Texas Instruments LM140K-12/NOPB

Overview

LM140K-12/NOPB from Texas Instruments is a monolithic 3-terminal positive voltage regulator delivering fixed +12 V output at up to 1.0 A, featuring internal current limiting, thermal shutdown, and safe-area protection. It operates across −55°C to +125°C, requires only 14.5 V minimum input for regulation, and maintains ±4% output tolerance at T_j = 25°C - used in industrial power supplies and local on-card regulation to suppress noise and distribution losses.

For engineers reviewing the LM140K-12/NOPB datasheet, LM140K-12/NOPB pinout, LM140K-12/NOPB application, or LM140K-12/NOPB equivalent, key selection criteria include dropout voltage (2.0 V @ 1 A), ripple rejection (≥60 dB at 120 Hz), quiescent current stability (6 mA typ.), and TO-3 metal-can thermal performance with θ_JA = 39°C/W.

Technical Context

The LM140K-12/NOPB implements a classic series-pass transistor architecture with built-in foldback current limiting and thermal foldback that activates above 150°C junction temperature. Its output stage includes safe-area compensation to prevent second breakdown during overload or short-circuit events.

It functions as a fixed-output linear regulator without requiring external feedback components, but supports adjustable configurations via external resistors and transistors (e.g., Figure 2 and Figure 22). Input bypassing is mandatory only when located >2 inches from the supply filter capacitor; output capacitance is optional but improves transient response.

Key Specifications

Pinout & Package

LM140K-12/NOPB uses the TO-3 (NDS) metal-can package: hermetically sealed steel case with two terminals (Input and Output); the case serves as the Ground (GND) terminal. Thermal path is optimized through direct metal-to-heatsink contact.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed positive voltage regulator applications.

Compared with LM7812CT and LM140K-12, the LM140K-12/NOPB delivers superior thermal robustness (θ_JA = 39°C/W), extended temperature range (−55°C to +125°C), and P+ reliability screening - making it the preferred choice for mission-critical industrial and aerospace power rails where long-term stability and fault resilience are essential.

Availability

LM140K-12/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, test equipment, military subsystems, and legacy control systems requiring stable component supply with guaranteed long-term availability and RoHS-compliant sourcing.

Supply support for LM140K-12/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 company specializing in analog, embedded processing, and power management technologies, with decades of leadership in linear regulator design and industrial-grade IC qualification.

The LM140K series was engineered for high-reliability fixed-voltage regulation in harsh environments - targeting applications demanding thermal resilience, intrinsic fault protection, and extended temperature operation beyond commercial-grade alternatives.

FAQ

What is the maximum input voltage rating for LM140K-12/NOPB?

The absolute maximum DC input voltage for LM140K-12/NOPB is 35 V. Operation above this level risks permanent damage. For reliable regulation, the input must remain within 14.5 V to 30 V per the Electrical Characteristics table - ensuring proper line regulation and thermal margin. Exceeding 30 V may trigger internal protection but is outside specified operating conditions.

Does LM140K-12/NOPB require an output capacitor for stability?

No, LM140K-12/NOPB is internally compensated and stable without an output capacitor. However, adding a 0.1 μF ceramic capacitor directly at the output pins significantly improves transient response to load steps. This is recommended in applications with dynamic current demands, such as driving multiplexed sensor arrays or relay drivers.

What thermal management is required for LM140K-12/NOPB at 1 A load?

At 1 A output with 24 V input, LM140K-12/NOPB dissipates ~12 W. With θ_JA = 39°C/W and max T_J = 150°C, ambient must stay below ~120°C without heatsinking - which is impractical. A heatsink reducing θ_CA to ≤10°C/W (combined with θ_JC = 4°C/W) keeps junction temperature within safe limits at +70°C ambient.

Is LM140K-12/NOPB pin-compatible with standard TO-3 voltage regulators?

Yes, LM140K-12/NOPB uses the industry-standard TO-3 (NDS) mechanical outline with Input and Output pins in identical positions to LM78xx and LM340xx TO-3 variants. The metal case serves as GND, matching conventional TO-3 linear regulator pinout - enabling drop-in replacement in existing TO-3 footprints designed for fixed positive regulators.

What does the "NOPB" suffix indicate for LM140K-12/NOPB?

The "NOPB" suffix on LM140K-12/NOPB denotes lead-free (Pb-free) packaging compliant with RoHS Directive 2011/65/EU. It confirms that all terminations and internal finishes meet TI's lead-free standards, with MSL Level-1 rating and no moisture sensitivity restrictions - distinguishing it from the non-RoHS LM140K-12 variant in the same TO-3 package.