onsemi MC78M24CTG

Overview

MC78M24CTG from onsemi is a 500 mA fixed-output +24 V positive linear voltage regulator in TO-220 package, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged local board-level regulation. It delivers stable 24 V output across 5.0 mA–500 mA load with ±2% initial accuracy (MC78M24C grade), dropout voltage of 2.0 V, and operates from 27–38 V input.

For engineers reviewing the MC78M24CTG datasheet, pinout, applications, or equivalent options, key selection criteria include its 24 V fixed output, 500 mA continuous current capability, TO-220 thermal performance with heatsink-connected ground pin, and suitability for industrial power supplies, legacy equipment upgrades, and automotive auxiliary rails requiring AEC-Q100-compatible alternatives.

Technical Context

The MC78M24CTG implements a monolithic series pass transistor architecture with built-in protection circuitry: thermal overload detection shuts down operation above +150°C junction temperature, while short-circuit current limiting caps peak output at 350 mA under fault conditions. Safe-area compensation dynamically reduces short-circuit current as input-to-output differential increases.

It requires no external components for basic operation but benefits from ≥0.33 µF input bypass capacitance when connected via long traces or driving large capacitive loads. Input bias current remains ≤7.0 mA across 27–38 V input range, and ripple rejection reaches 50 dB at 120 Hz with 300 mA load.

Key Specifications

Pinout & Package

MC78M24CTG uses the industry-standard TO-220 package (Case 221AB), with the metal tab (heatsink surface) internally connected to Pin 2 (Ground). This configuration enables direct mounting to a heatsink while maintaining electrical isolation of input/output terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC7824CTG and LM78M24CDT, MC78M24CTG uniquely combines 500 mA capability with integrated thermal shutdown, short-circuit limiting, and safe-area compensation in a standard TO-220 package - making it optimal for cost-sensitive, reliability-critical 24 V local regulation where fault resilience matters more than peak current.

Availability

MC78M24CTG is available at Aetrix Electronics and suitable for industrial control systems, automotive auxiliary power distribution, and legacy equipment maintenance requiring stable component supply and long-term obsolescence support.

Supply support for MC78M24CTG 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 manufacturer specializing in power management, analog, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The MC78Mxx series was designed as a rugged, drop-in replacement for legacy 78xx regulators - delivering enhanced thermal and short-circuit protection while maintaining pinout and functional compatibility for industrial and automotive applications.

FAQ

What is the maximum input voltage rating for MC78M24CTG?

The MC78M24CTG has an absolute maximum input voltage rating of 40 Vdc. Its recommended operating input range is 27–38 Vdc to ensure stable 24 V output across full load and temperature. Exceeding 40 Vdc risks permanent damage due to internal junction breakdown, even with thermal protection active.

Does MC78M24CTG require an input bypass capacitor?

Yes, MC78M24CTG requires a minimum 0.33 µF input bypass capacitor placed directly across Pins 1 and 2. This capacitor stabilizes regulation under high-frequency noise or long input trace inductance. Tantalum, ceramic, or low-ESR polymer types are preferred; placement within 5 mm of the device is critical for reliable operation.

Can MC78M24CTG be used in automotive applications?

MC78M24CTG itself is not AEC-Q100 qualified, but its NCV78M24BDTRKG variant is. For automotive use, select the NCV-grade part - it guarantees operation from −40°C to +125°C, includes PPAP documentation, and undergoes automotive-specific stress testing. MC78M24CTG is rated for 0°C to +125°C and suited for industrial or commercial environments.

What is the thermal resistance of MC78M24CTG in TO-220 package?

MC78M24CTG has a junction-to-case thermal resistance (θJC) of 5.0°C/W and a junction-to-air thermal resistance (θJA) of 70°C/W in free-air conditions. With a 20°C/W heatsink, effective θJA drops to ~25°C/W - enabling ~3.5 W continuous power dissipation at TA = 50°C before thermal shutdown activates.

How does the safe-area compensation feature work in MC78M24CTG?

Safe-area compensation in MC78M24CTG dynamically reduces short-circuit current as the input-to-output voltage differential (VI–VO) increases. At 2.0 V dropout, short-circuit current is ~350 mA; at 10 V differential, it drops to ~200 mA. This prevents the internal pass transistor from exceeding its safe operating area during sustained overloads or high-VI faults.