Texas Instruments LP3856ES-ADJ/NOPB

Overview

LP3856ES-ADJ/NOPB from Texas Instruments is an adjustable ultra-low-dropout linear regulator delivering up to 3A DC output current with dropout as low as 39 mV at 300 mA and 390 mV at 3 A. It operates from 2.5 V to 7.0 V input, features 1.216 V internal reference, 0.08% load regulation, and supports ceramic or tantalum output capacitors. It serves as a post-regulator in microprocessor power supplies requiring fast transient response and low-noise bias.

For engineers reviewing the LP3856ES-ADJ/NOPB datasheet, LP3856ES-ADJ/NOPB pinout, LP3856ES-ADJ/NOPB application, or LP3856ES-ADJ/NOPB equivalent, key selection criteria include dropout voltage vs. load, ground pin current behavior across temperature, shutdown quiescent current (10 nA), stability with ceramic COUT, and thermal derating in TO-263 package.

Technical Context

The LP3856ES-ADJ/NOPB uses a PMOS pass element on a CMOS process, enabling low quiescent current independent of load and operation under ultra-low dropout conditions. Its feedback loop relies on a precision 1.216 V bandgap reference at the ADJ pin and requires external R1/R2 for output programming.

It integrates overtemperature and overcurrent protection, delivers 73 dB PSRR at 120 Hz (VIN = VOUT + 1 V), and achieves 150 µVrms broadband noise (10 Hz–100 kHz) at 2.5 V output. Shutdown is controlled by a CMOS-compatible SD pin with 1.3 V threshold and 20 µs turn-off delay.

Key Specifications

Pinout & Package

LP3856ES-ADJ/NOPB is packaged in DDPAK/TO-263-5 (surface-mount), with exposed thermal pad for enhanced heat dissipation. The package is RoHS-compliant and lead-free (NOPB suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS75733KTTT and LT1963AES-ADJ, LP3856ES-ADJ/NOPB uniquely combines 3 A capability, sub-400 mV dropout at full load, adjustable output, and DDPAK thermal performance - making it optimal for high-current, low-voltage, thermally demanding applications where flexibility and efficiency are jointly critical.

Availability

LP3856ES-ADJ/NOPB is available at Aetrix Electronics and suitable for microprocessor power supplies, GTL bus terminators, DSP power management, SCSI termination, and battery-charger reference designs requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for LP3856ES-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 designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and communications markets.

The LP3856ES-ADJ/NOPB belongs to TI's ultra-low-dropout linear regulator family, engineered specifically for high-current, low-noise, fast-transient applications in microprocessor, DSP, and bus-termination systems.

FAQ

What is the minimum input voltage required for LP3856ES-ADJ/NOPB to regulate a 2.5 V output?

The minimum input voltage is the greater of [VOUT(NOM) + VDROPOUT] or 2.5 V. For 2.5 V output, dropout is 390 mV at 3 A, so minimum VIN = 2.5 V + 0.39 V = 2.89 V. LP3856ES-ADJ/NOPB will not regulate properly below this value under full load - always verify against actual load and temperature conditions using the dropout vs. load curve in the datasheet.

Can LP3856ES-ADJ/NOPB be used with only ceramic capacitors on input and output?

Yes - LP3856ES-ADJ/NOPB is explicitly characterized for stability with ceramic capacitors. With 10 µF ceramic CIN, it supports up to 500 µF ceramic COUT at 1 A, 50 µF at 2 A, and ~1:1 ratio at 3 A. Always follow Figure 26 in the datasheet and ensure X5R/X7R dielectrics are used to avoid capacitance collapse under bias or temperature.

How does the ADJ pin bias current affect output accuracy in LP3856ES-ADJ/NOPB?

LP3856ES-ADJ/NOPB ADJ pin bias current is ≤100 nA (max). When R1 exceeds 100 kΩ, this current introduces measurable error in the R1/R2 divider. For example, with R2 = 10 kΩ and R1 = 1 MΩ, 100 nA flowing through R1 adds ~100 mV offset - degrading VOUT accuracy. Use R1 ≤100 kΩ or compensate mathematically per Equation (1) in the Application Hints section of the LP3856ES-ADJ/NOPB datasheet.

Is a feed-forward capacitor (CFF) mandatory for LP3856ES-ADJ/NOPB stability?

Yes - CFF is required to add phase lead and ensure loop stability across all loads and capacitor types. Its value depends on R1: CFF ≈ 1/(2π × R1 × 45 kHz). Omitting CFF risks oscillation, especially with ceramic output capacitors. Use X5R/X7R ceramic CFF placed close to the ADJ and VOUT pins, as specified in the LP3856ES-ADJ/NOPB Application Hints.

What thermal considerations apply when using LP3856ES-ADJ/NOPB in DDPAK/TO-263 package at 3 A?

In DDPAK/TO-263, LP3856ES-ADJ/NOPB has θJA = 60°C/W (with 0.5 in², 1 oz copper). At 3 A and 1 V dropout, PD ≈ (1 V × 3 A) + (VIN × IGND) ≈ 3 W + ~0.03 W = ~3.03 W. With TA = 85°C and TJmax = 125°C, TRmax = 40°C → allowable θJA = 40°C / 3.03 W ≈ 13.2°C/W. Since 60°C/W > 13.2°C/W, a heatsink or large copper pour is mandatory - refer to TI's thermal design guidelines for LP3856ES-ADJ/NOPB layout recommendations.