Texas Instruments LP3981ILD-3.0

Overview

LP3981ILD-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 features 132 mV typical dropout at full load, ≤1 µA shutdown current, 35 µV_RMS output noise (10 Hz–100 kHz), and 60 dB PSRR at 1 kHz - enabling clean power for RF front-ends and baseband processors in cellular handsets.

For engineers reviewing the LP3981ILD-3.0 datasheet, LP3981ILD-3.0 pinout, LP3981ILD-3.0 application, or LP3981ILD-3.0 equivalent, key selection criteria include its WSON-6 package thermal performance (R_θJA = 56.5°C/W), logic-controlled enable with 1.4 V VIH threshold, ceramic-capacitor stability (2.2 µF C_OUT), and precise 3.0 V ±3% output tolerance across −40°C to +125°C.

Technical Context

The LP3981ILD-3.0 employs a PMOS pass transistor architecture enabling ultra-low dropout and minimal ground current increase in dropout - critical for extending battery runtime. Its internal bandgap reference (1.23 V) feeds a precision error amplifier that regulates output via OUT-SENSE feedback, supporting remote sensing for improved load regulation.

It integrates fast-turnon circuitry (240 µs typical t_ON with 0.033 µF BYPASS capacitor), thermal shutdown (160°C), and short-circuit current limiting (600 mA). The BYPASS pin connects to a high-impedance node in the reference circuit, allowing external 0.033 µF capacitor to reduce output noise without degrading transient response.

Key Specifications

Pinout & Package

LP3981ILD-3.0 is housed in a thermally enhanced 6-pin WSON package (4.00 mm × 3.00 mm) with exposed thermal pad connected to GND. This package delivers R_θJA = 56.5°C/W (High-K board), enabling higher power dissipation than VSSOP-8 alternatives in space-constrained layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3981ILD-3.0, TPL7407LDR trades dropout performance for lower active IQ, while MCP1700T-3002E/MB sacrifices current capability and thermal efficiency for minimal footprint - making LP3981ILD-3.0 optimal for 300 mA, low-noise, thermally demanding portable designs.

Availability

LP3981ILD-3.0 is available at Aetrix Electronics and suitable for CDMA/WCDMA handset power management, portable medical sensor nodes, GSM audio subsystems, and battery-powered IoT edge devices requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LP3981ILD-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 designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and consumer markets.

The LP3981 family was developed specifically for micropower, ultra-low-noise LDO regulation in battery-powered wireless handsets - emphasizing low dropout, ceramic-capacitor compatibility, and robust thermal performance in miniature WSON packages.

FAQ

What is the minimum input voltage required for LP3981ILD-3.0 to regulate at 3.0 V?

The LP3981ILD-3.0 requires VIN ≥ VOUT + 0.3 V for proper operation per datasheet Section 8.4.1. With a nominal 3.0 V output, the minimum functional input is 3.3 V. However, its 132 mV typical dropout allows regulation down to VIN = 3.132 V at 300 mA load - verified in Electrical Characteristics Table 6.5 under Dropout Voltage test conditions.

Can LP3981ILD-3.0 operate stably with a 1-µF ceramic output capacitor?

No - the LP3981ILD-3.0 requires a minimum 2.2 µF ceramic output capacitor for stability, as specified in Section 9.2.2.4 and Table 6.5. Using 1 µF violates the recommended COUT range (2.2–22 µF) and risks oscillation or poor transient response, especially under 300 mA load steps.

Does the BYPASS pin on LP3981ILD-3.0 require a specific capacitor dielectric type?

Yes - TI recommends NPO/COG ceramic or polypropylene/polycarbonate film capacitors for the BYPASS pin due to their extremely low leakage current, which prevents output voltage error. High-leakage dielectrics like Y5V or Z5U are discouraged, as DC leakage through BYPASS directly affects reference accuracy per Section 9.2.2.6.

Is the thermal pad on the LP3981ILD-3.0 WSON package electrically connected internally?

Yes - the exposed thermal pad on the LP3981ILD-3.0 WSON package is internally connected to GND (Pin 4), as confirmed in Pin Descriptions (Section 5) and Layout Guidelines (Section 11.1). It must be soldered to a PCB copper pour tied to the system ground plane to achieve the specified R_θJA = 56.5°C/W and prevent thermal shutdown.

How does LP3981ILD-3.0 behave when the EN pin is left floating?

The LP3981ILD-3.0 EN pin has no internal pull-up or pull-down; if left floating, its voltage is undefined and may drift near the 0.4 V VIL threshold, causing erratic enable/disable behavior. TI explicitly states in Section 8.3.1 that unused EN pins must be tied to VIN to ensure reliable operation - floating EN is not a valid configuration.