LT3991 Datasheet | Linear Technology

Features n Ultralow Quiescent Current: 2.8µA IQ Regulating 12VIN to 3.3VOUT n Fixed Output Voltages: 3.3V, 5V 2.1µA IQ Regulating 12VIN n Low Ripple Burst Mode® Operation: Output Ripple < 15m VP-P n Wide Input Voltage Range: 4.3V to 55V n 1.2A Maximum Output Current n Adjustable Switching Frequency: 200k Hz to 2MHz n Synchronizable Between 250k Hz to 2MHz n Fast Transient Response n Accurate 1V Enable Pin Threshold n Low Shutdown Current: IQ = 700n A n Power Good Flag n Soft-Start Capability V n Internal pensation n Saturating Switch Design: 0.44Ω On-Resistance n Output Voltage: 1.19V to 30V n Small Thermally Enhanced 10-Pin MSOP Package and (3mm × 3mm) DFN Packages Applications n Automotive Battery Regulation n Power for Portable Products n Industrial Supplies LT3991/LT3991-3.3/LT3991-5 55V, 1.2A Step-Down Regulator with 2.8µA Quiescent Current Description The LT®3991 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 55V. 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 15m V in a typical application. An internally pensated current mode topology is used for fast transient response and good loop stability. A high efficiency 0.44Ω 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 LT3991, reducing the input supply current to 700n A. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUT reaches 91% of the programmed output voltage. The LT3991 is available in small 10-pin MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance. L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered...