LTC3809

LTC3809 No RSENSE™, Low EMI, Synchronous DC/DC Controller FEATURES DESCRIPTION n No Current Sense Resistor Required n Selectable Spread Spectrum Frequency Modulation for Low Noise Operation n Constant Frequency Current Mode Operation for Excellent Line and Load Transient Response n True PLL for Frequency Locking or Adjustment (Frequency Range: 250kHz to 750kHz) n Wide VIN Range: 2.75V to 9.8V n Wide VOUT Range: 0.6V to VIN n 0.6V ±1.5% Reference n Low Dropout Operation: 100% Duty Cycle n Selectable Burst Mode®/Pulse-Skipping/Forced Continuous Operation n Auxiliary Winding Regulation n Internal Soft-Start Circuitry n Output Overvoltage Protection n Micropower Shutdown: IQ = 9μA n Tiny Thermally Enhanced Leadless (3mm × 3mm) DFN and 10-lead MSOP Packages APPLICATIONS n 1- or 2-Cell Lithium-Ion Powered Devices n Portable Instruments n Distributed DC Power Systems The LTC®3809 is a synchronous step-down switching regulator controller that drives external complementary power MOSFETs using few external components. The constant frequency current mode architecture with MOSFET VDS sensing eliminates the need for a current sense resistor and improves efficiency. For noise sensitive applications, the LTC3809 can be externally synchronized from 250kHz to 750kHz. Burst Mode is inhibited during synchronization or when the SYNC/MODE pin is pulled low to reduce noise and RF interference. To further reduce EMI, the LTC3809 incorporates a novel spread spectrum frequency modulation techniqu...