STMicroelectronics L79L05ACZ-AP

Overview

L79L05ACZ-AP 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 designed for local on-card regulation in noise-sensitive analog and mixed-signal circuits, such as sensor signal conditioning stages and low-power microcontroller power rails.

For engineers reviewing the L79L05ACZ-AP datasheet, L79L05ACZ-AP pinout, L79L05ACZ-AP application, or L79L05ACZ-AP equivalent, key selection criteria include guaranteed ±5% output tolerance at -5 V, 1.7 V dropout voltage, 40 µV RMS output noise (10 Hz–100 kHz), and TO-92 package thermal resistance of 200 °C/W (junction-to-ambient, with 6 cm² copper heatsink).

Technical Context

The L79L05ACZ-AP implements a monolithic PNP pass transistor architecture with built-in thermal overload and short-circuit protection circuitry. Its output voltage is internally trimmed to -5.0 V ±5% at 25 °C and maintains regulation across input voltages from -7 V to -20 V and load currents from 1 mA to 100 mA.

It achieves 49 dB supply voltage rejection at 120 Hz under 40 mA load and exhibits only 30 mV load regulation (1–40 mA) and 100 mV line regulation (-8 to -20 V), enabling stable operation in noisy industrial power environments without external filtering.

Key Specifications

Pinout & Package

Package: TO-92 (plastic, 3-lead, through-hole). Pin configuration verified per Figure 2 (top view) and Table 7 in ST DocID2511 Rev 18: leads are arranged with emitter (E), base (B), collector (C) - but electrically configured as Input, Ground, Output terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM79L05ACZ and MC79L05ACPRPG, the L79L05ACZ-AP offers superior noise performance (40 µV vs. 60/≥75 µV), higher SVR (49 dB), and explicitly documented thermal shutdown-making it the preferred choice for precision analog and industrial-grade designs.

Availability

L79L05ACZ-AP is available at Aetrix Electronics and suitable for industrial sensor interfaces, low-power microcontroller bias rails, RS-232 transceiver support, and analog front-end power delivery requiring stable component supply and long-term lifecycle continuity.

Supply support for L79L05ACZ-AP 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 power management applications.

The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for robust, low-cost, fixed-output negative voltage regulation in space-constrained and thermally demanding embedded systems.

FAQ

What is the maximum input voltage for L79L05ACZ-AP?

The absolute maximum DC input voltage is -30 V when the output is regulated at -5 V. This rating is defined in Table 1 of ST DocID2511 Rev 18 and applies only with adequate heatsinking; exceeding -20 V input in normal operation increases power dissipation and thermal stress significantly.

Does L79L05ACZ-AP require input and output capacitors?

Yes - ST specifies minimum 0.33 µF ceramic input capacitor (CI) and 0.1 µF ceramic output capacitor (CO) for stability and transient response, as shown in Figure 3 test circuit. Omitting either capacitor risks oscillation or poor load-step recovery, especially under 100 mA load conditions.

Can L79L05ACZ-AP be used in parallel for higher current?

No - the L79L05ACZ-AP lacks current-sharing features and has no built-in balancing circuitry. Parallel connection causes unequal current distribution due to output voltage tolerance mismatch (±5%), risking thermal runaway in one device; external ballast resistors are not recommended per ST application guidance.

What is the operating junction temperature range for L79L05ACZ-AP?

The L79L05ACZ-AP (AC grade) is rated for 0 °C to +125 °C junction temperature, as confirmed in Table 1 "Maximum ratings" and Table 3 "Electrical characteristics" of the official datasheet. Operation below 0 °C is not characterized and may result in degraded regulation or startup failure.