Texas Instruments LP3981IMM-3.0

Overview

LP3981IMM-3.0 from Texas Instruments is a micropower, ultra-low-dropout CMOS voltage regulator delivering 300 mA at fixed 3.0 V output, optimized for battery-powered wireless systems. It operates from 2.5 V to 6 V input, achieves 132 mV typical dropout at full load, maintains ≤1 µA shutdown current, and delivers 35 µV_RMS output noise (10 Hz–100 kHz) with ceramic capacitor support.

For engineers reviewing the LP3981IMM-3.0 datasheet, LP3981IMM-3.0 pinout, LP3981IMM-3.0 application, or LP3981IMM-3.0 equivalent, key selection criteria include low-noise LDO performance in space-constrained portable designs, thermal behavior in WSON-6 packaging, enable-controlled power sequencing, and compatibility with 2.2 µF ceramic output capacitors without external compensation.

Technical Context

The LP3981IMM-3.0 employs a CMOS pass transistor architecture enabling ultra-low quiescent current and minimal ground current increase in dropout-critical for extending battery life in GSM/CDMA handsets. Its internal bandgap reference (1.23 V) feeds a fast-turnon circuit that achieves 240 µs typical startup time with 0.033 µF bypass capacitance.

It integrates logic-controlled enable (VIH = 1.4 V, VIL = 0.4 V), thermal shutdown (160 °C), and short-circuit current limiting (600 mA). The OUT-SENSE pin provides remote sensing capability but must be tied directly to OUT for standard operation per TI's functional specification.

Key Specifications

Pinout & Package

LP3981IMM-3.0 is packaged in a 6-pin WSON (NGC) package measuring 4.00 mm × 3.00 mm with exposed thermal pad connected to GND. This thermally enhanced layout enables 56.5 °C/W junction-to-ambient resistance under JEDEC High-K board conditions.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TLS850F3TLE and TPS73030DBVR, LP3981IMM-3.0 uniquely balances ultra-low noise (35 µV_RMS), micropower shutdown (<1 µA), and WSON-6 thermal efficiency (56.5 °C/W)-making it optimal for battery-constrained RF subsystems where noise and standby current dominate design tradeoffs.

Availability

LP3981IMM-3.0 is available at Aetrix Electronics and suitable for CDMA handset design, portable information appliance development, and GSM RF module integration requiring stable component supply, consistent parametric performance, and long-term lifecycle availability.

Supply support for LP3981IMM-3.0 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 connectivity technologies, with leadership in power management innovation since 1930.

The LP3981 family was designed specifically for micropower, ultra-low-noise LDO regulation in battery-powered wireless terminals-including cellular handsets, portable radios, and handheld computing devices-prioritizing dropout, noise, and quiescent current over raw current capacity.

FAQ

What is the maximum input voltage rating for LP3981IMM-3.0?

The absolute maximum input voltage for LP3981IMM-3.0 is 6.5 V, but the recommended operating range is 2.7 V to 6 V per TI's SNVS159H datasheet. Operation above 6 V risks permanent damage, while inputs below 3.3 V may cause dropout depending on load current-specifically, VIN must exceed VOUT + 0.3 V (i.e., ≥3.3 V) for guaranteed regulation. The LP3981IMM-3.0 is not rated for automotive 12-V or industrial 24-V input rails.

Does LP3981IMM-3.0 require an external bypass capacitor for stable operation?

No-LP3981IMM-3.0 is stable without the BYPASS capacitor, but adding a 0.033 µF ceramic capacitor between BYPASS and GND reduces output noise from ~70 µV_RMS to 35 µV_RMS (10 Hz–100 kHz) without affecting load transient response. The BYPASS pin connects to a high-impedance reference node; low-leakage NPO/COG ceramics are recommended. Omitting it does not compromise regulation or stability, only noise performance.

Can LP3981IMM-3.0 be used with a 2.2 µF tantalum output capacitor?

Yes-LP3981IMM-3.0 is explicitly characterized for stability with high-quality tantalum capacitors (2.2–22 µF, 5–500 mΩ ESR), though ceramic is preferred for size, cost, and ESR consistency. Tantalum capacitors must meet surge current ratings if placed directly after batteries or large bulk caps, and their ESR increases ~2× at −40°C, requiring margin in low-temp designs. The LP3981IMM-3.0 datasheet confirms compatibility, but ceramic remains the default recommendation.

What is the thermal shutdown behavior of LP3981IMM-3.0?

LP3981IMM-3.0 activates thermal shutdown at 160 °C junction temperature and remains latched off until junction temperature falls by ~20 °C (hysteresis), per Electrical Characteristics table. During shutdown, output is disabled and quiescent current drops to ≤1.5 µA. Recovery is automatic-no external reset is needed. This protects against sustained overload or inadequate PCB copper area, especially critical in the compact WSON-6 package where RθJA = 56.5 °C/W assumes JEDEC High-K board conditions.

Is LP3981IMM-3.0 pin-compatible with other LP3981 variants like LP3981IMM-2.8 or LP3981IMM-3.3?

Yes-LP3981IMM-3.0 shares identical WSON-6 (NGC) pinout, package dimensions (4.00 mm × 3.00 mm), and terminal functions with all LP3981 fixed-output variants (2.5 V, 2.7 V, 2.8 V, 2.83 V, 3.03 V, 3.3 V). Only the internal feedback resistor network differs to set output voltage; no PCB redesign is needed when swapping between these variants, provided input/output capacitor values remain appropriate for the new VOUT and load conditions.