onsemi MC79L12ACD

Overview

MC79L12ACD from ON Semiconductor is a fixed-output, 100 mA negative voltage regulator delivering −12 V with ±4.2% output tolerance (−11.5 V to −12.5 V at +25°C), 1.7 V dropout at 40 mA, and integrated thermal shutdown and short-circuit current limiting. It operates across 0°C to +125°C and is used for on-card negative rail regulation in analog signal chains, sensor interfaces, and legacy industrial control systems.

For engineers reviewing the MC79L12ACD datasheet, pinout, applications, or equivalent options, key selection criteria include its SOIC-8 package, −12 V fixed output, 100 mA load capability, thermal protection behavior, and compatibility with standard 0.33 µF input / 0.1 µF output capacitor configuration.

Technical Context

This device implements a monolithic bipolar linear regulator architecture with internal current-limiting circuitry that clamps output current during overload and thermal shutdown circuitry that disables conduction when junction temperature exceeds +150°C. Its fixed −12 V output is trimmed at wafer level and stabilized via on-chip bandgap reference and error amplifier.

The MC79L12ACD requires no external feedback components and supports stable operation with only 0.33 µF input and 0.1 µF output ceramic or tantalum capacitors. Input voltage range is −14.5 V to −27 V for full-load regulation, with ripple rejection of 37–42 dB at 120 Hz.

Key Specifications

Pinout & Package

MC79L12ACD is housed in an SOIC-8 (Case 751) surface-mount package with 1.27 mm lead pitch, 4.9 mm × 3.9 mm body, and exposed thermal pad-compatible footprint per ON Semiconductor's soldering guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7912CD, MC79L12ACD offers tighter thermal protection coordination and RoHS-compliant packaging out-of-box, while MC79L12ACDR2G provides identical performance in volume-ready packaging-enabling design continuity across prototyping and production phases without circuit or layout changes.

Availability

MC79L12ACD is available at Aetrix Electronics and suitable for industrial sensor conditioning, RS-232 interface power, analog audio preamp stages, and embedded microcontroller peripherals requiring stable component supply with guaranteed long-term sourcing.

Supply support for MC79L12ACD 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, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MC79L00A Series was designed specifically for cost-sensitive, low-current negative voltage regulation in space-constrained industrial and legacy embedded systems where reliability and thermal robustness are critical.

FAQ

What is the maximum input voltage for MC79L12ACD under full-load conditions?

The MC79L12ACD supports a maximum input voltage of −27 V when delivering up to 100 mA across 0°C to +125°C. This limit ensures regulation is maintained with adequate dropout margin and avoids exceeding internal power dissipation limits in the SOIC-8 package. Exceeding −27 V may trigger thermal shutdown or degrade long-term reliability.

Does MC79L12ACD require external capacitors for stable operation?

Yes, MC79L12ACD requires a 0.33 µF input capacitor and a 0.1 µF output capacitor for stable operation under all load conditions. These values are specified in the datasheet for SOIC-8 devices and prevent oscillation, improve transient response, and reduce output noise. Ceramic or tantalum types with low ESR are recommended.

Can MC79L12ACD be used in automotive applications?

No, MC79L12ACD is rated for 0°C to +125°C operation and is not qualified for automotive AEC-Q100 stress testing. For automotive use, ON Semiconductor offers the MC79L12AB variant (−40°C to +125°C) with extended temperature screening and additional reliability tests - MC79L12ACD must not be deployed in vehicle-mounted systems.

How does the thermal shutdown feature operate in MC79L12ACD?

MC79L12ACD activates thermal shutdown when its silicon junction temperature reaches +150°C, disabling output conduction until the die cools below the hysteresis threshold (~135°C). This behavior is fully internal, requires no external circuitry, and protects against sustained overload, poor PCB heatsinking, or ambient temperature excursions beyond spec.

Is MC79L12ACD pin-compatible with TO-92 versions like MC79L12ACPG?

No, MC79L12ACD (SOIC-8) is not pin-compatible with MC79L12ACPG (TO-92). The SOIC-8 version has eight pins including multiple V_IN and NC terminals, while the TO-92 version uses three leads (GND, Input, Output) in different physical order. PCB layout and schematic symbol must be redesigned for package interchange.