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onsemi MC78M12CDTX
, SC-63.JPG)
- Part No.:
- MC78M12CDTX
- Manufacturer:
- onsemi
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
MC78M12CDTX.pdf
- Description:
- IC REG LINEAR 12V 500MA DPAK
- Quantity:
- Payment:
- Shipping:
Inventory:2,536
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Product details
Overview
MC78M12CDTX from Fairchild Semiconductor is a three-terminal fixed-output positive voltage regulator delivering 12 V at up to 0.5 A, featuring thermal overload protection, short-circuit protection, and SOA-protected output transistor. It operates with input voltages up to 35 V and is commonly used in industrial power supplies, embedded control modules, and low-power instrumentation.
For engineers reviewing the MC78M12CDTX datasheet, pinout, applications, or equivalent options, key selection considerations include dropout voltage (2 V at 500 mA), load regulation (≤240 mV over 5 mA–0.5 A), ripple rejection (80 dB at 120 Hz), and D-PAK package thermal resistance (92 °C/W).
Technical Context
The MC78M12CDTX implements a monolithic series-pass regulator architecture with internal reference voltage, error amplifier, current generator, and thermal shutdown circuitry. Its SOA protection ensures safe operation under transient overloads without external components.
It requires only two external capacitors - 0.33 µF input (CI) and 0.1 µF output (CO) - for stability and transient response enhancement. The device maintains regulation across 0 °C to +125 °C junction temperature and supports fixed 12 V output without adjustment circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 12 V ±5% (11.4–12.6 V over full load/line/temp range); enables stable biasing of 12 V logic, sensors, and analog circuitry. |
| Maximum Output Current | 0.5 A continuous; sufficient for powering microcontrollers, op-amps, and small relay drivers without heatsinking in low-duty-cycle applications. |
| Dropout Voltage | 2 V at 500 mA; mandates minimum 14 V input for reliable 12 V output under full load. |
| Ripple Rejection | 80 dB at 120 Hz; suppresses rectified AC noise from unregulated DC supplies, critical for noise-sensitive analog stages. |
| Quiescent Current | 4.1–6.0 mA; contributes <0.072 W loss at 12 V input, supporting efficiency in always-on subsystems. |
| Thermal Resistance (J-A) | 92 °C/W (D-PAK, still air); limits max ambient temperature to ~55 °C at full load without PCB copper heatsinking. |
| Protection Features | Integrated thermal shutdown, short-circuit current limiting (~300 mA), and SOA protection - eliminates need for external foldback or thermal sensors. |
Pinout & Package
D-PAK (TO-252) surface-mount package with exposed thermal pad; optimized for automated assembly and moderate power dissipation on standard FR-4 PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Input) | Voltage Input | Accepts unregulated DC input (14.5–35 V); must be decoupled with ≥0.33 µF ceramic capacitor near pin. |
| 2 (GND) | Ground Reference | Common return path for input, output, and internal circuitry; connects to PCB ground plane for thermal and noise control. |
| 3 (Output) | Regulated Output | Delivers stable 12 V; requires ≥0.1 µF ceramic capacitor at pin to ensure transient stability and reduce output noise. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 12 V output | No external resistors or feedback network required - simplifies BOM and layout for single-rail systems. |
| SOA-protected pass element | Prevents destructive second breakdown during output overload or capacitive load transients without derating. |
| Thermal overload shutdown | Automatically disables output above ~150 °C junction temperature and recovers when cooled - prevents permanent damage. |
| Short-circuit current limit | Holds output current at ~300 mA during hard fault, enabling safe operation with fuses or upstream current-limiting circuits. |
| Low output noise | 75 µV/VO (10 Hz–100 kHz); suitable for powering precision analog front-ends and ADC references without additional filtering. |
Applications
| Industrial Control Power | Embedded Microcontroller Supply |
|---|---|
Use Scenario: Providing clean 12 V rail to PLC I/O modules, sensor signal conditioners, and isolated RS-485 transceivers in factory automation cabinets. IC Role / Device Role / Timing Role: Primary local voltage regulator converting 24 V system bus to 12 V auxiliary supply. Use Value: Eliminates need for discrete pass transistor and feedback network while maintaining regulation under varying load (5 mA–400 mA) and ambient temperature (−25 °C to +70 °C). |
Use Scenario: Powering 8-bit/32-bit microcontrollers (e.g., PIC, STM32), their peripherals, and level-shifting interfaces in battery-backed or wall-powered edge devices. IC Role / Device Role / Timing Role: Main 12 V LDO for MCU core and analog subsystems; supports brown-out detection and reset generation via stable rail. Use Value: Delivers consistent 12 V within ±5% tolerance across load steps and line variations, ensuring reliable boot and runtime operation without external supervision. |
| Test & Measurement Instrumentation | DC Motor Driver Auxiliary Supply |
Use Scenario: Generating reference voltage rails for multimeters, oscilloscope front-ends, and calibration sources where low noise and drift are critical. IC Role / Device Role / Timing Role: Low-noise 12 V source for op-amp biasing and DAC reference buffers. Use Value: 75 µV/VO noise and −0.5 mV/°C drift enable sub-mV accuracy over temperature without post-regulation filtering. |
Use Scenario: Supplying gate drivers, logic-level translators, and current-sense amplifiers in 12 V brushed DC motor controllers. IC Role / Device Role / Timing Role: Isolated auxiliary regulator decoupled from noisy H-bridge switching node. Use Value: Withstands 120 Hz ripple from rectified AC input and rejects PWM coupling via 80 dB rejection, preventing false triggering of driver ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM78M12CDT | Same electrical specs and D-PAK package; manufactured by Texas Instruments (post-Fairchild acquisition); identical pinout and thermal characteristics. | No functional difference; qualified for same industrial temperature range (0 °C to +125 °C). | Select LM78M12CDT when TI-sourced parts are preferred for supply chain diversification or long-term availability assurance. |
| MC7812CD2TR4G | ON Semiconductor variant in D2PAK (TO-263) package; higher thermal resistance (60 °C/W J-C) but larger footprint; otherwise matches VO, IO, and protection features. | Requires PCB layout change due to larger D2PAK footprint and different thermal pad geometry; better suited for high-reliability, high-dissipation designs. | Choose MC7812CD2TR4G only if >0.5 A peak current capability or enhanced thermal margin is needed - not a drop-in replacement for MC78M12CDTX. |
Compared with LM78M12CDT, MC78M12CDTX offers identical performance but may differ in traceability and qualification documentation; versus MC7812CD2TR4G, it trades lower thermal performance for smaller board area and compatibility with D-PAK reflow profiles.
