STMicroelectronics L79L15ABD13TR

Overview

L79L15ABD13TR 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 specified for operation from -40 °C to +125 °C junction temperature, with 300 mV line regulation and 150 mV load regulation over full current range - used in local on-card regulation for noise-sensitive analog subsystems.

For engineers reviewing the L79L15ABD13TR datasheet, L79L15ABD13TR pinout, L79L15ABD13TR application, or L79L15ABD13TR equivalent, key selection criteria include guaranteed -15 V output tolerance (±5%), dropout voltage of 1.7 V, 90 µV output noise (10 Hz–100 kHz), 34–39 dB supply voltage rejection, and SO-8 package thermal resistance (R_thJA = 55 °C/W with 6 cm² copper heatsink).

Technical Context

The L79L15ABD13TR implements a monolithic PNP pass transistor architecture with built-in thermal shutdown and foldback current limiting. Its internal compensation eliminates need for external capacitors beyond standard input/output bypassing (CI = 0.33 µF, CO = 0.1 µF).

Designed for fixed negative rail generation, it operates with input voltages from -17.5 V to -30 V and maintains regulation under load currents from 1 mA to 100 mA. The SO-8 package integrates pins 2, 3, 6, and 7 to the die attach flag, reducing thermal resistance and enabling higher power dissipation when PCB copper area is used as heatsink.

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 performance. Standard SO-8 footprint per Figure 8 (DocID2511 Rev 18, p.16).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed negative voltage regulation applications.

Compared with LM7915CDT/NOPB and MC79L15ACDR2G, the L79L15ABD13TR offers superior thermal performance in SO-8, guaranteed -40 °C to +125 °C operation, tighter ±5% output tolerance, and lowest noise - making it optimal for industrial and test equipment requiring reliability and precision.

Availability

L79L15ABD13TR is available at Aetrix Electronics and suitable for industrial sensor conditioning, RS-232 transceiver power, and analog audio preamp biasing requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L79L15ABD13TR 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 robust, low-cost, fixed-voltage negative rail generation in space- and noise-constrained embedded systems.

FAQ

What is the minimum input voltage required for regulation with L79L15ABD13TR?

The absolute minimum input voltage is -17.5 V under all operating conditions, as specified in Table 6 (DocID2511 Rev 18, p.9). At full 100 mA load and 25 °C, regulation is maintained down to -16.7 V due to its 1.7 V dropout voltage. Input below -17.5 V risks violating absolute maximum ratings and may cause thermal shutdown.

Can L79L15ABD13TR be used in parallel to increase output current?

No - the L79L15ABD13TR lacks current-sharing capability and has no parallel operation guidance in its datasheet. Attempting parallel connection risks thermal runaway due to mismatched output voltages and unbalanced current distribution. For >100 mA, use an external pass transistor configured per Figure 3 (test circuit) in the datasheet.

Is the SO-8 package thermally enhanced compared to standard SO-8?

Yes - pins 2, 3, 6, and 7 are internally bonded to the die attach flag, reducing R_thJC to 20 °C/W and R_thJA to 55 °C/W (with 6 cm² PCB copper). This is explicitly documented in Note (1) of Table 1 (p.5) and distinguishes it from standard SO-8 regulators that lack this thermal frame modification.

Does L79L15ABD13TR require input and output capacitors?

Yes - the datasheet specifies CI = 0.33 µF (tantalum or aluminum electrolytic) at the input and CO = 0.1 µF (ceramic) at the output for stability. Omitting either capacitor risks oscillation or poor transient response, especially under fast load steps. These values are validated in all test circuits (Figures 3, 6, 10) and cannot be reduced without requalification.