STMicroelectronics L4995AKTR

Overview

L4995AKTR from STMicroelectronics is an AEC-Q100 qualified automotive 5 V, 500 mA low-dropout linear voltage regulator in PowerSSO-24 package, featuring integrated programmable reset, watchdog timer, 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 - designed for microprocessor power supply in engine control units (ECUs).

For engineers reviewing the L4995AKTR datasheet, L4995AKTR pinout, L4995AKTR application, or L4995AKTR equivalent, this device requires attention to its externally programmable reset (Vcr), watchdog timing (Vcw, Wi), enable logic thresholds (VEn_high = 3 V, VEn_low = 1 V), and thermal derating in PowerSSO-24 with Rthj-amb = 38 °K/W.

Technical Context

The L4995AKTR implements a p-channel MOS pass element enabling dropout as low as 500 mV at 400 mA while maintaining regulation across wide input transients up to 40 V. Its internal pre-trimmed reference ensures ±2% output accuracy over temperature and load, and its reset circuit monitors output voltage down to 1 V with programmable delay via external capacitor on Vcr.

Watchdog functionality is implemented through Wi input frequency monitoring and Vcw-based timing adjustment, with configurable high/low thresholds (44–50% and 10–16% of Vo_ref) and 20–80 ms period range. Enable logic uses hysteresis (830 mV) and supports shutdown of regulator, reset, and watchdog simultaneously.

Key Specifications

Pinout & Package

Package: PowerSSO-24 (exposed pad), thermally enhanced surface-mount package with 24 terminals and integrated heatsink pad (TAB connected to GND). Designed for high-power dissipation in constrained automotive PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP380LSN33T2G and TLV70733PDQNR, the L4995AKTR uniquely combines 5 V/500 mA regulation, AEC-Q100 Grade 0 rating, integrated watchdog+reset, and programmability - making it the sole fit for ASIL-B-compliant powertrain ECUs without supplemental ICs.

Availability

L4995AKTR is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera ECUs, and transmission control units requiring stable component supply across automotive production lifecycles.

Supply support for L4995AKTR 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 broad portfolio certified to AEC-Q100 and ISO 26262.

The L4995 family targets automotive microprocessor power management, integrating regulation, supervision, and protection in single-package solutions for ECU simplification and functional safety compliance.

FAQ

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

The L4995AKTR maintains 5 V output regulation down to 5.6 V input at 500 mA load, based on its 500 mV dropout specification. At lower loads, regulation is sustained even below 5.6 V - e.g., 5.1 V input supports 5 V output at 100 mA - but 5.6 V is the guaranteed minimum for full-rated current per datasheet Section 2.3.

How is the reset delay time calculated using the external capacitor on Vcr?

Reset delay (Trd) scales linearly with capacitor value on Vcr: Trd ≈ 0.28 × Ctr (nF) milliseconds. For example, a 47 nF capacitor yields 12–73 ms delay (min/typ/max per Table 6), determined by internal charge/discharge currents (Idr/Icr = 8–30 µA). No resistor is required - only capacitor-to-GND connection.

Can the watchdog function operate independently of the enable input?

No - the watchdog circuit is fully gated by the En input. When En is low, both regulator output and watchdog monitoring are disabled. The Wi input remains monitored only when En is high; no watchdog activity occurs in shutdown mode, preventing false resets during power-down sequences.

What PCB layout practices are critical for thermal performance in PowerSSO-24?

Optimal thermal performance requires soldering the exposed TAB (Pins 1 & 12) to a minimum 3 cm² copper pour on inner or outer layer, connected via ≥6 thermal vias (0.3 mm diameter, 1.2 mm spacing) to internal GND planes. Per Section 4.2, this achieves Rthj-amb = 38 °K/W; reducing copper area increases junction temperature significantly under 500 mA load.