Texas Instruments LP2985IM5-3.1

Overview

LP2985IM5-3.1 from Texas Instruments is a micropower, ultra-low-dropout linear regulator delivering 150 mA output current with 3.1 V fixed output voltage, 300 mV typical dropout at full load, 1% output voltage accuracy (A-grade), and <1 µA shutdown quiescent current - used in battery-powered portable electronics requiring stable low-noise supply rails.

For engineers reviewing the LP2985IM5-3.1 datasheet, LP2985IM5-3.1 pinout, LP2985IM5-3.1 application, or LP2985IM5-3.1 equivalent, key selection considerations include its SOT-23-5 package footprint, ON/OFF logic control interface, BYPASS pin for noise reduction, ceramic-capacitor compatibility down to 5 mΩ ESR, and thermal shutdown/overcurrent protection for robust operation in space-constrained designs.

Technical Context

The LP2985IM5-3.1 employs a vertically integrated PNP (VIP) pass transistor architecture enabling ultra-low dropout (280–575 mV at 150 mA over temperature) and low ground current (850 µA typical at 150 mA). Its internal reference and error amplifier deliver 1% initial accuracy with ±3.5% total variation over –40°C to 125°C junction temperature and full load range.

It integrates an active ON/OFF control input (logic-high enable, <0.15 V disable threshold), dedicated BYPASS pin for external 10-nF capacitor to reduce output noise to 30 µV_RMS, and foldback current limiting with thermal shutdown - all optimized for single-cell Li-ion, multi-cell alkaline, or DC-DC post-regulation in portable systems.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 0.95 mm height, gull-wing leads; thermally enhanced pad not present; suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700-3102E/TO and TLC7703IPK, the LP2985IM5-3.1 uniquely combines 3.1 V precision, BYPASS-enabled low noise, ON/OFF control, and ultra-low dropout - making it irreplaceable where battery life, RF integrity, and exact voltage matching are co-constrained.

Availability

LP2985IM5-3.1 is available at Aetrix Electronics and suitable for cellular handset power management, portable medical sensor modules, industrial handheld scanners, smart home motion sensor hubs, and other applications requiring stable component supply with tight voltage tolerance and low-noise performance.

Supply support for LP2985IM5-3.1 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 solutions for industrial, automotive, and personal electronics markets.

The LP2985-N product line delivers micropower, ultra-low-dropout, low-noise LDO regulators specifically for battery-powered portable equipment - emphasizing extended runtime, small form factor, and signal integrity in space- and power-constrained applications.

FAQ

What is the minimum input voltage required for LP2985IM5-3.1 to maintain regulation?

The LP2985IM5-3.1 requires VIN ≥ VOUT + dropout voltage. With a nominal 3.1 V output and maximum dropout of 575 mV at 150 mA and full temperature range, the minimum functional input is 3.675 V. The datasheet specifies recommended minimum VIN as 3.1 V - but this applies only under light loads where dropout is ≤7 mV; design margin requires ≥3.675 V for full-load operation.

Does LP2985IM5-3.1 require the BYPASS pin to be used?

The BYPASS pin is optional but strongly recommended for noise-sensitive applications. When left unconnected, LP2985IM5-3.1 delivers standard low-noise performance (~75 µV_RMS). Connecting a 10 nF ceramic capacitor between BYPASS and GND reduces output noise to 30 µV_RMS (300 Hz–50 kHz), which is critical for ADCs and RF circuits. The LP2985IM5-3.1 remains fully functional without it.

Can LP2985IM5-3.1 be used with a 10 µF output capacitor?

Yes - the LP2985IM5-3.1 is stable with output capacitance from 2.2 µF up to any value, including 10 µF ceramic. Its internal compensation is designed for low-ESR ceramics (≥5 mΩ), so larger capacitance improves load transient response and further reduces output impedance without risking instability. No series resistor or ESR tuning is needed.

What is the shutdown current of LP2985IM5-3.1 when ON/OFF is pulled low?

When the ON/OFF pin voltage is below 0.15 V, the LP2985IM5-3.1 enters shutdown mode with typical quiescent current of 0.01 µA and maximum of 2 µA over –40°C to 125°C. This ultra-low shutdown current is confirmed in Section 6.5 Electrical Characteristics and enables multi-year battery life in always-off standby applications such as remote sensors and security tags.

Is LP2985IM5-3.1 compatible with ceramic input capacitors?

Yes - the LP2985IM5-3.1 requires a minimum 1 µF ceramic input capacitor placed within 1 cm of the IN and GND pins. Ceramic types (X5R, X7R) are preferred due to low ESR and stable capacitance; tantalum or film capacitors may be used but offer no advantage. The device imposes no ESR requirement on the input capacitor, only minimum capacitance and placement proximity.