Texas Instruments LP3985IBP-3.3/NOPB

Overview

LP3985IBP-3.3/NOPB from Texas Instruments (formerly National Semiconductor) is a micropower, ultra-low-noise, ultra-low-dropout CMOS linear voltage regulator delivering 3.3V at up to 150mA from 2.5V–6.0V input. It features 30µV_rms output noise (10Hz–100kHz), 100mV max dropout at full load, and 1.5µA shutdown current-optimized for RF-sensitive battery-powered portable electronics including cellular handsets and portable information appliances.

For engineers reviewing the LP3985IBP-3.3/NOPB datasheet, LP3985IBP-3.3/NOPB pinout, LP3985IBP-3.3/NOPB application, or LP3985IBP-3.3/NOPB equivalent, key selection criteria include low-noise performance in RF sections, minimal PCB footprint (5-bump micro SMD), fast 200µs turn-on time, and stable operation with 1µF ceramic output capacitors-critical for space-constrained mobile designs requiring extended battery life.

Technical Context

The LP3985IBP-3.3/NOPB employs a CMOS pass transistor architecture enabling ultra-low quiescent current and near-zero ground current increase in dropout. Its internal bandgap reference and bypass-capacitor-assisted noise reduction circuitry deliver stable 3.3V regulation with <±3% output tolerance across −40°C to +125°C junction temperature.

It integrates logic-controlled enable (VEN), thermal shutdown (160°C), and short-circuit current limiting (600mA). The device maintains >50dB PSRR at 1kHz under VIN = VOUT + 0.2V conditions and sustains high rejection down to low input voltages typical of discharging Li-ion batteries.

Key Specifications

Pinout & Package

The LP3985IBP-3.3/NOPB uses a 5-bump micro SMD package (NS Package BPA05) with 0.170mm bump height and 0.900mm profile-occupying <2.0mm × 2.5mm PCB area. This ultra-compact footprint is ideal for thin mobile devices where board space is constrained.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL720F33 and MCP1700T-3302E/MB, the LP3985IBP-3.3/NOPB uniquely combines 5-bump micro SMD miniaturization, dedicated BYPASS pin for configurable noise suppression, and guaranteed 150mA performance in −40°C to +125°C - making it optimal for legacy space-constrained RF handset designs where footprint and noise are non-negotiable.

Availability

LP3985IBP-3.3/NOPB is available at Aetrix Electronics and suitable for CDMA/GSM handset power management, portable medical sensor modules, and industrial handheld terminals requiring stable component supply with long lifecycle visibility.

Supply support for LP3985IBP-3.3/NOPB 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 acquired National Semiconductor in 2011 and maintains its precision analog portfolio, including ultra-low-noise LDOs for high-reliability applications.

The LP3985IBP-3.3/NOPB belongs to National Semiconductor's micropower LDO family, engineered specifically for battery-powered wireless devices demanding minimal noise, ultra-small footprint, and extended runtime under dynamic load conditions.

FAQ

What is the maximum output current specification for the LP3985IBP-3.3/NOPB?

The LP3985IBP-3.3/NOPB is rated for 150mA guaranteed continuous output current across the full operating temperature range (−40°C to +125°C). This rating is validated with proper thermal design using the 5-bump micro SMD package and appropriate PCB copper pour. Peak output current reaches 550mA for short durations while maintaining VOUT ≥ nominal −5%, per the Electrical Characteristics table.

Does the LP3985IBP-3.3/NOPB require an external bypass capacitor for basic operation?

No, the LP3985IBP-3.3/NOPB operates stably without the BYPASS capacitor. The 0.01µF capacitor on the BYPASS pin is optional and used solely to reduce output noise - it does not affect stability, load transient response, or startup behavior. Basic regulation requires only VIN, GND, and VOUT capacitors per the recommended values (≥1µF input, ≥0.7µF output).

What is the shutdown current of the LP3985IBP-3.3/NOPB, and how is it achieved?

The LP3985IBP-3.3/NOPB draws ≤1.5µA in shutdown mode when the VEN pin is held ≤0.4V. This ultra-low quiescent state disables the internal reference, error amplifier, and pass transistor, effectively disconnecting the output from the input while retaining thermal and short-circuit protection circuitry in standby readiness.

Can the LP3985IBP-3.3/NOPB be used with a 1µF X5R ceramic capacitor instead of X7R?

Yes, a 1µF X5R ceramic capacitor may be used as the output capacitor if the application's operating temperature remains within −55°C to +85°C. However, X7R is strongly recommended for full-spec operation across −40°C to +125°C, as X5R exhibits greater capacitance loss at temperature extremes - potentially falling below the 0.7µF minimum required for stability in high-temperature environments.

Is the LP3985IBP-3.3/NOPB RoHS compliant and lead-free?

Yes, the LP3985IBP-3.3/NOPB is RoHS compliant and lead-free, meeting TI's Banned Substances and Materials of Interest Specification (CSP-9-111S2). The "/NOPB" suffix explicitly denotes lead-free packaging, and the device is manufactured using TI's standard green process for commercial-grade analog ICs.