Availability
MC78M12CDTX is available at Aetrix Electronics and suitable for industrial control power, embedded microcontroller supply, test instrumentation, and DC motor driver auxiliary supply requiring stable component supply and long-lifecycle support.
Supply support for MC78M12CDTX 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and interface ICs before its acquisition by ON Semiconductor in 2016.
The MC78MXX series was designed as cost-effective, robust three-terminal regulators for industrial and embedded applications where simplicity, reliability, and wide input voltage tolerance are prioritized over ultra-low quiescent current or adjustable output.
FAQ
What is the maximum input voltage rating for MC78M12CDTX?
The absolute maximum input voltage for MC78M12CDTX is 35 V for output voltages between 5 V and 18 V. Exceeding this rating risks permanent damage to the internal pass transistor and protection circuitry. For reliable operation, maintain input voltage ≤30 V under all conditions including line surges and ripple peaks, especially when operating near full load current.
Does MC78M12CDTX require external capacitors, and what values are recommended?
Yes, MC78M12CDTX requires an input capacitor (CI ≥ 0.33 µF ceramic) and output capacitor (CO ≥ 0.1 µF ceramic), placed as close as possible to their respective pins. These capacitors stabilize regulation, improve transient response, and reduce output noise. Larger CO values (e.g., 10 µF tantalum) further enhance load-step immunity but do not affect basic stability.
Can MC78M12CDTX be used in parallel to increase output current?
No, MC78M12CDTX is not designed for parallel operation. Its output voltage tolerance (±5%) and lack of current-sharing control cause unequal load distribution, leading to thermal runaway in one device. To deliver >0.5 A, use a higher-current regulator (e.g., MC7812CD2TR4G) or switch-mode solution instead of paralleling MC78M12CDTX units.
What is the thermal performance of MC78M12CDTX in the D-PAK package?
In still air, MC78M12CDTX has a junction-to-ambient thermal resistance (RθJA) of 92 °C/W. At 500 mA output and 2 V dropout (1 W dissipation), junction temperature rises ~92 °C above ambient. With TJMAX = +150 °C, max ambient temperature is ~58 °C - requiring PCB copper pour or forced airflow for sustained full-load operation.
Is MC78M12CDTX suitable for automotive applications?
MC78M12CDTX is rated for 0 °C to +125 °C junction temperature and meets industrial reliability standards, but it is not AEC-Q100 qualified. It lacks automotive-specific testing (e.g., HTOL, ESD, vibration) and is not recommended for safety-critical or engine-compartment locations. Use only in non-safety automotive infotainment or body-control modules with careful thermal and EMI validation.
MC78M12CDTX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 35V
- Voltage - Output (Min/Fixed):
- 12V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 2V @ 500mA (Typ)
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 6 mA
- Current - Supply (Max):
- -
- PSRR:
- 80dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DPAK
MC78M12CDTX FAQ
1.How can I place an order for MC78M12CDTX through Aetrix?
Please submit a Request for Quotation (RFQ) for MC78M12CDTX 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 MC78M12CDTX reliable?
The price and inventory of MC78M12CDTX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC78M12CDTX is usually 5 days.
3.What payment methods are accepted for MC78M12CDTX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC78M12CDTX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC78M12CDTX?
MC78M12CDTX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC78M12CDTX 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 MC78M12CDTX?
For technical support, including MC78M12CDTX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC78M12CDTX requirements.
6.How does Aetrix verify that MC78M12CDTX is sourced from the original manufacturer or authorized distributors?
All MC78M12CDTX 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 MC78M12CDTX meets industry standards.
7.What is the process for return or replacement of MC78M12CDTX?
All MC78M12CDTX units undergo pre-shipment inspection (PSI). If there is an issue with MC78M12CDTX, 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 MC78M12CDTX part is unused and in its original packaging.
Return procedure for MC78M12CDTX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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