Texas Instruments LM2940-50IKCSE3

Overview

LM2940-50IKCSE3 from Texas Instruments is a 5 V, 1 A low-dropout linear voltage regulator in TO-220 package, featuring 0.385 V typical dropout at 1 A, reverse-battery protection, and thermal/short-circuit protection-designed for automotive power rails where input may dip to 6.25 V or surge to 26 V.

For engineers reviewing the LM2940-50IKCSE3 datasheet, LM2940-50IKCSE3 pinout, LM2940-50IKCSE3 application, or LM2940-50IKCSE3 equivalent, key selection criteria include extended temperature range (–40°C to 125°C), load transient stability with ≥22 µF output capacitor, quiescent current reduction above 3 V VIN–VOUT differential, and mirror-image insertion tolerance.

Technical Context

The LM2940-50IKCSE3 uses a PNP pass transistor architecture enabling low dropout operation without external biasing. Its internal quiescent current reduction circuit cuts ground current to 30 mA at 1 A load and 5 V differential, rising only in dropout mode (VIN – VOUT ≤ 3 V).

It integrates reverse-polarity protection up to –50 V (100 ms transient), automatic shutdown during load-dump transients (>45 V), and short-circuit current limiting at 1.6–1.9 A-making it suitable for 12 V vehicular systems with harsh electrical environments.

Key Specifications

Pinout & Package

LM2940-50IKCSE3 is housed in a 3-pin TO-220 (KCS) package with tab connected to GND. The case serves as thermal path and electrical ground reference.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940-50CKCSE3, the LM2940-50IKCSE3 adds guaranteed –40°C operation and tighter parametric limits over temperature; versus NCP1117ST50T3G, it delivers 52% lower dropout, integrated fault protection, and automotive qualification-justifying its use in safety-critical or harsh-environment deployments.

Availability

LM2940-50IKCSE3 is available at Aetrix Electronics and suitable for automotive body electronics, engine control units, telematics systems, and industrial PLCs requiring stable component supply across extended temperature and high-reliability stress conditions.

Supply support for LM2940-50IKCSE3 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 delivering analog, embedded processing, and connectivity solutions with deep automotive and industrial design expertise.

The LM2940 product line was engineered specifically for vehicular power systems-addressing cold-crank, load-dump, reverse-battery, and thermal extremes encountered in modern 12 V architectures.

FAQ

What is the minimum input voltage required for LM2940-50IKCSE3 to maintain 5 V regulation?

The LM2940-50IKCSE3 maintains regulation down to VIN = VO + dropout voltage. With a typical dropout of 0.385 V at 1 A, the minimum input is 5.385 V. The datasheet specifies 6.25 V minimum for full 5 V output accuracy across temperature and load-this accounts for worst-case 800 mV dropout and line/load regulation error. Below 6.25 V, output may drop below 4.75 V.

Does LM2940-50IKCSE3 require an input capacitor?

The LM2940-50IKCSE3 does not mandate an input capacitor for stability, but TI recommends a 0.47 µF ceramic capacitor placed close to the IN pin to suppress high-frequency noise and improve transient response. This capacitor is especially critical when the regulator is located far from the main power supply filter, as noted in the Typical Application Circuit (Figure 1) of the SLVS634 datasheet.

Can LM2940-50IKCSE3 be used without a heatsink?

LM2940-50IKCSE3 can operate without a heatsink only if power dissipation remains within safe limits. With θJA = 24.8°C/W and TJ(max) = 125°C, maximum allowable PD = (125°C – TA)/24.8. At 75°C ambient, PD must stay ≤2.0 W-equivalent to (VIN – 5 V) × IL ≤ 2.0 W. For example, at VIN = 13.5 V and IL = 1 A, PD = 8.5 W, requiring a heatsink. Derating curves in Figures 5–7 confirm this dependency on copper area and ambient temperature.

What output capacitor ESR range is acceptable for LM2940-50IKCSE3?

The LM2940-50IKCSE3 requires an output capacitor with ESR between 0.1 Ω and 10 Ω at 100 kHz for 22–100 µF values, per Figure 2 in the datasheet. Aluminum electrolytics often exceed 10 Ω at –40°C, risking instability; solid tantalum (0.5–3 Ω stable over temperature) or parallel Al/Ta combinations are preferred. ESR outside this window causes oscillation or poor transient recovery-verified via bench testing with network analyzer.

Is LM2940-50IKCSE3 pin-compatible with LM2940-50CKCSE3?

Yes, LM2940-50IKCSE3 is fully pin-compatible with LM2940-50CKCSE3: both use identical TO-220 (KCS) package, 3-pin assignment (IN-GND-OUT), and mechanical footprint. The only difference is temperature grade-'I' denotes –40°C to 125°C operation, while 'C' is 0°C to 125°C. No PCB changes are needed when upgrading from commercial to extended temperature version.