Texas Instruments LP3965ET-ADJ/NOPB

Overview

LP3965ET-ADJ/NOPB from Texas Instruments is an adjustable ultra-low-dropout linear regulator delivering 1.5A DC output with dropout as low as 38 mV at 150 mA and 380 mV at full load, designed for microprocessor core supplies and post-regulation in battery-powered systems where precision, fast transient response, and low quiescent current are critical.

For engineers reviewing the LP3965ET-ADJ/NOPB datasheet, LP3965ET-ADJ/NOPB pinout, LP3965ET-ADJ/NOPB application, or LP3965ET-ADJ/NOPB equivalent, key selection considerations include its SOT-223-5 package, ±1.5% output voltage accuracy over temperature, 15 µA shutdown current, remote sense/adjust capability, and compatibility with 33 µF minimum output capacitance (ESR 0.2–5 Ω).

Technical Context

The LP3965ET-ADJ/NOPB uses a CMOS-based PMOS pass transistor architecture enabling ultra-low dropout and load-independent quiescent current. Its internal reference and error amplifier support precise output regulation across line, load, and temperature variations.

It features a dedicated SENSE/ADJ pin enabling either remote voltage sensing for improved load regulation or external resistor-divider adjustment of output voltage from 1.216 V to 5.1 V. The open-drain ERROR flag provides fault indication with built-in hysteresis and 10% output undervoltage threshold.

Key Specifications

Pinout & Package

SOT-223-5 package: thermally enhanced surface-mount plastic package with exposed thermal pad (pin 3 = VOUT, pin 5 = GND), rated for 90°C/W junction-to-ambient (0.5 in² copper area), suitable for compact PCB layouts with moderate power dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLS850F0TES/V33 and MCP1826T-ADJ/DC, the LP3965ET-ADJ/NOPB uniquely balances 1.5 A output, 38 mV dropout, adjustable/remote-sense capability, and 15 µA shutdown-making it optimal for space-constrained, battery-sensitive, high-transient digital loads where precision and efficiency are co-prioritized.

Availability

LP3965ET-ADJ/NOPB is available at Aetrix Electronics and suitable for microprocessor core supplies, GTL+ bus terminators, and battery-powered instrumentation requiring stable component supply, long-lifecycle availability, and guaranteed traceable sourcing.

Supply support for LP3965ET-ADJ/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 decades of expertise in power management IC design and manufacturing.

The LP3965ET-ADJ/NOPB belongs to TI's ultra-low-dropout linear regulator family engineered for high-efficiency, low-noise power delivery in portable and high-performance digital systems.

FAQ

What is the minimum input voltage required for LP3965ET-ADJ/NOPB to regulate a 1.5 V output?

The LP3965ET-ADJ/NOPB requires VIN ≥ VOUT + VDROPOUT. At 1.5 A load, dropout is 380 mV, so minimum VIN = 1.5 V + 0.38 V = 1.88 V. However, the absolute minimum operating VIN is specified as 2.5 V - therefore, 2.5 V is the practical lower limit regardless of output voltage. This constraint ensures internal bias circuits function correctly across temperature and process variation.

Can LP3965ET-ADJ/NOPB be used without connecting the SENSE/ADJ pin?

Yes - the SENSE/ADJ pin must be connected directly to the VOUT pin if remote sensing or output adjustment is not needed. Leaving it floating will cause regulation failure. When used as ADJ, a standard 10 kΩ resistor (R1) from SENSE/ADJ to GND and R2 from VOUT to SENSE/ADJ sets output voltage per VOUT = 1.216 V × (1 + R2/R1). The LP3965ET-ADJ/NOPB datasheet specifies this configuration.

Does LP3965ET-ADJ/NOPB require an external pull-up resistor on the ERROR pin?

Yes - the ERROR pin is open-drain and must be pulled high with a 10 kΩ to 1 MΩ resistor to a valid logic-high voltage (e.g., VIN or VOUT). Without this, the flag cannot assert a valid high state. If the ERROR function is unused, TI explicitly requires connecting the ERROR pin to GND - not leaving it open - to prevent leakage-induced instability. This applies to every LP3965ET-ADJ/NOPB implementation.

What output capacitor ESR range ensures stable operation of LP3965ET-ADJ/NOPB?

The LP3965ET-ADJ/NOPB requires an output capacitor with ESR between 0.2 Ω and 5 Ω for guaranteed loop stability. Ceramic capacitors alone are unsuitable due to their sub-10 mΩ ESR; instead, use solid tantalum (ideal ESR ~1–2 Ω) or mix ceramic with tantalum to achieve net ESR in spec. The minimum capacitance is 33 µF, but ESR compliance is mandatory - violating it risks oscillation even with correct capacitance value.

Is LP3965ET-ADJ/NOPB compatible with ceramic input capacitors?

Yes - LP3965ET-ADJ/NOPB supports ceramic input capacitors, and TI recommends low-ESR types (X7R/X5R dielectric) with ≥68 µF capacitance placed within 1 cm of the VIN and GND pins. Aluminum electrolytics are discouraged due to large ESR drift at low temperature; ceramics provide superior high-frequency bypassing and stable performance across −40°C to +125°C. The LP3965ET-ADJ/NOPB input stage is optimized for low-impedance ceramic sources.