Texas Instruments LM1086CT-ADJ/NOPB

Overview

LM1086CT-ADJ/NOPB from Texas Instruments is a 1.5-A adjustable low-dropout linear voltage regulator in TO-220 package, featuring 1.5 V dropout at full load, ±2% output accuracy, and operation across –40°C to 125°C. It delivers stable 1.25 V to 15 V output using two external resistors and supports ceramic output capacitors with appropriate ESR-commonly used in post-regulation for switching supplies and microprocessor power rails.

For engineers reviewing the LM1086CT-ADJ/NOPB datasheet, LM1086CT-ADJ/NOPB pinout, LM1086CT-ADJ/NOPB application, or LM1086CT-ADJ/NOPB equivalent, key selection criteria include dropout voltage at 1.5 A, thermal performance in TO-220, adjust-pin current (≤120 µA), ripple rejection (75 dB typ.), and compatibility with remote sensing for precision load regulation.

Technical Context

The LM1086CT-ADJ/NOPB uses a quasi-LDO NPN pass transistor architecture-distinct from PNP LDOs-enabling lower quiescent current and 1.5 V dropout at 1.5 A while maintaining stability with ceramic output capacitors. Its internal zener-trimmed bandgap reference (1.25 V nominal) sets output via resistor divider between ADJ and VOUT pins.

It integrates current limiting and thermal shutdown, detects only input-to-output differential voltage (not absolute VIN), and allows use as a precision current regulator by fixing a resistor between ADJ and VOUT. The TO-220 package provides 23.0°C/W junction-to-ambient thermal resistance under standard PCB mounting.

Key Specifications

Pinout & Package

LM1086CT-ADJ/NOPB is housed in a 3-pin TO-220 package (NDE variant) with exposed tab electrically connected to the output pin. The tab serves as primary heat dissipation path and must be thermally coupled to a heatsink or copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM1086CT-ADJ/NOPB, the TO-263 variant trades thermal efficiency for SMT compatibility, while TLV1117-ADJ sacrifices current capability and noise performance for lower cost and smaller footprint-neither offers identical combination of 1.5-A rating, 75-dB PSRR, and CADJ flexibility.

Availability

LM1086CT-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial control systems, battery-powered instrumentation, and embedded computing platforms requiring stable component supply with long-term manufacturability.

Supply support for LM1086CT-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 ICs.

The LM1086 product line was designed specifically for high-current, low-dropout linear regulation in industrial, computing, and communications infrastructure-emphasizing thermal robustness, precision, and compatibility with legacy LM317 layouts.

FAQ

What is the minimum input-to-output voltage differential required for regulation with LM1086CT-ADJ/NOPB?

The LM1086CT-ADJ/NOPB requires a minimum dropout voltage of 1.5 V at 1.5 A load current to maintain regulation. At lighter loads, dropout decreases-e.g., ~1.3 V at 1 A. This value is specified across –40°C to +125°C and ensures stable operation even under worst-case thermal conditions. Designers must ensure VIN − VOUT ≥ 1.5 V at peak load to avoid dropout-induced output collapse.

Can LM1086CT-ADJ/NOPB be used with ceramic output capacitors, and what ESR requirements apply?

Yes, LM1086CT-ADJ/NOPB is explicitly characterized for stability with ceramic output capacitors, unlike older LDOs requiring minimum ESR. No specific ESR range is mandated-TI confirms stability with zero-ESR ceramics when used with recommended capacitance (≥10 µF). This eliminates ESR-related design uncertainty and enables smaller, more reliable output filtering in space-constrained applications.

How does the adjust pin current affect output voltage accuracy in LM1086CT-ADJ/NOPB designs?

The LM1086CT-ADJ/NOPB adjust pin draws up to 120 µA, introducing error in the feedback divider. For example, with R1 = 240 Ω (standard for 1.25-V reference), this current causes ~29 mV offset-equivalent to ~2.3% error at 1.25 V. Using R1 ≤ 100 Ω minimizes this effect, and TI recommends keeping R1 ≤ 240 Ω and R2 ≤ 10 kΩ to balance accuracy, noise, and power loss in LM1086CT-ADJ/NOPB circuits.

Is LM1086CT-ADJ/NOPB compatible with remote voltage sensing, and how is it implemented?

Yes, LM1086CT-ADJ/NOPB supports true remote sensing: connect the R1 resistor directly to the load's positive terminal (not the regulator's VOUT pin), and return R2's ground side to the load's ground node. This compensates for IR drop in PCB traces or cables, enabling <0.1% load regulation accuracy even with 100-mΩ series resistance-critical for high-current, precision applications like FPGA core rails.

What thermal considerations apply to LM1086CT-ADJ/NOPB in TO-220 package at full 1.5-A load?

In TO-220 (NDE), LM1086CT-ADJ/NOPB has θJA = 23.0°C/W. At 1.5 A with 5-V dropout (7.5 W dissipation), junction temperature rise is ~173°C above ambient-exceeding 150°C max TJ. Therefore, a heatsink or ≥4 in² copper pour with thermal vias is mandatory. Derating to ≤1.0 A without heatsink is recommended for ambient >50°C; TI provides layout guidelines in AN-1187 for optimizing thermal performance of LM1086CT-ADJ/NOPB.