STMicroelectronics L4993MD

Overview

L4993MD from STMicroelectronics is an AEC-Q100 qualified automotive-grade 5 V low-dropout linear voltage regulator with integrated reset and watchdog functions, delivering up to 150 mA output current, 400 mV dropout at full load, ±2% output voltage tolerance, and operation across 5.6 V–31 V input range - used to power microcontroller core logic and peripheral rails in engine control units.

For engineers reviewing the L4993MD datasheet, L4993MD pinout, L4993MD application, or L4993MD equivalent, key selection considerations include its SO-20 package thermal performance (R_th-jamb = 51 °C/W), programmable reset delay via external capacitor on Vcr, watchdog timer adjustability on Vcw, and enable-controlled watchdog activation - all critical for functional safety-compliant automotive subsystems.

Technical Context

The L4993MD integrates a p-channel MOSFET pass element enabling regulation down to 400 mV dropout while maintaining stability under 40 V transient surges. Its internal precision reference is pre-trimmed to ensure ±2% output accuracy over −40°C to +150°C junction temperature.

Reset functionality monitors output voltage down to 1 V threshold with user-programmable delay (via Vcr capacitor); watchdog circuitry responds to low-frequency Wi input pulses and is activated only when WEn is high - both features are independently configurable and latch-free.

Key Specifications

Pinout & Package

Package: SO-20 (16+2+2 lead count), thermally enhanced with four dedicated GND pins (pins 4, 5, 15, 16) connected to PCB heat spreader for R_th-jamb = 51 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive voltage regulator with supervisory functions applications.

Compared with TLF35584QKV and MAX25210ATPA/VY+, the L4993MD offers superior thermal performance in SO-20, AEC-Q100 Grade 0 certification, and fully programmable reset/watchdog timing - making it optimal for space-constrained, high-temperature ECU designs where discrete timing control is required.

Availability

L4993MD is available at Aetrix Electronics and suitable for engine control units, body control modules, transmission control units, and ADAS camera ECUs requiring stable component supply across extended automotive temperature ranges and long production lifecycles.

Supply support for L4993MD 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The L4993MD belongs to ST's automotive power management portfolio, engineered specifically to meet stringent AEC-Q100 reliability requirements and simplify functional safety design in engine, chassis, and ADAS electronic control units.

FAQ

What is the minimum input voltage required for regulation?

The L4993MD maintains regulation down to 5.6 V input across its full operating temperature range. Below this, output voltage drops proportionally with input; the device remains functional but does not regulate. This threshold ensures compatibility with degraded 12 V battery conditions during vehicle cranking.

Can the watchdog function be disabled without affecting reset functionality?

Yes - asserting WEn low disables only the watchdog circuit while preserving full reset functionality (Vcr-based delay, Vo-threshold detection, and Res output). Quiescent current drops to 79 µA typical, enabling low-power sleep modes without compromising brown-out protection.

How is thermal performance affected by PCB copper area in SO-20 package?

With the recommended 6 cm² FR4 copper area (2 mm thickness, 35 µm Cu), R_th-jamb is 51 °C/W. Reducing copper area to 2 cm² increases thermal resistance to ~75 °C/W, limiting max continuous output current at 125°C ambient from 150 mA to ~90 mA - PCB layout must match datasheet thermal guidelines.

Is the Res output compatible with 3.3 V logic interfaces?

Yes - Res is an open-drain output referenced to Vos (5 V), so it can be pulled up to 3.3 V using an external resistor. The internal 12–50 kΩ pull-up to Vos ensures reliable low-state drive; external pull-up to 3.3 V allows direct interfacing with 3.3 V microcontrollers without level-shifting.