STMicroelectronics L4993D

Overview

L4993D from STMicroelectronics is an AEC-Q100 qualified automotive 5 V low-dropout voltage regulator with integrated reset and watchdog functions, delivering up to 150 mA output current, 400 mV dropout at 150 mA, ±2% output voltage tolerance, and operation across 5.6 V–31 V input range. It supplies microcontroller power rails in engine control units (ECUs) and body electronics where transient immunity and functional safety monitoring are required.

For engineers reviewing the L4993D datasheet, L4993D pinout, L4993D application, or L4993D equivalent, key selection criteria include its programmable reset delay (via external capacitor on Vcr), watchdog timer adjustability (via Vcw), enable-controlled watchdog activation, thermal shutdown at 150°C, and SO-8 package compatibility with automotive PCB layout constraints.

Technical Context

The L4993D integrates a p-channel MOSFET pass element enabling regulation down to 400 mV dropout at full load while maintaining stable 5 V output across wide input transients (up to 40 V). Its internal pre-trimmed reference ensures ±2% output accuracy over −40°C to +150°C junction temperature.

Reset functionality monitors output voltage down to 1 V threshold with programmable delay (100–1000 µs reaction time); watchdog logic responds to low-frequency Wi input pulses, with timing set by external capacitor on Vcw and enabled via WEn pin-both features support ISO 26262 ASIL-B–capable system supervision.

Key Specifications

Pinout & Package

Package: SO-8 (small outline, 8-pin, surface-mount, 1.27 mm pitch). Thermal pad on exposed underside connected to Gnd pins (pins 2, 5, 6, 15, 16 in SO-20 variant; only pins 2 and 5 used in SO-8).

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP380LSN33T2G and TPS7B6950QDCYRQ1, the L4993D uniquely combines 5 V regulation, AEC-Q100 qualification, programmable reset, and configurable watchdog in a single SO-8 package-reducing BOM count and PCB area while meeting ASIL-B system-level monitoring requirements without external components.

Availability

L4993D is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera ECUs, and electric power steering controllers requiring stable component supply with automotive-grade reliability and long-term lifecycle support.

Supply support for L4993D 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 L4993D belongs to ST's automotive power management IC portfolio, engineered specifically for functional-safety-aware power domains in engine, chassis, and driver assistance systems-emphasizing integration, transient robustness, and qualification to AEC-Q100 Grade 0.

FAQ

What is the minimum input voltage required for regulation at full 150 mA load?

The L4993D maintains 5 V regulation down to a minimum input of 5.4 V at 150 mA load, based on its 400 mV maximum dropout voltage specification. Below this, output voltage drops linearly with input; operation below 5.6 V is outside guaranteed specifications per datasheet Section 2.3.

Can the reset output (Res) drive a microcontroller's NRST pin directly?

Yes-the Res pin is an open-drain output rated for 5 V and can sink ≥10 mA. It requires an external pull-up resistor (typically 4.7–10 kΩ) to Vo or Vcc. When asserted, it pulls low to <0.4 V, compatible with standard CMOS NRST inputs; no level-shifting is needed.

How does the watchdog timer respond if the Wi input stops toggling?

If Wi remains static (no rising edge) beyond the programmed Twop window (e.g., >50 ms with 47 nF), the internal watchdog times out and forces Res low. This reset persists until Wi resumes valid toggling or Vs is cycled-ensuring fail-safe behavior during MCU lockup or clock failure.

Is the SO-8 package thermally adequate for 150 mA continuous operation in a sealed automotive enclosure?

With recommended PCB copper area (2 cm²), the SO-8 achieves R_th-jamb = 130°C/W. At 150 mA and 13.5 V input, power dissipation is ~1.275 W, resulting in ~166°C junction rise-exceeding 150°C limit. Use thermal vias to inner ground planes or consider SO-20 (R_th-jamb = 51°C/W) for continuous full-load operation in confined spaces.