Texas Instruments LP3990TLX-2.8/NOPB

Overview

LP3990TLX-2.8/NOPB from Texas Instruments is a 150-mA, 2.8-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 room temperature, operates from 2 V to 6 V input, achieves 120 mV typical dropout at full load, and consumes only 43 µA quiescent current when enabled-ideal for battery-powered handheld information appliances requiring stable low-noise power.

For engineers reviewing the LP3990TLX-2.8/NOPB datasheet, LP3990TLX-2.8/NOPB pinout, LP3990TLX-2.8/NOPB application, or LP3990TLX-2.8/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 µV_RMS output noise, and thermal-overload protection up to 155°C junction temperature.

Technical Context

The LP3990TLX-2.8/NOPB implements a PMOS pass transistor architecture enabling ultra-low quiescent current and fast 105 µs startup time. Its enable control uses an 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 if left floating.

It features integrated thermal shutdown (155°C trip, 140°C hysteresis) and short-circuit current limiting (550–1000 mA). Stability is guaranteed with 1-µF ceramic output capacitors (X7R/X5R, 5–500 mΩ ESR), eliminating need for noise-bypass caps while delivering 55 dB PSRR at 1 kHz and 35 dB at 10 kHz under 150-mA load.

Key Specifications

Pinout & Package

LP3990TLX-2.8/NOPB is housed in a thermally enhanced 6-pin WSON (NGG) package measuring 2.90 mm × 1.60 mm, featuring an exposed thermal pad (Pin 6) that must be soldered to PCB ground 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 linear regulator applications.

Compared with TPL7407LDR and MCP1700T-2802E/TT, LP3990TLX-2.8/NOPB uniquely balances 1.5% accuracy, 150 µV_RMS noise, and 43 µA IQ in a space-constrained WSON package - making it optimal for noise-sensitive, battery-limited digital loads where precision and stability outweigh raw IQ minimization.

Availability

LP3990TLX-2.8/NOPB is available at Aetrix Electronics and suitable for cellular handsets, handheld information appliances, and wearable health monitors requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.

Supply support for LP3990TLX-2.8/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 specializing in analog and embedded processing technologies, with over 50 years of innovation in power management ICs.

The LP3990TLX-2.8/NOPB belongs to TI's LP3990 family of ultra-low-noise, ceramic-capacitor-optimized LDOs-designed specifically for portable digital systems demanding high accuracy, minimal board area, and extended battery life.

FAQ

What is the minimum input voltage required for LP3990TLX-2.8/NOPB to regulate 2.8 V output?

The LP3990TLX-2.8/NOPB requires VIN ≥ (VOUT + VDO), where VDO is 120 mV typical at 150 mA. Thus, minimum functional input is 2.92 V. However, per datasheet Section 6.3, the absolute minimum recommended VIN is 2 V - but regulation only begins once VIN exceeds VOUT + VDO or 2 V, whichever is higher. For reliable 2.8-V output, maintain VIN ≥ 2.92 V under load.

Can LP3990TLX-2.8/NOPB operate without an enable signal connected?

Yes - LP3990TLX-2.8/NOPB has an internal 1-MΩ pull-down resistor on the EN pin. If left unconnected, EN defaults to GND (<0.4 V), disabling the regulator and reducing IQ to <10 nA. To enable operation, drive EN ≥0.95 V with a logic signal or tie it directly to VIN.

What ceramic capacitor specifications are mandatory for stable operation of LP3990TLX-2.8/NOPB?

LP3990TLX-2.8/NOPB requires a 1-µF ceramic output capacitor with ESR between 5 mΩ and 500 mΩ, and X7R or X5R dielectric for stable operation across –40°C to 125°C. Z5U/Y5V types are discouraged due to >50% capacitance loss at temperature extremes - risking instability in wide-temperature applications.

Does LP3990TLX-2.8/NOPB require a separate noise-bypass capacitor?

No - LP3990TLX-2.8/NOPB is explicitly designed to achieve 150 µV_RMS output noise without any external noise-bypass capacitor. Its internal architecture eliminates the need for a parallel 10-nF capacitor typically required by older LDOs, simplifying layout and reducing component count.

How does thermal shutdown behave in LP3990TLX-2.8/NOPB during sustained overload?

LP3990TLX-2.8/NOPB triggers thermal shutdown at ~155°C junction temperature and re-enables at ~140°C hysteresis. Under continuous overload, this causes auto-cycling - brief on/off pulses that limit average power dissipation but may disrupt downstream circuitry. Proper PCB thermal design (soldered thermal pad to ground plane) is essential to avoid cycling in normal operation.