Analog Devices

The LT3844 is a DC/DC controller used for medium power, low part count, high efficiency supplies. It offers a wide 4V to 60V input range (7.5V minimum startup voltage) and can implement step-down, step-up, inverting and SEPIC topologies.The LT3844 includes Burst Mode operation, which reduces quiescent current below 120µA and maintains high efficiency at light loads. An internal high voltage bias regulator allows for simple biasing.Additional features include current mode control for fast line and load transient response; programmable fixed operating frequency that can be synchronized to an external clock for noise sensitive applications; a gate driver capable of driving large N-channel MOSFETs; a precision undervoltage lockout function; 10µA shutdown current; short-circuit protection and a programmable soft-start function.The LT3844 is available in a 16-lead thermally enhanced TSSOP package.ApplicationsIndustrial Power Distribution12V and 42V Automotive and Heavy EquipmentHigh Voltage Single Board SystemsDistributed Power SystemsAvionicsTelecom Power

The LT3845A is a high voltage, synchronous, current mode controller used for medium to high power, high efficiency supplies. It offers a wide 4V to 60V input range (7.5V minimum start-up voltage). An onboard regulator simplifies the biasing requirements by providing IC power directly from VIN.Burst Mode®operation maintains high efficiency at light loads by reducing IC quiescent current to 120μA. Light load efficiency is also improved with the reverse inductor current inhibit function which supports discontinuous operation.Additional features include adjustable fixed operating frequency that can be synchronized to an external clock for noise sensitive applications, gate drivers capable of driving large N-channel MOSFETs, a precision undervoltage lockout, 10μA shutdown current, short-circuit protection and a programmable soft-start.The LT3845A is available in a 16-lead thermally enhanced TSSOP package.FeaturesLT3845-LT3845AImproved Performance In Over Current ConditionsApplications12V and 42V Automotive and Heavy Equipment48V Telecom Power SuppliesAvionics and Industrial Control SystemsDistributed Power Converters

The LT3905 is a fixed frequency current-mode step-up converter designed to bias avalanche photodiodes (APD) in optical receivers. The LT3905 features high side APD current monitoring over four decades of dynamic range with better than 2% relative accuracy over the 3μA to 3mA range.The maximum APD current is programmed with a single resistor, and a fast current limiter with indicator protects the APD during overload conditions. Adjustable output voltage provides dynamic bias control, and an adjustable loss-of-signal indicator flags low APD current.Coupled with the integrated DMOS power switch and Schottky rectifier, the LT3905 provides a compact total solution with few external components and low solution cost. Constant switching frequency results in predictable output noise that is easy to filter.The LT3905 is available in the tiny footprint (3mm × 3mm) 16-Lead QFN Package.ApplicationsAPD BiasPIN Diode BiasOptical Receivers and ModulesFiber Optic Network Equipment

The LT3909 is a 2-string × 60mA LED driver with a fixed 2MHz step-up DC/DC converter capable of driving up to 36V of LEDs. Each LED string contains an accurate high-side current source with ±2% current matching. Output voltage adapts to variations in LED VFfor optimum efficiency.Maximum LED current can be programmed from 10mA to 60mA per string using a single resistor. LED brightness can be reduced with analog dimming (up to 10:1) or with PWM dimming (up to 40,000:1 at 100Hz, up to 160:1 at 25kHz) (independent of leakage at VOUT). The LED pins can be paralleled for higher LED current.Additional features include: programmable maximum VOUTfor open LED protection, a fault flag to indicate open-LED or LED-short-to-GND and an internal regulation loop to safely limit junction temperature. The LT3909 also includes internal compensation, internal soft-start and micropower shutdown. The LT3909 is available in the 12-pin (3mm × 3mm) DFN and 12-pin MSOP packages.ApplicationsPDAs, Handheld ComputersGPS ReceiversAutomotive DisplaysHigh Contrast Instrument Clusters

The LT3922-1 is a monolithic, synchronous, step-up DC/ DC converter that utilizes fixed-frequency, peak current control and provides PWM dimming for a string of LEDs. The LED current is programmed by an analog voltage or the duty cycle of pulses at the CTRL pin. The LT3922-1 will maintain ±2.5% current regulation through an external sense resistor over a wide range of output voltages.The switching frequency is programmable from 200kHz to 2MHz by an external resistor at the RT pin or by an external clock applied at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI. The LT3922-1 also includes a driver for an external high side PMOS for PWM dimming and an internal PWM signal generator for analog control of PWM dimming. When an external signal is available, the LT3922-1 can perform 25,000:1 PWM dimming with 100Hz PWM pulses.Additional features include an accurate external reference voltage for use with the CTRL and PWM pins, an LED current monitor, an accurate EN/UVLO pin threshold, open-drain fault reporting for open-circuit and short-circuit load conditions, and thermal shutdown.APPLICATIONSAutomotive and Industrial LightingMachine Vision

