Analog Devices

The LTC3701 is a 2-phase dual constant frequency current mode step-down DC/DC controller providing excellent load and line regulation. Power loss and noise due to ESR of the input capacitor are minimized by operating the two controller output stages out-of-phase.The LTC3701 provides a 0.8V ±2% voltage reference and consumes only 460µA of quiescent current. To further maximize the life of a battery source, the external P-channel MOSFET is turned on continuously in dropout (100% duty cycle).Switching frequency is internally set at 550kHz, allowing the use of small inductors and capacitors. For noise sensitive applications, the LTC3701 can be externally synchronized using its phase-locked loop. The frequency can also be externally set from 300kHz to 750kHz by applying a voltage to the PLLLPF pin. Burst Mode operation is inhibited during synchronization or when the EXTCLK/MODE pin is pulled low to reduce noise and RF interference.The LTC3701 contains independent internal soft-start circuitry for each controller. Other features include a power good output voltage monitor and output overvoltage and short-circuit protection.The LTC3701 is available in a small footprint 16-lead narrow SSOP package.ApplicationsOne or Two Lithium-Ion Powered ApplicationsNotebook and Handheld ComputersPersonal Digital AssistantsPortable InstrumentsDistributed DC Power Systems

The LTC3703 is a synchronous step-down switching regulator controller that can directly step-down voltages from up to 100V, making it ideal for telecom and automotive applications. The LTC3703 drives external N-channel MOSFETs using a constant frequency (up to 600kHz), voltage mode architecture.A precise internal reference provides 1% DC accuracy. A high bandwidth error amplifier and patented line feed forward compensation provide very fast line and load transient response. Strong 1Ω gate drivers allow the LTC3703 to drive multiple MOSFETs for higher current applications. The operating frequency is user programmable from 100kHz to 600kHz and can also be synchronized to an external clock for noise-sensitive applications. Current limit is programmable with an external resistor and utilizes the voltage drop across the synchronous MOSFET to eliminate the need for a current sense resistor. For applications requiring up to 60V operation with logiclevel MOSFETS, refer to the LTC3703-5 data sheet.LTC3703-5LTC3703Maximum VIN60V100VMOSFET Gate Drive4.5V to 15V9.3V to 15VVCCUV+3.7V8.7VVCCUV-3.1V6.2VApplications48V Telecom and Base Station Power SuppliesNetworking Equipment, ServersAutomotive and Industrial Control

The LTC3704 is a wide input range, current mode, positive-to-negative DC/DC controller that drives an N-channel power MOSFET and requires very few external components. Intended for low to high power applications, it eliminates the need for a current sense resistor by utilizing the power MOSFET’s on-resistance, thereby maximizing efficiency.The IC’s operating frequency can be set with an external resistor over a 50kHz to 1MHz range, and can be synchronized to an external clock using the MODE/SYNC pin. Burst Mode operation at light loads, a low minimum operating supply voltage of 2.5V and a low shutdown quiescent current of 10µA make the LTC3704 ideally suited for battery-operated systems.For applications requiring constant frequency operation, the Burst Mode operation feature can be defeated using the MODE/SYNC pin. Higher than 36V switch voltage applications are possible with the LTC3704 by connecting the SENSE pin to a resistor in the source of the power MOSFET.The LTC3704 is available in the 10-lead MSOP package.ApplicationsSLIC Power SuppliesTelecom Power SuppliesPortable Electronic EquipmentCable and DSL ModemsRouter Supplies

The LTC3705 is a controller for a 2-switch forward converter and includes on-chip bottom and top gate drivers that do not require external transformers. For secondary-side control, combine the LTC3705 with the LTC3706 PolyPhase®secondary-side synchronous forward controller to create a complete forward converter using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals across the isolation barrier through a tiny pulse transformer. The on-chip rectifier and the same pulse transformer provide gate drive bias power.Alternatively, the LTC3705 can be used as a standalone voltage mode controller in a primary-side control architecture with optoisolator feedback. Voltage feedforward provides excellent line regulation and transient response.ApplicationsIsolated 48V Telecommunication SystemsInternet Servers and RoutersDistributed Power Step-Down ConvertersAutomotive and Heavy Equipment

