LTC1142L

U U FEATURES s Dual Outputs: 3.3V and 5V or User Programmable s Ultrahigh Efficiency: Over 95% Possible s Current Mode Operation for Excellent Line and Load Transient Response s High Efficiency Maintained over 3 Decades of Output Current s Low Standby Current at Light Loads: 160µA/Output s Independent Micropower Shutdown: IQ < 40µA s Wide VIN Range: 3.5V to 20V s Very Low Dropout Operation: 100% Duty Cycle s Synchronous FET Switching for High Efficiency s Available in Standard 28-Pin SSOP U APPLICATIO S s Notebook and Palmtop Computers s Battery-Operated Digital Devices s Portable Instruments s DC Power Distribution Systems LTC1142/LTC1142L/LTC1142HV Dual High Efficiency Synchronous Step-Down Switching Regulators DESCRIPTIO The LTC®1142/LTC1142L/LTC1142HV are dual synchronous step-down switching regulator controllers featuring automatic Burst ModeTM operation to maintain high efficiencies at low output currents. The devices are composed of two separate regulator blocks, each driving a pair of external complementary power MOSFETs, at switching frequencies up to 250kHz, using a constant off-time current mode architecture providing constant ripple current in the inductor. The operating current level for both regulators is user programmable via an external current sense resistor. Wide input supply range allows operation from 3.5V* to 18V (20V maximum). Constant off-time architecture provides low dropout regulation limited only by the RDS(ON) of the external MOSFET and resistanc...