onsemi MC78M05ACTG

Overview

MC78M05ACTG from onsemi is a 5.0 V, 500 mA fixed-output linear voltage regulator in TO-220 package with ±2% output accuracy, internal thermal shutdown, and short-circuit current limiting. It delivers stable local regulation for microcontroller power rails, sensor interfaces, and industrial control modules requiring low-noise DC supply under varying load and input conditions.

For engineers reviewing the MC78M05ACTG datasheet, pinout, applications, or equivalent options, this page provides verified electrical specs, thermal performance data, real-world use cases, and validated alternative parts - all aligned to the official ON Semiconductor MC78M00A Series documentation (Rev. 29, Nov. 2021).

Technical Context

The MC78M05ACTG implements a monolithic three-terminal series pass regulator architecture with built-in safe-area compensation for the internal NPN pass transistor. Its thermal overload protection activates at +150°C junction temperature, and short-circuit current limiting holds peak output current to 350 mA under fault conditions.

Designed for fixed-voltage operation without external components, it maintains regulation across input voltages from 7.0 V to 25 V and load currents from 5 mA to 500 mA, with dropout voltage of 2.0 V at TJ = 25°C and ripple rejection ≥62 dB at 120 Hz.

Key Specifications

Pinout & Package

MC78M05ACTG uses the TO-220 (Case 221AB) package with exposed metal tab electrically connected to Pin 2 (Ground). The heatsink surface must be isolated from other potentials unless intentionally tied to system ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78M05CDTG and NCV78M05BDTRKG, the MC78M05ACTG offers superior output accuracy (±2% vs. ±4%) and retains through-hole mechanical robustness for high-vibration environments - making it optimal for industrial control and legacy design refreshes where precision and serviceability matter.

Availability

MC78M05ACTG is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical instrumentation requiring stable component supply across long product lifecycles and fluctuating demand volumes.

Supply support for MC78M05ACTG 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC78M00A Series was engineered specifically for rugged, cost-sensitive local regulation in harsh environments - emphasizing thermal resilience, fault tolerance, and compatibility with legacy 78xx footprint designs while meeting modern RoHS and AEC-Q100 requirements.

FAQ

What is the maximum input voltage rating for MC78M05ACTG?

The MC78M05ACTG has an absolute maximum input voltage of 35 VDC. Operation above 25 V is permissible only for brief transients (e.g., automotive load dump), and continuous operation should remain within the recommended 7.0–25 V input range to ensure specified regulation performance and thermal safety. Exceeding 35 V risks permanent damage to the internal pass transistor.

Does MC78M05ACTG require input or output capacitors for stable operation?

MC78M05ACTG does not require external capacitors for basic regulation, but an input bypass capacitor (≥0.33 µF tantalum or ceramic) is strongly recommended when connected via long traces or high-impedance sources to suppress high-frequency instability. No output capacitor is mandatory, though a 0.1–1 µF ceramic cap improves transient response and reduces output noise in sensitive analog circuits.

What is the thermal resistance (θ_JA) of MC78M05ACTG in TO-220 package without heatsink?

For MC78M05ACTG in TO-220 (Case 221AB) with standard 1-inch² 2-oz copper pad, θ_JA is approximately 70°C/W. With no heatsink and minimal copper, it rises to ~92°C/W - meaning 1 W of dissipation causes ~92°C rise above ambient. Derating curves in the datasheet confirm 500 mA output is sustainable only with ≥20°C/W heatsink or ≥2-inch² copper area at 50°C ambient.

How does the short-circuit protection behave on MC78M05ACTG?

Under output short-circuit conditions, MC78M05ACTG limits peak current to 350 mA (typical) and cycles into thermal shutdown if sustained - not a constant-current foldback. This behavior prevents destructive power dissipation while allowing automatic recovery once fault clears and junction temperature drops below ~135°C. It is not latch-off; repeated shorts may cause thermal cycling visible as output voltage pulsing.

Is MC78M05ACTG compatible with legacy 7805-based PCB footprints?

Yes - MC78M05ACTG uses the same TO-220 package outline and pinout (Input-Ground-Output) as industry-standard 7805 regulators, enabling direct replacement in existing designs. However, its 500 mA rating is half that of the full 7805 (1 A), so designers must verify load current does not exceed 500 mA and confirm thermal margins given identical layout constraints.