STMicroelectronics L4995J

Overview

L4995J from STMicroelectronics is an AEC-Q100 qualified automotive 5 V, 500 mA low-dropout linear voltage regulator in PowerSSO-12 package, featuring integrated watchdog timer, programmable reset delay, and enable input. It operates from 5.6 V to 31 V DC supply, delivers ±2% output voltage tolerance, maintains regulation under 40 V transients, and supports junction temperatures from –40 °C to 150 °C - deployed in engine control units and body electronics.

For engineers reviewing the L4995J datasheet, L4995J pinout, L4995J application, or L4995J equivalent, key selection considerations include its 500 mV dropout at 400 mA, 3 µA quiescent current with regulator disabled, externally programmable reset and watchdog timing via capacitors, and dual thermal shutdown and short-circuit protection for robust automotive power management.

Technical Context

The L4995J uses a p-channel MOSFET pass element enabling low-dropout operation independent of input voltage transients up to 40 V. Regulation relies on a pre-trimmed reference voltage to achieve ±2% output accuracy across temperature and load.

Its integrated supervisory functions include a reset circuit sensing output voltage down to 1 V, a watchdog input (Wi) monitoring external clock frequency, and separate capacitor-programmable timing paths for reset delay (Vcr) and watchdog period (Vcw), all coordinated through a shared enable (En) control signal.

Key Specifications

Pinout & Package

Package: PowerSSO-12 (exposed pad), thermally enhanced surface-mount package with integrated heat sink via exposed substrate tab connected to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST50T3G and TLE42754G, the L4995J uniquely integrates enable, watchdog, and capacitor-programmable reset in a thermally optimized PowerSSO-12 package - delivering functional consolidation, design flexibility, and automotive-grade reliability in a single device.

Availability

L4995J is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS sensor hubs, and infotainment systems requiring stable component supply across automotive production lifecycles.

Supply support for L4995J 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 specializing in automotive, industrial, and power management solutions, with broad portfolio of AEC-Q100 qualified products.

The L4995J belongs to ST's automotive voltage regulator family designed specifically for microprocessor power supply and system supervision in harsh-temperature, high-reliability vehicle subsystems.

FAQ

What is the minimum input voltage required for regulation at full 500 mA load?

The L4995J maintains 5 V regulation down to 5.6 V input at 500 mA load, with a maximum dropout voltage of 500 mV. At 400 mA, typical dropout is 270 mV, meaning regulation is sustained with as little as 5.27 V input - critical for cold-cranking scenarios where battery voltage dips below 6 V.

How does the watchdog timer interact with the reset output?

The watchdog monitors the Wi input frequency; if it falls below the programmable threshold (set by Vcw capacitor), the Res pin is pulled low within 4–16 ms (twol). This action is identical to a reset triggered by Vo undervoltage, providing unified fault signaling to the MCU regardless of cause.

Can the L4995J be used without connecting the Vcr and Vcw pins?

Yes - Vcr and Vcw may be left floating if reset and watchdog functions are unused. The device operates as a standard 5 V LDO with enable control. However, En must be tied to VS or driven high to activate regulation; leaving En unconnected risks undefined behavior due to leakage paths.

What thermal design guidance applies to the PowerSSO-12 package?

The exposed TAB must be soldered to a minimum 3 cm² copper area on the PCB with thermal vias (0.3 mm diameter, 1.2 mm spacing) to achieve R_thj-amb = 52 °C/W. Without this, junction temperature rise exceeds safe limits at >200 mA load - verified per ST's PowerSSO-12 thermal data in DS5053 Rev 15 Section 4.1.