LT3490 Datasheet | Linear Technology

LTC3490 Single Cell 350m A LED Driver Features - - - - - - - - - - - - DESCRIPTIO U APPLICATIO S - - 350m A Constant Current Output 2.8V to 4V Output pliance 1- or 2-Cell Ni MH or Alkaline Input Synchronous Rectification: Up to 90% Efficiency Fixed Frequency Operation: 1.3MHz Low Quiescient Current: <1m A Very Low Shutdown Current: <50µA Open LED Output Limited to 4.7V VIN Range: 1V to 3.2V Dimming Control Undervoltage Lockout to Protect Batteries Low Profile (0.75mm) 3mm × 3mm Thermally Enhanced 8-Lead DD and S8 Packages The LTC®3490 provides a constant current drive for 1W LED applications. It is a high efficiency boost converter that operates from 1 or 2 Ni MH or alkaline cells and generates 350m A of constant current with up to 4V of pliance. 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 pensated to minimize ponent count. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Portable Lighting Rechargeable Flashlights TYPICAL APPLICATIO 3.3µH Single Cell Minimum ponent LED Driver 100 90 80 VIN ON/OFF 1 Ni MH OR ALKALINE CELL SW CAP LTC3490 CTRL/SHDN LED CELLS 1M GND LOBAT 350m A 4.7µF HIGH CURRENT LED Efficiency vs VIN at VLED = 3.5V IOUT = 350m A EFFICIENCY (%) 60 50 40 30 20 10 + 3490 TA01 0 1 1.5 2 VIN (V) 2.5 3 3490 TA02 3490f LTC3490...