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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

onsemi MC78M09CT

Name: MC78M09CT
Brand: onsemi
SKU: MC78M09CT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MC78M09CT

Manufacturer:: onsemi

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: TO-220-3

Datasheet:: MC78M09CT.pdf

Description:: IC REG LINEAR 9V 500MA TO220AB

Quantity:: RFQ Add To RFQ list

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Inventory:2,146

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Product details

Overview

MC78M09CT from onsemi is a 500 mA, fixed +9.0 V positive voltage regulator in TO-220 package with internal thermal shutdown, short-circuit current limiting, and safe-area compensation. It delivers stable local regulation for industrial power supplies, automotive subsystems, and embedded control boards requiring ±3% output accuracy over temperature and load.

For engineers reviewing the MC78M09CT datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (2.0 V typ), ripple rejection (56 dB min at 120 Hz), load regulation (25 mV max over 5–500 mA), and junction temperature range (−40°C to +125°C) for ruggedized designs.

Technical Context

The MC78M09CT uses a monolithic bipolar linear regulator architecture with an internal pass transistor compensated for safe operating area under high V_IN–V_OUT stress. Its thermal overload protection activates at +150°C junction temperature, and short-circuit current limit is fixed at 350 mA (typ) independent of input voltage up to 35 V.

It operates without external components but requires input bypassing (≥0.33 µF) for stability with long trace lengths or large capacitive loads. The device supports peak output current up to 700 mA for transient loads while maintaining regulation within specified line and load regulation limits.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	+9.0 V nominal, 8.64–9.45 V over temperature and load - ensures compatibility with 9 V logic rails and analog sensors
Max Output Current	500 mA continuous with adequate heatsinking - supports mid-power microcontroller peripherals and op-amp stages
Dropout Voltage	2.0 V typical at 350 mA - requires minimum 11.0 V input for regulated 9.0 V output
Ripple Rejection	56 dB minimum at 120 Hz, 100 mA load - suppresses rectified AC noise in unregulated DC supplies
Line Regulation	6.0 mV typical (11.5–25 V input) - maintains output stability across wide input variations
Load Regulation	25 mV maximum (5–500 mA) - holds output within ±0.28% across full load range
Junction Temp Range	−40°C to +125°C - qualified for automotive under-hood and industrial ambient environments

Pinout & Package

MC78M09CT is housed in a Pb-free TO-220 (Case 221AB) package with heatsink surface electrically connected to Pin 2 (Ground). The package provides low thermal resistance (θ_JC = 5.0°C/W) for efficient heat transfer to external heatsinks.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Input	Unregulated DC input terminal; must be bypassed with ≥0.33 µF capacitor near pin for stability
Pin 2	Ground	Common reference and thermal path; heatsink surface is internally tied to this pin
Pin 3	Output	Regulated +9.0 V output; capable of sourcing up to 500 mA continuously

Key Features

Feature	Design Value
No external components required	Self-contained regulation enables minimal BOM count and simplified layout for point-of-load applications
Internal thermal shutdown	Automatic disable above +150°C junction temperature prevents permanent damage during overload or poor heatsinking
Short-circuit current limiting	Clamps output to ~350 mA during fault, protecting both IC and upstream supply without fuse dependency
Safe-area compensated pass transistor	Prevents secondary breakdown under high V_CE/I_C stress - critical for reliability in variable-input systems
Pb-free TO-220 package	RoHS-compliant leadframe and termination; compatible with standard through-hole reflow and hand-solder processes

Applications

Industrial PLC I/O Module	Automotive Body Control Unit
Use Scenario: Powering isolated digital input buffers and relay drivers in programmable logic controller backplanes. IC Role / Device Role / Timing Role: Local +9 V rail generator for 24 V-tolerant optocoupler interfaces and level-shifting circuitry. Use Value: Maintains regulation despite 15–28 V field bus fluctuations and withstands 125°C ambient in enclosed cabinets.	Use Scenario: Supplying microcontroller peripherals (CAN transceivers, LIN drivers, sensor ADCs) in door module ECUs. IC Role / Device Role / Timing Role: Primary 9 V bias source for mixed-signal subsystems requiring AEC-Q100-grade reliability. Use Value: Withstands cold-crank (4.5 V) and load-dump (35 V) transients via built-in protection, eliminating need for external TVS.
Test Equipment Power Subsystem	Legacy Industrial Sensor Interface
Use Scenario: Providing clean, low-noise +9 V for precision op-amp front-ends and DAC reference buffers in benchtop analyzers. IC Role / Device Role / Timing Role: Low-drift analog supply rail with <±0.2 mV/°C tempco and 52 µV_RMS noise (10 Hz–100 kHz). Use Value: Enables 12-bit measurement accuracy without additional post-regulation filtering or LDO cascading.	Use Scenario: Replacing obsolete 9 V wall adapters in factory-floor analog sensor transmitters (4–20 mA loops, RTD conditioners). IC Role / Device Role / Timing Role: Drop-in replacement for legacy 7809-based supplies with identical pinout and thermal profile. Use Value: Direct mechanical and electrical compatibility with existing PCB footprints and heatsink mounts reduces redesign effort.

Industrial PLC I/O Module

Automotive Body Control Unit

Use Scenario: Powering isolated digital input buffers and relay drivers in programmable logic controller backplanes.

IC Role / Device Role / Timing Role: Local +9 V rail generator for 24 V-tolerant optocoupler interfaces and level-shifting circuitry.

Use Value: Maintains regulation despite 15–28 V field bus fluctuations and withstands 125°C ambient in enclosed cabinets.

