Texas Instruments LP3985ITL-2.9/NOPB

Overview

LP3985ITL-2.9/NOPB from Texas Instruments is a fixed-output, ultra-low-dropout CMOS LDO voltage regulator delivering 150 mA at 2.9 V with ≤100 mV dropout at full load, 30 µVRMS output noise (10 Hz–100 kHz), and 1.5 µA shutdown current. It serves as a low-noise power supply for RF and analog circuitry in space-constrained portable wireless devices.

For engineers reviewing the LP3985ITL-2.9/NOPB datasheet, LP3985ITL-2.9/NOPB pinout, LP3985ITL-2.9/NOPB application, or LP3985ITL-2.9/NOPB equivalent, key selection criteria include DSBGA-5 package footprint (1.502 mm × 1.045 mm), enable-controlled fast turn-on (200 µs), PSRR >50 dB at 1 kHz, and stability with 1-µF ceramic output capacitor.

Technical Context

The LP3985ITL-2.9/NOPB employs a PMOS pass transistor architecture enabling ultra-low dropout and minimal ground current variation across load (85–150 µA from 0 to 150 mA). Its internal bandgap reference (1.23 V) and feedback divider set the precise 2.9-V output, while the dedicated BYPASS pin supports external 0.01-µF capacitor for noise reduction without degrading transient response.

Operation is controlled via logic-level EN input (VIH = 1.4 V, VIL = 0.4 V), with integrated thermal shutdown (160°C) and short-circuit protection (600 mA steady-state limit). It operates over −40°C to 125°C junction temperature and remains stable with ceramic or high-quality tantalum output capacitors ≥1 µF.

Key Specifications

Pinout & Package

LP3985ITL-2.9/NOPB uses the YZR (DSBGA-5) package: 1.502 mm × 1.045 mm body size, 0.5-mm pitch, bottom-side solder balls. Total PCB area < 2 mm × 2.5 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL720F12-DBVR and MCP1700T-2902E/TT, LP3985ITL-2.9/NOPB uniquely combines 2.9-V output, DSBGA-5 miniaturization, EN control, BYPASS-enabled noise reduction, and sub-100-mV dropout-making it irreplaceable for space- and noise-constrained 2.9-V RF/analog rails.

Availability

LP3985ITL-2.9/NOPB is available at Aetrix Electronics and suitable for CDMA handset power management, GSM transceiver biasing, portable medical sensor nodes, wearable Bluetooth audio systems, and other applications requiring stable component supply with guaranteed long-term sourcing.

Supply support for LP3985ITL-2.9/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 is a global semiconductor company designing analog ICs, embedded processors, and system solutions for industrial, automotive, and consumer markets.

The LP3985 product line targets ultra-low-noise, micropower LDO regulation in battery-powered portable electronics-specifically engineered for RF, audio, and precision analog subsystems demanding minimal footprint and exceptional PSRR.

FAQ

What is the maximum input voltage rating for LP3985ITL-2.9/NOPB?

The absolute maximum input voltage for LP3985ITL-2.9/NOPB is 6.5 V, but the recommended operating range is 2.5 V to 6 V. Exceeding 6.5 V risks permanent damage. For reliable 2.9-V output regulation, minimum input must be ≥3.0 V (VOUT + 100 mV dropout), and optimal performance occurs with VIN = VOUT + 0.2–0.5 V. The LP3985ITL-2.9/NOPB maintains regulation even as input drops near this threshold, extending battery runtime in single-cell Li-ion systems.

Does LP3985ITL-2.9/NOPB require an external bypass capacitor to function?

No, LP3985ITL-2.9/NOPB operates stably without the BYPASS capacitor. The 0.01-µF capacitor on the BYPASS pin is optional and used solely to reduce output noise from 30 µVRMS to lower levels-it does not affect startup time, load transients, or basic regulation. If ultra-low noise is not required (e.g., digital I/O rails), the BYPASS pin may be left unconnected. The LP3985ITL-2.9/NOPB still delivers full 150-mA output, 200-µs turn-on, and thermal protection without it.

Can LP3985ITL-2.9/NOPB be used with ceramic output capacitors smaller than 1 µF?

No-LP3985ITL-2.9/NOPB is specified and tested for stability only with ≥1-µF ceramic (X7R/X5R) or high-quality tantalum output capacitors. Using smaller values (e.g., 0.47 µF) risks oscillation or poor transient response due to insufficient phase margin. The 1-µF minimum ensures adequate energy storage and loop compensation across −40°C to 125°C. Derating for DC bias and temperature must also be verified: a 1-µF 0402 X7R may fall below 0.7 µF at 2.9 V bias and 85°C, violating the spec. Always select case size and dielectric per TI's recommended capacitor table.

What is the thermal performance difference between LP3985ITL-2.9/NOPB in DSBGA vs. SOT-23 packages?

LP3985ITL-2.9/NOPB in DSBGA (YZR) has RθJA = 255°C/W, while the SOT-23 (DBV) version has RθJA = 220°C/W-meaning the SOT-23 dissipates heat slightly more efficiently in still air. However, the DSBGA's smaller footprint (1.5 mm × 1.0 mm vs. 2.9 mm × 1.6 mm) enables tighter thermal coupling to PCB copper, and its RθJB (junction-to-board) is 107.9°C/W versus 31.6°C/W for SOT-23, indicating superior heat transfer into the board when proper thermal vias are used. Thus, in compact layouts with 2+ internal ground/power planes, the DSBGA often achieves lower actual junction temperatures despite higher RθJA.

Is LP3985ITL-2.9/NOPB suitable for automotive applications?

LP3985ITL-2.9/NOPB is qualified for operation from −40°C to 125°C junction temperature and includes thermal shutdown and short-circuit protection-key features for automotive under-hood environments. However, it is not AEC-Q200 qualified, lacks automotive-specific reliability testing (e.g., HTOL, TC), and TI positions it for portable consumer electronics, not automotive safety-critical systems. For infotainment or telematics modules in passenger compartments (where ambient ≤85°C), LP3985ITL-2.9/NOPB may be used with derating, but AEC-Q100-qualified alternatives like TPS7A2029PDQNR are preferred for full automotive compliance.