Texas Instruments LP3991TLX-1.2/NOPB

Overview

LP3991TLX-1.2/NOPB from Texas Instruments is a fixed-output 1.2-V, 300-mA low-dropout linear regulator in a 4-pin DSBGA package. It operates from 1.65 V to 4 V input, delivers ±1% output accuracy at room temperature, maintains regulation down to 125-mV dropout at full load, and draws only 50 µA quiescent current at 1-mA load - ideal for post-regulation of DC-DC converters in space-constrained portable electronics.

For engineers reviewing the LP3991TLX-1.2/NOPB datasheet, LP3991TLX-1.2/NOPB pinout, LP3991TLX-1.2/NOPB application, or LP3991TLX-1.2/NOPB equivalent, key selection criteria include its ultra-low input voltage capability (1.65 V min), ceramic-capacitor stability (down to 0402 size), 100-µs startup time, and integrated enable control with 1.2-MΩ internal pulldown - all critical for battery-powered digital subsystems requiring clean, low-voltage rails.

Technical Context

The LP3991TLX-1.2/NOPB employs a PMOS pass transistor architecture enabling operation below 1.8 V input while maintaining low dropout and high PSRR (65 dB at 1 kHz). Its internal enable circuitry features a precise 0.95-V turn-on threshold and 0.4-V turn-off threshold, with negligible shutdown current (~2 nA).

Designed for post-buck regulation, it eliminates switching noise without significant efficiency penalty - validated with LM3673 buck outputs - and remains stable with 2.2-µF ceramic output capacitors for VOUT ≤ 1.3 V, reducing board area versus traditional LDOs requiring larger capacitance.

Key Specifications

Pinout & Package

LP3991TLX-1.2/NOPB uses a 4-pin DSBGA (YZR) package measuring 1.43 mm × 0.96 mm with 0.5-mm pitch, optimized for ultra-compact PCB layouts and compatible with 0402 ceramic capacitors.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL7407LADGQR and MCP1804T-1202I/OT, LP3991TLX-1.2/NOPB offers superior low-input-voltage operation (1.65 V vs. ≥2.3 V), lower dropout (125 mV vs. ≥200 mV), and smaller footprint - making it the only option qualified for space- and battery-limited portable digital systems requiring sub-1.8-V input compatibility.

Availability

LP3991TLX-1.2/NOPB is available at Aetrix Electronics and suitable for mobile baseband processors, wearable sensor hubs, and IoT edge node microcontrollers requiring stable component supply with guaranteed long-term sourcing.

Supply support for LP3991TLX-1.2/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, embedded processing, and connectivity technologies, with decades of expertise in power management ICs.

The LP3991TLX-1.2/NOPB belongs to TI's precision low-dropout regulator product line, engineered specifically for post-DC-DC regulation in battery-powered digital systems where minimal board area, ultra-low input voltage, and low noise are mandatory.

FAQ

What is the minimum input voltage required for LP3991TLX-1.2/NOPB to regulate at 1.2 V?

The LP3991TLX-1.2/NOPB requires a minimum input voltage of 1.65 V to maintain regulation at its fixed 1.2-V output. This is enabled by its PMOS pass element and low 125-mV dropout voltage at 300 mA, allowing operation even as battery voltage drops near end-of-life - a key advantage over NMOS-based LDOs that typically require ≥2.0 V input.

Can LP3991TLX-1.2/NOPB operate with a 2.2-µF output capacitor?

Yes, LP3991TLX-1.2/NOPB is explicitly qualified to operate stably with a 2.2-µF ceramic output capacitor when VOUT ≤ 1.3 V - which includes the 1.2-V variant. The datasheet confirms this reduces board area versus standard 4.7-µF designs, though minor degradation (<15%) in load transient response may occur compared to the 4.7-µF configuration.

Does LP3991TLX-1.2/NOPB include thermal protection?

Yes, LP3991TLX-1.2/NOPB integrates a thermal shutdown circuit that activates at 160°C junction temperature with 20°C hysteresis. This protects the device during overload or poor PCB thermal design. The shutdown is fully internal - no external components or configuration are needed, and LP3991TLX-1.2/NOPB resumes normal operation automatically once the die cools below 140°C.

What is the enable pin behavior of LP3991TLX-1.2/NOPB?

The EN pin of LP3991TLX-1.2/NOPB is active-high with a typical 0.95-V turn-on threshold and 0.4-V turn-off threshold. It includes an internal 1.2-MΩ pulldown resistor, ensuring the device remains off during power-up or floating conditions. When disabled, LP3991TLX-1.2/NOPB draws only ~2 nA, making it ideal for zero-power standby modes in portable systems.

Is LP3991TLX-1.2/NOPB stable with 0402-case ceramic capacitors?

Yes, LP3991TLX-1.2/NOPB is specifically designed and characterized for stability with 0402-size ceramic capacitors - including both input (1 µF) and output (2.2 µF or 4.7 µF) configurations. This capability eliminates layout constraints associated with larger case sizes and supports ultra-dense PCB designs common in modern wearables and handheld devices.