onsemi MC78M08CTG

Overview

MC78M08CTG from onsemi is a 500 mA, fixed +8.0 V positive linear voltage regulator in TO-220 package, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged local on-card regulation. It delivers stable output under load currents up to 500 mA with ≤8.30 V variation across temperature and line/load conditions, commonly used in industrial power supplies and embedded control subsystems.

For engineers reviewing the MC78M08CTG datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed ±2% output accuracy (MC78M08C grade), 2.0 V dropout voltage at 25°C, 56 dB ripple rejection at 100 mA/120 Hz, and operation across 0°C to +125°C junction temperature range.

Technical Context

The MC78M08CTG implements a monolithic three-terminal series pass regulator architecture with built-in protection circuitry: thermal overload shutdown triggers at ~150°C junction temperature, short-circuit current limit holds peak output at ~350 mA, and safe-area compensation dynamically reduces short-circuit current as input-output differential increases. Its internal design includes 28 active transistors and requires no external components for basic operation.

It operates with input voltages from 10.5 V to 25 V (min VI–VO = 2.0 V), supports peak output current up to 700 mA transiently, and maintains output stability with ≤25 mV load regulation over 5–500 mA and ≤6.0 mV line regulation across its input range - all verified at TJ = 25°C per onsemi's MC78M08C/AC/B/AB specification table.

Key Specifications

Pinout & Package

MC78M08CTG uses the TO-220 (Case 221AB) plastic package with heatsink surface electrically connected to Pin 2 (Ground). The device has three terminals: Pin 1 (Input), Pin 2 (Ground), Pin 3 (Output).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with MC78M08CTG, MC78M08CDTRKG offers identical regulation performance in a smaller DPAK footprint ideal for high-volume SMT production, while NCV78M08BDTRKG adds automotive qualification and wider temperature support - neither is pin-compatible due to differing packages (TO-220 vs. DPAK), requiring layout revision.

Availability

MC78M08CTG is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and embedded communication gateways requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for MC78M08CTG 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 supplier focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC78M00 series was designed as a robust, drop-in upgrade path from legacy 78xx regulators - optimized for local on-card regulation in cost-sensitive, thermally demanding environments with integrated protection and Pb-free packaging.

FAQ

What is the maximum input voltage rating for MC78M08CTG?

The MC78M08CTG has an absolute maximum input voltage rating of 35 V DC. Operation above this level risks permanent damage. For reliable regulation, the input must remain within 10.5 V to 25 V per datasheet specifications - with 2.0 V minimum dropout required. Exceeding 35 V violates the Absolute Maximum Ratings table and may trigger irreversible failure even if thermal protection activates.

Does MC78M08CTG require input or output capacitors for stable operation?

The MC78M08CTG does not require external capacitors for basic regulation, but an input bypass capacitor (≥0.33 µF tantalum or low-ESR ceramic) is recommended when connected via long traces or high-impedance sources to prevent oscillation. No output capacitor is mandatory, though adding one improves transient response and noise suppression - especially critical in noise-sensitive analog circuits powered by MC78M08CTG.

What is the thermal resistance and heatsinking requirement for MC78M08CTG?

MC78M08CTG in TO-220 package has θJC = 5.0°C/W and θJA = 70°C/W in free air. To sustain 500 mA continuous output at 8 V with 15 V input (7 W dissipation), a heatsink with θSA ≤ 20°C/W is required to keep junction temperature below 150°C. The heatsink surface is electrically connected to Pin 2 (Ground), so isolation washers are needed if mounting to a non-grounded chassis.

How accurate is the output voltage of MC78M08CTG across temperature and load?

The MC78M08CTG (C-grade) guarantees output voltage between 7.70 V and 8.30 V at TJ = 25°C, and 7.6 V to 8.4 V over full operating temperature (0°C to +125°C) and load (5–350 mA). Load regulation contributes ≤25 mV shift from 5 mA to 500 mA, and line regulation adds ≤6.0 mV across 10.5–25 V input - all confirmed in the "MC78M08C/AC/B/AB Electrical Characteristics" table on page 3 of the datasheet.

Can MC78M08CTG be used in automotive applications?

The standard MC78M08CTG is rated for 0°C to +125°C junction temperature and is not AEC-Q100 qualified. For automotive use, the NCV78M08BDTRKG variant is specified - it shares identical electrical characteristics but adds −40°C to +125°C operation, PPAP capability, and automotive-specific process controls. Using MC78M08CTG in automotive environments may compromise reliability and compliance without additional system-level validation.