Texas Instruments LM3671MF-1.5/NOPB

Overview

LM3671MF-1.5/NOPB from Texas Instruments is a fixed-output 1.5 V, 2-MHz synchronous step-down DC-DC converter optimized for single Li-Ion battery-powered portable electronics. It delivers up to 600 mA load current with 16 µA typical quiescent current in PFM mode, internal soft start, and integrated PFET/NFET power switches - used in mobile phones, MP3 players, and digital still cameras.

For engineers reviewing the LM3671MF-1.5/NOPB datasheet, LM3671MF-1.5/NOPB pinout, LM3671MF-1.5/NOPB application, or LM3671MF-1.5/NOPB equivalent, key selection criteria include input voltage range (2.7–5.5 V), fixed 1.5 V output accuracy (±4%), shutdown current (0.01 µA), thermal shutdown (150°C), and USON-6 package compatibility with space-constrained PCB layouts.

Technical Context

The LM3671MF-1.5/NOPB employs voltage-mode PWM control with input feed-forward compensation for stable line regulation across 2.7–5.5 V input. Its dual-mode operation automatically transitions between 2-MHz fixed-frequency PWM (≥80 mA load) and hysteretic PFM (light-load, 16 µA IQ) to maximize battery life.

Internal synchronous rectification uses a matched PFET/NFET pair with R_DS(ON) of 380 mΩ (PFET) and 250 mΩ (NFET) at 3.6 V, enabling high efficiency without external diodes. Feedback is referenced to a precision 0.5 V internal bandgap, with FB pin directly connected to V_OUT for fixed-output variants.

Key Specifications

Pinout & Package

LM3671MF-1.5/NOPB is packaged in a 2.00 mm × 2.00 mm, 0.5-mm-pitch USON-6 (NKH) package with wettable flanks for automated optical inspection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down DC-DC converter applications.

Compared with TPS62231DRYR and AP63202WU-15, LM3671MF-1.5/NOPB offers superior thermal protection (latched shutdown at 150°C), identical 600-mA capability and USON-6 footprint, and proven field reliability in consumer portable designs - making it optimal for cost-sensitive, high-volume handheld electronics.

Availability

LM3671MF-1.5/NOPB is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, and wireless handheld terminals requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LM3671MF-1.5/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 leader designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and personal electronics markets.

The LM3671 product line delivers highly integrated, low-quiescent-current DC-DC converters targeting battery-powered portable devices - emphasizing minimal external components, small footprint, and robust protection features for space- and power-constrained applications.

FAQ

What is the recommended input capacitor for LM3671MF-1.5/NOPB?

The LM3671MF-1.5/NOPB datasheet specifies a minimum 4.7 µF X5R/X7R ceramic capacitor placed as close as possible to the VIN and GND pins. This value ensures stable operation across the 2.7–5.5 V input range and suppresses high-frequency switching noise. For improved ripple rejection under dynamic loads, TI recommends paralleling with a 0.1 µF capacitor. The LM3671MF-1.5/NOPB's internal current limiting and soft-start reduce stress on the input capacitor during startup transients.

Does LM3671MF-1.5/NOPB require an external feedback resistor divider?

No, the LM3671MF-1.5/NOPB is a fixed-output variant with internal resistor divider configured for 1.5 V. The FB pin connects directly to the output capacitor - no external resistors are needed. This simplifies layout and eliminates tolerance drift errors. In contrast, the adjustable LM3671ADJ version requires external R1/R2 to set V_OUT, but the LM3671MF-1.5/NOPB's internal 0.5 V reference and factory-trimmed divider ensure ±4% output accuracy over temperature and line.

What thermal derating applies to LM3671MF-1.5/NOPB at 85°C ambient?

At 85°C ambient temperature, the LM3671MF-1.5/NOPB's maximum power dissipation is 242 mW on a 4-layer PCB (R_θJA = 174.7°C/W). This corresponds to ~400 mA load at 1.5 V output with 3.6 V input, assuming typical efficiency (~92%). Derating is necessary to maintain junction temperature below 125°C. TI provides thermal metrics including ψ_JB (109.0°C/W) to aid board-level thermal modeling. The LM3671MF-1.5/NOPB includes thermal shutdown that activates at 150°C to prevent damage.

Can LM3671MF-1.5/NOPB operate from a 2.5 V input?

No - the absolute minimum input voltage for functional operation of LM3671MF-1.5/NOPB is 2.7 V, as specified in Recommended Operating Conditions. Below 2.7 V, undervoltage lockout disables switching, and the device remains in shutdown even if EN is asserted. Attempting operation at 2.5 V may cause erratic regulation or failure to start. The LM3671MF-1.5/NOPB is designed for single Li-Ion (2.7–4.2 V operational range) and USB-powered systems; for sub-2.7 V inputs, consider boost or buck-boost alternatives.

How does the soft-start function work in LM3671MF-1.5/NOPB?

The LM3671MF-1.5/NOPB implements hardware-based soft-start by incrementally raising the internal current limit threshold in four discrete steps (70 mA → 140 mA → 280 mA → 1020 mA) upon EN assertion, provided VIN ≥2.7 V. This limits inrush current into the output capacitor, preventing input rail sag and output overshoot. Typical startup time is 275 µs (1 mA load) to 400 µs (300 mA load) with a 10 µF output capacitor. The LM3671MF-1.5/NOPB does not require external soft-start components.