The LT3474 is a fixed frequency step-down DC/DC converter designed to operate as a constant-current source.
The LT3474 is a constant‑frequency step‑down DC/DC converter designed for LED driving applications. It provides a wide input voltage range of 4 V to 36 V and can supply up to 1 A LED current, maintaining high accuracy from 35 mA to 1 A. The device features true‑color PWM dimming with a 400:1 range, integrated boost diode, and compact 16‑lead TSSOP packaging.
Typical applications include automotive and avionic lighting, architectural detail lighting, display backlighting, and constant‑current LED drivers. The part includes protection functions such as open‑LED and short‑circuit protection, over‑temperature shutdown, and frequency foldback during overload conditions.
| Input Voltage Range | 4 V to 36 V |
|---|---|
| LED Current Range | 35 mA to 1 A |
| Maximum LED Current | 1 A |
| Switching Frequency | 200 kHz – 2 MHz (adjustable) |
| Maximum Duty Cycle | up to 95 % |
| Package | 16‑Lead Plastic TSSOP |
The LT3474 operates with an input voltage from 4 V up to 36 V.
It can drive up to 1 A of LED current, with accurate regulation from 35 mA to 1 A.
The device provides open‑LED and short‑circuit protection, over‑temperature shutdown, and frequency foldback during overload.
The switching frequency is set by the external resistor on the Ry pin; a 80.6 kΩ resistor gives a 500 kHz frequency.