Analog Devices

The LTC3736-1 is a 2-phase dual synchronous stepdown switching regulator controller with tracking that drives external complementary power MOSFETs using few external components. The constant frequency current mode architecture with MOSFET VDSsensing eliminates the need for sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are minimized by operating the two controllers out of phase.A unique spread spectrum architecture randomly varies the LTC3736-1’s switching frequency from 450kHz to 580kHz, significantly reducing the peak radiated and conducted noise on both the input and output supplies, making it easier to comply with electromagnetic interference (EMI) standards.Pulse skipping operation provides high efficiency at light loads. 100% duty cycle capability provides low dropout operation, extending operating time in battery-powered systems. The high switching frequencies allow for the use of small surface mount inductors and capacitors.The LTC3736-1 is available in the low profile (0.75mm) 24-pin thermally enhanced (4mm × 4mm) QFN package and 24-lead narrow SSOP packages.Max Current Sense VoltageBurst ModeSoft StartSpread SpectrumLTC3736204mVYesNoNoLTC3736-1204mVNoNoYesLTC3736-2345mVNoYesNoApplicationsOne or Two Lithium-Ion Powered DevicesNotebook and Palmtop Computers, PDAsPortable InstrumentsDistributed DC Power Systems

The LTC3737 is a 2-phase dual step-down switching regulator controller that requires few external components. The constant frequency current mode architecture provides excellent AC and DC load and line regulation. MOSFET VDSsensing eliminates the need for current sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are minimized by operating the two controllers out of phase.Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation and extends battery operating time.Switching frequency can be programmed up to 750kHz, allowing the use of small surface mount inductors and capacitors. For noise sensitive applications, the LTC3737 can be externally synchronized from 250kHz to 850kHz.Other features include a power good output voltage monitor, a tracking input and internal soft-start.The LTC3737 is available in the low profile thermally enhanced (4mm × 4mm) QFN package or a 24-lead SSOP narrow package.Protected by U.S. Patents, including 5481178, 5731694, 5929620, 6144194, 6580258, 5994885ApplicationsOne or Two Lithium-Ion Powered DevicesNotebook and Palmtop Computers, PDAsPortable InstrumentsDistributed DC Power Systems

The LTC3738 is a 3-phase synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable, fixed frequency architecture. The 3-phase technique effectively triples the fundamental frequency, improving transient response while operating each controller at an optimal frequency for efficiency and ease of thermal design. Light load efficiency is optimized by using a choice of output Stage Shedding or Pulse Skip mode technology.The LTC3738 also allows users to program load slope via a resistor for AVP control. Both external and internal thermal sensing are available from the on-chip thermal detector and comparator.A differential amplifier provides sensing of both the high and low sides of the output voltage.Soft-start and a defeatable, timed short-circuit shutdown protect the MOSFETs and the load. A foldback current circuit also provides protection for the external MOSFETs under short-circuit or overload conditions. An all- "1" VID detector turns off the regulator after a 1µs timeout.ApplicationsHigh Performance Notebook ComputersServers, Desktop Computers and Workstations

The LTC3765 is a start-up controller and gate driver for use in a self-starting secondary-side control forward converter. When combined with the LTC3766 secondary-side synchronous forward controller, a complete isolated power supply is created using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals and bias power across the isolation barrier through a small pulse transformer. The LTC3765 contains an onchip bridge rectifier that extracts gate drive bias power from this pulse transformer, eliminating the need for a separate bias supply. A precision undervoltage lockout circuit and linear regulator controller ensure a quick and well-controlled start-up.The LTC3765 includes an active clamp output for driving an external PMOS, as well as an adjustable delay to optimize efficiency. The active clamp architecture reduces voltage stress on the main power switch, and provides the highest possible efficiency. Overcurrent protection and the Direct Flux Limit guarantee no transformer saturation without compromising transient response.ApplicationsIsolated Battery ChargersIsolated 48V Telecommunication SystemsServers and Embedded ComputingAutomotive and Heavy Equipment

The LTC3766 is a PolyPhase-capable secondary-side controller for synchronous forward converters. When used in conjunction with the LTC3765 active-clamp forward controller and gate driver, the part creates a complete isolated power supply that combines the power of multiphase operation with the speed of secondary-side control.The LTC3766 has been designed to simplify the design of active clamp forward converters. Working in concert with the LTC3765, the LTC3766 forms a robust, self-starting converter that eliminates the need for the separate bias regulator that is commonly used in secondary-side control applications. A precision current-limit coupled with clean start-up into a pre-biased load make the LTC3766 an excellent choice for high-power battery charger applications.The LTC3766 provides extensive remote sensing and output protection features, while Direct Flux Limit guarantees no transformer saturation without compromising transient response. A linear regulator controller and internal bypass LDO are also provided to simplify the generation of the secondary-side bias voltage.ApplicationsIsolated 48V Telecommunication SystemsIsolated Battery ChargersAutomotive and Military SystemsIndustrial, Avionics and Heavy Equipment

