STMicroelectronics L78L08ABZ-AP

Overview

L78L08ABZ-AP 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 shutdown, and short-circuit protection. It requires no external components, operates over −40 °C to +125 °C junction temperature, and is commonly used for local on-card regulation in industrial control modules and sensor interface power rails.

For engineers reviewing the L78L08ABZ-AP datasheet, L78L08ABZ-AP pinout, L78L08ABZ-AP application, or L78L08ABZ-AP equivalent, this device serves as a robust, drop-in replacement for Zener-diode/resistor regulators-offering lower quiescent current (6 mA typ.), improved line/load regulation (±125 mV max), and reduced output noise (60 µV RMS).

Technical Context

The L78L08ABZ-AP employs a monolithic bipolar silicon design with built-in thermal overload and short-circuit protection circuitry. Its internal current-limiting mechanism activates before destructive conditions occur, enabling reliable operation without external foldback or sensing components.

It functions as a fixed-output series pass regulator with a dropout voltage of 1.7 V (at 40 mA), supply voltage rejection of 37–45 dB (120 Hz), and load regulation of ≤40 mV across 1–40 mA output current-making it suitable for low-noise, space-constrained point-of-load applications where input headroom is limited.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-pin, straight lead configuration). Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The TO-92 outline conforms to ST's mechanical drawing 0102782_E with dimensions A = 4.32–4.95 mm, D = 4.45–4.95 mm, and E = 3.30–3.94 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L08ACZ/NOPB and MC78L08ACP, the L78L08ABZ-AP provides superior temperature resilience (−40 °C to +125 °C), tighter output accuracy (±4%), and lower noise-making it the optimal choice for ruggedized embedded systems where reliability and signal integrity are non-negotiable.

Availability

L78L08ABZ-AP is available at Aetrix Electronics and suitable for industrial automation, sensor interface modules, and IoT edge node designs requiring stable component supply, long lifecycle support, and guaranteed −40 °C to +125 °C operation.

Supply support for L78L08ABZ-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 belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications demanding robustness, simplicity, and wide-temperature reliability-without external support components.

FAQ

What is the minimum input voltage required for stable 8 V output from the L78L08ABZ-AP?

The minimum input voltage is determined by the dropout specification: 1.7 V at 40 mA. To guarantee regulation across full load (100 mA) and temperature (−40 °C to +125 °C), ST specifies VI ≥ 9.7 V. At light loads (<10 mA), operation down to ~9.0 V may be possible, but not guaranteed per datasheet.

Can the L78L08ABZ-AP be used in parallel to increase output current?

No-parallel operation is not recommended. The L78L08ABZ-AP lacks current-sharing circuitry, and minor output voltage mismatches between units will cause one device to dominate conduction, leading to thermal imbalance and premature failure. For >100 mA, use an external pass transistor or select a higher-current regulator.

Is a heat sink required for continuous 100 mA operation?

In TO-92 package, continuous 100 mA operation at elevated ambient temperatures (>60 °C) requires PCB copper heatsinking. With ≥6 cm² of 2-oz copper connected to Pin 2 (GND), thermal resistance drops to R_thJA ≈ 200 °C/W, allowing safe operation up to ~85 °C ambient. Without heatsinking, derate to ≤50 mA above 50 °C.

Does the L78L08ABZ-AP require input and output capacitors?

Yes-ST specifies a minimum 0.33 µF ceramic capacitor at the input and 0.1 µF ceramic capacitor at the output. These stabilize internal feedback, suppress high-frequency oscillation, and improve transient response. Omitting either risks instability, overshoot, or degraded PSRR-especially under dynamic load changes.