Features and Benefits
- Low Noise Constant-Frequency Operation
- Multi-Mode Operation: 1x or 2x Boost Mode
- Automatic Mode Switching
- High Output Current: 150mA (Continuous), 400mA (Pulsed) From Li-Ion/Polymer Input
- 2-Second Flash Current Timeout for LED Protection
- Automatic Soft-Start
- Output Disconnect
- No Inductors
- 220mΩ Internal High Side Current Sense Resistor
- Single Resistor Programming Capability
- Tiny Application Circuit (3mm × 2mm DFN Package, All Components < 1mm High)
The LTC3218 is a low-noise, high-current charge pump DC/DC converter capable of driving high current LEDs at up to 400mA from a 2.9V to 4.5V input. A low external parts count (one flying capacitor, two programming resistors and two bypass capacitors at VIN and CPO) make the LTC3218 ideally suited for small, battery-powered applications.
Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. A built-in 2-second timer protects the LED during flash mode.
Output current level is programmed by an external resistor. LED current is regulated using an internal high side 220mΩ sense resistor. Automatic mode switching optimizes efficiency by monitoring the voltage across the charge pump and switching modes only when dropout is detected. The part is available in a low profile 3mm × 2mm 10-lead DFN package.
- LED Torch/Flash Supply for DSCs/Cellphones
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 1030 is a 400mA Single Wire Charge Pump Camera LED Driver featuring the LTC3218. This circuit provides 50mA of continuous torch current and two flash current levels, 300mA and 400mA. The LTC3218 has a built-in 2-second flash timer to protect the LED in case of faults during flash mode.
The demo board operates with an input supply voltage range of 2.9V to 4.5V and includes an AOT-2015 LED. It generates a minimum LED voltage of 2.2V at 50mA LED current. The charge pump operates in 1x or 2x mode with automatic mode switching, and generates a maximum output voltage of 4.5V.
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.
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.