Analog Devices

The LTC3458L is a high efficiency, current mode, fixed frequency, step up DC/DC converter with true output disconnect and inrush current limiting. The LTC3458L is rated for up to 6V output and includes a 0.2Ω N-channel MOSFET switch and a 0.3Ω P-channel MOSFET synchronous rectifier. The LTC3458L is well suited for battery powered applications and includes programmable output voltage, switching frequency and loop compensation. The oscillator frequency can be set up to 1.5MHz or synchronized to an external clock.Quiescent current is only 12µA during Burst Mode operation maximizing battery life in portable applications. The Burst Mode current threshold, peak current limit, and softstart are externally programmable. Other features include <1µA shutdown current, antiringing control, and thermal limit. The LTC3458L is available in a low profile (0.75mm), 4mm × 3mm 12-pin DFN package.Protected by U.S. Patents including 5481178, 6304066, 6580258, 5511131, 6498466Vout RangeSwitch CurrentLTC34582.0V to 7.5V1.4ALTC3458L2.0V to 6.0V1.7AApplicationsPoint-of-Load RegulatorsUSB VBUSPowerPortable GPSMP3 Players

The LTC3459 is a low current, high efficiency synchronous boost converter intended for low power, size constrained portable applications. The LTC3459 can be powered from a single lithium ion battery, a 2- to 3-cell stack of Alkaline or Nickel batteries, or any low impedance voltage source between 1.5V and 5.5V. The output is programmable via an external divider between 2.5V and 10V. Although the part is primarily intended for boost applications, VOUTwill maintain regulation below VIN(at reduced efficiency).The LTC3459 offers Burst Mode operation with a fixed peak current, providing high conversion efficiency over a wide range of load currents. During start-up, inductor current is controlled preventing the inrush surge current found in many boost converters. In shutdown the output is disconnected from the input and quiescent current is reduced to <1µA.The LTC3459 is offered in low profile 6-pin 2mm × 2mm DFN, 2mm × 3mm DFN or SOT-23 (ThinSOT) packages, allowing a tiny footprint for the total solution.ApplicationsGeneral Purpose Micropower BoostDigital CamerasPDAsLCD BiasSmall OLED DisplaysSupercap Charging

The LTC3490 provides a constant current drive for 1W LED applications. It is a high efficiency boost converter that operates from 1 or 2 NiMH or alkaline cells and generates 350mA of constant current with up to 4V of compliance. It contains a 100mΩ NFET switch and a 130mΩ PFET synchronous rectifier. The fixed switching frequency is internally set to 1.3MHz.The LTC3490 limits the output voltage to 4.7V if the output load is disconnected. It also features an analog dimming capability that reduces the drive current proportional to the CTRL/SHDN pin voltage. A low-battery logic output signals when the battery has dropped below 1V/cell. An undervoltage lockout circuit shuts down the LTC3490 when the battery voltage drops below 0.85V/cell. The feedback loop is internally compensated to minimize component count.ApplicationsPortable LightingRechargeable Flashlights

The LTC3499/LTC3499B are synchronous, fixed frequency step-up DC/DC power converters with integrated reverse battery protection that protect and disconnect the devices and load when the battery polarity is reversed while delivering high efficiency in a small (3mm × 3mm) DFN package. True output disconnect eliminates inrush current and allows zero load current in shutdown.The devices feature an input voltage range of 1.8V to 5.5V enabling operation from two alkaline or NiMH batteries. The switching frequency is internally set at 1.2MHz allowing the use of tiny surface mount inductors and capacitors. A minimal number of external components are required to generate output voltages ranging from 2V to 6V. The LTC3499 features automatic Burst Mode operation to increase efficiency at light loads, while the LTC3499B features continuous switching at light loads.The soft-start time is externally programmable through a small capacitor. Anti-ring circuitry reduces EMI emissions by damping the inductor in discontinuous mode. The devices feature <1μA shutdown supply current, integrated overvoltage protection and are available in both 8-pin (3mm × 3mm) DFN and 8-pin MSOP packages.ApplicationsMedical EquipmentDigital CamerasMP3 PlayersHandheld Instruments

The LTC3520 combines 1A buck-boost and 600mA synchronous buck DC/DC converters in a tiny 4mm x 4mm package. A programmable switching frequency allows the efficiency to be optimized while minimizing the solution footprint. Both converters feature soft-start and current limit protection. The uncommitted gain block can be configured as an LDO or utilized as a battery-good comparator.The buck converter is current mode controlled with internal synchronous rectification to improve efficiency. Pin-selectable Burst Mode operation can be enabled to improve light load efficiency, or the buck converter can be operated in low noise PWM mode for sensitive applications.The buck-boost converter provides continuous conduction operation to maximize efficiency and minimize noise. At light loads, use of Burst Mode operation will improve efficiency.The LTC3520 provides a <1µA shutdown mode and over- temperature shutdown on both converters. The LTC3520 is available in a low profile (0.75mm) 24-lead 4mm x 4mm QFN package.ApplicationsPortable Media PlayersDigital CamerasHandheld PCs, PDAsGPS Receivers

