LT1938 Datasheet | Linear Technology

FEATURES - Wide Input Voltage Range: 3.6V to 25V - 2.2A Maximum Output Current - Adjustable Switching Frequency: 300k Hz to 2.8MHz - Low Shutdown Current: IQ < 1µA - Integrated Boost Diode - Power Good Flag - Saturating Switch Design: 0.18Ω On-Resistance - 1.265V Feedback Reference Voltage - Output Voltage: 1.265V to 20V - Soft-Start Capability - Small 10-Pin Thermally Enhanced (3mm × 3mm) DFN Package APPLICATIONS - Automotive Battery Regulation - Power for Portable Products - Distributed Supply Regulation - Industrial Supplies - Wall Transformer Regulation LT1938 25V, 2.2A, 2.8MHz Step-Down Switching Regulator DESCRIPTION The LT®1938 is an adjustable frequency (300k Hz to 2.8MHz) monolithic buck switching regulator that accepts input voltages up to 25V. A high efficiency 0.18Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control and logic circuitry. Current mode topology is used for fast transient response and good loop stability. The LT1938’s high operating frequency allows the use of small, low cost inductors and ceramic capacitors resulting in low output ripple while keeping total solution size to a minimum. The low current shutdown mode reduces input supply current to less than 1µA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT1938 is available in a 3mm × 3mm DFN package with Exposed Pad for low thermal resistance. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION VIN 4.5V TO 25V 3.3V Step-Down Converter 4.7µF OFF ON 16.2k 680p F VIN RUN/SS BD BOOST VC SW LT1938 RT PG BIAS 60.4k GND FB 0.47µF 4.7µH 324k 200k VOUT 3.3V 2.2A 22µF 1938...