STMicroelectronics L78L05ACZ-AP

Overview

L78L05ACZ-AP 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 for basic operation and is rated for 0 to 125 °C junction temperature with ±4% output tolerance (A grade). It serves as a low-cost, robust local regulation solution in microcontroller power rails, sensor interfaces, and industrial control modules.

For engineers reviewing the L78L05ACZ-AP datasheet, L78L05ACZ-AP pinout, L78L05ACZ-AP application, or L78L05ACZ-AP equivalent, key selection criteria include its 2 V dropout voltage, 40 µV RMS output noise (10 Hz–100 kHz), 41–49 dB supply voltage rejection at 120 Hz, 6 mA quiescent current at 25 °C, and TO-92 package thermal resistance of 200 °C/W (junction-to-ambient).

Technical Context

This device implements a monolithic silicon-based linear regulation architecture with built-in foldback current limiting and thermal overload protection. Its internal circuitry ensures stable 5 V output across input voltages from 7 V to 20 V under load currents from 1 mA to 100 mA, with line regulation ≤150 mV and load regulation ≤30 mV over specified conditions.

The regulator operates without external capacitors for stability but recommends 0.33 µF input and 0.1 µF output ceramic capacitors per ST's test circuits. Its SO-8 variant uses internally bonded pins 2/3/6/7 to the die attach flag for enhanced thermal performance, though L78L05ACZ-AP specifically uses TO-92 packaging with standard three-pin configuration (Input, Ground, Output).

Key Specifications

Pinout & Package

Package: TO-92 (plastic, 3-lead, through-hole). Standard pinout viewed from flat side with leads down: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L05ACP and LM78L05ACZ, L78L05ACZ-AP offers the lowest output noise (40 µV) and tightest initial tolerance (±4%) among TO-92 5 V regulators, making it optimal for noise-sensitive analog and mixed-signal applications where precision and stability are design-critical.

Availability

L78L05ACZ-AP is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller power rails, IoT edge node peripherals, and legacy serial communication modules requiring stable component supply and long-term manufacturability.

Supply support for L78L05ACZ-AP 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, microcontroller, power, and sensor solutions for automotive, industrial, and consumer markets.

L78L05ACZ-AP belongs to the L78L series of positive voltage regulators, engineered for cost-effective, robust local regulation in space-constrained and thermally demanding environments-especially where simplicity, reliability, and wide operating temperature range are essential.

FAQ

What is the maximum input voltage for L78L05ACZ-AP?

The absolute maximum DC input voltage is 30 V when the output is 5 V, per Table 1 of DS0424 Rev 30. However, recommended operating input is 7–20 V to ensure proper regulation, thermal safety, and specified electrical performance including line regulation ≤150 mV.

Does L78L05ACZ-AP require input and output capacitors?

While functional without external capacitors, ST specifies 0.33 µF ceramic at the input and 0.1 µF ceramic at the output (per test circuits in DS0424) to ensure stability, transient response, and noise suppression. Omitting them may cause oscillation or degraded ripple rejection.

Can L78L05ACZ-AP be used in automotive applications?

L78L05ACZ-AP is qualified for 0 to 125 °C junction temperature (AC grade), meeting under-hood ambient requirements in many non-safety-critical automotive subsystems. However, it lacks AEC-Q100 qualification and is not recommended for airbag, braking, or ADAS systems requiring automotive-grade reliability certification.

How does thermal performance differ between TO-92 and SO-8 packages of L78L05?

TO-92 has R_thJA = 200 °C/W (max, no heatsink), limiting continuous 100 mA operation to low ambient temperatures. SO-8 variant reduces R_thJA to 55 °C/W with 6 cm² copper pour, enabling higher sustained current and better thermal headroom-though L78L05ACZ-AP is TO-92 only.