Use Scenario: Supplying microcontroller peripherals (CAN transceivers, LIN drivers, sensor ADCs) in door module ECUs.

IC Role / Device Role / Timing Role: Primary 9 V bias source for mixed-signal subsystems requiring AEC-Q100-grade reliability.

Use Value: Withstands cold-crank (4.5 V) and load-dump (35 V) transients via built-in protection, eliminating need for external TVS.

Test Equipment Power Subsystem

Legacy Industrial Sensor Interface

Use Scenario: Providing clean, low-noise +9 V for precision op-amp front-ends and DAC reference buffers in benchtop analyzers.

IC Role / Device Role / Timing Role: Low-drift analog supply rail with <±0.2 mV/°C tempco and 52 µV_RMS noise (10 Hz–100 kHz).

Use Value: Enables 12-bit measurement accuracy without additional post-regulation filtering or LDO cascading.

Use Scenario: Replacing obsolete 9 V wall adapters in factory-floor analog sensor transmitters (4–20 mA loops, RTD conditioners).

IC Role / Device Role / Timing Role: Drop-in replacement for legacy 7809-based supplies with identical pinout and thermal profile.

Use Value: Direct mechanical and electrical compatibility with existing PCB footprints and heatsink mounts reduces redesign effort.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MC78M09CDTRKG	DPAK-3 surface-mount package (Case 369C); same electrical specs, lower θ_JA (92°C/W vs. 70°C/W)	Suitable for space-constrained PCBs; requires reflow-compatible layout and no through-hole mounting	Select when automated assembly and board density outweigh thermal performance needs
NCV78M09BDTRKG	Automotive-grade variant with −40°C to +125°C operation, AEC-Q100 qualified, PPAP-capable	Required for safety-critical automotive modules; includes enhanced process controls and traceability	Choose for OEM automotive programs where qualification documentation and lot traceability are mandatory

Compared with MC78M09CT, the DPAK alternative offers smaller footprint but reduced thermal margin, while the NCV version adds automotive compliance at no electrical trade-off - enabling direct substitution only where qualification requirements align.

Availability

MC78M09CT is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and test equipment requiring stable component supply with long lifecycle support and consistent parametric performance.

Supply support for MC78M09CT 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 MC78Mxx series was designed as a robust, drop-in upgrade to legacy 78xx regulators - delivering higher current capability (500 mA), improved thermal protection, and extended temperature range for mission-critical embedded power systems.

FAQ

What is the maximum input voltage rating for MC78M09CT?

The MC78M09CT has an absolute maximum input voltage of 40 Vdc for devices rated at 20–24 V output, and 35 Vdc for all other variants including MC78M09CT. Exceeding 35 Vdc risks permanent damage even with thermal protection active. Designers must ensure input filtering and transient suppression keep VI ≤ 35 V under worst-case conditions.

Does MC78M09CT require an input bypass capacitor?

Yes, MC78M09CT requires a minimum 0.33 µF input bypass capacitor placed directly across Pins 1 and 2. This capacitor stabilizes the regulator under high-frequency noise and long trace inductance. Tantalum, ceramic, or low-ESR polymer types are recommended; placement within 5 mm of the pins is critical for reliable operation.

Can MC78M09CT be used in parallel for higher current?

No, MC78M09CT is not designed for parallel operation. Its output voltage tolerance (±3%) and lack of current-sharing circuitry cause unequal load distribution and potential thermal runaway. For >500 mA, use a single higher-current regulator or implement external current-boosting with a PNP transistor as documented in Figure 12 of the datasheet.

What is the thermal resistance junction-to-case (θ_JC) for MC78M09CT?

The MC78M09CT has a junction-to-case thermal resistance (θ_JC) of 5.0°C/W, measured from die to the metal tab (Pin 2/heatsink surface). This value assumes proper mechanical contact between the TO-220 tab and heatsink using thermal compound and mounting pressure per onsemi's application notes.

Is MC78M09CT RoHS compliant and lead-free?

Yes, MC78M09CT is a Pb-free device per JEDEC J-STD-609, with "G" suffix indicating RoHS compliance. The TO-220 package uses matte tin plating on leads and leadframe, fully compatible with lead-free soldering processes and meeting EU RoHS Directive 2011/65/EU requirements.

MC78M09CT Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 35V

Voltage - Output (Min/Fixed):: 9V

Voltage - Output (Max):: -

Voltage Dropout (Max):: -

Current - Output:: 500mA

Current - Quiescent (Iq):: -

Current - Supply (Max):: -

PSRR:: 80dB (120Hz)

Control Features:: -

Protection Features:: Over Temperature, Short Circuit

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

MC78M09CT FAQ

1.How can I place an order for MC78M09CT through Aetrix?

Please submit a Request for Quotation (RFQ) for MC78M09CT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for MC78M09CT reliable?

The price and inventory of MC78M09CT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC78M09CT is usually 5 days.

3.What payment methods are accepted for MC78M09CT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC78M09CT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MC78M09CT?

MC78M09CT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MC78M09CT order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for MC78M09CT?

For technical support, including MC78M09CT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC78M09CT requirements.

6.How does Aetrix verify that MC78M09CT is sourced from the original manufacturer or authorized distributors?

All MC78M09CT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MC78M09CT meets industry standards.

7.What is the process for return or replacement of MC78M09CT?

All MC78M09CT units undergo pre-shipment inspection (PSI). If there is an issue with MC78M09CT, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The MC78M09CT part is unused and in its original packaging.

Return procedure for MC78M09CT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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