The LT3932, featuring the Silent Switcher®architecture to minimize EMI/EMC emissions, utilizes fixed-frequency, peak current control and provides PWM dimming for a string of LEDs. The LED current is programmed by an analog voltage or the duty cycle of pulses at the CTRL pin. An output voltage limit can be set with a resistor divider to the FB pin.The switching frequency is programmable from 200kHz to 2MHz by an external resistor at the RT pin or by an external clock at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI. The LT3932 also includes a driver for an external, high side PMOS for PWM dimming and an internal PWM signal generator for analog control of PWM dimming when an external signal is not available. The LT3932-1 permits higher dimming ratios.Additional features include an LED current monitor, an accurate EN/UVLO pin threshold, open-drain fault reporting for open-circuit and short-circuit load conditions, and thermal shutdown.APPLICATIONSAutomotive LightingIndustrial and General Purpose LightingMachine Vision Systems

The LT3935 is a monolithic, synchronous, step-down DC/DC converter that utilizes fixed-frequency, peak current control and provides PWM dimming for a string of LEDs. The LED current is programmed by an analog voltage or the duty cycle of pulses at the CTRL pin. An output voltage limit can be set with a resistor divider to the FB pin.The switching frequency is programmable from 200kHz to 2MHz by an external resistor at the RT pin or by an external clock at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI.Additional features include an LED current monitor, an accurate EN/UVLO pin threshold, open-drain fault reporting for open-circuit and short-circuit load conditions, and thermal shutdown. The LT3935 utilizes proprietary Silent Switcher technology for very low EMI.APPLICATIONSAutomotive LightingIndustrial and General Purpose Lighting

The LT3942 is a monolithic 4-switch synchronous buck-boost converter with constant voltage and constant current regulation, suitable for both voltage regulator and LED driver applications. The part can regulate the output voltage, or input/output current with input voltages above, below, or equal to the output voltage. The proprietary peak-buck peak-boost current mode control scheme allows adjustable and synchronizable 300kHz to 2MHz fixed frequency operation, or internal 25% triangle spread spectrum operation for low EMI. The LT3942 covers 3V to 36V input and 0V to 36V output with seamless low-noise mode transition.For voltage regulator applications, the LT3942 provides input or output current monitor. For LED driver applications, it provides current regulation with up to 128:1 internal and 5000:1 external PWM dimming using an optional high-side PMOS switch. Fault protection is also provided to detect output short-circuit condition and open or short LED condition.ApplicationsVoltage Regulator with Accurate Current LimitGeneral Purpose LED DriverAutomotive and Industrial Lighting

The LT3952A is a current mode step-up DC/DC converter with an internal, 60V, 80mΩ DMOS power switch. The LT3952A is specifically designed to drive high power LEDs in multiple configurations. It combines input and output current regulation loops with output voltage regulation to operate as a flexible current/voltage source.Programmable switching frequency with optional spread-spectrum modulation provides EMI reduction, while still allowing optimization of the external components for efficiency or component size. The LED current is programmable with an external sense resistor, and can be adjusted from zero to full scale with a voltage at the CTRL pin. The external PWM input provides LED ON/OFF control and 4000:1 dimming ratio, and an internal PWM generator delivers the efficiency of PWM dimming to standalone or I/O limited applications. The LT3952A is available in the thermally enhanced 28-lead TSSOP package.ApplicationsDisplay BacklightingAutomotive and Avionic LightingAccurate Current-Limited Voltage Regulators

The LT3954 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator. It features an internal low side N-channel MOSFET rated for 40V/5A. The LT3954 is ideally suited for driving high current LEDs, but also has features to make it suitable for charging batteries and supercapacitors. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. A voltage feedback pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1MHz to optimize efficiency, performance or external component size.The LT3954 senses output current at the high side or at the low side of the load. The internal PWM generator can be configured to self-oscillate at fixed frequency with duty ratio programmable from 4% to 96%. When driven by an external signal, the PWM input provides LED dimming ratios of up to 3000:1. The CTRL input provides additional analog dimming capability.ApplicationsHigh Power LEDsOutput Short-Circuit Protected BoostBattery and SuperCap ChargersAccurate Current Limited Voltage Regulators