Texas Instruments LM3670MF-1.6/NOPB

Overview

LM3670MF-1.6/NOPB from Texas Instruments is a fixed-output synchronous step-down DC-DC converter delivering 1.6 V at up to 350 mA from 2.5 V–5.5 V input, featuring 1-MHz PWM switching, 15-µA quiescent current in PFM mode, internal soft start, and low-dropout 100% duty-cycle operation. It powers core logic rails in battery-powered handheld devices requiring compact, high-efficiency regulation.

For engineers reviewing the LM3670MF-1.6/NOPB datasheet, LM3670MF-1.6/NOPB pinout, LM3670MF-1.6/NOPB application, or LM3670MF-1.6/NOPB equivalent, key selection criteria include output voltage accuracy (±4% over load/temperature), shutdown current (0.1 µA typical), peak switch current limit (750 mA), thermal performance (R_θJA = 163.3°C/W), and SOT-23-5 package compatibility with space-constrained PCB layouts.

Technical Context

The LM3670MF-1.6/NOPB implements voltage-mode control with input feed-forward for stable line regulation and uses internal PFET/NFET synchronous rectification to achieve 90–95% efficiency across 1–100 mA loads. Its dual-mode operation-fixed-frequency 1-MHz PWM above ~70 mA and hysteretic PFM below-enables dynamic efficiency optimization without external mode control.

It integrates undervoltage lockout (2.4 V threshold), thermal shutdown, cycle-by-cycle current limiting (620 mA typical trip), and soft-start (400 µs typical with 10-µF C_OUT). The FB pin is internally tied to a 0.5-V reference, eliminating external resistors for the fixed 1.6-V variant, simplifying layout and reducing BOM count.

Key Specifications

Pinout & Package

The LM3670MF-1.6/NOPB is housed in a 5-pin SOT-23 package (2.90 mm × 1.60 mm body size) with gull-wing leads, optimized for automated assembly and thermal dissipation via PCB copper pour under the exposed pad (GND-connected).

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-16, the LM3670MF-1.6/NOPB uniquely combines 0.1-µA shutdown, 100% duty-cycle dropout, and automatic PFM/PWM mode switching - making it optimal for battery-critical, space-constrained portable devices operating across full battery voltage range.

Availability

LM3670MF-1.6/NOPB is available at Aetrix Electronics and suitable for mobile phones, wearable sensors, portable medical instruments, and handheld industrial scanners requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LM3670MF-1.6/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 headquartered in Dallas, Texas, designing and manufacturing analog and embedded processing chips for industrial, automotive, and personal electronics markets.

The LM3670 product line delivers miniature, high-efficiency step-down converters optimized for ultralow-voltage circuits in battery-powered portable devices, emphasizing minimal external component count and intelligent power mode management.

FAQ

What is the recommended inductor value for LM3670MF-1.6/NOPB in a typical application?

A 4.7 µH or 10 µH shielded surface-mount inductor with ≥800 mA saturation current rating is recommended for LM3670MF-1.6/NOPB. TI's datasheet specifies 10 µH as optimal for most cases, balancing ripple current, transient response, and physical size. Inductor DCR should be <0.3 Ω to maintain >90% efficiency at full load. The LM3670MF-1.6/NOPB's 1-MHz switching frequency enables smaller magnetics than lower-frequency alternatives.

Does LM3670MF-1.6/NOPB require external feedback resistors?

No, LM3670MF-1.6/NOPB does not require external feedback resistors. As a fixed-output variant, its internal feedback network is trimmed to deliver 1.6 V with ±4% accuracy across load and temperature. The FB pin connects directly to the output capacitor and requires no external components - simplifying design, reducing BOM cost, and eliminating resistor tolerance errors that affect adjustable versions.

How does LM3670MF-1.6/NOPB handle input voltage dropout near battery depletion?

The LM3670MF-1.6/NOPB supports 100% duty-cycle operation, allowing it to regulate 1.6 V output down to VIN = 2.5 V - the absolute minimum specified input. When input drops below the undervoltage lockout threshold (2.4 V), the device disables output cleanly. This low dropout capability maximizes usable energy from single Li-ion or multi-cell alkaline batteries, extending operational time before shutdown compared to non-100% duty-cycle buck converters.

What is the thermal performance of LM3670MF-1.6/NOPB in SOT-23-5 package?

The LM3670MF-1.6/NOPB has a junction-to-ambient thermal resistance (R_θJA) of 163.3°C/W in the SOT-23-5 (DBV) package. With proper PCB layout - including ≥100 mm² copper pour connected to Pin 2 (GND) - it sustains 350 mA continuous output at +85°C ambient. Derating begins above 100°C junction temperature, triggering thermal shutdown at 125°C. R_θJB = 26.8°C/W confirms effective heat transfer to the board, critical for compact handheld designs.

Can LM3670MF-1.6/NOPB be used with ceramic output capacitors only?

Yes, LM3670MF-1.6/NOPB is fully compatible with ceramic-only output capacitance. The datasheet specifies a 10-µF X5R/X7R ceramic capacitor with ≤10 mΩ ESR as optimal for stability and transient response. Unlike older buck controllers, it does not require tantalum or electrolytic capacitors and remains stable with low-ESR ceramics across temperature and aging - reducing component count, board area, and failure risk in high-reliability portable applications.