Texas Instruments LP3965ESX-2.5/NOPB

Overview

LP3965ESX-2.5/NOPB from Texas Instruments is a 2.5V fixed-output, 1.5A ultra-low-dropout linear regulator in SOT-223-5 package. It delivers ±1.5% output voltage accuracy at room temperature, achieves 38mV dropout at 150mA and 380mV at 1.5A, and operates from 2.5V to 7.0V input with 15µA shutdown quiescent current. It serves as a primary power supply for low-voltage microprocessors requiring fast transient response and tight regulation.

For engineers reviewing the LP3965ESX-2.5/NOPB datasheet, LP3965ESX-2.5/NOPB pinout, LP3965ESX-2.5/NOPB application, or LP3965ESX-2.5/NOPB equivalent, key selection criteria include dropout performance under full load, remote-sense capability (via SENSE/ADJ pin), thermal shutdown behavior at 165°C, ground pin current vs. load, and compatibility with 33µF/0.2–5Ω output capacitor ESR range.

Technical Context

The LP3965ESX-2.5/NOPB uses a CMOS-based PMOS pass element with 240mΩ typical R_DS(on), enabling ultra-low dropout and load-independent quiescent current. Its error amplifier and reference circuitry are optimized for high-speed load step response-critical for microprocessor core rails where current demand changes rapidly.

Unlike the LP3962, the LP3965 variant integrates a dedicated SENSE/ADJ pin that enables remote voltage sensing at the load, improving regulation accuracy by compensating for PCB trace IR drop. This pin functions as a high-impedance sense input-not an adjustment terminal-for the fixed 2.5V version.

Key Specifications

Pinout & Package

SOT-223-5 surface-mount package with exposed thermal pad (pin 3 is VOUT; pin 5 is GND; pin 4 is SENSE/ADJ; pins 1 and 2 are SD and VIN respectively). Thermal resistance θ_JA = 90°C/W with 0.5in² 1oz copper area-requires proper thermal pad soldering for full 1.5A capability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSS721AIDR and TPS7A4701RGWR, the LP3965ESX-2.5/NOPB uniquely combines 1.5A current, remote sense, thermal hysteresis, and 380mV dropout in a single SOT-223 package-making it optimal for space-constrained, high-accuracy, high-current point-of-load regulation.

Availability

LP3965ESX-2.5/NOPB is available at Aetrix Electronics and suitable for microprocessor core supplies, GTL+/SSTL bus terminators, and battery-powered instrumentation requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production lots.

Supply support for LP3965ESX-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 leader specializing in analog, embedded processing, and connectivity technologies-with over 50 years of power management innovation.

The LP3965 belongs to TI's ultra-low-dropout linear regulator product line, engineered specifically for high-current, low-voltage digital systems where transient response, accuracy, and thermal robustness are critical-such as FPGA, DSP, and memory interface power rails.

FAQ

What is the minimum input voltage required for LP3965ESX-2.5/NOPB to regulate 2.5V output?

The LP3965ESX-2.5/NOPB requires a minimum input voltage equal to VOUT + dropout voltage. At 1.5A load, dropout is 380mV, so minimum VIN = 2.5V + 0.38V = 2.88V. At light loads (150mA), dropout drops to 38mV, allowing VIN as low as 2.538V. The datasheet specifies absolute minimum operating VIN as 2.5V, but regulation is only guaranteed above the calculated dropout threshold.

Can LP3965ESX-2.5/NOPB be used without connecting the SENSE/ADJ pin?

Yes-LP3965ESX-2.5/NOPB operates normally with the SENSE/ADJ pin tied directly to the VOUT pin. This configures it as a standard local-sense regulator. Leaving the pin floating is not allowed; it must be connected to VOUT for fixed-output operation. The SENSE function is optional and only active when the pin is routed to the remote load.

Does LP3965ESX-2.5/NOPB include reverse current protection?

No-the LP3965ESX-2.5/NOPB contains an inherent body diode in its PMOS pass transistor. If VOUT exceeds VIN, reverse current flows up to 200mA continuous or 1A peak. For bidirectional isolation, an external Schottky diode in series with VIN is required. This behavior is documented in the Absolute Maximum Ratings section under "Maximum Voltage for SENSE Pin" and "Reverse Current Path".

What output capacitor ESR range ensures stability for LP3965ESX-2.5/NOPB?

The LP3965ESX-2.5/NOPB requires an output capacitor with ESR between 0.2Ω and 5Ω for guaranteed stability. A 33µF solid tantalum capacitor meeting this range is the recommended default. Ceramic capacitors alone are unsuitable due to their sub-10mΩ ESR; however, adding ~3µF ceramic in parallel with a 100µF tantalum can improve high-frequency bypassing while maintaining loop stability.

How does the ERROR flag function on LP3965ESX-2.5/NOPB?

The LP3965ESX-2.5/NOPB does not include an ERROR flag-this feature is exclusive to the LP3962 variant. The LP3965ESX-2.5/NOPB has a SENSE/ADJ pin instead of ERROR on pin 4 (SOT-223). Confusion arises because both devices share the same datasheet, but pin functionality differs: LP3962 pin 4 = ERROR; LP3965 pin 4 = SENSE/ADJ. No error reporting circuitry exists in LP3965ESX-2.5/NOPB.