Analog Devices

The LT3495/LT3495B/LT3495-1/LT3495B-1 are low noise boost converters with integrated power switch, feedback resistor and output disconnect circuitry. The parts control power delivery by varying both the peak inductor current and switch off-time. This novel* control scheme results in low output voltage ripple as well as high efficiency over a wide load range. For the LT3495/LT3495-1, the off-time of the switch is not allowed to exceed a fixed level, guaranteeing the switching frequency stays above the audio band for the entire load range. The parts feature a high performance NPN power switch with a 650mA and 350mA current limit for the LT3495/LT3495B and LT3495-1/LT3495B-1 respectively. The quiescent current is a low 60μA, which is further reduced to 0.1μA in shutdown. The internal disconnect circuitry allows the output voltage to be isolated from the input during shutdown. An auxiliary reference input (CTRL pin) overrides the internal 1.235V feedback reference with any lower value allowing full control of the output voltage during operation. The LT3495 series are available in a tiny 10-lead 3mm × 2mm DFN package.ApplicationsOLED PowerLow Noise PowerMP3 Player

The LT3496 is a triple output DC/DC converter designed to operate as a constant-current source and is ideal for driving LEDs. The LT3496 works in buck, boost or buck-boost mode. The LT3496 uses a fixed frequency, current mode architecture resulting in stable operation over a wide range of supply and output voltages. A frequency adjust pin allows the user to program switching frequency between 330kHz and 2.1MHz to optimize efficiency and external component size.The LT3496 supports 3000:1 dimming control on each channel. Each of the three regulators is independently operated by that channel’s PWM signal. The PWM feature allows precise adjustment of the color mixing or dimming ratio of the LED source. Each of the three channels has a built-in gate driver to drive an external LED-disconnect P-channel MOSFET, allowing high dimming range. The output current range of each channel of the LT3496 is programmed with an external sense resistor.The CTRL pins are used to adjust the LED currents either for analog dimming or overtemperature protection.ApplicationsRGB LightingBillboards and Large DisplaysAutomotive and Avionic LightingConstant-Current Sources

The LT3497 is a dual full function step-up DC/DC converter specifically designed to drive up to 12 white LEDs (6 white LEDs in series per converter) from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors and expensive factory calibration.The two independent converters are capable of driving asymmetric LED strings. Accurate LED dimming and shutdown of the two LED strings can also be controlled independently. The LT3497 features a unique high side LED current sense that enables the part to function as a "one wire current source;" one side of the LED string can be returned to ground anywhere, allowing a simpler 1-wire LED connection. Traditional LED drivers use a grounded resistor to sense LED current, requiring a 2-wire connection to the LED string.The 2.3MHz switching frequency allows the use of tiny inductors and capacitors. Few external components are needed for the dual white LED Driver: open-LED protection and the Schottky diodes are all contained inside the 3mm × 2mm DFN package. With such a high level of integration, the LT3497 provides a high efficiency dual white LED driver solution in the smallest of spaces.ApplicationsCellular PhonesPDAs, Handheld ComputersDigital CamerasMP3 PlayersGPS Receivers

The LT3500 is a current mode PWM step-down DC/DC converter with an internal 2.3A switch. The wide input range of 3V to 40V makes the LT3500 suitable for regulating power from a wide variety of sources, including automotive batteries, 24V industrial supplies and unregulated wall adapters.Resistor-programmable 250kHz to 2.2MHz frequency range and synchronization capability enable optimization between efficiency and external component size. Cycle-by-cycle current limit, frequency foldback and thermal shutdown provide protection against a shorted output. The soft-start feature controls the ramp rate of the output voltage, eliminating input current surge during start-up, and also provides output tracking.The LT3500 contains an internal NPN transistor with feedback control which can be configured as a linear regulator or as a linear regulator controller.The LT3500’s low current shutdown mode (<12μA) enables easy power management in battery-powered systems.ApplicationsAutomotive Battery RegulationIndustrial ControlWall Transformer RegulationDistributed Power Regulation

