Texas Instruments LP2985IM5-1.8

Overview

LP2985IM5-1.8 from Texas Instruments is a micropower, low-noise, ultra-low-dropout linear regulator delivering 150 mA at fixed 1.8 V output with 1% accuracy (A-grade), 280 mV typical dropout at 150 mA, and 30 µV_RMS output noise when using a 10-nF bypass capacitor - designed for battery-powered portable electronics requiring stable, quiet voltage regulation.

For engineers reviewing the LP2985IM5-1.8 datasheet, LP2985IM5-1.8 pinout, LP2985IM5-1.8 application, or LP2985IM5-1.8 equivalent, key selection criteria include guaranteed 150-mA load capability, <1-µA shutdown current, SOT-23-5 package compatibility, ceramic-capacitor stability down to 5 mΩ ESR, and ON/OFF logic control with 1.6 V enable threshold.

Technical Context

The LP2985IM5-1.8 uses a vertically integrated PNP (VIP) process to achieve ultra-low dropout (280 mV typ. @ 150 mA) and low ground current (825 µA typ. @ 150 mA), enabling operation from as low as 2.05 V input while maintaining 1.8 V regulation. Its internal bandgap reference and dedicated BYPASS pin support low-noise performance via external 10-nF capacitor coupling.

It integrates foldback current limiting and thermal shutdown protection, operates across –40°C to +125°C junction temperature, and is stable with 2.2-µF ceramic output capacitors having ESR ≥5 mΩ - eliminating need for tantalum or electrolytic types in space-constrained designs.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm footprint, surface-mount, thermally enhanced plastic case with exposed pad not present - compatible with standard reflow profiles and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, 150-mA LDO applications.

Compared with TCS2101-1.8 and MCP1703T-1802E/MB, the LP2985IM5-1.8 uniquely combines 1% accuracy, <1-µA shutdown, and BYPASS-enabled 30-µV noise in SOT-23-5 - making it optimal for portable systems demanding both precision regulation and battery longevity.

Availability

LP2985IM5-1.8 is available at Aetrix Electronics and suitable for cellular phone baseband, wearable sensor nodes, industrial handheld terminals, and medical point-of-care monitors requiring stable component supply across production lifecycles.

Supply support for LP2985IM5-1.8 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 precision analog solutions.

The LP2985LV-N product line was engineered specifically for ultra-low-noise, micropower regulation in space-constrained, battery-powered portable electronics - emphasizing dropout performance, shutdown efficiency, and ceramic-capacitor compatibility.

FAQ

What is the minimum input voltage required for LP2985IM5-1.8 to maintain regulation at full 150 mA load?

The LP2985IM5-1.8 requires a minimum input voltage of 2.05 V at 25°C to sustain 1.8 V output regulation at 150 mA. Over the full –40°C to +125°C junction temperature range, VIN(MIN) increases to 2.2 V due to increased dropout. This ensures reliable operation from single-cell Li-ion batteries down to end-of-discharge voltage.

How does the BYPASS pin on LP2985IM5-1.8 reduce output noise, and what capacitor value is recommended?

The BYPASS pin connects directly to the internal bandgap reference node; adding a 10-nF ceramic capacitor (NPO/COG) between BYPASS and GND shunts high-frequency noise, reducing output noise to 30 µV_RMS. Leakage current must remain below 100 nA - so film or high-quality ceramic types are mandatory. Omitting this cap increases noise to ~120 µV_RMS.

Is LP2985IM5-1.8 pin-compatible with other regulators in the LP2985 family, such as LP2985IM5-2.5 or LP2985IM5-3.3?

Yes - all LP2985IM5-x.x variants share identical SOT-23-5 (DBV) pinout, thermal characteristics, and functional pin definitions (IN, GND, ON/OFF, BYPASS, OUT). Only the output voltage differs; no PCB layout changes are needed when substituting between 1.5 V, 1.8 V, 2.5 V, or 3.3 V versions within the same grade (e.g., A-grade).

What output capacitor is required for stable operation of LP2985IM5-1.8, and why is ESR important?

LP2985IM5-1.8 requires ≥2.2 µF ceramic output capacitance with ESR ≥5 mΩ for stability across 1–150 mA load range. Unlike older LDOs, it's optimized for low-ESR ceramics - enabling smaller, more reliable, and lower-cost solutions. Using capacitors with ESR <5 mΩ may cause oscillation; X7R dielectrics are acceptable if capacitance remains ≥2.2 µF over temperature.

Does LP2985IM5-1.8 include built-in protection features, and how do they behave under fault conditions?

Yes - LP2985IM5-1.8 integrates foldback current limiting and thermal shutdown. During short-circuit, output current reduces to ~400 mA (steady-state) then folds back further as V_OUT collapses; simultaneous overtemperature causes cyclical shutdown until power dissipation decreases. These features prevent permanent damage without external components.