Texas Instruments LM2941CT/LF03

Overview

LM2941CT/LF03 from Texas Instruments is a 1-A adjustable low-dropout linear regulator in TO-220-5 package, delivering stable output voltage from 5 V to 20 V with typical dropout of 0.5 V at 1 A load, reverse-battery protection, and TTL/CMOS-compatible ON/OFF control - used in automotive power rails and industrial 12 V–24 V systems requiring robust input transient immunity.

For engineers reviewing the LM2941CT/LF03 datasheet, LM2941CT/LF03 pinout, LM2941CT/LF03 application, or LM2941CT/LF03 equivalent, key selection considerations include its 0–125°C operating temperature range, 30 mA quiescent current at 1 A load and 5 V VIN–VOUT differential, adjustable output via external resistors R1/R2, and integrated thermal shutdown and short-circuit current limiting.

Technical Context

The LM2941CT/LF03 implements a PNP-based LDO architecture with trimmed 1.275 V bandgap reference, enabling precise output adjustment across 5–20 V using two external resistors. Its quiescent current reduction circuit activates when VIN − VOUT exceeds ~3 V, lowering ground current to 30 mA (typ) under full load - critical for battery-powered systems.

It integrates reverse-battery protection, overvoltage shutdown (OVSD) at ~30 V, and thermal overload protection that limits junction temperature to ~155°C. The ON/OFF pin requires active pull-down to enable regulation and has defined threshold voltages (ON ≤0.8 V, OFF ≥2 V), supporting direct microcontroller GPIO interfacing without level-shifting.

Key Specifications

Pinout & Package

LM2941CT/LF03 uses the TO-220-5 (KC) plastic package with exposed tab thermally and electrically connected to GND. Pin 3 is GND; pins 2 and 4 are dedicated GND terminals for improved thermal and noise performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2941T, LM2941CT/LF03 trades extended temperature capability for lower cost and qualification in commercial-grade automotive modules; versus LT1129CS8-5, it provides full adjustability and control flexibility at the expense of fixed-output simplicity and smaller footprint.

Availability

LM2941CT/LF03 is available at Aetrix Electronics and suitable for automotive body electronics, industrial programmable logic controllers, and marine navigation systems requiring stable component supply with long lifecycle support and traceable sourcing.

Supply support for LM2941CT/LF03 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 power management ICs, with decades of automotive-grade product validation and AEC-Q100 alignment.

The LM2941 series was designed specifically for vehicular power systems requiring reverse-battery resilience, wide-input operation, and integrated protection - targeting body control, telematics, and infotainment subsystems.

FAQ

What is the maximum input voltage the LM2941CT/LF03 can withstand without damage?

The LM2941CT/LF03 has an absolute maximum input survival voltage of 45 V for ≤100 ms, per its datasheet. Continuous operation above 26 V is not recommended, as device performance is not ensured beyond that point. For automotive load dump events, this 45 V rating provides margin against transient spikes while maintaining safe operation within the 6–26 V recommended range. Always verify layout thermal design when operating near maximum ratings.

How do I calculate the external resistor values to set a specific output voltage for the LM2941CT/LF03?

Use the formula VOUT = VREF × ((R1 + R2) / R1), where VREF = 1.275 V (typ). For best accuracy and minimal temperature drift, select R1 = 1 kΩ and solve for R2 = R1 × ((VOUT / 1.275) – 1). For example, for 12 V output: R2 = 1000 × ((12 / 1.275) – 1) ≈ 8.4 kΩ. Use 1% metal-film resistors with matched tempcos; avoid bypassing R1 or R2, as that causes instability in the LM2941CT/LF03 feedback loop.

Does the LM2941CT/LF03 require an output capacitor, and what are its specifications?

Yes, the LM2941CT/LF03 requires a minimum 22 µF output capacitor with ESR between 100 mΩ and 1 Ω for loop stability. Tantalum capacitors meet this directly; X5R/X7R ceramics may be used only with a series resistor (0.1–1 Ω) to emulate required ESR. The capacitor must be placed ≤1 cm from the OUT and GND pins. Failure to meet these requirements risks oscillation or poor transient response in the LM2941CT/LF03 regulator.

Can the LM2941CT/LF03 be used in parallel to increase output current?

No, the LM2941CT/LF03 is not designed for parallel operation. Its output voltage tolerance (±3% on reference) and lack of current-sharing circuitry make paralleling unreliable and potentially unstable. To deliver >1 A, select a higher-current regulator such as the LM2941S (same family, TO-263-5, 1 A rated) or consider a switching pre-regulator stage. Attempting to parallel LM2941CT/LF03 units may cause thermal imbalance and premature failure.

What thermal considerations apply when using the LM2941CT/LF03 in a TO-220-5 package?

The LM2941CT/LF03 in TO-220-5 has RθJA = 32.1°C/W. At 1 A load with 12 V input and 5 V output, power dissipation is ~7 W - raising junction temperature by ~224°C above ambient, exceeding safe limits. Therefore, a heatsink is mandatory. Mount the tab directly to a copper pour with ≥2 cm² area and thermal vias to internal ground planes. Derate output current above 25°C ambient using PD(MAX) = (125°C − TA) / 32.1; at 70°C ambient, max continuous current drops to ~650 mA.