Texas Instruments LP3966ESX-2.5/NOPB

Overview

LP3966ESX-2.5/NOPB from Texas Instruments is a 2.5V fixed-output, 3A ultra-low-dropout linear regulator in DDPAK/TO-263-5 package, featuring 800mV dropout at 3A, ±1.5% output voltage accuracy, and remote sense capability for precision load regulation in microprocessor power supplies.

For engineers reviewing the LP3966ESX-2.5/NOPB datasheet, LP3966ESX-2.5/NOPB pinout, LP3966ESX-2.5/NOPB application, or LP3966ESX-2.5/NOPB equivalent, key selection criteria include dropout performance under full 3A load, thermal shutdown threshold (165°C), ground current behavior across load range, and SENSE pin implementation for remote load regulation.

Technical Context

The LP3966ESX-2.5/NOPB uses a CMOS-based PMOS pass element with 240mΩ typical R_DS(on), enabling ultra-low dropout operation independent of load current. Its internal error amplifier compares feedback from the SENSE pin (or VOUT if unconnected) to a precision bandgap reference, delivering fast transient response to step-load changes up to 3A.

Shutdown control is implemented via a CMOS-compatible SD pin requiring active pull-up; when asserted low, quiescent current drops to 15µA and the ERROR flag is disabled. The open-drain ERROR pin monitors output regulation status with 10% hysteresis relative to nominal VOUT.

Key Specifications

Pinout & Package

LP3966ESX-2.5/NOPB is housed in a thermally enhanced DDPAK/TO-263-5 surface-mount package with exposed thermal pad for PCB heat sinking. Pin 1 is SD (Shutdown), Pin 2 is VIN, Pin 3 is GND, Pin 4 is VOUT, and Pin 5 is SENSE/ADJ - configured as remote sense input for improved load regulation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-dropout linear regulator applications.

Compared with LP3966ESX-2.5/NOPB, TPS75725KC offers smaller footprint and lower cost but cannot support 3A loads or remote sensing, while LT1963AES-2.5 delivers lower noise and better PSRR yet sacrifices both current capacity and SENSE-based load regulation accuracy.

Availability

LP3966ESX-2.5/NOPB is available at Aetrix Electronics and suitable for microprocessor core supplies, GTL bus terminators, SCSI termination circuits, and post-regulation of switching power supplies requiring stable component supply with guaranteed long-term availability.

Supply support for LP3966ESX-2.5/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 company specializing in analog and embedded processing technologies, with leadership in power management ICs for industrial, automotive, and computing markets.

The LP3966 series belongs to TI's ultra-low-dropout linear regulator product line, designed specifically for high-current, low-voltage microprocessor and bus-termination applications demanding precision regulation, fast transient response, and thermal robustness.

FAQ

What is the minimum input voltage required for LP3966ESX-2.5/NOPB to maintain regulation?

The minimum input voltage for LP3966ESX-2.5/NOPB is determined by its dropout specification: at 3A load, 800mV dropout requires VIN ≥ 3.3V to sustain 2.5V output. At lighter loads, dropout decreases - e.g., 80mV at 300mA means VIN ≥ 2.58V suffices. The absolute minimum operating VIN is 2.5V per datasheet limits, but actual minimum depends on load and temperature.

How should the SENSE pin be connected on LP3966ESX-2.5/NOPB?

For remote load regulation, connect the SENSE pin directly to the load's VCC point using a dedicated trace - not shared with power or ground returns. If remote sensing is unused, tie SENSE to VOUT at the regulator's output pin (not at the load). Never leave SENSE floating, as this causes regulation instability and potential output overvoltage.

Does LP3966ESX-2.5/NOPB include reverse current protection?

LP3966ESX-2.5/NOPB does not include active reverse current protection. Its internal PMOS pass device contains a parasitic body diode that conducts if VOUT exceeds VIN. This diode tolerates up to 200mA continuous or 1A peak reverse current. External reverse-blocking circuitry (e.g., series Schottky) is required in applications where VOUT may exceed VIN.

What output capacitor ESR range ensures stability for LP3966ESX-2.5/NOPB?

LP3966ESX-2.5/NOPB requires an output capacitor with ESR between 0.2Ω and 5Ω for loop stability. Ceramic capacitors alone are unsuitable due to sub-10mΩ ESR; instead, use solid tantalum (ideal ESR ~1–2Ω) or aluminum electrolytic with verified ESR specs at 100kHz. Minimum capacitance is 33µF, but higher values improve transient response.

Can LP3966ESX-2.5/NOPB be used in automotive applications?

LP3966ESX-2.5/NOPB operates across −40°C to +125°C junction temperature and includes overtemperature and overcurrent protection, meeting base requirements for under-hood automotive modules. However, it is not AEC-Q100 qualified. For production automotive use, TI recommends AEC-Q100 qualified alternatives such as TPS7B8725.