Texas Instruments LP3961EMP-1.8/NOPB

Overview

LP3961EMP-1.8/NOPB from Texas Instruments is a fixed-output 1.8-V, 800-mA ultra-low-dropout linear regulator in SOT-223 package, featuring 24 mV dropout at 80 mA, ±1.5% output voltage accuracy, and integrated ERROR flag for output monitoring-designed for microprocessor core power in space-constrained embedded systems.

For engineers reviewing the LP3961EMP-1.8/NOPB datasheet, LP3961EMP-1.8/NOPB pinout, LP3961EMP-1.8/NOPB application, or LP3961EMP-1.8/NOPB equivalent, key selection criteria include dropout performance under 800-mA load, ERROR flag hysteresis behavior, thermal shutdown threshold (165°C), ground current vs. load, and compatibility with low-ESR output capacitors (0.2–5 Ω).

Technical Context

The LP3961EMP-1.8/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 and 240 mV at full 800-mA load. Its ERROR flag is an open-drain comparator with 10% output voltage threshold and 5% hysteresis, active only when SD = high.

It operates across −40°C to 125°C junction temperature, supports input voltages from 2.5 V to 7 V, and delivers ±0.02% load regulation and ±0.02% line regulation-enabling stable core supply for low-voltage logic without external feedback compensation.

Key Specifications

Pinout & Package

SOT-223 (5-pin) package: 6.50 mm × 3.56 mm body, exposed thermal pad (pin 3 = OUT), thermally enhanced for up to 1.2 W dissipation in standard PCB layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLS850F0TESA1 and TPS7A2018PDQNR, the LP3961EMP-1.8/NOPB uniquely balances 800-mA drive, 24 mV dropout, and integrated ERROR flag in SOT-223-making it optimal for industrial microprocessor supplies where fault awareness and high-current headroom coexist.

Availability

LP3961EMP-1.8/NOPB is available at Aetrix Electronics and suitable for microprocessor core supplies, GTL+ bus termination, SCSI termination, battery-powered sensor nodes, and other applications requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LP3961EMP-1.8/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 and embedded processing solutions, with decades of LDO design heritage and broad automotive, industrial, and personal electronics reach.

The LP396x series was developed to address demand for fast-response, ultra-low-dropout regulators in space-constrained 1.8-V and 3.3-V digital systems-emphasizing precision, thermal robustness, and integrated fault signaling without external components.

FAQ

What is the minimum input voltage required for LP3961EMP-1.8/NOPB to regulate 1.8 V?

The LP3961EMP-1.8/NOPB requires a minimum input voltage of 2.08 V to maintain regulation at full 800-mA load (based on 240 mV dropout). At lighter loads, it can operate down to 1.824 V (24 mV dropout at 80 mA). The absolute minimum operating input is 2.5 V per recommended conditions, but functional regulation begins at VOUT + VDROPOUT across the specified temperature and load range.

How does the ERROR flag behave during shutdown of LP3961EMP-1.8/NOPB?

When the SD pin of LP3961EMP-1.8/NOPB is pulled low, the ERROR flag is forced invalid and its output becomes indeterminate-TI documentation explicitly states the ERROR function is disabled in shutdown mode to conserve power. The pin must be tied to GND if unused, and any external pullup remains active but yields no meaningful status.

Can LP3961EMP-1.8/NOPB be used with ceramic output capacitors?

No-LP3961EMP-1.8/NOPB requires an output capacitor with ESR between 0.2 Ω and 5 Ω for loop stability, and standard ceramic capacitors fall far below this range (typically <10 mΩ). Using ceramics alone causes oscillation. A stable solution combines a 33 µF tantalum (or aluminum polymer) with optional small-ceramic bypass (<3 µF) only if total ESR remains within spec.

What thermal performance can be expected from LP3961EMP-1.8/NOPB in SOT-223 package?

In standard 2-layer PCB layout with 1-in² copper pour on top layer connected to the exposed thermal pad, LP3961EMP-1.8/NOPB achieves R_θJA ≈ 65.2°C/W. At 800 mA and 1.8-V output, power dissipation is ~0.19 W, resulting in ~12°C junction-to-ambient rise-well within the −40°C to 125°C operating range without forced airflow.

Is LP3961EMP-1.8/NOPB compatible with reverse input-to-output voltage conditions?

Yes-LP3961EMP-1.8/NOPB contains an inherent parasitic body diode in its PMOS pass device. If VOUT exceeds VIN, reverse current flows up to 200 mA DC (1 A peak), provided external circuitry limits current. This enables safe operation in back-drive scenarios like hot-swap or battery backup switchover, but sustained reverse conduction must be externally managed.