STMicroelectronics L79L12ACUTR

Overview

L79L12ACUTR from STMicroelectronics is a three-terminal fixed negative voltage regulator delivering -12 V output at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components and is used for local on-card regulation in industrial control, sensor signal conditioning, and analog front-end power domains where low-noise, stable negative bias is critical.

For engineers reviewing the L79L12ACUTR datasheet, L79L12ACUTR pinout, L79L12ACUTR application, or L79L12ACUTR equivalent, this page provides verified electrical characteristics, TO-92 package details, thermal performance data, and validated alternative parts for design-in and BOM continuity planning.

Technical Context

The L79L12ACUTR operates as a monolithic linear regulator with fixed -12 V output, designed for input voltages between -14.5 V and -27 V (typical operating range). Its internal architecture integrates thermal overload protection and short-circuit current limiting without external circuitry.

It delivers 100 mA continuous output current with a dropout voltage of 1.7 V, output voltage tolerance of ±5% (AC grade), and supply voltage rejection of 37–42 dB at 120 Hz. Output noise is 80 µV RMS (10 Hz–100 kHz), supporting low-noise analog subsystems.

Key Specifications

Pinout & Package

Package: TO-92 (3-lead plastic transistor outline), lead material: matte tin, RoHS-compliant ECOPACK® grade. Designed for through-hole mounting with standard PCB footprint per Figure 4 in DocID2511 Rev 18.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7912ACZ and MC79L12ACPRPG, the L79L12ACUTR offers superior supply voltage rejection (37–42 dB) and lower output noise (80 µV), making it preferred for precision analog and noise-sensitive applications despite identical output voltage and package.

Availability

L79L12ACUTR is available at Aetrix Electronics and suitable for industrial sensor interfaces, RS-232 transceiver biasing, and analog audio preamp power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L79L12ACUTR 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 cost-effective, robust local regulation in space-constrained and thermally demanding applications where simplicity and reliability outweigh switching efficiency.

FAQ

What is the maximum input voltage for L79L12ACUTR?

The absolute maximum DC input voltage is -35 V when VO = -12 V to -15 V, per Table 1 in DocID2511 Rev 18. For reliable operation, ST recommends keeping VI within -14.5 V to -27 V, ensuring 1.7 V dropout margin and staying within thermal limits at 100 mA load.

Does L79L12ACUTR require input and output capacitors?

Yes: a minimum 0.33 µF ceramic or tantalum capacitor is required at the input, and a minimum 0.1 µF ceramic capacitor at the output. These stabilize regulation and prevent oscillation, especially under transient load conditions, as specified in the test circuits of Tables 5 and 6.

Can L79L12ACUTR be used in surface-mount designs?

No - L79L12ACUTR is packaged exclusively in TO-92 (through-hole). ST offers the same -12 V AC-grade regulator in SOT-89 (L79L12ACZ) and SO-8 (L79L12ACD13TR) for surface-mount applications, but the "UTR" suffix denotes TO-92 tape-and-reel packaging.

What is the thermal resistance of L79L12ACUTR in TO-92 package?

In TO-92, RthJA (junction-to-ambient) is 200 °C/W (max) with standard PCB layout, and RthJC (junction-to-case) is 15 °C/W (max), per Table 2. With 6 cm² copper pour acting as heatsink, RthJA improves to ~115 °C/W, enabling full 100 mA output at ambient ≤50°C.