Texas Instruments LP2981A-30DBVR

Overview

LP2981A-30DBVR from Texas Instruments is a 3.0 V fixed-output, ultra-low dropout linear regulator in SOT-23-5 package, delivering up to 100 mA with ±0.75% output tolerance (A-grade), 200 mV typical dropout at full load, and 0.01 µA shutdown current. It serves as a precision local power supply for low-noise, battery-sensitive subsystems such as microcontroller core rails or analog sensor interfaces.

For engineers reviewing the LP2981A-30DBVR datasheet, LP2981A-30DBVR pinout, LP2981A-30DBVR application, or LP2981A-30DBVR equivalent, this page delivers verified electrical specs, validated pin functions, confirmed thermal behavior across –40°C to 125°C, real-world capacitor stability guidance, and two technically documented alternative parts for design flexibility.

Technical Context

The LP2981A-30DBVR uses a vertical PNP pass transistor architecture enabling ultra-low dropout (7 mV at 1 mA, 200 mV at 100 mA) and low ground current (600 µA typical at full load). Its internal reference is trimmed to 1.23 V, feeding an error amplifier that controls the pass element via feedback from R1/R2 - though for the fixed 3.0 V variant, these resistors are internal and non-accessible.

It integrates active overcurrent and thermal shutdown protection, supports active-low ON/OFF control with 0.15 V logic threshold, and requires external output capacitance with defined ESR range (e.g., 3.3 µF minimum, 0.1–1 Ω typical) to maintain loop stability across temperature and load.

Key Specifications

Pinout & Package

SOT-23-5 package (2.90 mm × 1.60 mm body size), surface-mount, RoHS-compliant. Pin 4 is NC (no connect) and must remain unconnected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout regulator applications.

Compared with LP2981-30DBVR and MCP1700T-3002E/TT, the LP2981A-30DBVR uniquely combines A-grade accuracy, 100 mA capability, active shutdown, and ultra-low dropout in SOT-23-5 - making it optimal for precision, low-power, space-limited applications where all four attributes are required simultaneously.

Availability

LP2981A-30DBVR is available at Aetrix Electronics and suitable for smart metering, motor control logic, portable audio bias, and industrial sensor signal chain applications requiring stable component supply, long-term lifecycle support, and guaranteed A-grade parametric performance.

Supply support for LP2981A-30DBVR 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 and embedded processing technologies, with leadership in power management ICs and industrial-grade reliability validation.

The LP2981A family was designed specifically for ultra-low dropout, high-accuracy local regulation in portable and industrial systems where battery life, thermal constraints, and signal integrity are critical.

FAQ

What is the minimum input voltage required for LP2981A-30DBVR to regulate 3.0 V output?

The LP2981A-30DBVR requires a minimum input voltage of 2.2 V for proper biasing of its internal control circuitry. However, to maintain regulation at full 100 mA load, VIN must exceed VOUT by at least the dropout voltage - typically 200 mV, so ≥3.2 V input is recommended for full-load operation. At light loads (1 mA), dropout drops to 7 mV, allowing regulation down to ~3.007 V input.

Can LP2981A-30DBVR use ceramic capacitors on the output?

Yes, but only with a 1 Ω series resistor to raise effective ESR - because the LP2981A-30DBVR's PNP architecture requires 0.1–1 Ω ESR for loop stability. A standard 3.3 µF X7R ceramic capacitor alone has ~10–20 mΩ ESR and will cause oscillation. Adding the resistor brings total ESR into the stable range while preserving ceramic benefits like small size and temperature stability.

What happens if the ON/OFF pin of LP2981A-30DBVR is left floating?

Leaving the ON/OFF pin floating risks undefined behavior due to noise coupling or internal leakage, potentially causing intermittent shutdown or erratic start-up. The datasheet explicitly requires active termination: tie ON/OFF to VIN if shutdown is unused, or drive it actively to ≤0.15 V (OFF) or ≥1.6 V (ON). A pullup resistor to VIN is the standard implementation for default-enable operation.

Does LP2981A-30DBVR include reverse-voltage protection?

No, LP2981A-30DBVR does not include reverse-voltage protection. Its internal PNP pass transistor has a parasitic emitter-base diode that becomes forward-biased if VOUT exceeds VIN by ~0.7 V, risking latch-up or damage. In applications where output voltage may exceed input (e.g., hot-swap, backup battery), an external Schottky diode (anode to VOUT, cathode to VIN) is mandatory to clamp reverse voltage to ~0.3 V.

How does LP2981A-30DBVR handle thermal overload?

LP2981A-30DBVR incorporates thermal foldback protection: when junction temperature exceeds ~150°C, it reduces output current to limit power dissipation and prevent permanent damage. This is not a simple shutdown - it dynamically throttles current while maintaining regulation as much as possible. Recovery occurs automatically once temperature falls below the hysteresis threshold (~140°C), without requiring ON/OFF pin cycling.