Texas Instruments LP2985AIM5-1.8

Overview

LP2985AIM5-1.8 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 full load, and <1 µA shutdown current. It serves as the primary voltage source for core logic in space-constrained portable electronics such as baseband processors in cellular handsets.

For engineers reviewing the LP2985AIM5-1.8 datasheet, LP2985AIM5-1.8 pinout, LP2985AIM5-1.8 application, or LP2985AIM5-1.8 equivalent, key selection criteria include guaranteed 150-mA output under 125°C junction temperature, stability with 2.2-µF ceramic output capacitors (ESR ≥5 mΩ), low 30-µV_RMS noise with 10-nF bypass capacitor, and ON/OFF-controlled sleep mode for battery runtime extension.

Technical Context

The LP2985AIM5-1.8 uses a vertically integrated PNP (VIP) process to achieve ultra-low dropout and minimal ground current-825 µA at 150 mA load and 75 µA at 1 mA load. Its internal bandgap reference feeds a precision error amplifier driving a PNP pass transistor, enabling tight regulation across −40°C to +125°C.

It integrates active ON/OFF control logic that disables the regulator when the ON/OFF pin falls below 0.15 V, reducing quiescent current to <1 µA. Stability is ensured via internal compensation optimized for ceramic output capacitors down to 2.2 µF with ESR as low as 5 mΩ, eliminating need for external compensation networks.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm footprint, surface-mount, thermally enhanced with exposed pad (not electrically connected). 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 LP2985AIM5-1.8, TCS2117-1.8 offers lower dropout but no noise-reduction flexibility, while MCP1703T-1802E/MB provides higher current headroom at the cost of significantly higher noise and no enable function-making LP2985AIM5-1.8 optimal for battery-powered, noise-sensitive, and power-gated designs.

Availability

LP2985AIM5-1.8 is available at Aetrix Electronics and suitable for cellular handset power management, wearable sensor hubs, industrial handheld terminals, and automotive infotainment displays requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LP2985AIM5-1.8 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 leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability, low-power linear regulators for portable and industrial markets.

The LP2985LV-N product line was designed specifically for battery-powered applications demanding ultra-low dropout, low noise, and active enable control-targeting cellular phones, PDAs, camcorders, and other space- and power-constrained portable electronics.

FAQ

What is the minimum input voltage required for LP2985AIM5-1.8 to maintain regulation at 150 mA load?

The LP2985AIM5-1.8 requires a minimum input voltage of 2.08 V at 25°C to sustain 1.8 V output regulation at 150 mA load, based on its 280-mV typical dropout voltage. Over the full −40°C to +125°C junction temperature range, the maximum dropout rises to 600 mV, so VIN must be ≥2.4 V to guarantee regulation across temperature extremes.

Can LP2985AIM5-1.8 operate without the BYPASS capacitor?

Yes, LP2985AIM5-1.8 functions without the BYPASS capacitor, delivering 1.8 V output with standard LDO performance. However, omitting the 10-nF ceramic capacitor on the BYPASS pin increases output noise from 30 µV_RMS to approximately 120 µV_RMS, which may degrade signal integrity in noise-sensitive applications like RF receivers or high-resolution ADCs.

Is LP2985AIM5-1.8 compatible with ceramic output capacitors smaller than 2.2 µF?

No-TI specifies a minimum 2.2-µF ceramic output capacitor for LP2985AIM5-1.8 to ensure loop stability across all load and temperature conditions. Using a smaller value risks oscillation or poor transient response. The device is optimized for 2.2 µF to 10 µF ceramics with ESR ≥5 mΩ; values beyond this range are permissible if stability is verified.

What happens to LP2985AIM5-1.8 when the ON/OFF pin is left floating?

Leaving the ON/OFF pin floating on LP2985AIM5-1.8 causes undefined behavior due to lack of internal pull-up or pull-down. TI recommends actively terminating the pin: tie to VIN for always-on operation or to GND for permanent disable. A weak pull-up resistor (e.g., 100 kΩ to VIN) may be used if dynamic control is not required.

Does LP2985AIM5-1.8 include reverse-voltage protection?

No, LP2985AIM5-1.8 does not integrate reverse-voltage protection. Its internal PNP pass transistor contains a parasitic diode from IN to OUT; applying reverse polarity (OUT > IN) forward-biases this diode, potentially causing excessive current flow and damage. External protection-such as a series Schottky diode or ideal diode controller-is required in systems prone to reverse connection.