Analog Devices Inc./Maxim Integrated

The LTC3805 is a current mode controller for flyback DC/DC converters designed to drive an N-channel MOSFET in high input and output voltage converter applications. Operating frequency and slope compensation can be programmed by external resistors. Programmable overcurrent sensing protects the converter from short-circuits. Soft-start can be programmed using an external capacitor and the soft-start capacitor also programs an automatic restart feature.The LTC3805 provides ±1.5% output voltage accuracy and consumes only 360μA of quiescent current during normal operation and only 40μA during micropower startup. Using a 9.5V internal shunt regulator, the LTC3805 can be powered from a high VINthrough a resistor or it can be powered directly from a low impedance DC voltage of 9V or less.The LTC3805 is available in the 10-lead MSOP package and the 3mm × 3mm DFN package.Turn On VoltageLTC38058.4VLTC3805-54.5VApplicationsTelecom Power Supplies42V and 12V Automotive Power SuppliesIsolated Electronic Equipment

The LTC3805-5 is a current mode DC/DC controller designed to drive an N-channel MOSFET in flyback, boost and SEPIC converter applications. Operating frequency and slope compensation can be programmed by external resistors. Programmable overcurrent sensing protects the converter from overload and short-circuit conditions. Soft-start can be programmed using an external capacitor and the soft-start capacitor also programs an automatic restart feature.The LTC3805-5 provides ±1.5% output voltage accuracy and consumes only 360μA of quiescent current during normal operation and only 40μA during micropower startup. Using a 9.5V internal shunt regulator, the LTC3805-5 can be powered from a high VINthrough a resistor or it can be powered directly from a low impedance DC voltage from 4.7V to 8.8V.The LTC3805-5 is available in the 10-lead MSOP package and the 3mm × 3mm DFN package.Turn On VoltageLTC38058.4VLTC3805-54.5VApplicationsAutomotive Power SuppliesTelecom Power SuppliesIsolated Electronic EquipmentAuxiliary/Housekeeping Power SuppliesPower over Ethernet

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

The LTC3810-5 is a synchronous step-down switching regulator controller that can directly step-down voltages from up to 60V, making it ideal for telecom and automotive applications. The LTC3810-5 uses a constant on-time valley current control architecture to deliver very low duty cycles with accurate cycle-by-cycle current limit, without requiring a sense resistor.A precise internal reference provides 0.5% DC accuracy. A high bandwidth (25MHz) error amplifier provides very fast line and load transient response. Large 1O gate drivers allow the LTC3810-5 to drive multiple MOSFETs for higher current applications. The operating frequency is selected by an external resistor and is compensated for variations in VINand can also be synchronized to an external clock for switching-noise sensitive applications. A shutdown pin allows the LTC3810-5 to be turned off, reducing the supply current to 240µA.Integrated bias control generates gate drive power from the input supply during start-up or when an output shortcircuit occurs, with the addition of a small external SOT23 MOSFET. When in regulation, power is derived from the output for higher efficiency.FeaturesAdj. UVLO, Sync & TrackingPackageLTC3810Vin 6.2V to 100V, 10V Driver VoltageYesSSOP-28LTC3810-5Vin 4.35V to 60V, 5.5V Driver VoltageYesQFN-32LTC3812-5Vin 4.35V to 60V, 5.5V Driver VoltageNoTSSOP-16EApplications48V Telecom and Base Station Power SuppliesNetworking Equipment, ServersAutomotive and Industrial Control Systems