STMicroelectronics L78L15ABZ

Overview

L78L15ABZ from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 15 V output at up to 100 mA, featuring thermal overload protection, short-circuit protection, and no requirement for external components. It operates across -40 °C to +125 °C junction temperature and maintains ±4% output voltage tolerance (A-grade), commonly used in local on-card regulation for noise-sensitive analog subsystems and microcontroller power domains.

For engineers reviewing the L78L15ABZ datasheet, L78L15ABZ pinout, L78L15ABZ application, or L78L15ABZ equivalent, key selection criteria include dropout voltage (1.7 V), quiescent current (6.5 mA typ. at 25 °C), supply voltage rejection (34–39 dB at 120 Hz), output noise (90 µV RMS, 10 Hz–100 kHz), and TO-92 package thermal resistance (R_thJA = 200 °C/W).

Technical Context

The L78L15ABZ employs internal current limiting and thermal shutdown circuitry, enabling robust operation without external protection components. Its architecture integrates a bandgap reference, error amplifier, and pass transistor in a monolithic silicon structure optimized for low-noise, fixed-output regulation.

It functions as a drop-in replacement for Zener diode–resistor networks, offering lower quiescent current, tighter output tolerance, and improved line/load regulation-specifically 250 mV max line regulation (VI = 20–30 V) and 75 mV max load regulation (IO = 1–40 mA) at 25 °C.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-lead plastic transistor-style housing), with standardized pinout: Pin 1 = VOUT, Pin 2 = GND, Pin 3 = VIN. The package provides R_thJA = 200 °C/W (no PCB copper heatsink) and R_thJC = 15 °C/W, enabling direct mounting on standard through-hole PCBs without auxiliary thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L15ACZ and MC78L15ABP, the L78L15ABZ offers superior supply voltage rejection (34–39 dB vs. ≤32 dB) and lower output noise (90 µV vs. ≥120 µV), making it preferred for noise-sensitive analog applications despite identical pinout and package.

Availability

L78L15ABZ is available at Aetrix Electronics and suitable for industrial sensor interfaces, embedded microcontroller power domains, automotive body control modules, and test equipment requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for L78L15ABZ 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 industrial, automotive, and consumer markets.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications requiring robustness, simplicity, and wide-temperature operation without external components.

FAQ

What is the minimum input voltage required for the L78L15ABZ to maintain regulation?

The L78L15ABZ requires a minimum input voltage of 16.7 V to sustain 15 V output under full 100 mA load, based on its 1.7 V typical dropout voltage. At lighter loads (e.g., 40 mA), regulation holds down to ~16.5 V. Input below this threshold causes output to track input minus dropout, resulting in unregulated behavior.

Can the L78L15ABZ be used with ceramic output capacitors?

Yes-the L78L15ABZ is explicitly characterized and stabilized with a 0.1 µF ceramic capacitor (CO) at the output, as specified in ST's datasheet test conditions. Unlike older regulators, it does not require ESR-based damping, making it compatible with low-ESR MLCCs for compact, high-reliability designs.

How does the L78L15ABZ handle short-circuit conditions?

Under output short-circuit, the L78L15ABZ limits current to approximately 150 mA (typical) and activates thermal shutdown if junction temperature exceeds ~165 °C. Once fault clears and temperature drops, it automatically recovers-no manual reset or latch is needed, ensuring fail-safe behavior in field-deployed systems.

Is the L78L15ABZ RoHS compliant and halogen-free?

Yes-L78L15ABZ is manufactured in accordance with EU RoHS Directive 2011/65/EU and is halogen-free per STMicroelectronics' specification. The TO-92 package uses matte tin lead finish, and material declarations confirm compliance with REACH SVHC thresholds and J-STD-609 moisture sensitivity level 1 (MSL-1).