The LT3501 is a dual current mode PWM step-down DC/DC converter with two internal 3.5A switches. Independent input voltage, feedback, soft-start and power good pins for each channel simplify complex power supply tracking/sequencing requirements.Both converters are synchronized to either a common external clock input or a resistor programmable fi xed 250kHz to 1.5MHz internal oscillator. At all frequencies, a 180° phase relationship between channels is maintained, reducing voltage ripple and component size. Programmable frequency allows for optimization between effi ciency and external component size.Minimum input-to-output voltage ratios are improved by allowing the switch to stay on through multiple clock cycles, only switching off when the boost capacitor needs recharging, resulting in ~95% maximum duty cycle.Each output can be independently disabled using its own soft-start pin, or by using the SHDN pin the entire part can be placed in a low quiescent current shutdown mode.The LT3501 is available in a 20-lead TSSOP package with exposed leadframe for low thermal resistance.ApplicationsDSP Power SuppliesDisc DrivesDSL/Cable ModemsWall Transformer RegulationDistributed Power Regulation

The LT3502/LT3502A are current mode PWM step-down DC/DC converters with an internal 500mA power switch, in tiny 8-lead 2mm × 2mm DFN and 10-lead MS10 packages. The wide input voltage range of 3V to 40V makes the LT3502/LT3502A suitable for regulating power from a wide variety of sources, including 24V industrial supplies and automotive batteries. Its high operating frequency allows the use of tiny, low cost inductors and capacitors, resulting in a very small solution. Constant frequency above the AM band avoids interfering with radio reception, making the LT3502A particularly suitable for automotive applications.Cycle-by-cycle current limit and frequency foldback provide protection against shorted outputs. Soft-start and frequency foldback eliminates input current surge during start-up. DA current sense provides further protection in fault conditions. An internal boost diode reduces component count.ApplicationsAutomotive SystemsBattery-Powered EquipmentWall Transformer RegulationDistributed Supply Regulation

The LT3504 consists of four 1A output current buck regulators. The LT3504 has a wide operating input range of 3.2V to 40V. An on-chip boost regulator allows each channel to operate up to 100% duty cycle and eliminates the need for four external charge pump circuits. The LT3504 is designed to minimize external component count and results in a simple and small application circuit.The LT3504 operates robustly in fault conditions. Cycle-by-cycle peak current limit and catch diode current limit sensing protect the part during overload conditions. Thermal shutdown protects the power switches at elevated temperatures. Soft-start helps keep the peak inductor current under control during startup.The LT3504 also features output voltage tracking and sequencing, programmable frequency, programmable undervoltage lockout, and a power good pin to indicate when all outputs are in regulation.ApplicationsAutomotive Battery RegulationIndustrial Control SuppliesWall Transformer RegulationDistributed Supply Regulation

The LT3505 is a current mode PWM step-down DC/DC converter with an internal 1.4A power switch. The wide operating input range of 3.6V to 36V (40V maximum) makes the LT3505 ideal for regulating power from a wide variety of sources, including unregulated wall transformers, 24V industrial supplies and automotive batteries. The oscillator can be programmed for high frequency operation allowing the use of tiny, low cost external components or it can be programmed for lower frequency operation to maximize efficiency.Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The low current (<2µA) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems.ApplicationsAutomotive Battery RegulationIndustrial Control SuppliesWall Transformer RegulationDistributed Supply RegulationBattery-Powered Equipment

The LT3506 is a dual current mode PWM step-down DC/DC converter with internal 2A power switches. Both converters are synchronized to a single oscillator and run with opposite phases, reducing input ripple current. The output voltages are set with external resistor dividers, and each regulator has independent shutdown and soft-start circuits. Each regulator generates a power-good signal when its output is in regulation, easing power supply sequencing and interfacing with microcontrollers and DSPs.The LT3506 switching frequency is 575kHz and the LT3506A is 1.1MHz. These high switching frequencies allow the use of tiny inductors and capacitors, resulting in a very small dual 1.6A output solution. Constant frequency and ceramic capacitors combine to produce low, predictable output ripple voltage. With its wide input range of 3.6V to 25V, the LT3506 regulates a wide variety of power sources, from 4-cell batteries and 5V logic rails to unregulated wall transformers, lead acid batteries and distributed-power supplies. Current mode PWM architecture provides fast transient response with simple compensation components and cycle-by-cycle current limiting. Frequency foldback and thermal shutdown provide additional protection.ApplicationsDisk DrivesDSP Power SuppliesWall Transformer RegulationDistributed Power RegulationDSL ModemsCable Modems