STMicroelectronics L78L24ABZ-TR

Overview

L78L24ABZ-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 24 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components and is rated for operation from −40 °C to +125 °C junction temperature, making it suitable for industrial power rail conditioning in programmable logic controllers and sensor signal conditioning circuits.

For engineers reviewing the L78L24ABZ-TR datasheet, L78L24ABZ-TR pinout, L78L24ABZ-TR application, or L78L24ABZ-TR equivalent, this device serves as a drop-in replacement for Zener-diode/resistor regulators where lower quiescent current (6.5 mA typ.), tighter output tolerance (±4% over temperature), and improved ripple rejection (31–37 dB at 120 Hz) are required.

Technical Context

The L78L24ABZ-TR implements a monolithic silicon-based series pass regulator with built-in thermal shutdown and foldback current limiting. Its architecture eliminates need for external compensation or stability components across its full operating range (VI = 27–38 V, IO ≤ 100 mA).

It operates with a dropout voltage of 1.7 V at 40 mA and maintains output regulation under line variations up to 300 mV (VI = 28–38 V) and load variations up to 100 mV (IO = 1–40 mA), while exhibiting 200 µV RMS output noise (10 Hz–100 kHz) and 31–37 dB supply voltage rejection at 120 Hz.

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 operation 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 LM78L24ACZ/NOPB and MC78L24CP, the L78L24ABZ-TR offers superior cold-start capability (−40 °C), tighter output accuracy, lower dropout, and better ripple suppression - making it the preferred choice for new industrial designs requiring robustness across full temperature range.

Availability

L78L24ABZ-TR is available at Aetrix Electronics and suitable for industrial automation, building management systems, and sensor interface modules requiring stable component supply with long-term manufacturability and consistent parametric performance.

Supply support for L78L24ABZ-TR 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, specializing in automotive, industrial, and power management ICs with strong emphasis on reliability and environmental compliance.

The L78L series belongs to ST's legacy linear regulator product line, designed specifically for cost-sensitive, space-constrained industrial applications requiring rugged, no-frills fixed-voltage regulation without external components.

FAQ

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

The L78L24ABZ-TR requires a minimum input voltage of 25.7 V to maintain 24 V output at 100 mA, based on its 1.7 V dropout specification. Below this, output voltage drops linearly with input; operation below 27 V is not recommended for guaranteed regulation across temperature and tolerance.

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

No - the L78L24ABZ-TR is not designed for parallel operation. Its output voltage tolerance (±4%) and lack of current-sharing features make mismatched loading likely, risking 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?

A heat sink is not required for continuous 100 mA operation in TO-92 package when mounted on ≥6 cm² of 1-oz copper PCB area. Thermal resistance is 200 °C/W junction-to-ambient under those conditions, resulting in ~13 °C rise above ambient - well within the −40 °C to +125 °C junction limit.

Does this part support reverse-input protection?

No - the L78L24ABZ-TR has no internal reverse-polarity protection. Applying reverse voltage to the input pin can cause permanent damage. An external series diode (e.g., 1N4001) is required if reverse input is possible in the application.