2.5%LT3971AAdj1.3A1.5%LT3971A-55V1.3A1.5%ApplicationsUSB VBUS RegulationAutomotive Battery RegulationPower for Portable ProductsIndustrial Supplies