STMicroelectronics L4940D2M5-TR

Overview

L4940D2M5-TR from STMicroelectronics is a fixed 5 V, 1.5 A low-dropout linear voltage regulator in D2PAK package, featuring 500 mV typical dropout at full load, reverse polarity protection, and thermal shutdown. It serves as a primary post-regulator in battery-powered industrial controllers and portable instrumentation where stable 5 V rail and extended runtime are critical.

For engineers reviewing the L4940D2M5-TR datasheet, L4940D2M5-TR pinout, L4940D2M5-TR application, or L4940D2M5-TR equivalent, key selection criteria include dropout voltage at 1.5 A, quiescent current under light and full load, output voltage accuracy across temperature, short-circuit current limit, and thermal resistance in D2PAK.

Technical Context

The L4940D2M5-TR employs an internal antisaturation circuit and safe-area protection to sustain 1.5 A output while limiting junction temperature rise. Its architecture integrates current limiting, thermal shutdown, and reverse-polarity protection without external components.

It operates with input voltages up to 30 V and maintains regulation down to VI = VO + Vd (e.g., 5.5 V min for 5 V output), supporting wide-input industrial supplies and battery systems with variable headroom.

Key Specifications

Pinout & Package

D2PAK (TO-263) package: surface-mount, single-row 3-lead thermally enhanced outline with exposed metal pad for heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1085V50TR and TLV1117-50CDR, the L4940D2M5-TR uniquely balances 1.5 A capability, 500 mV dropout, and D2PAK thermal performance-making it optimal for high-current, low-input-voltage industrial and portable applications where both output stability and efficiency are design-critical.

Availability

L4940D2M5-TR is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, and automotive diagnostic tools requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for L4940D2M5-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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L4940 series belongs to ST's high-reliability linear regulator product line, engineered specifically for industrial and battery-powered equipment demanding robust protection, low dropout, and stable output under wide thermal and load conditions.

FAQ

What is the minimum input voltage required for regulation at 1.5 A load?

The L4940D2M5-TR requires VI ≥ VO + Vd = 5 V + 0.5 V = 5.5 V minimum for regulation at 1.5 A (typical). Absolute minimum per datasheet is 6.5 V for guaranteed 5 V output across temperature and tolerance, due to worst-case dropout of 900 mV and output tolerance of ±2%.

Does this regulator require an input bypass capacitor?

Yes - a 0.1 µF ceramic capacitor is specified at the input (CI) in all test circuits. It stabilizes the regulator under fast line transients and prevents oscillation caused by source inductance, especially critical in PCB layouts with long input traces or shared supply rails.

Can the D2PAK package be soldered using standard reflow profiles?

Yes - the D2PAK package is RoHS-compliant and qualified for standard lead-free reflow (JEDEC J-STD-020). Peak temperature must not exceed 260 °C for ≤30 seconds; the exposed thermal pad must be soldered to a large copper pour for thermal performance and mechanical reliability.

Is reverse polarity protection active during startup or only in steady state?

Reverse polarity protection is implemented via an internal series p-channel MOSFET or diode structure that blocks conduction when VIN < VOUT or reversed - it functions immediately upon connection, including during power-up, brown-out, and hot-swap events, with no delay or enable sequence required.