STMicroelectronics L79L05ABD

Overview

L79L05ABD from STMicroelectronics is a three-terminal fixed negative voltage regulator delivering −5 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components, operates over −40°C to +125°C junction temperature, and achieves 41–49 dB supply voltage rejection at 120 Hz with 40 µV RMS output noise (10 Hz–100 kHz).

For engineers reviewing the L79L05ABD datasheet, L79L05ABD pinout, L79L05ABD application, or L79L05ABD equivalent, this device is selected for local on-card regulation in industrial control, embedded power rails, and analog subsystems where low-noise, stable negative bias and wide input voltage tolerance (−7 V to −20 V) are required.

Technical Context

The L79L05ABD implements a monolithic bipolar linear regulator architecture with built-in thermal shutdown and foldback current limiting. Its dropout voltage is fixed at 1.7 V, enabling operation with input as low as −6.7 V while maintaining regulated −5 V output under full 100 mA load.

It delivers ±2% output voltage accuracy over temperature and load (−4.75 V to −5.25 V at 1–40 mA, TJ = 25°C), with line regulation of ≤100 mV and load regulation of ≤30 mV-enabling direct replacement of Zener/resistor networks in noise-sensitive analog circuits.

Key Specifications

Pinout & Package

Supplied in SO-8 package with pins 2, 3, 6, and 7 internally connected to the die attach flag for enhanced thermal performance (R_thj-case = 20°C/W). Requires ≥6 cm² copper pour for full 100 mA capability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM79L05AC and MC79L05ABP, the L79L05ABD offers superior temperature range, tighter output tolerance, and significantly better thermal dissipation in SO-8-making it optimal for industrial and automotive applications demanding reliability across environmental extremes.

Availability

L79L05ABD is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and medical sensor signal chains requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for L79L05ABD 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L79L00 series belongs to ST's legacy linear regulator product line, engineered specifically for robust, low-cost, no-component-required negative voltage regulation in harsh industrial and automotive environments.

FAQ

What is the minimum input voltage required for L79L05ABD to maintain regulation?

The L79L05ABD requires a minimum input voltage of −6.7 V (−5.0 V output + 1.7 V dropout) to sustain regulation at full 100 mA load. At lighter loads (<10 mA), regulation holds down to −6.2 V. Input below −6.7 V causes output to track input minus dropout, losing regulation.

Can L79L05ABD replace a Zener diode/resistor network in existing designs?

Yes-L79L05ABD directly replaces −5 V Zener/resistor combinations, offering two orders-of-magnitude lower output impedance, 6 mA vs. >20 mA quiescent current, and 40 µV vs. >200 µV output noise. No layout changes are needed beyond adding 0.33 µF input and 0.1 µF output capacitors.

Does L79L05ABD require heat sinking for 100 mA operation?

Yes-full 100 mA continuous output requires ≥6 cm² of 2-oz copper connected to pins 2, 3, 6, and 7 (die flag) to achieve R_thj-amb ≈ 55°C/W. Without copper pour, safe continuous current drops to ~45 mA at 25°C ambient due to SO-8's 200°C/W natural thermal resistance.

What is the significance of the 'AB' suffix in L79L05ABD?

The 'AB' suffix denotes the industrial temperature grade (−40°C to +125°C junction) and ±2% output voltage tolerance. The 'D' suffix indicates SO-8 package with tape-and-reel packaging (13TR), distinguishing it from tube-packaged variants like L79L05ABU (SO-8 tube) or L79L05ABZ (TO-92).