STMicroelectronics L79L05ABD13TR

Overview

L79L05ABD13TR from STMicroelectronics is a three-terminal fixed negative voltage regulator delivering -5 V output at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components and is specified for operation from -40 °C to +125 °C junction temperature, with 40 µV RMS output noise (10 Hz–100 kHz) and 41–49 dB supply voltage rejection at 120 Hz - used in local on-card regulation for noise-sensitive analog and mixed-signal circuits.

For engineers reviewing the L79L05ABD13TR datasheet, L79L05ABD13TR pinout, L79L05ABD13TR application, or L79L05ABD13TR equivalent, key selection criteria include guaranteed -5 V output tolerance (±5% over full load/temperature), dropout voltage of 1.7 V, thermal overload resilience, and SO-8 package compatibility with board-level heat sinking via pins 2/3/6/7 tied to die attach flag.

Technical Context

The L79L05ABD13TR implements a monolithic PNP pass transistor-based linear regulation architecture with built-in foldback current limiting and thermal shutdown circuitry. Its internal design eliminates need for external compensation or bypass capacitors beyond minimum input (0.33 µF) and output (0.1 µF) ceramics.

It operates as a fixed-output negative regulator with stable performance across input voltages from -7 V to -20 V (for -5 V version), maintaining ≤60 mV load regulation (1–100 mA) and ≤100 mV line regulation, while dissipating power via thermally enhanced SO-8 package with R_thJA = 55 °C/W (with 6 cm² copper pour).

Key Specifications

Pinout & Package

Package: SO-8 (ECOPACK® compliant), with pins 2, 3, 6, and 7 internally connected to the die attach flag for enhanced thermal conduction to PCB copper.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative linear regulator applications.

Compared with LM79L05ACM/NOPB and MC79L05ACDR, the L79L05ABD13TR offers superior thermal performance in SO-8 due to its integrated die-flag connection, guaranteed operation down to -40 °C, and lowest output noise - making it optimal for compact, high-reliability industrial and automotive applications.

Availability

L79L05ABD13TR is available at Aetrix Electronics and suitable for industrial sensor conditioning, automotive body control modules, medical analog front-ends, and test equipment reference supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for L79L05ABD13TR 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, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for robust, low-cost, no-compromise negative voltage regulation in space- and reliability-constrained embedded systems.

FAQ

What is the minimum input voltage required for regulation with L79L05ABD13TR?

The minimum input voltage is -6.7 V, calculated as VO + V_dropout = -5 V + 1.7 V. Operation below this violates regulation specification; datasheet guarantees stable -5 V output only for VI between -7 V and -20 V across full temperature and load range.

Can L79L05ABD13TR be used in parallel to increase output current?

No - the L79L05ABD13TR lacks current-sharing capability and has no parallel operation guidance in its datasheet. Attempting parallel connection risks thermal runaway due to mismatched output voltages and unbalanced current distribution; use a single higher-current regulator instead.

Is an input capacitor mandatory for stable operation?

Yes - a minimum 0.33 µF ceramic capacitor is required at the input pin to prevent oscillation and ensure transient response stability, especially with long or inductive input traces. Omitting it may cause regulation loss or high-frequency ringing under dynamic load changes.

Does the SO-8 package require special PCB layout considerations?

Yes - pins 2, 3, 6, and 7 must be connected to a large, low-thermal-resistance copper pour (≥6 cm² recommended) to achieve the specified R_thJA = 55 °C/W. Isolating these pins or using minimal copper will degrade thermal performance and risk premature thermal shutdown at >50 mA loads.