STMicroelectronics L78L08ACZ

Overview

L78L08ACZ from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 8 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 an input voltage range of 10.5–23 V, and maintains ±4% output voltage tolerance (A grade) over 0–125 °C junction temperature. It is used for local on-card regulation in industrial control modules, sensor signal conditioning circuits, and low-power microcontroller power rails.

For engineers reviewing the L78L08ACZ datasheet, L78L08ACZ pinout, L78L08ACZ application, or L78L08ACZ equivalent, this device serves as a drop-in replacement for Zener-diode/resistor regulators-offering lower quiescent current (6 mA typ.), reduced output noise (60 µV), and improved line/load regulation (125 mV / 40 mV) in space-constrained PCB designs.

Technical Context

The L78L08ACZ employs a monolithic bipolar architecture with built-in thermal shutdown and foldback current limiting, enabling robust operation without external protection circuitry. Its dropout voltage is 1.7 V at 40 mA, allowing stable regulation even with marginal input headroom.

It achieves supply voltage rejection of 37–45 dB (120 Hz, 12–23 V input) and load regulation of ≤40 mV across 1–40 mA output current, making it suitable for noise-sensitive analog front-ends and mixed-signal subsystems where ripple suppression and output stability are critical.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-pin, vertical mounting), with standardized pinout: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The package uses epoxy-molded plastic construction and is RoHS-compliant per ECOPACK2 specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L08ACZ and MC78L08ACP, the L78L08ACZ provides superior output accuracy (±4% vs. ±5%), lower noise (60 µV vs. ≥75 µV), and extended temperature support (0–125 °C), making it the preferred choice for industrial and medical applications demanding long-term DC stability.

Availability

L78L08ACZ is available at Aetrix Electronics and suitable for industrial sensor nodes, programmable logic controller (PLC) I/O modules, medical diagnostic handsets, and microcontroller-based edge devices requiring stable component supply and long-lifecycle support.

Supply support for L78L08ACZ 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 belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local regulation in space- and power-constrained embedded systems - emphasizing simplicity, reliability, and wide operating temperature support.

FAQ

What is the minimum input voltage required for L78L08ACZ to regulate at full 100 mA load?

The L78L08ACZ requires a minimum input voltage of 9.7 V to maintain 8 V output under 100 mA load, based on its 1.7 V dropout voltage specification at 40 mA and confirmed derating behavior up to 100 mA. At 100 mA, dropout increases slightly; 10.5 V input is recommended for guaranteed regulation across temperature and process variation.

Can L78L08ACZ be used with ceramic output capacitors?

Yes - the L78L08ACZ is stable with ceramic output capacitors as low as 0.1 µF, per datasheet test circuit requirements. Unlike older 78Lxx regulators, it does not require ESR-based damping, enabling smaller, more reliable, and lower-ESR ceramic solutions instead of tantalum or aluminum electrolytics.

Does L78L08ACZ support operation at -40 °C?

No - the 'AC' suffix denotes the commercial temperature grade (0 to +125 °C junction), not industrial (-40 to +125 °C). For -40 °C operation, the L78L08ABZ variant (AB grade) must be selected, which is explicitly rated across -40 to +125 °C and validated for startup and regulation at cold extremes.

How does thermal performance differ between TO-92 and SO-8 packages for L78L08AC?

In TO-92, R_thJA is 200 °C/W (no heatsink), limiting continuous 100 mA operation to <25 °C ambient unless PCB copper area is added. In SO-8, R_thJA drops to 55 °C/W with 6 cm² copper pour, enabling full 100 mA output up to 85 °C ambient - making SO-8 preferable for thermally demanding applications.