Texas Instruments LM2941T/LF03/NOPB

Overview

LM2941T/LF03/NOPB from Texas Instruments is a 1-A adjustable low-dropout linear regulator with 0.5 V typical dropout at 1 A, 5 V to 20 V output range set by external resistors, and reverse-battery protection - used in automotive power rails where input may drop to 6 V and transient surges exceed 30 V.

For engineers reviewing the LM2941T/LF03/NOPB datasheet, LM2941T/LF03/NOPB pinout, LM2941T/LF03/NOPB application, or LM2941T/LF03/NOPB equivalent, key selection criteria include dropout voltage under full load, ON/OFF control threshold compatibility with TTL/CMOS logic, thermal resistance of TO-220 package (32.1°C/W), quiescent current reduction above 3 V VIN–VOUT differential, and reverse-polarity survival down to −30 V DC.

Technical Context

The LM2941T/LF03/NOPB implements a PNP pass transistor architecture enabling true low-dropout operation with 0.5 V typical dropout at 1 A across −40°C to +125°C. Its internal bandgap reference (1.275 V typ) feeds an error amplifier controlling the pass element, while separate ON/OFF logic disables output when the pin exceeds 2 V.

It integrates reverse-battery protection that clamps input transients to −30 V DC and shuts down during load-dump events exceeding 30 V. Thermal shutdown activates at ~155°C junction temperature, and short-circuit current limiting holds peak output at 1.6–1.9 A without latch-off.

Key Specifications

Pinout & Package

LM2941T/LF03/NOPB uses the TO-220 (KC) 5-pin plastic package with exposed tab thermally and electrically connected to GND. Pin 1 = ADJ, Pin 2 = ON/OFF, Pin 3 = GND, Pin 4 = IN, Pin 5 = OUT. The tab must be soldered to a large copper pour tied to GND for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2941CT/NOPB, LM2941T/LF03/NOPB adds −40°C capability for cold-crank operation, while TPS7A4700RGWR trades ruggedness for noise performance - making LM2941T/LF03/NOPB the sole choice when reverse-battery survival, wide temperature range, and integrated ON/OFF control are mandatory.

Availability

LM2941T/LF03/NOPB is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, off-highway telematics, and marine navigation systems requiring stable component supply across extended temperature and harsh electrical environments.

Supply support for LM2941T/LF03/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 delivering analog, embedded processing, and connectivity solutions with emphasis on automotive, industrial, and power management applications.

LM2941T/LF03/NOPB belongs to TI's automotive-grade LDO family designed specifically for vehicular power systems requiring reverse-battery tolerance, load-dump immunity, and extended temperature operation without external protection components.

FAQ

What is the minimum input voltage required for LM2941T/LF03/NOPB to regulate a 5 V output?

The LM2941T/LF03/NOPB requires a minimum input voltage of 5.5 V to maintain regulation at 5 V output, based on its 0.5 V typical dropout voltage at 1 A load. At light loads (<100 mA), dropout drops to 110 mV, allowing regulation from as low as 5.11 V. Input below 6 V risks instability per recommended operating conditions.

Does LM2941T/LF03/NOPB require an external capacitor on the ADJ pin?

No, the LM2941T/LF03/NOPB does not require an external capacitor on the ADJ pin. The ADJ pin draws only ≤100 nA bias current and is intended solely for connection to the R1–R2 feedback divider. Adding capacitance here would destabilize the control loop and is explicitly discouraged in the datasheet.

Can LM2941T/LF03/NOPB be used with ceramic output capacitors?

Yes, LM2941T/LF03/NOPB can use X5R/X7R ceramic output capacitors provided a 0.1 Ω to 1 Ω series resistor is added to emulate the required 100 mΩ–1 Ω ESR. Pure ceramic caps without series resistance risk oscillation due to insufficient phase margin; tantalum or aluminum polymer caps meeting ESR specs are plug-and-play alternatives.

What thermal derating applies to LM2941T/LF03/NOPB in a TO-220 package at 85°C ambient?

With RθJA = 32.1°C/W and TJ(max) = 125°C, LM2941T/LF03/NOPB must limit power dissipation to PD(max) = (125 − 85)/32.1 ≈ 1.25 W. At 12 V output and 1 A load, this corresponds to a maximum input of ~13.25 V - beyond which thermal shutdown will activate unless heatsinking is added.

Is the ON/OFF pin of LM2941T/LF03/NOPB internally pulled to any voltage?

No, the ON/OFF pin of LM2941T/LF03/NOPB has no internal pull-up or pull-down resistor. It must be actively terminated - either tied directly to GND for always-on operation or driven by a microcontroller GPIO. Leaving it floating risks undefined output state and potential malfunction during power-up or ESD events.