onsemi MC78M08CDTG

Overview

MC78M08CDTG from onsemi is a 500 mA, fixed +8.0 V positive voltage regulator in DPAK-3 package, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged local on-card regulation. It delivers stable output under 10.5–23 V input, supports peak currents up to 700 mA, and operates across 0°C to +125°C junction temperature.

For engineers reviewing the MC78M08CDTG datasheet, pinout, applications, or equivalent options, this device is selected for cost-sensitive, non-adjustable DC power rails in industrial control modules, automotive body electronics, and embedded sensor interfaces where simplicity, reliability, and Pb-free compliance are required.

Technical Context

The MC78M08CDTG implements a monolithic series pass transistor with built-in protection circuitry - including thermal overload shutdown triggered at +150°C junction temperature and foldback current limiting that reduces short-circuit current as dropout increases. Its architecture requires no external components for basic operation and maintains regulation without feedback loop compensation.

It operates as a three-terminal linear regulator with fixed 8.0 V output, designed for local point-of-load regulation where input-to-output differential is ≥2.0 V (typical dropout), ripple rejection exceeds 56 dB at 120 Hz, and load regulation holds within ±25 mV over 5–500 mA load range at 25°C.

Key Specifications

Pinout & Package

MC78M08CDTG uses the DPAK-3 (TO-252-3) plastic surface-mount package (Case 369C), with exposed thermal pad connected internally to Pin 2 (GND). The heatsink surface is electrically tied to ground, enabling direct PCB copper pour attachment for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78M08BDTRKG, the MC78M08CDTG offers lower cost and simpler qualification for commercial-temperature applications; versus LM78M08CDT/NOPB, it provides superior ripple rejection and tighter output tolerance, making it preferable for noise-sensitive analog subsystems.

Availability

MC78M08CDTG is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical instrumentation requiring stable component supply, RoHS compliance, and DPAK-3 surface-mount compatibility.

Supply support for MC78M08CDTG 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 MC78M00 series is part of onsemi's legacy linear regulator portfolio, engineered for robust, low-cost, fixed-output DC power conversion in space-constrained, thermally demanding environments.

FAQ

What is the maximum input voltage for MC78M08CDTG?

The absolute maximum input voltage for MC78M08CDTG is 35 V DC, as specified in the Absolute Maximum Ratings table. Operation above 23 V is not recommended for normal use - the device is characterized for 10.5–23 V input range, and exceeding 23 V increases power dissipation and thermal stress without functional benefit. Sustained input above 35 V risks permanent damage.

Does MC78M08CDTG require input and output capacitors?

Yes, MC78M08CDTG requires an input bypass capacitor (≥0.33 µF tantalum or low-ESR ceramic) placed close to Pin 1 to suppress high-frequency noise and ensure stability, especially with long input traces. An output capacitor (≥0.1 µF) is also recommended to improve transient response and reduce output impedance. These are not optional for reliable operation per the datasheet's Applications Information section.

What is the thermal resistance of MC78M08CDTG in DPAK-3 package?

The MC78M08CDTG in DPAK-3 (Case 369C) has a junction-to-case thermal resistance (θJC) of 5.0°C/W and a junction-to-air thermal resistance (θJA) of 92°C/W under standard test conditions (free air, no heatsink). Effective thermal performance depends heavily on PCB copper area - adding ≥1 in² of 2 oz. copper connected to Pin 2 significantly lowers θJA and enables higher continuous current capability.

Can MC78M08CDTG be used in automotive applications?

MC78M08CDTG is rated for 0°C to +125°C junction temperature and is Pb-free, but it is not AEC-Q100 qualified. For automotive applications requiring qualification, use MC78M08BDTRKG or NCV78M08BDTRKG instead - these variants are explicitly designed for automotive environments with −40°C to +125°C operation and PPAP capability. MC78M08CDTG may be used in non-safety-critical aftermarket or cabin modules only after full system-level validation.

How does MC78M08CDTG handle short-circuit conditions?

MC78M08CDTG features internal short-circuit current limiting that limits output current to approximately 350 mA (typical) when the output is shorted to ground at 35 V input. This foldback behavior reduces power dissipation during fault conditions and works in conjunction with thermal shutdown (triggered at +150°C) to protect the device. Recovery is automatic once the fault is removed and junction temperature falls below the thermal shutdown threshold.