Features and Benefits
- 350mA Constant Current Output
- 2.8V to 4V Output Compliance
- 1- or 2-Cell NiMH or Alkaline Input
- Synchronous Rectification: Up to 90% Efficiency
- Fixed Frequency Operation: 1.3MHz
- Low Quiescent Current: <1mA
- 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 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.
- Portable Lighting
- Rechargeable Flashlights
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 762 is a 350mA, 1W synchronous boost white LED driver featuring the LTC3490 and a Lumileds Luxeon LED. The input voltage range of the LT3490 is 1V to 3.4V; however the demo board operates with a 1.8V to 3.5V range. The board comes with two AA alkaline battery cells to be stuffed in the battery pack on the back of the PCB. The LED compliance voltage range is 2.8V to 4V. Other features include a low battery detect output and analog dimming control. The LT3490's simple design, low quiescent current and minimal external components make it an ideal solution for space-constrained ~1W flashlight or portable LED driver solutions.
Tools & Simulations
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Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.