The LTC3809 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 VDSsensing 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 technique.Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation, extending operating time in battery-powered systems.The switching frequency can be programmed up to 750kHz, allowing the use of small surface mount inductors and capacitors.The LTC3809 is available in the tiny footprint thermally enhanced DFN and 10-lead MSOP packages.FeaturesPackageLTC3809PLL, Selectable Spread Spectrum, Power Good3x3 DFN-10, MS-10ELTC3809-1Tracking3x3 DFN-10, MS-10ELTC3808PLL, Selectable Spread Spectrum, Tracking, Power Good4x3 DFN-14, SSOP-16Applications1- or 2-Cell Lithium-Ion Powered DevicesPortable InstrumentsDistributed DC Power Systems