STMicroelectronics L78L05ACUTR

Overview

L78L05ACUTR from STMicroelectronics is a 5 V, 100 mA fixed-output linear voltage regulator in SOT-89 package, featuring thermal overload and short-circuit protection, ±4% output voltage tolerance at 25 °C, 2 V dropout voltage, and 40 µV RMS output noise (10 Hz–100 kHz). It serves as a local on-card regulator for noise-sensitive analog and digital subsystems in industrial control modules.

For engineers reviewing the L78L05ACUTR datasheet, L78L05ACUTR pinout, L78L05ACUTR application, or L78L05ACUTR equivalent, key selection criteria include guaranteed 5 V ±4% regulation across 0–125 °C junction temperature, 100 mA continuous output with internal current limiting, low quiescent current (6 mA typ. at 25 °C), and compatibility with minimal external components (0.33 µF input / 0.1 µF output capacitors).

Technical Context

The L78L05ACUTR implements a monolithic three-terminal positive regulator architecture with built-in current limiting, thermal shutdown, and safe-area protection-enabling robust operation without external compensation. Its internal bandgap reference and error amplifier maintain stable 5 V output under varying load (1–100 mA) and line (7–20 V input) conditions.

Designed for local regulation, it replaces discrete Zener/resistor networks with lower quiescent current, reduced output noise, and tighter voltage tolerance. The SOT-89 package provides enhanced thermal performance over TO-92 (R_thJA = 55 °C/W with 6 cm² PCB copper), supporting reliable operation up to 125 °C junction temperature.

Key Specifications

Pinout & Package

SOT-89 package: 3-pin surface-mount device with exposed die attach flag (pins 2, 3, and 7 internally connected to flag for improved thermal conduction). Requires ≥6 cm² PCB copper area for optimal power dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L05ACZ/NOPB, L78L05ACUTR offers superior thermal performance in SOT-89 and tighter ±4% tolerance; versus MCP1700T-5002E/TT, it supports higher input voltage and robust fault protection at the cost of higher quiescent current-making it the preferred choice for industrial 5 V rail generation.

Availability

L78L05ACUTR is available at Aetrix Electronics and suitable for industrial sensor interfaces, embedded microcontroller power domains, legacy system upgrades, and low-power analog signal chains requiring stable component supply across multi-year production cycles.

Supply support for L78L05ACUTR 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 targets cost-sensitive, reliability-critical local regulation in industrial controls and legacy-compatible designs-emphasizing ruggedness, minimal external components, and wide-temperature operation (0–125 °C).

FAQ

What is the maximum input voltage for L78L05ACUTR?

The absolute maximum DC input voltage is 30 V for output voltages ≤9 V, per STMicroelectronics DS0424 Rev 30. For L78L05ACUTR (5 V output), the rated maximum is 30 V, but recommended operating range is 7–20 V to ensure proper regulation, thermal margin, and dropout compliance. Exceeding 20 V increases power dissipation and junction temperature significantly.

Does L78L05ACUTR require input and output capacitors?

Yes-STMicroelectronics specifies a 0.33 µF ceramic capacitor at the input pin and a 0.1 µF ceramic capacitor at the output pin for stability and transient response. These values are validated in the datasheet test circuits (Table 4, DS0424 Rev 30) and omission may cause oscillation or poor load step recovery, especially with long PCB traces or high ESR capacitors.

Can L78L05ACUTR be used in automotive applications?

L78L05ACUTR is qualified for industrial temperature range (0–125 °C junction), not AEC-Q100 automotive grade. While it operates within ambient temperatures found in some under-hood or cabin environments, it lacks automotive-specific qualification (e.g., PPAP, stress testing, failure mode analysis) and is not recommended for safety-critical or ASIL-rated systems without additional validation and derating.

How does the SOT-89 package improve thermal performance over TO-92?

The SOT-89 package features an internally connected die attach flag (pins 2, 3, 7) that lowers thermal resistance: R_thJA is 55 °C/W (vs. 200 °C/W for TO-92) when mounted on 6 cm² copper PCB area. This allows L78L05ACUTR to sustain 100 mA output continuously at 125 °C ambient-whereas TO-92 would thermally limit well below that current without external heatsinking.