STMicroelectronics L78L08ABZTR

Overview

L78L08ABZTR from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 8 V ±4% output at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components, operates across -40 °C to +125 °C junction temperature, and achieves 1.7 V dropout at 40 mA - ideal for local on-card regulation in industrial control and embedded sensor interfaces.

For engineers reviewing the L78L08ABZTR datasheet, L78L08ABZTR pinout, L78L08ABZTR application, or L78L08ABZTR equivalent, this device serves as a robust replacement for Zener-diode/resistor regulators with 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 L78L08ABZTR implements a monolithic bipolar linear regulator architecture with built-in thermal overload and short-circuit protection circuitry. Its internal current limiting prevents damage during sustained overloads, while thermal shutdown activates at ~165 °C junction temperature.

It functions as a fixed-output voltage source with no external feedback network required. Input voltage range is 10.5 V to 23 V for stable 8 V regulation, and it maintains output accuracy across load currents from 1 mA to 100 mA and ambient temperatures from -40 °C to +125 °C.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-pin, through-hole), with standardized pinout: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The package provides adequate thermal dissipation for ≤100 mA loads without heatsinking in free-air conditions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L08ACZ and MC78L08CP, the L78L08ABZTR offers superior cold-temperature performance (-40 °C), tighter output tolerance (±4%), and documented thermal protection behavior - making it the preferred choice for mission-critical embedded systems demanding reliability across full industrial and automotive ambient ranges.

Availability

L78L08ABZTR is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, medical front-end electronics, and POS terminal peripheral interfaces requiring stable component supply and long-term lifecycle support.

Supply support for L78L08ABZTR 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local regulation in space- and reliability-constrained embedded systems - emphasizing simplicity, protection integrity, and wide-temperature operability.

FAQ

What is the minimum input voltage required for regulation at full 100 mA load?

The L78L08ABZTR requires a minimum input voltage of 9.7 V to maintain 8 V output at 100 mA load, based on its 1.7 V dropout specification and worst-case output tolerance (7.68 V). At 40 mA, the dropout drops to 1.7 V, so 9.38 V suffices - but design margin should include 0.5 V headroom for line and load transients.

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

No - the L78L08ABZTR is not designed for parallel operation. Its output voltage tolerance (±4%) and lack of current-sharing features cause unequal load distribution, risking thermal runaway in one unit. For >100 mA, use an external pass transistor configured per Figure 14 in DS0424 or select a higher-current regulator like L7808CD2T.

Is a heat sink required for continuous 100 mA operation in TO-92 package?

A heat sink is not required for continuous 100 mA operation at ambient temperatures ≤50 °C with ≥1 cm² copper pour on the ground pin. At 25 °C ambient, junction temperature rises ~100 °C above ambient (R_thJA = 200 °C/W), reaching ~125 °C - within spec. Above 50 °C ambient, derating or PCB copper thermal relief is necessary.

Does the L78L08ABZTR support reverse-input protection?

No - the device lacks internal reverse-polarity protection. Applying negative voltage to the input pin relative to ground may damage the IC. A series Schottky diode (e.g., BAT54) on the input is recommended in battery-reversal-prone applications, accepting the resulting 0.3 V forward drop and slight increase in effective dropout.