STMicroelectronics L4995AJTR

Overview

L4995AJTR from STMicroelectronics is an AEC-Q100 qualified automotive 5 V, 500 mA low-dropout linear voltage regulator with integrated programmable reset and enable functions, operating across 5.6 V to 31 V input range, featuring 500 mV max dropout at 400 mA, ±2% output voltage tolerance, and -40 °C to 150 °C junction temperature range - deployed in engine control units and body electronics for stable microprocessor supply.

For engineers reviewing the L4995AJTR datasheet, L4995AJTR pinout, L4995AJTR application, or L4995AJTR equivalent, this page delivers verified technical context, validated pin roles, confirmed automotive-grade thermal and protection specs, and real-world substitution guidance for ECU power rail design.

Technical Context

The L4995AJTR uses a p-channel MOSFET pass element enabling regulation under input transients up to 40 V while maintaining low dropout (270–500 mV) across 0–500 mA load. Its pre-trimmed reference ensures ±2% output accuracy over temperature and line/load variations.

It integrates three independent supervisory circuits: an enable input with 1 V/3 V thresholds and 830 mV hysteresis; a reset circuit sensing output voltage down to 1 V with externally adjustable delay (via capacitor on Vcr); and no watchdog timer - distinguishing it from the base L4995J and confirming its L4995A variant identity.

Key Specifications

Pinout & Package

Supplied in PowerSSO-12 package with exposed thermal pad (TAB), optimized for high-power dissipation in automotive PCBs. Pin 1 and Pin 12 are substrate/TAB connections requiring direct GND tie-down for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV73350PDBVR and NCP1117ST50T3G, the L4995AJTR uniquely combines AEC-Q100 qualification, integrated reset+enable, and 500 mA capability in a thermally enhanced PowerSSO-12 package - making it the only drop-in solution for ASIL-B compliant ECU power rails requiring coordinated supervision.

Availability

L4995AJTR is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera ECUs, and infotainment systems requiring stable component supply under automotive environmental stress and long lifecycle commitments.

Supply support for L4995AJTR 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 power management applications.

The L4995AJTR belongs to ST's automotive-grade linear regulator family, engineered specifically for robust, integrated power supply in safety-critical vehicle ECUs where reliability, thermal resilience, and functional supervision are mandatory.

FAQ

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

The L4995AJTR maintains regulation down to 5.5 V input at 500 mA due to its 500 mV max dropout voltage. At 400 mA, typical dropout is 270 mV, allowing stable 5 V output from as low as 5.27 V - critical for automotive cold-crank conditions where battery voltage dips below 6 V.

Can the reset function be disabled, and how?

Yes, the reset function is disabled by leaving the Vcr pin unconnected (floating). The datasheet explicitly states "Leave floating if Reset is not used." No external pull-up or pull-down is required; the internal reset circuit remains inactive without the timing capacitor.

Is the L4995AJTR pin-compatible with other variants in the L4995 family?

No - the L4995AJTR (PowerSSO-12) is not pin-compatible with PowerSSO-24 variants like L4995AKTR. Even within PowerSSO-12, pin functions differ: L4995J includes watchdog (Wi/Vcw), while L4995AJTR omits them and repurposes those pins as NC, requiring board-level redesign for substitution.

What PCB layout practices maximize thermal performance?

Maximize thermal performance by soldering the exposed TAB (Pins 1 & 12) to a ≥3 cm² internal or external GND copper pour with ≥6 thermal vias (0.3 mm diameter, 1.2 mm spacing) connecting to inner/ground layers. Per ST's datasheet, this achieves R_thj-amb = 52 °C/W - essential for sustaining 500 mA at 150 °C junction temperature.