The LTC3707-SYNC is a high performance dual step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows phase-lockable frequency of up to 300kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out of phase.OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The precision 0.8V reference and power good output indicator are compatible with future microprocessor generations, and a wide 4.5V to 28V (30V maximum) input supply range encompasses all battery chemistries.A RUN/SS pin for each controller provides both soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when overcurrent latchoff is disabled. Output overvoltage protection circuitry latches on the bottom MOSFET until VOUTreturns to normal. The FCB mode pin can select among Burst Mode, constant frequency mode and continuous inductor current mode or regulate a secondary winding. The IC includes a power good output pin that indicates when both outputs are within 7.5% of their designed set point.External SynchronizationLTC3707NoLTC3707-SYNCYesApplicationsNotebook and Palmtop Computers, PDAsTelecom SystemsPortable InstrumentsBattery-Operated Digital DevicesDC Power Distribution Systems

The LTC3708 is a dual, 2-phase synchronous step-down switching regulator with output voltage up/down tracking capability. The IC allows either coincident or ratiometric tracking. Multiple LTC3708s can be daisy-chained in applications requiring more than two voltages to be tracked. Power supply sequencing is accomplished using an external soft-start timing capacitor.The LTC3708 uses a constant on-time, valley current mode control architecture to deliver very low duty factors without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in input supply voltage. An internal phase-locked loop allows the IC to be synchronized to an external clock.Fault protection is provided by an output overvoltage comparator and an optional short-circuit shutdown timer. The regulator current limit level is user programmable. A wide supply range allows voltages as high as 36V to be stepped down to 0.6V output.ApplicationsNotebook and Palmtop Computers, PDAsDigital Signal ProcessorsNetwork Servers

The LTC3709 is a single output, dual phase, synchronous step-down switching regulator. The controller uses a constant on-time, valley current control architecture to deliver very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in input supply voltage. An internal phase-locked loop allows the LTC3709 to be synchronized to an external clock.A TRACK pin is provided for tracking or sequencing the output voltage among several LTC3709 chips or an LTC3709 and other DC/DC regulators. Soft-start is accomplished using an external timing capacitor.Fault protection is provided by an output overvoltage comparator and an optional short-circuit shutdown timer. The current limit level is user programmable. A wide supply range allows voltages as high as 31V to step down to 0.6V.Protected by U.S. Patents, including 5481178, 6476589, 6144194, 5847554, 6177678, 6304066, 6580258, 6674274, 6462525, 6593724.ApplicationsNotebook ComputersPower Supply for DSP, ASIC, Graphic Processors

The LTC3711 is a synchronous step-down switching regulator controller for CPU power. An output voltage between 0.925V and 2.000V is selected by a 5-bit code (Intel mobile VID specification). The controller uses a valley current control architecture to deliver very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VINand VOUT.Discontinuous mode operation provides high efficiency operation at light loads. A forced continuous control pin reduces noise and RF interference and can assist secondary winding regulation by disabling discontinuous mode operation when the main output is lightly loaded.Fault protection is provided by internal foldback current limiting, an output overvoltage comparator and optional short-circuit shutdown timer. Soft-start capability for supply sequencing is accomplished using an external timing capacitor. The regulator current limit level is user programmable. Wide supply range allows operation from 4V to 36V at the input.ApplicationsPower Supplies for Mobile Pentium®ProcessorsNotebook and Palmtop Computers, PDAs

The LTC3713 is a high current, high efficiency synchronous buck switching regulator controller optimized for use with very low input supply voltages. It operates from inputs as low as 1.5V and provides a regulated output voltage from 0.8V up to (0.9)VIN. The controller uses a valley current control architecture to enable high operating frequencies without requiring a sense resistor.Operating frequency is selected by an external resistor and is compensated for variations in VINand VOUT. The LTC3713 uses a pair of standard 5V logic-level N-channel external MOSFETs, eliminating the need for expensive P-channel or low threshold devices.Discontinuous mode operation provides high efficiency operation at light loads. A forced continuous control pin reduces noise and RF interference, and can assist secondary winding regulation by disabling discontinuous operation when the main output is lightly loaded. Fault protection is provided by internal foldback current limiting,an output overvoltage comparator and an optional short-circuit shutdown timer.ApplicationsTelecom Card 3.3V, 2.5V, 1.8V Step-DownBus Termination (DDR memory, SSTL)Synchronous Buck with General Purpose BoostLow VINSynchronous Boost