The LTC3521 combines a 1A buck-boost DC/DC converter and dual 600mA synchronous buck DC/DC converters. The 1.1MHz switching frequency minimizes the solution footprint while maintaining high efficiency. All three converters feature soft-start and internal compensation to minimize the solution footprint and simplify the design process.The buck converters are current mode controlled and utilize an internal synchronous rectifier to improve efficiency. The buck converters support 100% duty cycle operation to extend battery life. If the PWM pin is held low, the buck converters automatically transition from Burst Mode operation to PWM mode at high loads. With the PWM pin held high, the buck converters remain in low noise, 1.1MHz PWM mode.The buck-boost converter features continuous conduction operation to maximize efficiency and minimize noise. At light loads, the buck-boost converter can be operated in Burst Mode operation to improve efficiency and reduce no-load standby current.The LTC3521 provides a <2μA shutdown mode, overtemperature shutdown and current limit protection on all converters. The LTC3521 is available in a 24-pin 0.75mm × 4mm × 4mm QFN package, and a 20-pin thermally enhanced TSSOP package.ApplicationsBar Code ReadersMedical InstrumentsHandy TerminalsPDAs, Handheld PCsGPS Receivers

The LTC3522 combines a 400mA buck-boost DC/DC converter with a 200mA synchronous buck DC/DC converter in a tiny 3mm × 3mm package. The 1MHz switching frequency minimizes the solution footprint while maintaining high efficiency. Both converters feature internal soft-start and compensation, simplifying the design process.The buck converter is current mode controlled and utilizes an internal synchronous rectifier for high efficiency. The buck converter supports 100% duty cycle operation to extend battery life. If the PWM pin is held low, the buck converter automatically transitions from Burst Mode operation to PWM mode. With the PWM pin held high, the buck converter remains in low noise, 1MHz PWM mode.The buck-boost converter provides continuous conduction operation to maximize efficiency and minimize noise. At light loads, the buck-boost converter can be placed in Burst Mode operation to improve efficiency and reduce no-load standby current.The LTC3522 provides a 1µA shutdown mode, overtemperature shutdown and current limit protection on both converters. The LTC3522 is available in a 16-pin low profile 3mm × 3mm QFN package.ApplicationsFlash-Based MP3 PlayersMedical InstrumentsDigital CamerasPDAs, Handheld PCsPersonal Navigation Devices

The LTC3523/LTC3523-2 combine a 600mA step-up DC/DC converter with a 400mA synchronous step-down DC/DC converter in a tiny 3mm × 3mm package. The 1.2MHz/2.4MHz switching frequencies minimize the solution footprint while maintaining high efficiency. Both converters feature soft-start and internal compensation, simplifying the design.Both the step-up and step-down converters are current mode controlled and utilize an internal synchronous rectifier for high efficiency. The step-up supports 0% duty cycle operation and the step-down converter supports 100% duty cycle operation to extend battery run time. If the MODE pin is held high, both converters automatically transition between Burst Mode operation and PWM operation improving light load efficiency. Fixed, low noise 1.2MHz/2.4MHz PWM operation is selected when MODE is grounded.The LTC3523/LTC3523-2 provide a sub-2μA shutdown mode, overtemperature shutdown and current limit protection on both converters. The LTC3523/LTC3523-2 are housed in a 16-lead 3mm × 3mm × 0.75mm QFN package.ApplicationsDigital CamerasMedical InstrumentsIndustrial HandheldsGPS Navigators

The LTC3524 is an integrated BIAS and white LED power converter solution for small/medium-sized polysilicon thin film transistor (TFT) liquid crystal (LCD) display panels. The device operates from a single Lithium-Ion/polymer battery or any voltage source between 2.5V and 6V.A 1.5MHz synchronous boost converter generates a programmable low noise, high efficiency 25mA TFT supply of up to 6.0V. Regulated, low ripple charge pumps are used to generate up to +20V and –20V at 2mA. Output sequencing is internally controlled to insure proper initialization and rapid discharge of the LCD panel in shutdown.A second 1.5MHz boost converter powers one or two LED strings with up to five series elements each. LED current and display brightness can be controlled over a wide range using analog or digital means up to 25mA.The LTC3524 is offered in the 4mm × 4mm 24-pin QFN package, minimizing the total solution footprint.ApplicationsPDAs, Palmtop ComputersDigital Still and Video CamerasHandheld GPSPortable Instrument DisplaysPortable Media Players

The LTC3525-3/LTC3525-3.3/LTC3525-5 are high efficiency synchronous step-up DC/DC converters with output disconnect that can start up with an input as low as 0.85V. They offer a compact, high efficiency alternative to charge pumps in single cell or dual cell alkaline or Li-Ion applications. Only three small external components are required. The LTC3525 is offered in fixed output voltages of 3V, 3.3V or 5V.The device includes a 0.5Ω N-channel MOSFET switch and a 0.8Ω P-channel synchronous rectifier. Peak switch current ranges from 150mA to 400mA, depending on load, providing enhanced efficiency. Quiescent current is an ultralow 7μA, maximizing battery life in portable applications.Other features include <1μA shutdown current, antiringing control and thermal shutdown. The LTC3525 is available in a tiny 6-Lead SC70 package.List of LTC3525 OptionsPART NAMEINPUT START-UP VOLTAGEOUTPUT VOLTAGEVOUTSTATUS IN SHUTDOWN MODELTC3525-30.85V3VOutput DisconnectLTC3525-3.30.85V3.3VOutput DisconnectLTC3525-50.85V5VOutput DisconnectLTC3525D-3.30.85V3.3VPass Through ModeLTC3525L-30.7V3VOutput DisconnectApplicationsMP3 PlayersPortable InstrumentsGlucose MetersDigital Cameras