Texas Instruments LM3404HVMRX

Overview

LM3404HVMRX from Texas Instruments is a monolithic 1-A constant-current buck regulator IC designed for high-power LED driving in automotive and industrial lighting systems. It integrates a high-side N-channel MOSFET (R_DS(on) = 0.75 Ω typ), supports 6 V to 75 V input, delivers 1.2-A output current with cycle-by-cycle current limiting, and uses controlled-on-time (COT) hysteretic control to eliminate loop compensation. It operates in continuous conduction mode (CCM) with PWM dimming capability via the DIM pin.

For engineers reviewing the LM3404HVMRX datasheet, LM3404HVMRX pinout, LM3404HVMRX application, or LM3404HVMRX equivalent, key selection considerations include its 75-V max input rating, 200-mV current-sense threshold, thermal shutdown at 165°C, SO PowerPAD-8 package thermal performance (R_θJA = 44.7°C/W), and compatibility with ceramic-only or capacitor-less LED output configurations.

Technical Context

The LM3404HVMRX implements a controlled-on-time (COT) architecture combining hysteretic regulation with an external R_ON-programmable one-shot timer - on-time varies inversely with VIN (e.g., 325–505 ns at 70 V with 200 kΩ). It regulates LED current by comparing CS pin voltage against a 200-mV reference and disables the internal MOSFET if VSNS exceeds 300 mV (OVP/OCP protection).

Its integrated 7-V linear regulator powers internal circuitry from VIN and activates above 5.25 V; VCC must be bypassed with ≥0.1-µF X5R/X7R ceramic. The BOOT-SW bootstrap circuit (10-nF CB) enables high-side gate drive, while the DIM pin provides TTL-compatible PWM dimming with 75-µA internal pullup and <300-ns response delay.

Key Specifications

Pinout & Package

LM3404HVMRX is packaged in an 8-pin SO PowerPAD™ (DDA) package (3.90 mm × 4.89 mm) with exposed thermal pad (DAP) that must be soldered to PCB ground plane 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 LM3404MX/NOPB, LM3404HVMRX extends input range to 75 V for transient-hardened designs, while MPQ4425HG-AEC1-P adds automotive qualification and diagnostics at the cost of increased complexity and bill-of-materials.

Availability

LM3404HVMRX is available at Aetrix Electronics and suitable for automotive lighting, industrial high-bay fixtures, and commercial streetlighting requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM3404HVMRX 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 and embedded processing technologies, with leadership in power management, signal chain, and high-reliability ICs.

The LM3404HVMRX belongs to TI's LED driver product line, engineered specifically for efficient, robust constant-current regulation in high-power lighting applications - emphasizing simplicity, thermal resilience, and wide-input operation.

FAQ

What is the maximum input voltage supported by the LM3404HVMRX?

The LM3404HVMRX supports a maximum input voltage of 75 V, as specified in its absolute maximum ratings. This extended range accommodates automotive load-dump conditions and higher-voltage DC distribution systems. Operation above 75 V risks permanent damage; the device enters undervoltage lockout below 6 V. The LM3404HVMRX datasheet confirms this rating under "Recommended Operating Conditions" and "Absolute Maximum Ratings" sections.

Does the LM3404HVMRX require external compensation components?

No, the LM3404HVMRX does not require external compensation components due to its controlled-on-time (COT) hysteretic control architecture. This eliminates the need for loop-stabilizing resistors and capacitors typically used in voltage-mode or current-mode controllers. The LM3404HVMRX achieves stable regulation solely through its internal 200-mV current-sense comparator and R_ON-programmed on-time, simplifying layout and reducing BOM count.

How is LED dimming implemented on the LM3404HVMRX?

LED dimming on the LM3404HVMRX is implemented via the DIM pin, which accepts a TTL-compatible PWM signal. A logic-low input (≤0.8 V) disables the internal MOSFET, turning off LED current; a logic-high input (≥2.2 V) enables regulation. The LM3404HVMRX features a 75-µA internal pullup, ensuring default ON operation when DIM is unconnected. Dimming frequency must remain well below the switching frequency to avoid aliasing.

What package type is used for the LM3404HVMRX, and why is thermal design critical?

The LM3404HVMRX uses the SO PowerPAD™-8 (DDA) package with an exposed thermal pad (DAP). Thermal design is critical because the device dissipates significant power during 1.2-A operation; its R_θJB is 24.5°C/W only when the DAP is properly soldered to a ground plane with 4–6 thermal vias. Without adequate thermal relief, junction temperature can exceed 125°C, triggering thermal shutdown or reliability degradation. The LM3404HVMRX datasheet specifies layout guidelines in Section 10.

Can the LM3404HVMRX operate without an output capacitor?

Yes, the LM3404HVMRX is explicitly designed to operate without an output capacitor - a key feature highlighted in its datasheet. Because it regulates LED current (not voltage), the inductor and LED form a direct current path, eliminating the need for output capacitance to maintain regulation. This reduces cost, size, and failure points. When used capacitor-less, a small 10-nF capacitor across the LED array is recommended to dampen switching-node oscillation, as confirmed in LM3404HVMRX Application Note SNVS465G.