STMicroelectronics L78L05ACD13TR

Overview

L78L05ACD13TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 5 V output at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components, supports input voltages up to 30 V (for 5 V output), and exhibits ±4% output voltage tolerance (A-grade) over 0–125 °C junction temperature. It is used for local on-card regulation in microcontroller power rails, sensor interface supplies, and low-power industrial control modules.

For engineers reviewing the L78L05ACD13TR datasheet, L78L05ACD13TR pinout, L78L05ACD13TR application, or L78L05ACD13TR equivalent, key selection criteria include dropout voltage (2 V), quiescent current (6 mA typ. at 25 °C), output noise (40 µV RMS, 10 Hz–100 kHz), supply voltage rejection (41–49 dB at 120 Hz), and thermal resistance (R_thJA = 55 °C/W for SO-8 with 6 cm² copper heatsink).

Technical Context

The L78L05ACD13TR implements a monolithic bipolar linear regulator architecture with built-in foldback current limiting and thermal overload protection-no external compensation or feedback network required. Its internal structure integrates a reference, error amplifier, pass transistor, and protection circuitry into a single silicon die.

It operates as a fixed-output, low-dropout-adjacent regulator optimized for stability with minimal capacitance: 0.33 µF input and 0.1 µF output ceramic capacitors suffice. The SO-8 package features pins 2, 3, 6, and 7 internally connected to the die attach flag for enhanced thermal performance when mounted on copper heatsink areas.

Key Specifications

Pinout & Package

Supplied in SO-8 package (ECOPACK® compliant), with pins 2, 3, 6, and 7 internally bonded to the die attach flag for improved thermal conduction to PCB copper heatsink areas. External dimensions match standard SO-8; no mechanical modification required.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with LM78L05ACZ/NOPB, L78L05ACD13TR offers superior thermal management in SO-8 and tighter initial tolerance; versus MCP1700-5002E/TO, it trades ultra-low I_Q for robustness, simplicity, and direct drop-in replacement capability in legacy 78L-style circuits.

Availability

L78L05ACD13TR is available at Aetrix Electronics and suitable for industrial sensor nodes, microcontroller core supplies, RS-232 interface circuits, and IoT edge device bias rails requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for L78L05ACD13TR 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 analog, MCU, power, and sensing solutions for automotive, industrial, and consumer markets.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, reliability-critical applications requiring simple, robust, no-compensation fixed-voltage regulation in space-constrained industrial and embedded systems.

FAQ

What is the maximum allowable input voltage for L78L05ACD13TR?

The absolute maximum DC input voltage is 30 V when regulating 5 V output, as specified in Table 1 of DS0424 Rev 30. Operation above this risks permanent damage due to junction breakdown. For reliable long-term use, ST recommends limiting VI to ≤24 V to maintain adequate power dissipation margin and thermal safety.

Can L78L05ACD13TR be used with ceramic output capacitors?

Yes-ST explicitly qualifies 0.1 µF ceramic capacitors for output stabilization (per Table 4 test conditions). Unlike older 78xx regulators, the L78L series is internally compensated and stable with low-ESR ceramics, eliminating the need for tantalum or aluminum electrolytic capacitors.

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

Yes-pins 2, 3, 6, and 7 are internally connected to the die attach flag. To achieve the rated R_thJA = 55 °C/W, these pins must be soldered to a minimum 6 cm² copper area on the PCB layer, preferably using multiple thermal vias to inner ground planes.

How does the ±4% output tolerance ('A' grade) compare to the ±8% ('C' grade) version?

The 'A' grade (L78L05A) guarantees VO between 4.8 V and 5.2 V at 25 °C, while the 'C' grade (L78L05C) allows 4.6–5.4 V. This tighter tolerance ensures compatibility with 5 V logic families having narrow VIH/VIL margins and improves ADC reference accuracy in precision measurement systems.