STMicroelectronics L79L05ACZ

Overview

L79L05ACZ from STMicroelectronics is a fixed -5 V negative linear voltage regulator in TO-92 package, delivering up to 100 mA output current with ±5% output voltage tolerance, thermal overload and short-circuit protection, and no external components required. It serves as a local on-card regulation solution for noise-sensitive analog and mixed-signal circuits in industrial control and embedded power subsystems.

For engineers reviewing the L79L05ACZ datasheet, L79L05ACZ pinout, L79L05ACZ application, or L79L05ACZ equivalent, key selection criteria include guaranteed -5 V output accuracy over temperature, dropout voltage of 1.7 V, low 40 µV RMS output noise (10 Hz–100 kHz), and compatibility with standard TO-92 PCB footprints and heat-sinking practices.

Technical Context

The L79L05ACZ implements a monolithic PNP pass transistor architecture with internal current limiting and thermal shutdown circuitry, enabling robust operation without external protection components. Its design targets low-noise, low-quiescent-current (-5 V) regulation where input-to-output differential is ≥1.7 V and load current remains ≤100 mA.

It operates across 0 °C to +125 °C junction temperature range with specified line regulation (≤100 mV over VI = -8 V to -20 V) and load regulation (≤30 mV over IO = 1–40 mA), making it suitable for stable biasing of op-amps, sensors, and logic interfaces in space-constrained designs.

Key Specifications

Pinout & Package

Package: TO-92 (plastic, 3-lead, through-hole). Standard outline per ST DocID2511 Rev 18 Section 5.1; mechanical dimensions: A = 4.32–4.95 mm, D = 4.45–4.95 mm, E = 3.30–3.94 mm, L = 12.70–15.49 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM79L05ACZ and MC79L05ACPR, the L79L05ACZ offers superior noise performance (40 µV vs. 100 µV) and supply rejection (49 dB vs. 35 dB), making it optimal for precision analog supply rails-though it lacks extended temperature support and has slightly lower current margin than MC79L05ACPR.

Availability

L79L05ACZ is available at Aetrix Electronics and suitable for industrial sensor conditioning, RS-232 interface power, and embedded analog peripheral supply requiring stable component supply, long-term lifecycle continuity, and RoHS-compliant TO-92 packaging.

Supply support for L79L05ACZ 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 silicon solutions for automotive, industrial, and consumer markets with emphasis on energy efficiency and reliability.

The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local negative voltage regulation in space-constrained PCB layouts where simplicity, thermal resilience, and noise performance are prioritized over programmability or ultra-low IQ.

FAQ

What is the minimum input voltage required for stable -5 V output from L79L05ACZ?

The L79L05ACZ requires a minimum input-to-output differential of 1.7 V to maintain regulation. For a nominal -5 V output, the input must be ≤ -6.7 V under full 100 mA load. At lighter loads (e.g., 40 mA), regulation holds down to -6.5 V input, per datasheet Table 3 dropout characterization.

Can L79L05ACZ be used in parallel to increase output current?

No-L79L05ACZ is not designed for parallel operation. Its output voltage tolerance (±5%) and lack of current-sharing features mean mismatched units will cause one device to dominate conduction, risking thermal runaway. For >100 mA, use a higher-current regulator (e.g., L7905) or external pass transistor configuration per ST application notes.

Is a heat sink required for continuous 100 mA operation in TO-92 package?

Yes-under continuous 100 mA load at ambient temperatures above 50 °C, TO-92 thermal resistance (R_thJA = 200 °C/W) causes junction temperature rise exceeding 125 °C unless PCB copper area ≥6 cm² is used as heatsink. Derate output current or add thermal relief pads if ambient exceeds 40 °C without board-level heatsinking.

What capacitor values are mandatory for stable operation of L79L05ACZ?

ST specifies 0.33 µF tantalum or aluminum electrolytic on the input (VIN) and 0.1 µF ceramic on the output (VOUT) for stability across all operating conditions. Omitting either capacitor risks oscillation or poor transient response; X7R dielectric is recommended for the 0.1 µF output cap due to stable capacitance vs. DC bias.