Texas Instruments LP3990TLX-1.5/NOPB

Overview

LP3990TLX-1.5/NOPB from Texas Instruments is a 150-mA, 1.5-V fixed-output linear voltage regulator in a 6-pin WSON package, designed for portable digital systems. It delivers ±1.5% output voltage accuracy at 25°C, operates from 2 V to 6 V input, achieves 120 mV typical dropout at 150 mA, and consumes only 43 µA quiescent current when enabled-enabling long battery life in cellular handsets and handheld information appliances.

For engineers reviewing the LP3990TLX-1.5/NOPB datasheet, LP3990TLX-1.5/NOPB pinout, LP3990TLX-1.5/NOPB application, or LP3990TLX-1.5/NOPB equivalent, key selection considerations include its ceramic-capacitor stability (1 µF min), logic-controlled enable with internal 1-MΩ pull-down, <10 nA shutdown current, 150 µVRMS output noise, and thermal/short-circuit protection across –40°C to 125°C junction temperature.

Technical Context

The LP3990TLX-1.5/NOPB implements a low-noise LDO architecture with an internal 800-mV reference and PMOS pass transistor, enabling fast 105 µs start-up and high PSRR (55 dB at 1 kHz). Its enable control uses a dedicated active-high EN pin with VIH = 0.95 V and VIL = 0.4 V, internally pulled down to GND via 1-MΩ resistor-ensuring default-off behavior and deterministic power sequencing.

Thermal overload protection activates at ~155°C junction temperature with ~15°C hysteresis, while short-circuit current limiting holds output at 550–1000 mA. The device is specified for stable operation with 1-µF ceramic output capacitors (X7R/X5R, 5–500 mΩ ESR) and requires no noise-bypass capacitor-reducing BOM count and PCB area in space-constrained applications.

Key Specifications

Pinout & Package

LP3990TLX-1.5/NOPB uses the WSON-6 (NGG) package: 2.90 mm × 1.60 mm body, exposed thermal pad on bottom, moisture sensitivity level 1. Thermal pad must be soldered to PCB ground plane for optimal thermal performance (R_θJA = 53.9°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL720F15-DBVR and MCP1826-1502E/DB, LP3990TLX-1.5/NOPB uniquely combines 1-µF ceramic stability, 150 µVRMS noise, <10 nA shutdown, and integrated thermal/short-circuit protection in a 2.9×1.6 mm WSON package-making it optimal for miniaturized, battery-sensitive digital systems requiring guaranteed robustness.

Availability

LP3990TLX-1.5/NOPB is available at Aetrix Electronics and suitable for cellular handsets, handheld information appliances, wearable fitness trackers, industrial sensor nodes, and portable medical devices requiring stable component supply, long-term lifecycle support, and consistent parametric performance.

Supply support for LP3990TLX-1.5/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 leader delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

LP3990TLX-1.5/NOPB belongs to TI's LP3990 family of ultra-low-noise, ceramic-capacitor-optimized LDOs-designed specifically for portable digital applications demanding minimal board area, low quiescent current, and high power-supply rejection in battery-powered systems.

FAQ

What is the output voltage tolerance of the LP3990TLX-1.5/NOPB over temperature and load?

The LP3990TLX-1.5/NOPB maintains ±1.5% output voltage tolerance over full operating conditions (–40°C to 125°C junction temperature, 0–150 mA load, 2–6 V input). At room temperature (25°C), tolerance tightens to ±1%. This specification is verified across all WSON-6 units and ensures reliable operation for 1.5-V digital logic rails without external trimming.

Does the LP3990TLX-1.5/NOPB require an external bypass capacitor for noise reduction?

No, the LP3990TLX-1.5/NOPB does not require an external noise-bypass capacitor. Its internal design achieves 150 µVRMS output noise (10 Hz–100 kHz) with only a 1-µF ceramic output capacitor. This eliminates the need for additional components, reducing BOM cost and PCB footprint-confirmed in TI's SNVS251J datasheet Section 1 and Feature Description.

How is the enable pin (EN) of the LP3990TLX-1.5/NOPB configured, and what happens if it's left unconnected?

The LP3990TLX-1.5/NOPB EN pin features an internal 1-MΩ pull-down resistor to GND. If left unconnected, the pin defaults to ≤0.4 V, disabling the regulator and reducing IQ to <10 nA. To enable the device, apply ≥0.95 V to EN-compatible with 1.8-V and 3.3-V logic families without external pull-ups.

What is the minimum input voltage required for the LP3990TLX-1.5/NOPB to regulate at 1.5 V output?

The LP3990TLX-1.5/NOPB requires a minimum input voltage of 2 V or (VOUT + VDO), whichever is greater. With a typical 120 mV dropout at 150 mA, the minimum functional VIN is 1.62 V-but the datasheet specifies 2 V as the absolute minimum operating condition. Below 2 V, internal circuitry is not fully functional, and regulation is not guaranteed.

Can the LP3990TLX-1.5/NOPB operate without any load connected to its output?

Yes, the LP3990TLX-1.5/NOPB remains stable and in regulation with zero load current-a feature explicitly confirmed in Section 8.2.2.5 ("No-Load Stability") of the SNVS251J datasheet. This makes it suitable for applications like CMOS RAM keep-alive circuits or always-on real-time clock supplies where load current drops to near-zero during sleep.