STMicroelectronics L4941BDT-TR

Overview

L4941BDT-TR from STMicroelectronics is a 5V fixed-output, very low-dropout (LDO) linear regulator in DPAK package, delivering up to 1A output current with 450mV typical dropout at full load, 4–8mA quiescent current at 5mA load, and integrated thermal shutdown, short-circuit, reverse-polarity, and safe-area protection. It is designed for battery-powered industrial and consumer systems where efficiency and reliability under low VIN–VOUT margin are critical.

For engineers reviewing the L4941BDT-TR datasheet, L4941BDT-TR pinout, L4941BDT-TR application, or L4941BDT-TR equivalent, key selection criteria include dropout voltage at 1A, quiescent current vs. load, output voltage accuracy (±4%), thermal resistance (RthJA = 100°C/W), and DPAK package compatibility with board-level thermal management.

Technical Context

The L4941BDT-TR employs an internal antisaturation circuit and current-limiting architecture to maintain regulation during transient overloads while preventing thermal runaway. Its feedback loop is internally compensated for stability with ≥22µF ceramic or electrolytic output capacitance.

It operates across –40°C to +150°C junction temperature, supports input voltages from 6V to 16V (absolute max 30V), and delivers 5V ±4% output with line regulation of 5–20mV and load regulation of 5–20mV - enabling stable rail generation in distributed power architectures with minimal headroom.

Key Specifications

Pinout & Package

The L4941BDT-TR is housed in a surface-mount DPAK (TO-252) package with exposed drain pad for thermal conduction. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 5V LDO regulator applications.

Compared with LD1117S50TR and TLV1117-50CDR, the L4941BDT-TR uniquely combines 1A capability with true reverse-polarity tolerance and DPAK thermal performance - making it the only option among the three qualified for unguarded battery inputs and sustained high-current operation in compact industrial PCBs.

Availability

L4941BDT-TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart home hub controllers, and automotive body control modules requiring stable component supply with consistent DPAK packaging and traceable STMicroelectronics sourcing.

Supply support for L4941BDT-TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The L4941 belongs to ST's legacy linear regulator product line, engineered specifically for high-reliability, low-headroom DC/DC conversion in cost-sensitive industrial and battery-powered equipment where protection features outweigh programmability needs.

FAQ

What is the minimum input voltage required for 5V output at 1A load?

The L4941BDT-TR requires a minimum input voltage of 5.45V (5.0V + 450mV dropout) to maintain regulation at 1A. At ambient temperature and with adequate PCB copper, it sustains output down to VI = 5.2V for brief transients, but continuous operation below 5.45V risks dropout and output collapse.

Does the L4941BDT-TR require an external capacitor on the output pin?

Yes - ST specifies a minimum 22µF output capacitor with ESR ≤100 mΩ for stability and transient response. Ceramic capacitors are acceptable if derated for DC bias; aluminum or tantalum types must meet ESR and ripple current ratings per the datasheet's Figure 6 and Table 3.

Can the L4941BDT-TR be used in automotive applications?

It is not AEC-Q100 qualified and lacks automotive-specific qualification, but has been deployed in non-safety-critical automotive body electronics (e.g., interior lighting, HVAC controls) where ambient temperature stays within –40°C to +125°C and input transients are clamped externally. ST explicitly disclaims use in safety-critical or engine-bay locations.

How does the thermal shutdown behave during repeated fault events?

Thermal shutdown activates at ~150°C junction temperature and holds output off until T_J drops below ~135°C (hysteresis ≈15°C). During repeated short-circuit faults, this results in duty-cycled operation - typically 1–3 seconds on, 5–10 seconds off - which prevents permanent damage but requires system-level fault logging to avoid undetected latch-up.