STMicroelectronics L4979MD013TR

Overview

L4979MD013TR from STMicroelectronics is an AEC-Q100 qualified automotive low-dropout linear voltage regulator with integrated reset and watchdog functions. It delivers a precise 5.0 V ±2% output at up to 150 mA, operates from 5.6 V to 31 V input, achieves <400 mV dropout at full load, and features programmable reset delay (via external capacitor on Vcr) and watchdog timeout (via external capacitor on Vcw). It serves as a system power supervisor in engine control units and body electronics.

For engineers reviewing the L4979MD013TR datasheet, L4979MD013TR pinout, L4979MD013TR application, or L4979MD013TR equivalent, key selection criteria include its automotive temperature range (−40 °C to +150 °C), 6 µA quiescent current in enable-low mode, internal thermal shutdown, and SO-20 package with multiple ground pins for thermal management.

Technical Context

The device integrates a p-channel MOSFET pass element enabling low dropout (<400 mV at 150 mA) and high line/load regulation (±25 mV). Its reset circuit monitors Vo down to 1 V and triggers within 2 µs when Vo falls below 4 V, while the watchdog responds to missing pulses on Wi using a sawtooth waveform generated across Ctw by controlled charge/discharge currents (Icwd = 1.0–4.5 µA).

Reset delay time (trd) is set by an external capacitor on Vcr and scaled via a 512-cycle oscillator; watchdog period (Twop) is similarly capacitor-programmable (e.g., 25–90 ms with 47 nF). Both functions operate independently of regulator enable state, and all protections-including short-circuit current limiting (150–500 mA) and thermal shutdown (Tj = 150–190 °C)-are fully integrated.

Key Specifications

Pinout & Package

Package: SO-20, ECOPACK® RoHS-compliant surface-mount package with 8 ground pins (pins 2, 4, 5, 6, 15, 16, 17, 18) thermally optimized for PCB heat spreading.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV70733PDRVR and MAX6715AATA+T, L4979MD013TR uniquely combines 5 V regulation, AEC-Q100 Grade 0 qualification, programmable reset *and* watchdog, and SO-20 thermal robustness-making it the sole option for compact, safety-aware automotive supervisors requiring dual hardware monitoring.

Availability

L4979MD013TR 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 across automotive production lifecycles.

Supply support for L4979MD013TR 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 microcontrollers, power management ICs, and automotive-grade analog devices.

L4979MD013TR belongs to ST's automotive LDO supervisor product line, engineered specifically for functional safety-critical power monitoring in engine, chassis, and driver assistance systems.

FAQ

What is the maximum input voltage the L4979MD013TR can withstand?

The absolute maximum DC supply voltage is 40 V, though normal operating range is specified from 5.6 V to 31 V. This 40 V rating allows survival during automotive load-dump transients without damage, provided external input protection (e.g., TVS diode) is used per ISO 7637-2 recommendations.

How does the watchdog function interact with the enable pin?

The watchdog remains fully operational even when EN is low-only the voltage regulator output is disabled. The WI input continues monitoring pulses, and if missed, RES will still assert low. This enables continuous MCU health checking during system sleep modes where regulated power is not needed but supervision must persist.

Can the reset threshold be adjusted externally?

No-the reset threshold (Vo_th) is factory-trimmed to 6–10% below the nominal 5.0 V output and is not user-adjustable. However, the reset *delay time* (trd) is fully programmable via external capacitor on Vcr, allowing design flexibility in how long the system waits before asserting reset after undervoltage detection.

What thermal performance can be expected in a standard SO-20 layout?

With a 6 cm² copper heatsink area on FR4 PCB, the SO-20 package achieves Rth(j-amb) of ~50–68 °C/W. At 150 mA load and 13.5 V input, power dissipation is ~1.3 W; this yields ~100 °C junction rise above ambient-well within the 150 °C thermal shutdown threshold and supporting reliable operation in under-hood environments.