Analog Devices Inc./Maxim Integrated

The LTC3729L-6 is a PolyPhase™synchronous stepdown current mode switching regulator controller with a 0.6V reference that drives N-channel external power MOSFET stages in a phase-lockable fixed frequency architecture. The PolyPhase controller drives its two output stages out of phase at frequencies up to 550kHz to minimize the RMS ripple currents in both input and output capacitors. The output clock signal allows expansion for up to 12 evenly phased controllers for systems requiring 15A to 200A of output current. This PolyPhase technique effectively multiplies the fundamental frequency by the number of channels used, improving transient response while operating each channel at an optimum frequency for efficiency. Thermal design is also simplified.An internal differential amplifier provides true remote sensing of the regulated supply’s positive and negative output terminals as required for high current applications.A RUN/SS pin provides both soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when the overcurrent latchoff is disabled. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3729L-6 includes a power good output pin that indicates when the output voltage is inside the ±10% tolerance window.Vin MaxVrefLTC372936V0.8LTC3729L-630V0.6ApplicationsDesktop ComputersInternet ServersLarge Memory ArraysDC Power Distribution Systems

The LTC3731 is a PolyPhase®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 controller drives its output stages with 120° phase separation at frequencies of up to 600kHz per phase to minimize the RMS current losses in both the input and output filter capacitors. 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 Burst Mode operation.A differential amplifier provides true remote sensing of both the high and low side of the output voltage at the point of load. The precision reference supports output voltages from 0.6V to 6V.Soft-start and a defeatable, timed short-circuit shutdown protect the MOSFETs and the load. Current foldback provides protection for the external MOSFETs under short-circuit or overload conditions.ApplicationsDesktop Computers and ServersHigh Performance Notebook ComputersHigh Output Current DC/DC Power Supplies

The LTC3731H is a PolyPhase synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable fixed frequency architecture. The LTC3731H is rated for operation up to 140°C junction temperature. The 3-phase controller drives its output stages with 120° phase separation at frequencies up to 680kHz per phase to minimize the RMS current losses in both the input and output filter capacitors. 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 Burst Mode operation.The precision reference supports output voltages from 0.6V to 6V. Current foldback provides protection for the external MOSFETs under short-circuit or overload conditions. Please refer to the LTC3731 data sheet for 0°C to 70°C and –40°C to 85°C rated versions.ApplicationsAutomotive and Industrial Power SuppliesHigh Output Current DC/DC Power Supplies

The LTC3732 is a PolyPhase®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 controller drives its output stages with 120° phase separation at frequencies of up to 600kHz per phase to minimize the RMS current losses in both the input and output filter capacitors. The 3-phase technique effectively triples the fundamental frequency, improving transient response while operating each controller at an optimal frequency for high efficiency and ease of thermal design. Light load efficiency is optimized by using a choice of output Stage Shedding or Burst Mode technology.A differential amplifier provides true remote sensing of both the high and low side of the output voltage at load points.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.ApplicationsDesktop ComputersHigh Performance Notebook ComputersHigh Output Current DC/DC Power Supplies

The LTC3734 is a single-phase synchronous step-down switching regulator controller that drives all N-channel power MOSFETs in a constant frequency architecture. The output voltage is programmable by six VID bits during normal operation and by external resistors during initial boot-up and deeper sleep state. The LTC3734 drives its output stage at frequencies up to 550kHz. Powerful onchip gate drivers eliminate the need for external gate driver ICs, thus simplifying the design.An Intel compatible PSIB input is provided to select between two modes of operation. Fully enhanced synchronous mode achieves a very small output ripple and very fast transient response while power saving mode realizes very high efficiency. OPTI-LOOP®compensation allows the transient response to be optimized for a wide range of output capacitance and ESR values.The LTC3734 is available in a small 5mm × 5mm QFN package. For 2-phase applications refer to the LTC3735.ApplicationsMobile and Desktop ComputersInternet Servers

The LTC3735 is a 2-phase synchronous step-down switching regulator controller that drives all N-channel power MOSFETs in a constant frequency architecture. The output voltage is programmable by six VID bits during normal operation and by external resistors during initial boot-up and deeper sleep state. The LTC3735 drives its two output stages out-of-phase at frequencies up to 550kHz to minimize the RMS ripple currents in both input and output capacitors. This antiphase technique also doubles the apparent switching frequency, improving the transient response while operating each phase at an optimum frequency for efficiency. Thermal design is further simplified by cycle-by-cycle current sharing between the two phases.An Intel compatible PSIB input is provided to select between two modes of operation. Fully enhanced synchronous mode achieves a very small output ripple and very fast transient response while power saving mode realizes very high efficiency. OPTI-LOOP®compensation allows the transient response to be optimized for a wide range of output capacitance and ESR values.ApplicationsMobile and Desktop ComputersInternet Servers

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 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