onsemi MC79L12ACP

Overview

MC79L12ACP from ON Semiconductor is a three-terminal, fixed-output, 100 mA negative voltage regulator delivering −12 V output with ±5% tolerance at +25°C, 1.7 V dropout at 40 mA, and thermal shutdown protection. It operates across 0°C to +125°C junction temperature range and is packaged in Pb-free TO-92 (Case 29), commonly used for on-card regulation in industrial power supplies and analog signal conditioning circuits.

For engineers reviewing the MC79L12ACP datasheet, pinout, applications, or equivalent options, key selection criteria include its fixed −12 V output, TO-92 thermal performance (R_JA = 160°C/W), input voltage range up to −35 V, load regulation of 50 mV (1–40 mA), and compatibility with minimal external components (0.33 µF input / 0.1 µF output capacitors).

Technical Context

The MC79L12ACP implements a monolithic bipolar linear regulator architecture with internal current limiting and thermal overload protection. Its design centers on stable fixed-voltage regulation without external feedback components, relying on internal bandgap reference and error amplifier control loop.

It requires common ground between input and output, mandates ≥2.0 V differential between input and output even under ripple conditions, and specifies 0.33 µF input bypass capacitance for stability when located remotely from the filter source - confirming its role as a local point-of-load negative rail generator.

Key Specifications

Pinout & Package

MC79L12ACP is housed in a Pb-free TO-92 package (Case 29, P suffix), with straight or bent leads and standard 2.54 mm lead pitch. The package supports through-hole mounting and provides adequate thermal dissipation for ≤390 mW continuous operation at room ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC79L12ACP, MC79L12ACPRAG offers identical regulation performance in a machine-ready format, while LM7912ACZ trades compact TO-92 size for higher current capability and significantly better thermal dissipation - making it viable only when board space and heatsinking allow.

Availability

MC79L12ACP is available at Aetrix Electronics and suitable for industrial sensor interfaces, legacy serial communications, analog audio subsystems, and microcontroller analog peripheral power requiring stable component supply with long-term continuity.

Supply support for MC79L12ACP 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 manufacturer specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and cloud power applications.

The MC79L00A Series was designed specifically for cost-sensitive, low-current negative voltage regulation in commercial and industrial equipment - emphasizing ruggedness, simplicity, and drop-in replacement of Zener-diode networks.

FAQ

What is the maximum input voltage for MC79L12ACP?

The MC79L12ACP supports a maximum input voltage of −35 V DC under specified conditions (−12 V output version). This rating applies at TA = +25°C and accounts for worst-case ripple superimposed on the DC input. Exceeding −35 V risks permanent damage due to junction breakdown, as confirmed in the Absolute Maximum Ratings table on page 2 of the datasheet.

Does MC79L12ACP require input and output capacitors?

MC79L12ACP does not require external capacitors for basic regulation, but the datasheet strongly recommends a 0.33 µF input capacitor (tantalum, mylar, or low-ESR ceramic) when the device is located more than a few centimeters from the main filter, and a 0.1 µF output capacitor to improve transient response and high-frequency stability. These values are validated in Figure 3 and Applications Information section on page 5.

What is the thermal shutdown threshold of MC79L12ACP?

The MC79L12ACP activates internal thermal shutdown at +150°C junction temperature, as stated in the Maximum Ratings table (page 2). Once triggered, the device ceases regulation until junction temperature falls below the hysteresis threshold (~135°C), enabling automatic recovery without external intervention - a feature verified across all MC79L00A Series devices.

Can MC79L12ACP be used in automotive applications?

MC79L12ACP is rated for 0°C to +125°C junction operation and is not qualified to AEC-Q100 standards. While the MC79L12AB variant (−40°C to +125°C) is explicitly designated for automotive use with additional testing, MC79L12ACP is intended for commercial/industrial environments. Its datasheet notes automotive temperature options exist only for 5 V, 12 V, and 15 V devices - but only in AB-grade variants.

How does MC79L12ACP compare to MC7912 in terms of current capability?

MC79L12ACP delivers up to 100 mA output current, whereas the MC7912 (non-L variant) supports 1.5 A. The "L" suffix denotes low-current (100 mA) operation with TO-92 packaging and correspondingly higher thermal resistance (160°C/W vs. ~50°C/W for TO-220 MC7912). Both share identical −12 V nominal output and protection features, but MC79L12ACP is optimized for space-constrained, low-power designs where heat sinking is impractical.