Texas Instruments LM2940C-12 MWC

Overview

LM2940C-12 MWC from Texas Instruments is a 12 V, 1 A low-dropout linear regulator in TO-220 package, featuring 0.5 V typical dropout at full load, reverse-battery protection, and internal short-circuit/thermal shutdown. It delivers stable output for automotive post-regulation and industrial instrumentation where input voltage ranges from 13.6 V to 26 V.

For engineers reviewing the LM2940C-12 MWC datasheet, LM2940C-12 MWC pinout, LM2940C-12 MWC application, or LM2940C-12 MWC equivalent, key selection criteria include dropout voltage at 1 A, quiescent current under 5 V differential, output capacitor ESR stability requirements (100 mΩ–1 Ω), and thermal performance in TO-220 without heatsink up to 125°C ambient.

Technical Context

The LM2940C-12 MWC uses a PNP pass transistor architecture enabling low dropout and inherent reverse-polarity protection. Its quiescent current reduction circuit activates when VIN − VOUT exceeds ~3 V, lowering ground current to 30 mA at 1 A load and 5 V differential - critical for battery-powered systems.

It integrates overvoltage shutdown (typically 30 V), thermal shutdown (150°C junction limit), and current limiting (~1.6–1.9 A). Unlike standard LDOs, it lacks enable or UVLO; regulation begins when VIN > VOUT + 1 V, with optimal dynamic response above VIN ≥ VOUT + 2 V.

Key Specifications

Pinout & Package

LM2940C-12 MWC is housed in a TO-220 (NDE) package measuring 14.986 mm × 10.16 mm, with pin 2 (GND) electrically connected to the metal tab for thermal and electrical grounding.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940C-12 MWC, LM2940T-12/NOPB offers identical performance with updated environmental compliance, while MC7812CD2TR4G trades protection and efficiency for lower cost and broader legacy availability - making the former a drop-in upgrade and the latter a fallback for non-automotive use cases.

Availability

LM2940C-12 MWC is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC I/O power, medical patient monitor PSUs, and test & measurement front-end designs requiring stable component supply across extended temperature and transient-voltage conditions.

Supply support for LM2940C-12 MWC 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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and high-reliability ICs for industrial, automotive, and aerospace markets.

The LM2940 product line was designed specifically for automotive and industrial applications demanding robustness against reverse polarity, load dump, and thermal stress - delivering 1 A output with integrated protection in standard packages.

FAQ

What is the minimum input voltage required for stable 12 V output from the LM2940C-12 MWC?

The LM2940C-12 MWC requires a minimum input voltage of 13.6 V to maintain regulation at full 1 A load, based on its 0.5 V typical dropout voltage. At lighter loads (<100 mA), dropout drops to 110 mV, allowing stable operation down to ~12.11 V input. Operation below VOUT + 1 V (13 V) results in unregulated tracking behavior.

Does the LM2940C-12 MWC require an external output capacitor, and what are its critical specifications?

Yes, the LM2940C-12 MWC requires a minimum 22 µF output capacitor with ESR between 100 mΩ and 1 Ω for stability across temperature. Aluminum electrolytic or solid tantalum types are acceptable; hybrid configurations (e.g., 75% Al + 25% Ta) improve low-temperature ESR performance. The capacitor must be placed adjacent to the OUT pin.

How does the quiescent current of the LM2940C-12 MWC behave under varying input-output differentials?

The LM2940C-12 MWC features an active quiescent current reduction circuit that lowers ground current to 30 mA when VIN − VOUT exceeds ~3 V (e.g., 17 V input at 12 V output). In dropout mode (VIN − VOUT ≤ 3 V), quiescent current rises to 45–60 mA. This behavior improves standby efficiency in battery-powered automotive modules.

Can the LM2940C-12 MWC survive reverse battery connection, and what are its limits?

Yes, the LM2940C-12 MWC includes integrated reverse-battery protection and withstands −30 V DC indefinitely and −75 V transients (≤100 ms) without damage. This eliminates the need for external series diodes in automotive applications and ensures robustness during service or jump-start scenarios.

What thermal considerations apply when using the LM2940C-12 MWC in a TO-220 package without a heatsink?

In still air with no heatsink, the TO-220 package has RθJA = 23.3°C/W. At 125°C maximum ambient temperature and 12 V output, maximum continuous power dissipation is ~1.7 W - corresponding to ~1.4 A at 1.2 V dropout (VIN = 13.2 V). For sustained 1 A operation above 85°C ambient, a heatsink is strongly recommended to prevent thermal shutdown.