STMicroelectronics L79L15ACD13TR

Overview

L79L15ACD13TR from STMicroelectronics is a three-terminal fixed negative linear voltage regulator delivering -15 V output at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components, operates over 0 to 125 °C junction temperature, and is used for local on-card regulation in industrial power supplies and analog signal conditioning circuits where low-noise, stable negative bias is required.

For engineers reviewing the L79L15ACD13TR datasheet, L79L15ACD13TR pinout, L79L15ACD13TR application, or L79L15ACD13TR equivalent, key selection criteria include guaranteed -15 V ±5% output accuracy across load (1–100 mA) and input (-17.5 to -30 V), dropout voltage of 1.7 V, 90 µV RMS output noise (10 Hz–100 kHz), and SO-8 package thermal performance with R_thJA = 55 °C/W (with 6 cm² PCB copper heatsink).

Technical Context

The L79L15ACD13TR implements a monolithic PNP pass transistor-based linear regulation architecture with built-in thermal overload and short-circuit foldback protection. Its internal current limit prevents destructive operation under fault conditions, while the fixed -15 V reference ensures stable output without external feedback components.

Designed for use in dual-rail analog systems and legacy industrial controllers, it replaces discrete Zener-resistor regulators-offering two orders-of-magnitude lower output impedance, reduced quiescent current (6.5 mA typ. at 25 °C), and improved supply voltage rejection (34–39 dB at 120 Hz) compared to passive solutions.

Key Specifications

Pinout & Package

Supplied in SO-8 package (ECOPACK® compliant), with pins 2, 3, 6, and 7 internally connected to the die attach flag for enhanced thermal conduction. Requires minimum 6 cm² copper area on PCB for rated 100 mA operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7915CDT/NOPB and MC7915BD2TR4G, the L79L15ACD13TR offers optimal balance of SO-8 footprint, 55 °C/W thermal resistance with PCB heatsink, and ±5% accuracy - making it ideal for cost-sensitive, medium-current industrial PCBs where board area and manufacturability are prioritized over ultra-tight tolerance or extreme temperature range.

Availability

L79L15ACD13TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, analog sensor signal conditioning, and legacy control board refurbishment requiring stable component supply, long-term lifecycle support, and RoHS-compliant SO-8 packaging.

Supply support for L79L15ACD13TR 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 industrial control, instrumentation, and legacy system upgrades where reliability and ease of use outweigh programmability.

FAQ

What is the maximum input voltage for L79L15ACD13TR?

The absolute maximum DC input voltage is -35 V, specified for -12 V to -15 V output variants. For reliable operation, ST recommends keeping input between -17.5 V and -30 V to maintain regulation margin and avoid excessive power dissipation. Exceeding -35 V risks permanent damage even with thermal protection active.

Can L79L15ACD13TR be used in parallel for higher current?

No - the L79L15ACD13TR lacks current-sharing capability and has no built-in balancing features. Parallel connection risks thermal runaway due to mismatched output voltages and unequal current distribution. For >100 mA, use a single higher-current regulator like MC7915BD2TR4G or add an external pass transistor with proper biasing.

Is an input capacitor required for stability?

Yes - ST specifies a minimum 0.33 µF ceramic or tantalum input capacitor (CI) placed close to Pin 2 (IN) to prevent oscillation and improve transient response. Omitting CI may cause instability under fast load steps or high-source-impedance input conditions, especially with long PCB traces.

Does the SO-8 package require special PCB layout for thermal performance?

Yes - Pins 2, 3, 6, and 7 are internally tied to the die attach flag. To achieve rated 100 mA output, ST mandates a minimum 6 cm² copper pour connected to these pins via multiple thermal vias. Without this, junction temperature rises rapidly, triggering thermal shutdown at ~60 mA load.