onsemi MC79L24ABP

Overview

MC79L24ABP from onsemi is a three-terminal, fixed-output, negative-voltage linear regulator delivering −24 V at up to 100 mA. It features internal thermal shutdown and short-circuit current limiting, operates without external components in most applications, and is rated for −40°C to +125°C junction temperature. It is commonly used for local regulation of analog circuitry requiring stable negative bias in industrial control and instrumentation.

For engineers reviewing the MC79L24ABP datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed −24 V output tolerance (±4.2%), dropout voltage of 1.7 V at 40 mA, input voltage range up to −40 V, thermal protection behavior, and TO-92 package compatibility with legacy through-hole layouts.

Technical Context

The MC79L24ABP implements a monolithic bipolar transistor-based series pass architecture with built-in current-limiting foldback and thermal shutdown circuitry. Its feedback network is trimmed to deliver −24 V nominal output with ±4.2% tolerance over full temperature and load range.

It requires no external compensation capacitors under typical conditions but specifies 0.33 µF input and 0.1 µF output bypass capacitors for stability with long trace lengths or large capacitive loads. Input rejection at 120 Hz is 31 dB minimum, and output noise is 200 µV RMS (10 Hz–100 kHz).

Key Specifications

Pinout & Package

MC79L24ABP is housed in a TO-92 (Case 29) plastic package with straight leads and Pb-free finish. The package has a thermal resistance of 160°C/W (junction-to-ambient) at T_A = 25°C, requiring careful PCB copper area planning for power dissipation above ~150 mW.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative fixed-voltage regulator applications.

Compared with LM7924ACZ and MC79L24ACPG, the MC79L24ABP uniquely combines −40°C start-up capability, TO-92 footprint, and 1.7 V dropout in a single Pb-free device - making it the only option among the three qualified for full industrial temperature deployment without layout or thermal redesign.

Availability

MC79L24ABP is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, legacy op-amp bias rails, PLC I/O modules, and analog front-end power for data acquisition systems requiring stable component supply and long-lifecycle support.

Supply support for MC79L24ABP 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC79L00A Series was designed specifically to replace discrete Zener-resistor regulators in cost-sensitive, low-current negative rail applications while delivering improved stability, thermal robustness, and long-term reliability.

FAQ

What is the output voltage tolerance of the MC79L24ABP over its full operating temperature range?

The MC79L24ABP guarantees an output voltage of −22.8 V to −25.2 V (±4.2%) across −40°C to +125°C junction temperature and 1.0 mA to 40 mA load current, as specified in the Electrical Characteristics table for MC79L24AC/AB devices. This tolerance ensures reliable biasing for precision analog circuits without external trimming.

Can the MC79L24ABP operate without input or output capacitors?

Yes, the MC79L24ABP can operate without external capacitors in low-noise, low-ripple environments with short trace lengths. However, the datasheet recommends a 0.33 µF input capacitor (tantalum or low-ESR film) and 0.1 µF output capacitor to ensure stability under high-frequency transients or long supply traces - both values are validated for the MC79L24ABP in Figure 3 and Applications Information.

What is the maximum input voltage the MC79L24ABP can withstand continuously?

The MC79L24ABP supports a continuous input voltage of up to −38 V under normal operating conditions (−27 V ≤ V_I ≤ −38 V), with an absolute maximum rating of −40 V DC. Exceeding −40 V risks permanent damage, as stated in the Maximum Ratings table on page 2 of the datasheet.

Does the MC79L24ABP include thermal protection, and how does it behave during overload?

Yes, the MC79L24ABP includes internal thermal overload protection that disables the output when junction temperature exceeds +150°C. Once the die cools below the hysteresis threshold (~140°C), regulation resumes automatically - this behavior is inherent to the MC79L24ABP's monolithic design and requires no external circuitry.

Is the MC79L24ABP pin-compatible with other regulators in the MC79L00A Series?

Yes, all MC79L00A Series devices - including MC79L05ABP, MC79L12ABP, MC79L15ABP, MC79L18ABP, and MC79L24ABP - share identical TO-92 pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) and package dimensions. This allows direct substitution across output voltages without PCB changes, provided input voltage and load requirements are met for each variant.