Texas Instruments LP2985IM5-3.5

Overview

LP2985IM5-3.5 from Texas Instruments is a micropower, ultra-low-dropout linear regulator delivering 150 mA output current with 3.5 V fixed output voltage, 300 mV typical dropout at full load, 1% output accuracy (A-grade), and <1 µA shutdown quiescent current - designed for battery-powered portable electronics requiring low noise and high efficiency.

For engineers reviewing the LP2985IM5-3.5 datasheet, LP2985IM5-3.5 pinout, LP2985IM5-3.5 application, or LP2985IM5-3.5 equivalent, key selection criteria include dropout voltage at 150 mA, BYPASS-pin-enabled 30 µV_RMS noise performance, SOT-23-5 package thermal limits, and ON/OFF logic-level compatibility with 1.6 V enable threshold.

Technical Context

The LP2985IM5-3.5 uses a vertically integrated PNP (VIP) pass transistor architecture enabling ultra-low dropout (280–575 mV over temperature at 150 mA) and low ground current (75 µA at 1 mA, 850 µA at 150 mA). Its internal reference and error amplifier deliver 1% initial output accuracy across –40°C to 125°C junction temperature.

Stability is ensured with ceramic output capacitors as low as 2.2 µF and ESR down to 5 mΩ; noise is reduced via dedicated BYPASS pin accepting a 10 nF capacitor to achieve 30 µV_RMS (300 Hz–50 kHz), while ON/OFF control provides logic-compatible shutdown with <2 µA max quiescent current.

Key Specifications

Pinout & Package

LP2985IM5-3.5 is housed in a standard 5-pin SOT-23 package (2.90 mm × 1.60 mm body size) with exposed pad not electrically connected. Thermal resistance R_θJA = 169.0°C/W on JEDEC High-K board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700-3502E/TO and TPS78235DRVR, LP2985IM5-3.5 uniquely combines 1% accuracy, 30 µV_RMS noise via BYPASS, and sub-1 µA shutdown - making it optimal for precision, battery-sensitive, noise-critical portable systems where SOT-23-5 size is mandatory.

Availability

LP2985IM5-3.5 is available at Aetrix Electronics and suitable for cellular handsets, wearable health monitors, industrial handheld terminals, and medical point-of-care displays requiring stable component supply across long-lifecycle production programs.

Supply support for LP2985IM5-3.5 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 designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and personal electronics markets.

The LP2985-N product line delivers micropower, ultra-low-dropout, low-noise LDO regulators optimized for battery-powered portable devices where size, efficiency, and signal integrity are critical design constraints.

FAQ

What is the minimum input voltage required for LP2985IM5-3.5 to maintain regulation?

The LP2985IM5-3.5 requires VIN ≥ VOUT + dropout voltage. At 150 mA and 25°C, dropout is typically 280 mV, so minimum VIN is ~3.78 V. Over temperature and process variation, maximum dropout reaches 575 mV, requiring VIN ≥ 4.075 V to guarantee regulation across all conditions. The recommended minimum operating VIN is 3.1 V per datasheet, but this assumes light load; full-load designs must budget for worst-case dropout.

Can LP2985IM5-3.5 operate without the BYPASS capacitor?

Yes, LP2985IM5-3.5 functions normally without the BYPASS capacitor, delivering 3.5 V output with standard LDO performance. However, omitting the 10 nF capacitor increases output noise to ~120 µV_RMS. The BYPASS pin is optional but essential for noise-sensitive applications like ADC references or RF synthesizers - its absence does not affect stability or basic regulation.

What is the purpose of the ON/OFF pin on LP2985IM5-3.5, and what logic levels enable it?

The ON/OFF pin controls regulator enable/disable state. Driving it to ≥1.6 V (over temperature) enables output regulation; pulling it to ≤0.15 V disables the output and reduces quiescent current to <2 µA. It is not a true logic input - no internal pull-up/down exists, so external termination (e.g., to VIN or GND via resistor) is required to prevent floating states that may cause erratic behavior.

Which output capacitor types and values are validated for LP2985IM5-3.5 stability?

LP2985IM5-3.5 is validated for stability with ceramic output capacitors ≥2.2 µF and ESR as low as 5 mΩ. Tantalum or film capacitors may be used but are not recommended due to size, cost, and ESR variability. The datasheet specifies 2.2 µF minimum - larger values (e.g., 4.7 µF or 10 µF) improve transient response and PSRR without compromising stability, provided ESR remains within the 5–300 mΩ range shown in Figure 22.

Does LP2985IM5-3.5 include overtemperature and overcurrent protection?

Yes, LP2985IM5-3.5 integrates both thermal shutdown and foldback current limiting. When junction temperature exceeds ~160°C, the device cycles ON/OFF to limit die temperature. During overload, peak current is limited to ~350 mA initially, then folds back to ~400 mA steady-state short-circuit current - preventing destructive power dissipation. These protections are fully specified in the Electrical Characteristics table and Typical Characteristics curves.