Texas Instruments LP3981ILD-2.7/NOPB

Overview

LP3981ILD-2.7/NOPB from Texas Instruments is a micropower, ultra-low-dropout CMOS voltage regulator delivering 300 mA at fixed 2.7 V output, with 132 mV typical dropout at full load, ≤1 µA shutdown quiescent current, and 35 µV_RMS output noise (10 Hz–100 kHz). It serves as the primary power supply for RF front-end ICs in cellular handsets requiring stable low-noise bias.

For engineers reviewing the LP3981ILD-2.7/NOPB datasheet, LP3981ILD-2.7/NOPB pinout, LP3981ILD-2.7/NOPB application, or LP3981ILD-2.7/NOPB equivalent, key selection criteria include dropout performance under 300-mA load, PSRR >55 dB at 10 kHz, thermal resistance in WSON-6 package, and compatibility with 2.2-µF ceramic output capacitors without external compensation.

Technical Context

The LP3981ILD-2.7/NOPB employs a PMOS pass transistor architecture enabling ultra-low dropout and minimal ground current increase in dropout. Its internal bandgap reference (1.23 V) feeds an error amplifier driving the pass element, with fast turnon circuitry reducing startup time to 240 µs (typical) when using 0.033 µF bypass capacitor.

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 connected directly to OUT for standard operation per TI's functional specification.

Key Specifications

Pinout & Package

LP3981ILD-2.7/NOPB is packaged in a 6-pin WSON (NGC) with 4.00 mm × 3.00 mm body size and exposed thermal pad (connected to GND). Thermal resistance R_θJA = 56.5°C/W enables 1.77 W power dissipation at T_A = 25°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL720F27DBVR and MCP1826-2702E/DB, LP3981ILD-2.7/NOPB uniquely balances 300 mA capability, 132 mV dropout, 35 µV_RMS noise, and WSON-6 thermal performance - making it optimal for space-constrained, noise-sensitive RF power domains where both current and spectral purity are critical.

Availability

LP3981ILD-2.7/NOPB is available at Aetrix Electronics and suitable for CDMA/GSM handset design, portable GPS modules, Bluetooth audio systems, and industrial IoT sensor nodes requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LP3981ILD-2.7/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 designing analog ICs, embedded processors, and system-on-chip solutions for industrial, automotive, and communications markets.

The LP3981 family was engineered specifically for battery-powered wireless infrastructure and mobile terminals, emphasizing ultra-low noise, micropower shutdown, and ultra-low dropout to maximize runtime and signal integrity in RF subsystems.

FAQ

What is the minimum input voltage required for LP3981ILD-2.7/NOPB to regulate at full 300 mA load?

The LP3981ILD-2.7/NOPB requires VIN ≥ VOUT + 0.3 V for proper regulation, meaning a minimum input of 3.0 V is needed to sustain 300 mA output at 2.7 V. Below this threshold, dropout behavior begins and output voltage drops linearly with input; the 132 mV typical dropout value applies only when VIN is ≥2.83 V.

Can LP3981ILD-2.7/NOPB operate without connecting the OUT-SENSE pin?

Yes - LP3981ILD-2.7/NOPB operates correctly only when OUT-SENSE is shorted to the OUT pin. Leaving OUT-SENSE floating or unconnected violates TI's functional specification and causes output voltage inaccuracy and potential instability. The pin has no internal connection unless externally tied to OUT.

Is a bypass capacitor mandatory for LP3981ILD-2.7/NOPB to meet its 35 µV_RMS noise specification?

Yes - the 35 µV_RMS output noise (10 Hz–100 kHz) is measured with a 0.033 µF capacitor connected between BYPASS and GND. Without this capacitor, output noise rises to ~120 µV_RMS. TI specifies NPO or COG ceramic dielectrics for lowest leakage and best accuracy.

Does LP3981ILD-2.7/NOPB support ceramic output capacitors smaller than 2.2 µF?

No - TI's datasheet specifies 2.2 µF as the minimum stable output capacitance for LP3981ILD-2.7/NOPB. Using <2.2 µF ceramic capacitors risks oscillation and loss of regulation under load transients. The 2.2–22 µF range with 5–500 mΩ ESR is validated across temperature and process corners.

What thermal derating applies to LP3981ILD-2.7/NOPB at 85°C ambient temperature?

At T_A = 85°C, the maximum continuous output current for LP3981ILD-2.7/NOPB is reduced to ~220 mA based on R_θJA = 56.5°C/W and T_J(MAX) = 125°C. This derating ensures junction temperature remains within safe limits; actual current depends on PCB copper area and airflow.