STMicroelectronics L79L15ACZ

Overview

L79L15ACZ from STMicroelectronics is a three-terminal fixed negative voltage regulator delivering -15 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components and is designed for local on-card regulation in industrial power supplies, analog sensor interfaces, and legacy TTL/CMOS logic systems requiring stable negative rail generation.

For engineers reviewing the L79L15ACZ datasheet, L79L15ACZ pinout, L79L15ACZ application, or L79L15ACZ equivalent, this device is selected for low-noise, ±5% output accuracy (-14.25 V to -15.75 V), 1.7 V dropout, and SO-8 package compatibility in space-constrained PCBs with copper heat-sink areas.

Technical Context

The L79L15ACZ implements a monolithic PNP pass transistor architecture with built-in thermal shutdown and foldback current limiting. Its regulation loop maintains output stability across input voltages from -17.5 V to -30 V and load currents from 1 mA to 100 mA.

It achieves 34–39 dB supply voltage rejection at 120 Hz and delivers 90 µV RMS output noise (10 Hz–100 kHz), making it suitable for noise-sensitive analog circuitry where Zener-based solutions fail to meet ripple and quiescent current requirements.

Key Specifications

Pinout & Package

Package: SO-8 (modified internal frame with pins 2, 3, 6, and 7 electrically connected to die attach flag for enhanced thermal performance; compatible with standard SO-8 footprints).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7915CD and MC79L15ACDR2G, the L79L15ACZ uniquely combines ±5% accuracy, SO-8 thermal flag integration, and 55 °C/W thermal resistance with PCB heatsinking-making it optimal for compact, thermally constrained industrial SMT applications.

Availability

L79L15ACZ is available at Aetrix Electronics and suitable for industrial power supplies, analog sensor interfaces, legacy logic support, and test equipment requiring stable component supply, long-life continuity, and RoHS-compliant sourcing.

Supply support for L79L15ACZ 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 cost-sensitive, space-constrained applications requiring robust fixed-voltage negative regulation without external components.

FAQ

What is the minimum input voltage required for L79L15ACZ to maintain regulation?

The L79L15ACZ requires a minimum input voltage of -16.7 V (i.e., |V_IN| ≥ |V_OUT| + V_DROP = 15 V + 1.7 V) to sustain regulation at full 100 mA load. At lighter loads, it can operate down to -17.5 V per absolute maximum ratings, but output voltage may deviate beyond ±5% if input falls below -16.7 V under full load.

Can L79L15ACZ be used in parallel to increase output current?

No-L79L15ACZ is not designed for parallel operation. Its internal current limiting and thermal shutdown are per-device, and mismatched output voltages between units would cause unequal current sharing and potential thermal runaway. For >100 mA, use an external pass transistor configured per ST's AN1057 application note.

Is the SO-8 package of L79L15ACZ pin-compatible with standard SO-8 linear regulators?

Yes, the external dimensions match standard SO-8, but pins 2, 3, 6, and 7 are internally bonded to the die attach flag for thermal conduction-not signal pins. This differs from generic SO-8 regulators; PCB layout must allocate copper area under these pins for heatsinking, and no signals should be routed to them.

Does L79L15ACZ require input and output capacitors, and what values are recommended?

Yes-ST specifies a minimum 0.33 µF ceramic capacitor at VIN and 0.1 µF ceramic capacitor at VOUT, placed as close as possible to the device. These stabilize the control loop, suppress input ripple, and improve transient response. Larger values (e.g., 1 µF) are acceptable but do not improve regulation beyond datasheet performance.