Analog Devices LT3922

Description

The LT®3922 is a monolithic, synchronous, step-up DC/DC converter that utilizes fixed-frequency, peak currentcontrol and provides PWM dimming for a string of LEDs.The LED current is programmed by an analog voltage orthe duty cycle of pulses at the CTRL pin. The LT3922 willmaintain ±2% current regulation through an external senseresistor over a wide range of output voltages.The switching frequency is programmable from 200kHzto 2MHz by an external resistor at the RT pin or by anexternal clock applied at the SYNC/SPRD pin. With theoptional Spread Spectrum Frequency Modulation enabled,the frequency varies from 100% to 125% to reduce EMI.The LT3922 also includes a driver for an external highsidePFET for PWM dimming and an internal PWM signalgenerator for analog control of PWM dimming when anexternal signal is not available.Additional features include an accurate external referencevoltage for use with the CTRL and PWM pins, an LEDcurrent monitor, an accurate EN/UVLO pin threshold,open-drain fault reporting for open-circuit and short-circuitload conditions, and thermal shutdown

Features

±2% LED Current Regulation±2% Output Voltage Regulation5000:1 PWM Dimming at 100Hz128:1 Internal PWM DimmingSpread-Spectrum Frequency ModulationSilent Switcher® Architecture for Low EMIOperates in Boost, Buck Mode and Buck-Boost Mode2.8V to 36V Input Voltage RangeUp to 34V LED String Voltage2A, 40V Internal Switches200kHz to 2MHz with SYNC FunctionAnalog or Duty Cycle LED Current ControlOpen/Short LED Protection and Fault IndicationThermally Enhanced 28-Pin (4mm × 5mm) QFN

Typical applications

• Machine Vision
• Automotive and Industrial Lighting

More information

• Datasheet
• IC product information