STMicroelectronics L78L15ACZ-AP

Overview

L78L15ACZ-AP from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 15 V output at up to 100 mA, with ±4% output voltage tolerance (A-grade), thermal overload protection, short-circuit protection, and no external components required. It serves as a local on-card regulator for noise-sensitive analog and digital subsystems in industrial control modules, sensor signal conditioning circuits, and low-power microcontroller power rails.

For engineers reviewing the L78L15ACZ-AP datasheet, L78L15ACZ-AP pinout, L78L15ACZ-AP application, or L78L15ACZ-AP equivalent, key selection criteria include dropout voltage (1.7 V), quiescent current (6.5 mA at 25 °C), output noise (90 µV RMS, 10 Hz–100 kHz), and supply voltage rejection (34–39 dB at 120 Hz), all critical for stable low-noise biasing in embedded systems.

Technical Context

The L78L15ACZ-AP employs internal current limiting and thermal shutdown circuitry, enabling robust operation without external protection components. Its architecture integrates a bandgap reference, error amplifier, pass transistor, and protection logic in a monolithic silicon structure optimized for fixed-output regulation.

It operates across an input voltage range of 17.5 V to 30 V (for 15 V output), maintains regulation over junction temperatures from 0 °C to 125 °C, and achieves 1.7 V dropout-enabling use with modest input headroom in battery-backed or post-regulated supplies.

Key Specifications

Pinout & Package

Package: TO-92 (Z = TO-92 variant per ST ordering code convention; "Z-AP" denotes tape-and-reel packaging in TO-92). This through-hole package features low-cost assembly and adequate thermal performance for ≤100 mA loads with minimal PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L15ACZ and MC78L15ACP, the L78L15ACZ-AP delivers tighter output tolerance (±4% vs. ±5%), lower output noise (90 µV vs. ≥120 µV), and superior supply rejection-making it the optimal choice for noise-sensitive analog and precision measurement applications where regulation accuracy and spectral purity are design-critical.

Availability

L78L15ACZ-AP is available at Aetrix Electronics and suitable for industrial sensor nodes, microcontroller peripheral power, legacy equipment refurbishment, and analog test equipment requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for L78L15ACZ-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 industrial, automotive, and consumer markets.

The L78L series was developed as a cost-effective, robust replacement for Zener-resistor regulators in low-current fixed-voltage applications-emphasizing simplicity, reliability, and compatibility with legacy through-hole assembly processes.

FAQ

What is the minimum input voltage required for stable 15 V output?

The L78L15ACZ-AP requires a minimum input voltage of 16.7 V to maintain regulation under full 100 mA load, based on its 1.7 V dropout specification. At lighter loads (e.g., 40 mA), input can be as low as 16.7 V; for guaranteed operation across temperature and tolerance, ST specifies 17.5 V as the lower limit in datasheet Table 19.

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

No-L78L15ACZ-AP is not designed for parallel operation. Its internal architecture lacks current-sharing circuitry, and mismatched output voltages between units would cause one device to dominate conduction, risking thermal runaway. For >100 mA, use a higher-current regulator (e.g., L7815CV) or external pass transistor configuration per ST Application Note AN105.

Is a heat sink required for continuous 100 mA operation?

A heat sink is not required for continuous 100 mA operation at ambient temperatures ≤50 °C with ≥1 cm² of 2-oz copper on the PCB connected to Pin 2 (GND). The TO-92 package's R_thJA is 200 °C/W; at 100 mA and 17.5 V input, power dissipation is ~0.25 W, resulting in ~50 °C rise-within the 125 °C max junction limit.

What capacitor values are recommended for input and output stability?

ST specifies a minimum 0.33 µF ceramic or tantalum capacitor on VIN and 0.1 µF ceramic on VOUT, placed as close as possible to the device pins. These values ensure stability across all operating conditions; larger values (e.g., 10 µF electrolytic + 0.1 µF ceramic) improve transient response but are not required for basic regulation.