STMicroelectronics L78L05ABZ-TR

Overview

L78L05ABZ-TR 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 overload protection, and short-circuit protection. It requires no external components, operates across −40 °C to +125 °C junction temperature, and maintains ±4% output voltage tolerance (A-grade) with 2 V dropout voltage-ideal for local regulation in microcontroller power domains and sensor interface circuits.

For engineers reviewing the L78L05ABZ-TR datasheet, L78L05ABZ-TR pinout, L78L05ABZ-TR application, or L78L05ABZ-TR equivalent, this device serves as a robust, drop-in replacement for legacy 78L05 regulators in space-constrained industrial control modules, low-power IoT edge nodes, and automotive body electronics where stable 5 V rail integrity and thermal resilience are critical.

Technical Context

The L78L05ABZ-TR implements a monolithic bipolar linear regulator architecture with built-in foldback current limiting and thermal shutdown circuitry, ensuring fault tolerance without external sensing components. Its internal bandgap reference and error amplifier maintain output regulation under varying load (1–100 mA) and input voltage (7–20 V) conditions.

Designed for direct integration into PCBs with minimal layout overhead, it supports TO-92 package mounting with through-hole soldering and exhibits 40 µV RMS output noise (10 Hz–100 kHz) and 41–49 dB supply voltage rejection at 120 Hz-enabling clean power delivery to noise-sensitive analog front-ends and digital logic.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-pin, through-hole), with lead material compliant to RoHS and ECOPACK2 environmental standards. Package dimensions: 4.95 mm × 3.94 mm × 15.49 mm (L×W×H), weight ≈ 0.3 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L05ACP and TL750L05ACZ, the L78L05ABZ-TR delivers superior noise performance and wider temperature qualification at the expense of slightly higher dropout-making it optimal for retrofitting existing through-hole systems requiring high signal integrity.

Availability

L78L05ABZ-TR is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, and low-power MCU subsystems requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for L78L05ABZ-TR 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 consumer markets since 1987.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications demanding ruggedness, simplicity, and long-term availability-especially in industrial automation and automotive body electronics.

FAQ

What is the minimum input voltage required for stable 5 V output?

The L78L05ABZ-TR requires a minimum input voltage of 7 V to maintain regulation at full 100 mA load, based on its 2 V dropout specification. At lighter loads (e.g., 10 mA), input can drop to ~6.5 V while retaining output accuracy within ±4%. Input below 6.3 V risks dropout and unregulated output.

Can this regulator be used in parallel to increase output current?

No-L78L05ABZ-TR lacks current-sharing capability and should not be paralleled. Its internal current limiting is not matched between units, leading to uneven load distribution and potential thermal runaway. For >100 mA, use an external pass transistor configured per Figure 14 in DS0424 or select a higher-current regulator like L7805CV.

Is a heat sink required for continuous 100 mA operation?

In TO-92 package, continuous 100 mA operation at ambient temperatures above 50 °C requires a PCB copper pour ≥6 cm² connected to Pin 2 (GND) as a thermal pad. Without heatsinking, power dissipation (e.g., 12 V input → 5 V @ 100 mA = 0.7 W) raises junction temperature beyond 125 °C, triggering thermal shutdown.

Does the L78L05ABZ-TR support reverse-input protection?

No-this device has no internal reverse-voltage protection. Applying reverse polarity (>−0.3 V) to Pin 1 (Input) relative to Pin 2 (GND) may cause irreversible damage due to parasitic diode conduction. An external series Schottky diode (e.g., BAT54) is required in applications with risk of incorrect battery insertion or supply reversal.