The LT3491 is an efficient Li-Ion driver that provides up to 600mA of drive current for four white LEDs. The driver features a unique high side LED current sense that enables the LED string to be connected with one side to ground, which simplifies LED connection. The driver uses a fixed frequency step-up DC/DC converter that is specifically designed to drive up to six white LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors.
The LT3491 is a fixed‑frequency step‑up DC/DC converter designed to drive up to six white LEDs in series from a Li‑ion cell. It integrates a Schottky diode, open‑LED protection and a one‑wire current‑sense architecture, allowing a single pin to provide both shutdown and PWM dimming control. The device operates at a typical 2.3 MHz switching frequency, enabling the use of very small inductors and capacitors.
The datasheet provides absolute maximum ratings, electrical characteristics, pin functions, and recommended external components such as 10 µH inductors and X5R/X7R ceramic capacitors. Package options include an 8‑lead SC70 and a 6‑lead 2 mm × 2 mm DFN, with detailed solder‑pad layouts. Application notes cover inrush current, over‑voltage protection, and programming of LED current and dimming methods.
| Input Voltage Range | 2.5 V to 12 V |
|---|---|
| Switching Frequency (typ) | 2.3 MHz |
| Maximum Duty Cycle | 92 % |
| Switch Current Limit (typ) | 350 mA |
| Number of LEDs Supported | Up to 6 white LEDs |
The LT3491 operates with an input voltage from 2.5 V up to 12 V.
It can drive up to six white LEDs in series from a 3 V supply.