Texas Instruments LP2981-28DBVRE4

Overview

LP2981-28DBVRE4 from Texas Instruments is a 2.8 V fixed-output, ultra-low dropout linear regulator in SOT-23-5 package, delivering up to 100 mA with ±1.25% output tolerance (standard grade), 200 mV typical dropout at full load, and 0.01 µA shutdown current - deployed in mobile phones, PDAs, and digital cameras for stable low-power rail generation.

For engineers reviewing the LP2981-28DBVRE4 datasheet, LP2981-28DBVRE4 pinout, LP2981-28DBVRE4 application, or LP2981-28DBVRE4 equivalent, key selection criteria include dropout voltage under 100 mA load, ON/OFF control interface compatibility, thermal performance in SOT-23, output capacitor ESR requirements, and reverse input-output protection necessity.

Technical Context

The LP2981-28DBVRE4 uses a PNP pass transistor architecture enabling ultra-low dropout (7 mV at 1 mA, 200 mV at 100 mA) and low quiescent current (600 µA typ at full load). Its internal reference is 1.23 V, with feedback resistors R1/R2 set for 2.8 V output.

It integrates overcurrent and thermal shutdown protection, supports fast transient response, and requires an external Schottky diode when VOUT may exceed VIN to prevent SCR latch-up via the inherent PNP base-collector diode.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.92 mm × 1.6 mm × 1.1 mm body, surface-mount, RoHS-compliant, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP2981A-28DBVR, the LP2981-28DBVRE4 trades initial accuracy for cost; versus MCP1700T-2802E/MB, it provides superior dropout, lower IQ, and active enable - making it optimal for battery-constrained portable systems requiring dynamic power gating.

Availability

LP2981-28DBVRE4 is available at Aetrix Electronics and suitable for mobile phones, digital cameras, PDAs, and MP3 players requiring stable component supply with consistent parametric performance across production batches.

Supply support for LP2981-28DBVRE4 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 connectivity solutions for industrial, automotive, and consumer markets.

The LP2981 family was engineered specifically for portable electronics demanding ultra-low dropout, low quiescent current, and small-footprint packaging - targeting battery-powered devices where efficiency and board space are critical constraints.

FAQ

What is the output voltage tolerance of the LP2981-28DBVRE4?

The LP2981-28DBVRE4 has a standard-grade output voltage tolerance of ±1.25% at 25°C and ±3.5% over the full operating temperature range (–40°C to 125°C). This specification applies to the nominal 2.8 V output and is confirmed in the Electrical Characteristics table of the SLVS521F datasheet. The LP2981-28DBVRE4 does not carry the "A" grade designation, so the tighter ±0.75% tolerance does not apply to this specific part number.

Does the LP2981-28DBVRE4 require an external Schottky diode?

Yes, the LP2981-28DBVRE4 requires an external Schottky diode connected anode-to-VOUT and cathode-to-VIN whenever the output voltage may exceed the input voltage - for example, during battery hot-swap or when downstream capacitance discharges into the regulator. This prevents forward-biasing of the internal PNP parasitic diode and potential SCR latch-up, which could damage the LP2981-28DBVRE4. The diode's forward voltage must be ≤0.3 V to ensure safe operation.

What is the minimum output capacitance required for stability with the LP2981-28DBVRE4?

The LP2981-28DBVRE4 requires a minimum output capacitance of 3.3 µF with appropriate ESR, as specified in the Application Information section. Ceramic capacitors alone are insufficient due to their ultra-low ESR; solid tantalum capacitors meeting the ESR vs. load current curves in Figures 2–5 of the datasheet are recommended. Increasing COUT beyond 3.3 µF improves transient response and stability margin without restriction.

Can the ON/OFF pin of the LP2981-28DBVRE4 be left floating?

No, the ON/OFF pin of the LP2981-28DBVRE4 must never be left floating. It must be actively terminated: connect to VIN if shutdown functionality is unused, or drive with a logic signal meeting VIH ≥1.6 V and VIL ≤0.3 V. An unterminated ON/OFF pin may cause erratic enable/disable behavior, output instability, or excessive ground current due to undefined input state affecting internal bias networks.

What is the thermal resistance (θJA) of the LP2981-28DBVRE4 in its SOT-23-5 package?

The junction-to-ambient thermal resistance (θJA) of the LP2981-28DBVRE4 in the SOT-23-5 (DBV) package is 206°C/W, as specified in the Absolute Maximum Ratings table. This value assumes standard JEDEC test conditions (single-layer board, no copper pour). Actual θJA in a production PCB will vary based on copper area, layer count, and airflow; design margins should use derated power dissipation calculated as PD = (125°C – TA)/206°C/W to ensure TJ remains ≤125°C.