onsemi MC78M09CDT

Overview

MC78M09CDT from onsemi is a 500 mA, fixed +9.0 V positive voltage regulator in DPAK-3 (TO-252) package, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged local on-card regulation. It delivers stable output across 5.0 mA–500 mA load, supports input voltages up to 35 V, and operates from 0°C to +125°C junction temperature.

For engineers reviewing the MC78M09CDT datasheet, pinout, applications, or equivalent options, this page provides verified electrical specs, thermal performance data, PCB layout guidance for DPAK-3 copper area, and validated alternatives for industrial power supply design, embedded control rails, and automotive subsystems requiring ±3% output accuracy and Pb-free compliance.

Technical Context

The MC78M09CDT implements a monolithic three-terminal linear regulator architecture with an internal pass transistor thermally coupled to the die. Its dropout voltage remains fixed at 2.0 V (typ) across temperature and load, enabling reliable operation with ≥11.5 V input under full 500 mA load. Internal protection circuitry activates at 150°C junction temperature and limits peak short-circuit current to 350 mA.

Designed for fixed-output use without external components, it achieves 56 dB ripple rejection at 120 Hz (IO = 100 mA) and maintains ±0.2 mV/°C average temperature coefficient. Output noise is specified at 52 µVrms (10 Hz–100 kHz), and line/load regulation are 6.0 mV and 25 mV respectively over full operating conditions.

Key Specifications

Pinout & Package

DPAK-3 (Case 369C) package with exposed thermal pad soldered to PCB copper pour; heatsink surface electrically connected to Pin 2 (GND). Dimensions: 6.10 × 6.54 × 2.28 mm, 2.29 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78M09BDTRKG and NCV78M09BDTRKG, the MC78M09CDT provides identical electrical performance and DPAK-3 packaging but targets cost-sensitive commercial applications where −40°C operation or AEC-Q100 certification are unnecessary - simplifying qualification and procurement without sacrificing reliability.

Availability

MC78M09CDT is available at Aetrix Electronics and suitable for industrial automation, test equipment, and consumer electronics requiring stable component supply, consistent DPAK-3 footprint compatibility, and long-term manufacturing continuity.

Supply support for MC78M09CDT 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 silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC78M00 series was designed as a robust, drop-in upgrade to legacy 78xx regulators - delivering 500 mA output in compact DPAK-3 and TO-220 packages with enhanced thermal protection and Pb-free compliance for modern manufacturing.

FAQ

What is the maximum input voltage rating for MC78M09CDT?

The MC78M09CDT has an absolute maximum input voltage rating of 40 Vdc (for 20–24 V output variants) and 35 Vdc for the 9 V version per its datasheet. Continuous operation above 35 Vdc risks permanent damage. For reliable 9 V output at 500 mA, maintain input between 11.5 V and 23 V to stay within thermal limits and ensure regulation stability.

Does MC78M09CDT require an input bypass capacitor?

Yes, MC78M09CDT requires a minimum 0.33 µF tantalum or ceramic capacitor placed directly across Pins 1 and 2 (input-to-ground) to prevent high-frequency oscillation and ensure stability - especially when input traces exceed 2 inches or source impedance is high. This is explicitly recommended in the datasheet's Applications Information section.

Can MC78M09CDT be used in parallel to increase output current?

No, MC78M09CDT is not designed for parallel operation. Its output voltage tolerance (±3.5% over temperature and load) and lack of current-sharing circuitry make direct paralleling unstable and prone to thermal runaway. To achieve >500 mA, use a current-boost configuration with an external PNP transistor as shown in Figure 12 of the datasheet.

What is the thermal resistance (θ_JA) of MC78M09CDT in typical PCB layout?

For MC78M09CDT in DPAK-3 package, θ_JA is 92°C/W in free air. With 1 in² (645 mm²) of 2-oz copper connected to the thermal pad, θ_JA improves to ~50°C/W. The datasheet Figure 2 shows that 25 mm² copper reduces θ_JA to approximately 70°C/W - critical for sustaining 500 mA at ambient temperatures above 50°C.

Is MC78M09CDT pin-compatible with TO-220 versions like MC78M09CTG?

No, MC78M09CDT (DPAK-3) and MC78M09CTG (TO-220) have different footprints and pinouts: DPAK-3 uses Pin 1=Input, Pin 2=GND, Pin 3=Output; TO-220 uses Pin 1=Output, Pin 2=GND, Pin 3=Input. They are functionally equivalent but not mechanically interchangeable - PCB layout redesign is required for substitution.