onsemi MC79L12ABP

Overview

MC79L12ABP from ON Semiconductor is a 100 mA negative fixed-voltage linear regulator delivering −12 V output with ±5% tolerance (−11.4 V to −12.6 V), 1.7 V dropout at 40 mA, and thermal shutdown/current limiting protection. It operates across −40°C to +125°C and is used in low-power analog circuitry, sensor biasing, and dual-rail op-amp supplies where compact, rugged regulation is required.

For engineers reviewing the MC79L12ABP datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed −12 V output stability under 100 mA load, TO-92 package thermal performance (R_JA = 160°C/W), input voltage range up to −35 V, and integrated short-circuit/thermal protection without external components.

Technical Context

The MC79L12ABP implements a monolithic bipolar transistor-based series pass architecture with internal current-limiting foldback and thermal shutdown circuitry. Its regulation relies on a precision bandgap reference and error amplifier driving a PNP pass transistor.

It requires no external compensation capacitors in most applications but specifies 0.33 µF input and 0.1 µF output bypass capacitors for stability with long trace lengths or large load capacitance. Input-to-output differential must remain ≥2.0 V minimum during ripple valleys to maintain regulation.

Key Specifications

Pinout & Package

MC79L12ABP uses the TO-92 (Case 29) through-hole plastic package with bent leads, rated for 160°C/W junction-to-ambient thermal resistance at 25°C ambient. The package is Pb-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC79L12ACPG, MC79L12ABP extends operational reliability to −40°C ambient, critical for outdoor or automotive deployments; versus LM7912ACZ, it offers smaller footprint and lower system cost at the expense of current capability and thermal headroom.

Availability

MC79L12ABP is available at Aetrix Electronics and suitable for industrial sensor conditioning, dual-rail op-amp supplies, and legacy control backplane upgrades requiring stable component supply and long-term obsolescence management.

Supply support for MC79L12ABP 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

ON Semiconductor (now onsemi) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MC79L12ABP belongs to the MC79L00A Series of low-current negative voltage regulators designed for cost-sensitive, space-constrained applications needing rugged, self-protected regulation without external components.

FAQ

What is the maximum input voltage rating for MC79L12ABP?

The MC79L12ABP has an absolute maximum input voltage rating of −35 V DC for the −12 V version. This limit applies across the full operating temperature range and must not be exceeded to prevent permanent damage. Typical recommended operating input is −14.5 V to −27 V, ensuring sufficient headroom above the −12 V output while maintaining regulation under ripple conditions.

Does MC79L12ABP require external capacitors to operate?

The MC79L12ABP does not require external capacitors for basic regulation, but ON Semiconductor recommends a 0.33 µF input bypass capacitor when the device is located more than ~2 cm from the main power supply filter, and a 0.1 µF output capacitor to improve transient response and stability. These values are specified in the datasheet's standard application circuit and should be used for reliable performance.

What is the thermal resistance of MC79L12ABP in its TO-92 package?

The MC79L12ABP in the TO-92 (Case 29) package has a junction-to-ambient thermal resistance (R_JA) of 160°C/W at T_A = +25°C with standard PCB mounting. This value assumes no heatsink and typical copper land patterns; actual thermal performance depends on PCB copper area and airflow. The junction-to-case resistance (R_JC) is 83°C/W.

Is MC79L12ABP pin-compatible with older 79L12 variants?

Yes, MC79L12ABP maintains identical TO-92 pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) and electrical specifications with legacy 79L12 devices, including the original Motorola MC79L12. It is a direct replacement in existing designs, supporting seamless migration with no PCB or schematic changes required.

What protection features are built into MC79L12ABP?

The MC79L12ABP integrates two critical protection functions: internal short-circuit current limiting that folds back output current during overload or fault conditions, and thermal shutdown that disables the output when junction temperature exceeds +150°C. Both features are fully self-contained and require no external components to function.