Texas Instruments LM3407MYX/NOPB

Overview

LM3407MYX/NOPB from Texas Instruments is a 350-mA constant-current floating buck switching converter IC designed to drive high-power LED strings. It integrates an N-channel MOSFET, operates from 4.5 V to 30 V input, delivers regulated current with ±10% accuracy via external ISNS resistor, and supports PWM dimming and independent enable control for automotive and industrial lighting.

For engineers reviewing the LM3407MYX/NOPB datasheet, LM3407MYX/NOPB pinout, LM3407MYX/NOPB application, or LM3407MYX/NOPB equivalent, key selection criteria include its floating buck topology, 300 kHz–1 MHz adjustable switching frequency, no external loop compensation requirement, thermal shutdown at 165°C, and MSOP-8 PowerPAD package with exposed thermal pad.

Technical Context

The LM3407MYX/NOPB implements Pulse Level Modulation (PLM) for true average current regulation-sensing voltage across R_ISNS (198 mV nominal) to dynamically adjust duty cycle independent of input voltage or inductance. Its floating buck architecture uses a low-side N-MOSFET switch referenced to ground, simplifying layout and enabling accurate current sensing without high-side sensing complexity.

It features an internal 4.5-V VCC regulator powered from VIN, UVLO with 3.6 V turn-on threshold and 200 mV hysteresis, CMOS-compatible EN and DIM inputs, and frequency setting via resistor on FS pin. Thermal shutdown (165°C) and undervoltage lockout ensure robust operation in harsh environments like automotive lighting systems.

Key Specifications

Pinout & Package

LM3407MYX/NOPB is housed in an MSOP-8 PowerPAD package (3.00 mm × 3.00 mm) with exposed thermal pad (EP) electrically connected to GND for enhanced thermal dissipation. The package supports surface-mount assembly and requires PCB copper area under EP for optimal junction-to-board thermal resistance (R_θJB = 28.8°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3407MYX/NOPB, LM3409MYX/NOPB offers higher current headroom and extended input range but shares identical control architecture and pinout; TPS92630QPWPRQ1 provides automotive qualification and diagnostics at lower current and higher cost, making it suitable only where AEC-Q100 compliance is mandatory.

Availability

LM3407MYX/NOPB is available at Aetrix Electronics and suitable for automotive headlamp drivers, industrial high-bay lighting, and outdoor streetlight modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM3407MYX/NOPB 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 LM3407MYX/NOPB belongs to TI's LED driver product line, engineered specifically for efficient, thermally robust constant-current regulation in high-power lighting applications where simplicity, accuracy, and ruggedness are critical.

FAQ

What is the recommended R_ISNS value for 350 mA output current with LM3407MYX/NOPB?

The LM3407MYX/NOPB regulates LED current using a fixed 198 mV sense voltage across R_ISNS. For 350 mA output, R_ISNS = 198 mV / 0.35 A = 565.7 Ω. A standard 1% tolerance 565 Ω metal-film or thick-film resistor is recommended, rated for ≥1/8 W to handle 69 mW steady-state dissipation. This value ensures ±10% current accuracy across temperature and line variations.

Does LM3407MYX/NOPB require external compensation components?

No, the LM3407MYX/NOPB does not require external compensation components. Its proprietary Pulse Level Modulation (PLM) control architecture internally manages loop stability, eliminating the need for external RC networks or type-II/type-III compensators. This simplifies design, reduces BOM count, and guarantees stable operation across all valid input voltages, output currents, and inductor values when operated in Continuous Conduction Mode.

Can LM3407MYX/NOPB drive multiple parallel LED strings?

The LM3407MYX/NOPB is designed to drive a single LED string with precise constant current. Driving multiple parallel strings directly is not recommended due to current mismatch risks. For multi-string applications, use one LM3407MYX/NOPB per string - its MSOP-8 PowerPAD footprint and thermal performance support dense layouts. Alternatively, pair with a current-mirror or active balancer IC if shared-string topology is required.

What is the minimum inductance required for stable CCM operation with LM3407MYX/NOPB at 12 V input and 350 mA output?

For 12 V input driving a 3-LED string (VF ≈ 9.6 V total), the minimum inductance is calculated per TI's Equation 6. Using R_ISNS = 565 Ω, f_SW = 500 kHz, and n×V_F = 9.6 V, L_min ≈ 14.2 µH. A 15 µH, 2 A saturation-rated shielded inductor is recommended to maintain Continuous Conduction Mode across full input and temperature range while limiting peak current to <500 mA.

How does the DIM pin function on LM3407MYX/NOPB, and what PWM frequency range is supported?

The DIM pin on LM3407MYX/NOPB accepts logic-level PWM signals (1.3–2.4 V thresholds) to modulate LED brightness without affecting color temperature. It supports PWM frequencies from 100 Hz to 20 kHz. At frequencies above 1 kHz, the internal response ensures <1 µs rise/fall time on LED current, enabling flicker-free dimming. The DIM pin can also serve as a secondary enable - floating or grounded disables output, providing redundant shutdown capability.