Texas Instruments LP2981A-33DBVRE4

Overview

LP2981A-33DBVRE4 from Texas Instruments is a 3.3 V, 100-mA ultra-low dropout linear regulator in SOT-23-5 package with shutdown control, ±0.75% output tolerance (A grade), 200 mV typical dropout at 100 mA, and 0.01 µA shutdown current - designed for power management in space-constrained portable electronics including digital cameras and PDAs.

For engineers reviewing the LP2981A-33DBVRE4 datasheet, LP2981A-33DBVRE4 pinout, LP2981A-33DBVRE4 application, or LP2981A-33DBVRE4 equivalent, key selection criteria include guaranteed A-grade accuracy, PNP-based ultra-low dropout performance across –40°C to 125°C, integrated overcurrent/thermal protection, and compatibility with solid tantalum output capacitors meeting ESR requirements.

Technical Context

The LP2981A-33DBVRE4 uses a vertical PNP pass element 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 fixed 3.3 V output.

It features active ON/OFF control (logic-high ≥1.6 V enables regulation; logic-low ≤0.3 V reduces supply current to 0.01 µA), reverse-input-protection diode awareness requiring external Schottky clamp if VOUT > VIN, and stability dependent on minimum 3.3 µF output capacitance with specified ESR range per load current and temperature.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.92 mm × 1.6 mm × 1.1 mm, surface-mount, RoHS-compliant, moisture sensitivity level 1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSS721AIDR and MCP1700T-3302E/TT, LP2981A-33DBVRE4 uniquely combines A-grade accuracy, ultra-low dropout, nanoamp shutdown, and SOT-23-5 integration - making it optimal for precision, low-power portable systems where all four attributes are simultaneously required.

Availability

LP2981A-33DBVRE4 is available at Aetrix Electronics and suitable for digital camera modules, PDA mainboards, and portable audio devices requiring stable component supply with guaranteed A-grade specifications and long-term production continuity.

Supply support for LP2981A-33DBVRE4 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 specializing in analog and embedded processing technologies, with decades of expertise in power management IC design and manufacturing.

The LP2981 family was engineered specifically for ultra-low-power portable applications demanding high accuracy, minimal dropout, and robust protection - targeting mobile phones, PDAs, and digital imaging equipment.

FAQ

What is the output voltage tolerance of LP2981A-33DBVRE4 over temperature?

The LP2981A-33DBVRE4 has a guaranteed output voltage tolerance of ±0.75% over the full operating junction temperature range of –40°C to 125°C. This A-grade specification applies under all load conditions from 1 mA to 100 mA and ensures consistent 3.3-V rail accuracy for sensitive digital interfaces without requiring post-production calibration or margining.

Can LP2981A-33DBVRE4 operate with an input voltage below 3.3 V?

No - LP2981A-33DBVRE4 requires a minimum input voltage of 2.2 V for internal circuit biasing, but regulation requires VIN ≥ VOUT + dropout. With a typical dropout of 200 mV at 100 mA, LP2981A-33DBVRE4 cannot regulate at 3.3 V with VIN < 3.5 V. At light loads (1 mA), dropout drops to 7 mV, allowing regulation down to ~3.307 V input.

Is pin 4 (NC) on LP2981A-33DBVRE4 required to be grounded or left open?

Pin 4 on LP2981A-33DBVRE4 is explicitly designated "NC" (No Connect) and must be left open - physically unconnected and un-routed on the PCB. Connecting it to ground, VOUT, or any other node may disrupt internal biasing or cause unpredictable regulation behavior, as confirmed in TI's Functional Block Diagram and Application Information sections.

What output capacitor type and value are mandatory for stable operation of LP2981A-33DBVRE4?

LP2981A-33DBVRE4 requires a minimum 3.3 µF output capacitor with ESR within manufacturer-specified ranges (e.g., 0.1–1 Ω depending on load current and temperature). Solid tantalum capacitors are recommended; ceramic capacitors require a 1-Ω series resistor to meet minimum ESR. Using undersized or low-ESR ceramics without compensation causes instability and oscillation.

Does LP2981A-33DBVRE4 include reverse-voltage protection?

LP2981A-33DBVRE4 does not include internal reverse-voltage protection. Its PNP pass transistor contains an inherent diode (anode to VOUT, cathode to VIN) that becomes forward-biased if VOUT exceeds VIN by ~0.7 V - risking latch-up and damage. TI mandates an external Schottky diode (anode to VOUT, cathode to VIN) to clamp reverse differential to ~0.3 V in any application where output could float above input.