The LM3407 is a 350mA constant current output floating buck switching converter from Texas Instruments, designed to provide constant current to high power LEDs. It has an integrated power N-MOSFET that makes the application solution compact and easy to implement. An external 1% thick-film resistor allows the converter output voltage to adjust as needed to deliver constant current within 10% accuracy to a serially connected LED string of varying number and type. Converter switching frequency is adjustable from 300 kHz to 1 MHz. The LM3407 features a dimming input to enable LED brightness control by Pulse Width Modulation (PWM). Additionally, a separate enable pin allows for low power shutdown. An eMSOP-8 package provides excellent heat dissipation and thermal performance. Input UVLO and output open-circuit protection ensure a robust LED driver solution.
The LM3407 is a constant‑current floating‑buck switching regulator designed for high‑power LED applications such as automotive, industrial and general lighting. It provides a stable 350 mA output over a wide input range and includes PWM dimming, an enable pin for low‑power shutdown, and built‑in protection features.
Key features include an integrated power N‑MOSFET, adjustable switching frequency (300 kHz‑1 MHz) via the FS pin, UVLO and thermal‑shutdown protection, and a compact eMSOP‑8 package. The device is specified for use with external 1 % thick‑film resistors for current sensing and can drive LED strings of varying numbers and types.
| Input voltage range | 4.5 V to 30 V |
|---|---|
| Constant output current | 350 mA |
| PWM dimming input pin | DIM |
| Package type | eMSOP‑8 (8‑Lead Plastic) |
| Thermal shutdown threshold | 165 °C |
The device operates with an input voltage from 4.5 V up to 30 V.
Connect a resistor to the FS pin; the frequency can be adjusted between 300 kHz and 1 MHz.
The DIM pin accepts a PWM signal to control LED brightness.
It includes input UVLO, thermal shutdown, and open‑circuit protection.