Texas Instruments LM3404MA

Overview

LM3404MA from Texas Instruments is a monolithic 1-A constant-current buck regulator optimized for driving high-power LED arrays in automotive and industrial lighting systems. It integrates a high-side N-channel MOSFET (R_DS(on) = 0.75 Ω typ), operates from 6 V to 42 V input, delivers up to 1.2-A output current, features cycle-by-cycle current limiting, and supports PWM dimming via the DIM pin. Its hysteretic controlled-on-time architecture eliminates loop compensation.

For engineers reviewing the LM3404MA datasheet, LM3404MA pinout, LM3404MA application, or LM3404MA equivalent, key selection considerations include its 200-mV current-sense threshold, programmable on-time via R_ON, thermal shutdown at 165°C, SOIC-8 PowerPAD™ package, and compatibility with ceramic-only or capacitor-less output configurations.

Technical Context

The LM3404MA implements a controlled-on-time (COT) architecture combining hysteretic mode control with an input-voltage-dependent one-shot timer - enabling stable regulation without external compensation. Its CS pin compares sensed voltage across RSNS against a precise 200-mV reference to initiate switching, while RON sets t_ON inversely proportional to VIN.

It integrates a 7-V internal linear regulator (VCC) with undervoltage lockout (5.3 V), drives the high-side MOSFET via a bootstrap circuit (BOOT–SW), and includes dedicated protection: cycle-by-cycle current limit (1.5-A typ), overvoltage/overcurrent comparator (300-mV threshold), and thermal shutdown with 25°C hysteresis.

Key Specifications

Pinout & Package

LM3404MA is housed in an SOIC-8 package with exposed PowerPAD™ (DDA variant), measuring 3.90 mm × 4.89 mm. The PowerPAD must be soldered to a grounded copper area using 4–6 thermal vias for optimal thermal performance (R_θJB = 24.5°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with LM3404MH/NOPB, LM3404MA offers identical performance but with standard lead finish; versus MPQ4425AGU-AEC1-P, it trades AEC-Q100 compliance and diagnostics for simpler layout, no compensation, and lower system cost in non-automotive industrial lighting.

Availability

LM3404MA is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay fixtures, commercial signage backlights, and emergency exit lighting requiring stable component supply and long-lifecycle support.

Supply support for LM3404MA includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management ICs, with leadership in automotive, industrial, and personal electronics markets.

The LM3404MA belongs to TI's LED lighting controller product line, designed specifically for efficient, robust, and easy-to-implement constant-current drivers targeting high-reliability illumination systems.

FAQ

What is the maximum input voltage supported by the LM3404MA?

The LM3404MA supports a maximum input voltage of 42 V, with absolute maximum rating at 45 V. This makes it compatible with standard 12 V and 24 V automotive and industrial power rails, including transient spikes up to 45 V. Operation above 42 V risks exceeding recommended conditions and may trigger thermal or overvoltage protection.

How does the LM3404MA achieve constant LED current without external compensation components?

The LM3404MA uses a controlled-on-time (COT) hysteretic architecture that compares the CS pin voltage against a 200-mV internal reference. When current falls below the setpoint, the integrated MOSFET turns on for a precisely timed duration determined by VIN and RON. This self-regulating timing eliminates the need for external compensation networks, simplifying design and improving transient response.

Can the LM3404MA drive LED strings without an output capacitor?

Yes, the LM3404MA supports capacitor-less operation due to its current-mode control and direct inductor-to-LED connection. The inductor inherently filters current ripple, allowing stable LED current without output capacitance. A small 10-nF capacitor across the LED array is recommended to dampen switching-node oscillation, but bulk output capacitance is optional.

What is the purpose of the RON pin on the LM3404MA, and how is it used?

The RON pin on the LM3404MA programs the controlled on-time (t_ON) by connecting an external resistor between RON and VIN. t_ON scales inversely with VIN and linearly with RON value (e.g., 200 kΩ yields ~2.75 µs at 10 V). This directly sets switching frequency and maximum duty cycle, enabling optimization for efficiency, EMI, or output voltage range.

Does the LM3404MA include protection against LED open-circuit failure?

Yes, the LM3404MA includes open-LED protection via its CS pin overvoltage comparator, which triggers at 300 mV. During an open-circuit event, CS voltage drops to 0 V, causing the controller to maximize duty cycle - but the 300-mV OVP threshold disables the MOSFET before output voltage reaches dangerous levels. External Zener-based clamping (e.g., Figure 18) extends this protection to defined safe limits.