LTC3769 is a high performance single output synchronous boost converter controller that drives an all N-channel power MOSFET stage. Synchronous rectification increases efficiency, reduces power losses and eases thermal requirements, simplifying high power boost applications. The 28μA no-load quiescent current extends operating run time in battery-powered systems.A 4.5V to 60V input supply range encompasses a wide range of system architectures and battery chemistries. When biased from the output of the boost converter or another auxiliary supply, the LTC3769 can operate from an input supply as low as 2.3V after start-up. The operating frequency can be set within a 50kHz to 900kHz range or synchronized to an external clock using the internal PLL.The SS pin ramps the output voltage during start-up. The PLLIN/MODE pin selects Burst Mode®operation, pulse-skipping mode or forced continuous mode at light loads.APPLICATIONSIndustrialAutomotiveMedicalMilitary

The LTC3770 is a synchronous step-down switching regulator controller with output voltage up/down tracking capability and voltage margining. Its advanced functions and high accuracy reference are ideal for powering high performance server, ASIC and computer memory systems.The LTC3770 uses a constant on-time, valley current mode control architecture to deliver very low duty factors without requiring a sense resistor. The operating frequency is selected by an external resistor and is compensated for variations in input supply voltage. An internal phase-lock loop allows the IC to be synchronized to an external clock.Fault protection is provided by an overvoltage comparator and input undervoltage lockout. The regulator current limit is user programmable. A wide supply range allows voltages as high as 32V to be stepped down to as low as a 0.6V output. Power supply sequencing is accomplished using an external soft-start timing capacitor.ApplicationsDistributed Power SystemsServer Power Supply

The LTC3772B is a constant frequency current mode step-down DC/DC controller in a low profile 8-lead SOT-23 (ThinSOT™) and a 3mm × 2mm DFN package. The No RSENSE™architecture eliminates the need for a current sense resistor, improving efficiency and saving board space.The LTC3772B automatically switches into pulse skipping operation at light loads. It consumes only 200μA of quiescent current under a no-load condition.The LTC3772B incorporates an undervoltage lockout feature that shuts down the device when the input voltage falls below 2V. To maximize the runtime from a battery source, the external P-channel MOSFET is turned on continuously in dropout (100% duty cycle). High switching frequency of 550kHz allows the use of a small inductor and capacitors. An internal soft-start smoothly ramps the output voltage from zero to its regulation point.Burst ModeLTC3772YesLTC3772BNoApplications1- or 2-Cell Li-Ion Battery-Powered ApplicationsWireless DevicesPortable ComputersDistributed Power Systems

The LTC3773 is a high performance, 3-phase, triple output synchronous step-down switching regulator controller with output voltage power up/down tracking capability. The controller allows for sequential, coincident or ratiometric tracking.This 3-phase controller drives its output stages with 120° phase separation at frequencies of up to 700kHz per phase minimizing the RMS input current. Light load efficiency can be maximized by using selectable Burst Mode operation. The 0.6V precision reference supports output voltages from 0.6V to 5V.Fault protection features include output overvoltage, input undervoltage lockout plus current foldback under short-circuit or overload conditions.ApplicationsServers, Telecom, Industrial Power SuppliesGeneral Purpose Multiple Rail DC/DCFPGA and DSP Requirements

The LTC3774 is a dual PolyPhase®current mode synchronous step-down switching regulator controller that drives power blocks, DRMOS or external gate drivers and power MOSFETs. It offers an LTC-proprietary technique that enhances the signal-to-noise ratio of the current sense signal, allowing the use of inductors with very low DC winding resistances as the current sense element for maximum efficiency and reduced jitter.The maximum current sense voltage is programmable from 10mV to 30mV. High speed, low offset remote sense differential amplifiers and a precise 0.6V reference provide accurate output voltages between 0.6V and 3.5V from a wide 4.5V to 38V input supply range. Soft recovery from output shorts or overcurrent minimizes output overshoot. Burst Mode®operation, continuous and pulse-skipping modes are supported. The constant operating frequency can be synchronized to an external clock or linearly programmed from 200kHz to 1.2MHz. Up to six LTC3774 controllers can be paralleled for 1-, 2-, 3-, 4-, 6-, 8- or 12-phase operation.The LTC3774 is available in a 36-lead (5mm × 6mm) QFN package.ApplicationsComputer SystemsTelecom and Datacom SystemsIndustrial EquipmentDC Power Distribution Systems