Texas Instruments LP3966ESX-3.3/NOPB

Overview

LP3966ESX-3.3/NOPB from Texas Instruments is a 3A ultra-low-dropout linear regulator with fixed 3.3V output, designed for high-current microprocessor and DSP power supplies. It delivers ±1.5% output voltage accuracy at room temperature, achieves 800mV dropout at 3A load, and operates from 2.5V to 7.0V input while maintaining 15µA shutdown current.

For engineers reviewing the LP3966ESX-3.3/NOPB datasheet, LP3966ESX-3.3/NOPB pinout, LP3966ESX-3.3/NOPB application, or LP3966ESX-3.3/NOPB equivalent, key selection criteria include remote-sense capability for load regulation, thermal/overcurrent protection behavior, dropout performance under full 3A load, and compatibility with low-ESR tantalum output capacitors (0.2–5Ω).

Technical Context

The LP3966ESX-3.3/NOPB uses a CMOS-based PMOS pass transistor architecture enabling ultra-low quiescent current independent of load, with typical ground pin current of 6mA at 3A. Its internal error amplifier drives the pass element with fast transient response optimized for digital load steps.

Unlike the LP3963, this variant integrates a dedicated SENSE/ADJ pin (Pin 5) enabling remote voltage sensing at the load to compensate for PCB trace IR drop-critical for maintaining 3.3V regulation at point-of-load in high-current applications such as GTL+ bus terminators or post-regulation stages.

Key Specifications

Pinout & Package

LP3966ESX-3.3/NOPB is packaged in DDPAK/TO-263-5 surface-mount format with exposed thermal pad for enhanced heat dissipation in high-power applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3A fixed-output LDO applications.

Compared with TPS75733KTTT and MCP1826-3302E/DC, the LP3966ESX-3.3/NOPB uniquely combines 3A capability, 800mV dropout, remote sense, and −40°C to +125°C operation - making it the only option qualified for high-reliability, high-current, precision point-of-load regulation in automotive and industrial control systems.

Availability

LP3966ESX-3.3/NOPB is available at Aetrix Electronics and suitable for microprocessor power supplies, GTL+/SSTL bus terminators, and DSP power post-regulation requiring stable component supply across extended temperature and high-current operating conditions.

Supply support for LP3966ESX-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 is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability linear regulators and power solutions.

The LP3966 belongs to TI's ultra-low-dropout LDO family engineered for high-current, low-noise, and thermally robust power delivery in demanding digital systems - particularly targeting microprocessor, DSP, and high-speed interface applications.

FAQ

What is the minimum input voltage required for LP3966ESX-3.3/NOPB to regulate 3.3V at 3A?

The LP3966ESX-3.3/NOPB requires a minimum input voltage of 4.1V to maintain regulation at 3A load, based on its 800mV typical dropout voltage (3.3V + 0.8V = 4.1V). The device will cease regulation if VIN drops below this threshold, triggering the ERROR flag if enabled. Input voltage must also remain ≥2.5V per absolute ratings, but functional operation demands VIN ≥ VOUT + VDROPOUT.

Can the SENSE pin of LP3966ESX-3.3/NOPB be left floating?

No, the SENSE pin of LP3966ESX-3.3/NOPB must never be left floating. If remote sensing is not used, the SENSE pin must be directly connected to the VOUT pin using a low-inductance trace. Floating the pin risks instability, inaccurate regulation, or undefined behavior due to internal comparator biasing - as explicitly stated in TI's Application Hints section.

Does LP3966ESX-3.3/NOPB support ceramic output capacitors?

LP3966ESX-3.3/NOPB does not support standalone ceramic output capacitors due to their extremely low ESR (<10mΩ), which falls below the required 0.2Ω minimum for loop stability. However, a small ceramic capacitor (e.g., 3µF) may be paralleled with a 100µF tantalum output capacitor - provided the total equivalent ESR remains within 0.2–5Ω across the full operating temperature range.

How does the ERROR flag behave during shutdown of LP3966ESX-3.3/NOPB?

When the SD pin of LP3966ESX-3.3/NOPB is pulled low to initiate shutdown, the ERROR flag is forced invalid and ceases to reflect output status. This is an intentional power-saving feature - the internal comparator is disabled to reduce current draw. The ERROR pin returns to functional operation only after SD is released and the regulator fully powers up.

What thermal considerations apply to LP3966ESX-3.3/NOPB in DDPAK/TO-263 package?

In the DDPAK/TO-263-5 package, LP3966ESX-3.3/NOPB has a junction-to-ambient thermal resistance (θ_JA) of 60°C/W with 0.5in² of 1oz copper. At 3A load with 4.1V input, power dissipation reaches ~2.4W - requiring careful PCB layout: thermal pad soldering, adequate copper pour, and possible airflow or heatspreading to keep junction temperature ≤125°C under worst-case ambient conditions.