Texas Instruments LP3981ILD-3.03/NOPB

Overview

LP3981ILD-3.03/NOPB from Texas Instruments is a micropower, ultra-low-dropout CMOS voltage regulator delivering 300 mA at fixed 3.03 V output, optimized for battery-powered wireless systems. It features 132 mV typical dropout at full load, ≤1 µA shutdown quiescent current, and 35 µV_RMS output noise (10 Hz–100 kHz), enabling clean power for RF front-ends and baseband ICs in cellular handsets.

For engineers reviewing the LP3981ILD-3.03/NOPB datasheet, LP3981ILD-3.03/NOPB pinout, LP3981ILD-3.03/NOPB application, or LP3981ILD-3.03/NOPB equivalent, key selection criteria include dropout performance under 300-mA load, ceramic-capacitor stability with 2.2-µF C_OUT, EN-controlled shutdown leakage (<1.5 µA), PSRR >55 dB at 10 kHz, and WSON-6 thermal resistance (R_θJB = 30.9 °C/W).

Technical Context

The LP3981ILD-3.03/NOPB employs a CMOS pass element with internal 1.23-V reference and fast-turnon circuitry, achieving 240 µs typical enable response with 0.033-µF BYPASS capacitor. Its feedback loop uses OUT-SENSE for remote sensing, requiring direct connection to OUT for regulation accuracy.

It operates across −40°C to +125°C with input range 2.7 V to 6 V, maintains 60-dB PSRR at 1 kHz down to low VIN, and integrates thermal shutdown (160°C) and short-circuit current limit (600 mA). Ground current rises only modestly in dropout-170 µA at 150 mA-preserving battery life.

Key Specifications

Pinout & Package

LP3981ILD-3.03/NOPB is housed in a thermally enhanced 6-pin WSON package (4.00 mm × 3.00 mm) with exposed thermal pad connected to GND. The package supports high-power-density layouts and achieves R_θJB = 30.9 °C/W for efficient PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3981ILD-3.03/NOPB, TLS850F2TLE trades RF noise performance for automotive robustness and higher current, while TPS7A20303PDBVR delivers significantly lower noise but sacrifices remote sensing capability and thermal pad integration-critical for compact, thermally constrained handset PCBs.

Availability

LP3981ILD-3.03/NOPB is available at Aetrix Electronics and suitable for CDMA/WCDMA handset design, portable information appliance power management, and battery-powered RF module development requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for LP3981ILD-3.03/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 digital signal solutions for industrial, automotive, and communications markets.

The LP3981 family targets battery-powered wireless infrastructure and mobile devices, delivering ultra-low-noise, micropower LDO regulation with ceramic-capacitor compatibility and thermal resilience in space-constrained WSON packages.

FAQ

What is the minimum input voltage required for LP3981ILD-3.03/NOPB to regulate at full 300-mA load?

The LP3981ILD-3.03/NOPB requires VIN ≥ VOUT + dropout voltage. With 132 mV typical dropout at 300 mA, minimum VIN is 3.03 V + 0.132 V = 3.162 V. At −40°C to +125°C, max dropout is 200 mV, so VIN must be ≥3.23 V for guaranteed regulation across temperature. Input below 2.7 V is outside recommended operating conditions.

Can LP3981ILD-3.03/NOPB operate stably with a 1-µF ceramic output capacitor?

No. LP3981ILD-3.03/NOPB requires 2.2–22 µF output capacitance per datasheet Section 6.5 and Application Section 9.2.2.4. A 1-µF capacitor falls below the minimum 2.2 µF and risks instability, especially under load transients. X7R dielectric 2.2-µF ceramics with 5–500 mΩ ESR are validated for stable operation.

Is the OUT-SENSE pin mandatory for LP3981ILD-3.03/NOPB operation?

Yes. Per Pin Descriptions in Section 5, OUT-SENSE must be connected directly to OUT for proper regulation. Leaving it floating or connecting it elsewhere causes output voltage error and potential instability. This remote-sense configuration compensates for PCB trace resistance between the LDO and load.

What is the thermal performance difference between LP3981ILD-3.03/NOPB in WSON-6 versus VSSOP-8 packages?

LP3981ILD-3.03/NOPB in WSON-6 achieves R_θJB = 30.9 °C/W versus 97.4 °C/W for VSSOP-8 (Section 6.4). This 3.1× better junction-to-board resistance allows the WSON package to dissipate ~3× more power at the same board temperature rise-critical for sustained 300-mA loads in compact handset PCBs with limited copper area.

Does LP3981ILD-3.03/NOPB require an external bypass capacitor on the BYPASS pin for basic functionality?

No. The BYPASS pin is optional: LP3981ILD-3.03/NOPB regulates correctly without it. However, connecting a 0.033-µF ceramic capacitor reduces output noise from ~80 µV_RMS (typical un-bypassed) to 35 µV_RMS. The capacitor must be low-leakage (e.g., COG/NPO ceramic) to avoid output voltage error.