STMicroelectronics L4995K

Overview

L4995K from STMicroelectronics is an AEC-Q100 qualified automotive 5 V, 500 mA low-dropout linear voltage regulator in PowerSSO-24 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, sustains 40 V transient immunity, and supports junction temperatures from –40 °C to 150 °C - deployed in engine control units and body electronics for stable microprocessor power.

For engineers reviewing the L4995K datasheet, L4995K pinout, L4995K application, or L4995K equivalent, this page provides verified technical context, validated pin functions, confirmed automotive-grade specifications, and real-world use cases for ECU power sequencing, reset supervision, and watchdog-enabled safety-critical subsystems.

Technical Context

The L4995K implements a p-channel MOSFET pass element enabling dropout voltage as low as 270 mV at 400 mA while maintaining regulation across input transients up to 40 V. Its internal pre-trimmed reference ensures 5.00 V output with ±2% tolerance over full temperature and load range.

It integrates three supervisory functions: a voltage-sensing reset circuit triggered when Vo drops below 8% of nominal (i.e., ~4.6 V), a capacitor-programmable reset delay (12–73 ms with 47 nF), and a watchdog timer with 20–80 ms period (47 nF) monitoring external clock pulses on Wi pin - all independently controllable via dedicated pins.

Key Specifications

Pinout & Package

Package: PowerSSO-24 (exposed thermal pad), RoHS-compliant, ECOPACK® certified, designed for high-power dissipation in automotive PCBs with thermal vias and copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP380LSN33T2G and TLV70733PDQNR, the L4995K uniquely combines 5 V/500 mA regulation, AEC-Q100 Grade 0 qualification, capacitor-programmable reset delay, and watchdog timer in one PowerSSO-24 package - eliminating four discrete components in ECU designs while meeting ASIL-B functional safety prerequisites.

Availability

L4995K is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS sensors, and infotainment head units requiring stable component supply, long-lifecycle support, and automotive-grade reliability.

Supply support for L4995K 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 ICs, with over 30 years of automotive qualification expertise and AEC-Q100-compliant manufacturing.

The L4995K belongs to ST's automotive voltage regulator family designed specifically for microprocessor power supply and functional safety supervision in harsh-temperature, high-reliability vehicle systems.

FAQ

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

The L4995K maintains 5 V regulation down to a minimum input voltage of 5.27 V at 400 mA load (270 mV dropout). At 500 mA, typical dropout rises to 500 mV, requiring ≥5.5 V input. This enables operation during automotive cold-crank events where battery voltage dips to 6.5 V - well above the 5.5 V minimum.

How does the watchdog timer interact with the reset output?

The watchdog timer monitors pulses on the Wi pin; if the input frequency falls below threshold, it triggers the Res pin low within twol (4–16 ms). This action is identical to a voltage-based reset event - both assert the same open-drain Res signal, allowing unified fault handling by the MCU without separate interrupt lines.

Can the L4995K be used without connecting the Vos (sense) pin?

Yes - Vos is optional. When left unconnected, the device regulates Vo directly at the output pin. Using Vos enables remote sensing to compensate for PCB trace voltage drop between the regulator and load, improving regulation accuracy by up to 25 mV under 500 mA load conditions.

What thermal design practices ensure reliable operation at 150 °C junction temperature?

To sustain 150 °C junction temperature, the PowerSSO-24 TAB must be soldered to ≥3 cm² of 2-oz copper with ≥9 thermal vias (0.3 mm diameter, 1.2 mm spacing) connecting to inner ground planes. Per ST's thermal model (Figure 38), this achieves R_thj-amb = 38 °C/W, limiting temperature rise to 114 °C at 2.7 W dissipation (500 mA × 5.4 V dropout).