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
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.