LTC1267 Datasheet | Linear Technology

LTC1267 LTC1267-ADJ/LTC1267-ADJ5 Dual High Efficiency Synchronous Step-Down Switching Regulators Features s s s s s DESCRIPTIO s s s s s Dual Outputs: 3.3V and 5V, Two Adjustables or Adjustable and 5V Wide VIN Range: 4V to 40V Ultra-High Efficiency: Up to 95% Low Supply Current in Shutdown: 20µA Current Mode Operation for Excellent Line and Load Transient Response High Efficiency Maintained Over a Wide Output Current Range Independent Micropower Shutdown Very Low Dropout Operation: 100% Duty Cycle Synchronous FET Switching for High Efficiency Available in Standard 28-Pin SSOP The LTC®1267 series are dual synchronous step-down switching regulator controllers featuring automatic Burst Mode TM operation to maintain high efficiencies at low output currents. The LTC1267 is posed of two separate regulator blocks, each driving a pair of external plementary power MOSFETs at switching frequencies up to 400k Hz. The LTC1267 uses a constant off-time currentmode architecture to provide constant ripple current in the inductor and provide excellent line and load transient response. A separate pin and on-board switch allow the MOSFET driver power to be derived from the regulated output voltage, providing significant efficiency improvement when operating at high input voltage. The output current level is user-programmable via an external current sense resistor. The LTC1267 series is ideal for applications requiring dual output voltages with high conversion efficiencies over a wide load current range in a small amount of board space. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. APPLICATI s s s s Notebook and Palmtop puters Battery-Operated Digital Devices Portable Instruments DC Power Distribution Systems TYPICAL APPLICATI + CIN3 100µF 50V VIN 5.4V to 25V + 3.3µF 0.15µF 1N4148 8 0.1µF 4 5 14 1000p F 13 12 SENSE - 3 SHDN3 NGATE 3 PGND3 SGND3 CT3 7 11 9 VCC3 PGATE 3 PDRIVE 3...