LT3975 Datasheet | Linear Technology

LT3975 42V, 2.5A, 2MHz Step-Down Switching Regulator with 2.7µA Quiescent Current Features Ultralow Quiescent Current: 2.7µA IQ at 12VIN to 3.3VOUT n Low Ripple Burst Mode® Operation Output Ripple < 15m VP-P n Wide Input Range: Operation from 4.3V to 42V n 2.5A Maximum Output Current n Excellent Start-Up and Dropout Performance n Adjustable Switching Frequency: 200k Hz to 2MHz n Synchronizable Between 250k Hz to 2MHz n Accurate Programmable Undervoltage Lockout n Low Shutdown Current: I = 700n A Q n Power Good Flag n Soft-Start Capability n Thermal Shutdown Protection n Current Limit Foldback with Soft-Start Override n Saturating Switch Design: 75mΩ On Resistance n Small, Thermally Enhanced 16-Lead MSOP Package n DESCRIPTION The LT®3975 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 42V. Low quiescent current design consumes only 2.7µA 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. The LT3975 can supply up to 2.5A of load current and has current limit foldback to limit power dissipation during short circuit. A low dropout voltage of 500m V is maintained when the input voltage drops below the programmed output voltage, such as during automotive cold crank. An internally pensated current mode topology is used for fast transient response and good loop stability. A high efficiency 75mΩ switch is included on the die along with a boost Schottky diode and the necessary oscillator, control, and logic circuitry. An accurate 1.02V threshold enable pin can be driven directly from a microcontroller or used as a programmable undervoltage lockout. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUT reaches 91.6% of the programmed output voltage. The LT3975 is available in a small 16-lead...