Texas Instruments LP2985IM5-2.8

Overview

LP2985IM5-2.8 from Texas Instruments is a micropower, ultra-low-dropout linear regulator delivering 150 mA output current with 2.8 V fixed output voltage, 300 mV typical dropout at full load, 75 µA quiescent current at 1 mA load, and 30 µV_RMS output noise (300 Hz–50 kHz) when using a 10 nF bypass capacitor. It serves as a precision, low-noise power supply for battery-powered portable electronics requiring stable low-voltage rails.

For engineers reviewing the LP2985IM5-2.8 datasheet, LP2985IM5-2.8 pinout, LP2985IM5-2.8 application, or LP2985IM5-2.8 equivalent, key selection criteria include its SOT-23-5 package footprint, ON/OFF logic control interface, compatibility with low-ESR ceramic capacitors (≥2.2 µF), 1% output voltage accuracy (A-grade), and thermal/overcurrent protection - all critical for space-constrained, energy-sensitive designs.

Technical Context

The LP2985IM5-2.8 employs a vertically integrated PNP (VIP) pass transistor architecture enabling ultra-low dropout (280–575 mV at 150 mA over temperature) and minimal ground current (75–850 µA across 1–150 mA load). Its internal reference and feedback loop deliver 1% initial accuracy and maintain regulation down to 2.5 V input.

It integrates an active ON/OFF control pin with TTL-compatible thresholds (enable >1.6 V, disable <0.15 V), shutdown current <2 µA, and foldback current limiting. Stability is ensured with ceramic output capacitors as low as 5 mΩ ESR, eliminating need for tantalum or electrolytic types.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 0.95 mm height, gull-wing leads, JEDEC standard footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1702T-2802E/MB and TLC7L33QDBVRQ1, the LP2985IM5-2.8 uniquely combines 2.8 V output, sub-300 mV dropout, and 30 µV_RMS noise via BYPASS - making it optimal for battery-powered, noise-sensitive 2.8 V applications where size and efficiency are constrained.

Availability

LP2985IM5-2.8 is available at Aetrix Electronics and suitable for cellular modems, wearable sensor hubs, industrial handheld terminals, medical point-of-care devices, and battery-backed real-time clocks requiring stable component supply and long-term manufacturability.

Supply support for LP2985IM5-2.8 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 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 regulators optimized for battery-powered portable equipment - emphasizing low noise, small footprint, and robust protection in SOT-23 packaging.

FAQ

What is the minimum input voltage required for LP2985IM5-2.8 to regulate 2.8 V at 150 mA?

The LP2985IM5-2.8 requires a minimum input voltage of 3.375 V to maintain regulation at 150 mA load, based on its maximum dropout voltage of 575 mV over temperature (–40°C to 125°C). At room temperature, dropout is typically 280 mV, so 3.08 V suffices. Input below 3.1 V risks loss of regulation and output droop.

Can LP2985IM5-2.8 operate without the BYPASS capacitor?

Yes, LP2985IM5-2.8 functions normally without the BYPASS capacitor, delivering 2.8 V with standard LDO performance. However, omitting the 10 nF capacitor increases output noise to approximately 65 µV_RMS. The BYPASS pin is optional and only required for applications demanding ultra-low noise, such as precision ADCs or RF receivers.

Is LP2985IM5-2.8 compatible with ceramic output capacitors smaller than 2.2 µF?

No - the LP2985IM5-2.8 requires a minimum 2.2 µF ceramic output capacitor for guaranteed stability across all loads and temperatures. Using smaller values may cause oscillation or poor transient response. Capacitance can be increased without limit, but ESR must remain ≥5 mΩ; X7R/X5R dielectrics are recommended for stable performance.

How does the ON/OFF pin behave during power-up of LP2985IM5-2.8?

The ON/OFF pin of LP2985IM5-2.8 must be actively driven: tying it to VIN enables the regulator immediately upon input application. If left floating, leakage paths may cause unpredictable startup or partial enablement. For controlled sequencing, drive ON/OFF with a microcontroller GPIO after system reset - the device enters shutdown if voltage falls below 0.15 V.

What thermal derating applies to LP2985IM5-2.8 in a standard SOT-23 PCB layout?

With R_θJA = 169.0°C/W on a standard JEDEC High-K test board, LP2985IM5-2.8 dissipates 150 mW at 150 mA and 3.375 V input (2.8 V out), resulting in ~25°C junction rise above ambient. At 85°C ambient, junction temperature reaches ~110°C - within the –40°C to 125°C rating. Adding copper pour or thermal vias reduces R_θJA and improves margin.