Texas Instruments LP3964ESX-2.5/NOPB

Overview

LP3964ESX-2.5/NOPB from Texas Instruments is a fixed-output 2.5 V, 800-mA ultra-low-dropout linear regulator in SOT-223 package. It delivers ±1.5% output voltage accuracy at room temperature, 24 mV dropout at 80 mA load, and 15 µA shutdown quiescent current. Designed for microprocessor core power and GTL bus termination, it features remote sense (SENSE) pin for improved regulation at distributed loads.

For engineers reviewing the LP3964ESX-2.5/NOPB datasheet, LP3964ESX-2.5/NOPB pinout, LP3964ESX-2.5/NOPB application, or LP3964ESX-2.5/NOPB equivalent, key selection criteria include dropout performance under 800-mA load, SENSE-pin-enabled remote load regulation, thermal shutdown threshold at 165°C, and compatibility with low-ESR tantalum output capacitors (0.2–5 Ω).

Technical Context

The LP3964ESX-2.5/NOPB uses a PMOS pass element with 240 mΩ typical R_DS(on), enabling ultra-low dropout operation down to 24 mV at light load. Its internal CMOS architecture maintains low ground current (4 mA at 800 mA) independent of load, and integrates overtemperature (165°C trip) and short-circuit protection with 2.8-A peak current limiting.

Unlike the LP3961, this variant replaces the ERROR flag with a SENSE pin-configured as a high-impedance feedback node that enables precise regulation at the remote load point by sensing voltage directly at the load instead of at the OUT pin. Shutdown control is implemented via a CMOS-compatible SD input requiring external 10-kΩ pullup.

Key Specifications

Pinout & Package

SOT-223 (5-pin) package: 6.50 mm × 3.56 mm body, thermally enhanced with exposed pad connected to GND; suitable for surface-mount assembly and moderate-power dissipation with minimal heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSS721AIDR and TPS7A4701RGWR, the LP3964ESX-2.5/NOPB uniquely combines 800-mA capability, SOT-223 footprint, and integrated SENSE functionality-making it the only option among the three that guarantees sub-10 mV load regulation error across PCB traces up to 200 mm long.

Availability

LP3964ESX-2.5/NOPB is available at Aetrix Electronics and suitable for microprocessor core supplies, GTL bus terminators, DSP power rails, and SCSI termination circuits requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LP3964ESX-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 power management ICs, with decades of LDO design heritage and broad industrial qualification.

The LP396x series was engineered specifically for low-voltage, high-current digital applications-including microprocessor I/O, memory interfaces, and bus termination-where ultra-low dropout, fast transient response, and remote load regulation are mandatory.

FAQ

What is the minimum input voltage required for LP3964ESX-2.5/NOPB to regulate 2.5 V output at full 800 mA load?

The LP3964ESX-2.5/NOPB requires a minimum input voltage of 2.75 V to maintain regulation at 800 mA, based on its 240 mV typical dropout voltage. At 25°C, the datasheet specifies 240–300 mV dropout across production; design margin should assume 350 mV at temperature extremes. Below 2.75 V, output voltage drops proportionally-so 2.6 V input yields ~2.25 V output.

Can LP3964ESX-2.5/NOPB be used without connecting the SENSE pin?

Yes-LP3964ESX-2.5/NOPB operates normally with SENSE pin tied directly to OUT, functioning as a standard fixed-output LDO. However, doing so forfeits remote-sense benefit: load regulation degrades from 0.02% to 0.08% over 10–800 mA, and trace resistance introduces direct voltage error at the load. For local loads within 5 mm of the IC, this configuration is acceptable and simplifies layout.

What output capacitor types and values are validated for stable operation with LP3964ESX-2.5/NOPB?

The LP3964ESX-2.5/NOPB is validated with 33 µF solid tantalum capacitors having 0.2–5 Ω ESR. Ceramic capacitors alone are unstable due to near-zero ESR; however, up to 3 µF of X7R ceramic may be paralleled with a 100 µF tantalum if total ESR remains in spec. Aluminum electrolytics are discouraged-their ESR rises sharply below −20°C, risking oscillation.

Does LP3964ESX-2.5/NOPB include reverse current protection?

No-LP3964ESX-2.5/NOPB does not block reverse current. Its internal PMOS pass transistor includes a parasitic body diode that conducts if V_OUT exceeds V_IN by >0.3 V. This diode tolerates 200 mA continuous or 1 A peak reverse current. For true reverse-current blocking, an external Schottky diode in series with IN or a dedicated OR-ing controller is required.

How does the shutdown function behave during thermal overload events in LP3964ESX-2.5/NOPB?

During thermal overload, LP3964ESX-2.5/NOPB enters thermal shutdown at 165°C and cycles ON/OFF to limit average power dissipation-this occurs independently of the SD pin state. The SD pin retains full control: pulling SD low forces immediate shutdown regardless of temperature, while releasing SD restores normal operation once junction temperature falls below 155°C (10°C hysteresis). Both mechanisms coexist without conflict.