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onsemi MC78M12BDT
- Part No.:
- MC78M12BDT
- Manufacturer:
- onsemi
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
MC78M12BDT.pdf
- Description:
- IC REG LINEAR 12V 500MA DPAK
- Quantity:
- Payment:
- Shipping:
Inventory:2,031
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Product details
Overview
MC78M12BDT from onsemi is a 12 V, 500 mA fixed-output linear voltage regulator in DPAK-3 (TO-252) package, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged local regulation. It delivers stable 12 V output across −40°C to +125°C with ±4% initial tolerance and supports industrial power rails, embedded controllers, and sensor interface supplies.
For engineers reviewing the MC78M12BDT 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 automotive-grade 12 V regulation where input voltage ranges from 14.5 V to 27 V.
Technical Context
The MC78M12BDT implements a monolithic three-terminal series pass architecture with PNP-based output transistor, internal bandgap reference, and error amplifier. Its dropout voltage remains fixed at 2.0 V across load and temperature, enabling operation with ≥14.5 V input for full 12 V output compliance.
Thermal protection activates at +150°C junction temperature, and short-circuit current is internally limited to 350 mA at 35 V input. Output noise is 75 µVRMS (10 Hz–100 kHz), and ripple rejection reaches 55 dB at 100 mA/120 Hz with 15–25 V input range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 12 V nominal, 11.4–12.6 V over full line/load/temperature range - ensures compatibility with 12 V logic and analog circuitry requiring tight rail stability |
| Max Output Current | 500 mA continuous with adequate heatsinking - supports mid-power microcontrollers, op-amps, and I/O peripherals without external boost |
| Dropout Voltage | 2.0 V typical at 25°C - mandates minimum 14.0 V input for regulated 12 V output under worst-case conditions |
| Ripple Rejection | 55 dB at 120 Hz, 100 mA load - suppresses AC line-derived ripple in unregulated DC-DC front-end stages |
| Thermal Shutdown | Activates at +150°C junction temperature - prevents permanent damage during sustained overload or poor PCB thermal design |
| Short-Circuit Limit | 350 mA typical at 35 V input - protects upstream supply and enables self-recovery after fault clearance |
| Quiescent Current | 3.2–6.0 mA - enables low-standby-power designs when combined with enable control via external circuitry |
Pinout & Package
DPAK-3 (TO-252) package with exposed thermal pad (pin 2 connected to GND); requires ≥20 mm² of 2 oz. copper for 500 mA operation at 50°C ambient per Figure 2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Input | Unregulated DC input (14.5–27 V); must be bypassed with ≥0.33 µF low-ESR capacitor placed adjacent to pin |
| 2 | GND | Ground reference and thermal pad connection; electrically tied to heatsink surface - critical for thermal performance and noise immunity |
| 3 | Output | Regulated 12 V output; requires local 0.1 µF ceramic capacitor for high-frequency stability |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Operates stably with only input/output capacitors - reduces BOM count and board space vs. adjustable regulators |
| Internal thermal overload protection | Auto-shutdown at +150°C junction temperature with automatic recovery - eliminates need for discrete thermal sensors or reset logic |
| Safe-area compensated pass transistor | Prevents second breakdown during output short-circuit events - enables reliable operation without external current-sense resistors |
| Pb-free DPAK-3 package | RoHS-compliant 6.10 × 6.54 mm outline with exposed thermal pad - supports automated reflow assembly and meets IPC-J-STD-020 moisture sensitivity level 3 |
| −40°C to +125°C operating range | Qualified for extended industrial and automotive under-hood applications - validated across full temperature range without derating |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
Use Scenario: Powering isolated digital input buffers and relay drivers in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Local 12 V rail generator from 24 V system bus, providing noise-isolated supply for optocoupler interfaces and level-shifting circuits. Use Value: 55 dB ripple rejection maintains signal integrity in noisy factory environments; thermal shutdown prevents latch-up during field wiring faults. | Use Scenario: Supplying 12 V to door module microcontrollers, window motor drivers, and LED lighting controllers. IC Role / Device Role / Timing Role: Secondary regulator downstream of vehicle battery or DC-DC converter, delivering robust 12 V for CAN transceivers and LIN slaves. Use Value: −40°C to +125°C rating ensures operation in extreme under-hood conditions; 350 mA short-circuit limit protects against wiring harness shorts. |
| Medical Patient Monitor Sensor Interface | Point-of-Sale Terminal Power Management |
Use Scenario: Providing clean 12 V bias for analog front-end amplifiers and ADC reference circuits in portable diagnostic devices. IC Role / Device Role / Timing Role: Low-noise local regulator for precision analog signal chains, decoupled from noisy digital subsystems. Use Value: 75 µVRMS output noise minimizes baseline drift in ECG/SpO₂ measurements; no external compensation simplifies FDA-cleared design validation. | Use Scenario: Generating 12 V for receipt printer motors, EMV card readers, and display backlight drivers in retail terminals. IC Role / Device Role / Timing Role: Primary 12 V source for mixed-signal peripherals sharing a common 24 V input rail. Use Value: 500 mA output supports simultaneous motor stall and display peak loads; DPAK-3 footprint enables compact 4-layer PCB layout with minimal thermal vias. |
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 |
|---|---|---|---|
| MC78M12CDTRKG | 0°C to +125°C temp range; ±4% output tolerance same; identical DPAK-3 package and pinout | Not qualified for automotive or extended industrial use below 0°C ambient | Select when operating environment stays above freezing and cost sensitivity outweighs extended temp coverage |
| NCV78M12BDTRKG | AEC-Q100 qualified; same −40°C to +125°C range and electrical specs; Pb-free DPAK-3 | Designed specifically for automotive ECUs with PPAP documentation and unique site controls | Required for OEM automotive programs; adds qualification overhead but guarantees automotive lifecycle support |
Compared with MC78M12CDTRKG and NCV78M12BDTRKG, the MC78M12BDT offers identical electrical performance and thermal behavior in the −40°C to +125°C range but targets industrial applications requiring automotive-grade reliability without formal AEC-Q100 certification overhead.
Availability
MC78M12BDT is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical sensor interfaces, and point-of-sale terminals requiring stable component supply with guaranteed long-term sourcing.
Supply support for MC78M12BDT 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 specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and cloud infrastructure markets.
The MC78Mxx series was designed as a rugged, drop-in replacement for legacy 78xx regulators - optimized for local voltage regulation in space-constrained, thermally demanding applications where simplicity and reliability are critical.
FAQ
What is the maximum input voltage rating for the MC78M12BDT?
The MC78M12BDT has an absolute maximum input voltage of 40 Vdc, as specified in the Maximum Ratings table. However, for reliable operation within its 12 V output specification, the recommended input range is 14.5 V to 27 V - exceeding 27 V increases power dissipation and thermal stress without improving regulation performance.
Does the MC78M12BDT require input and output capacitors?
Yes, the MC78M12BDT requires both input and output capacitors for stable operation. A minimum 0.33 µF low-ESR capacitor (e.g., tantalum or ceramic) must be placed directly across pins 1 and 2, and a 0.1 µF ceramic capacitor is recommended across pins 2 and 3. These prevent oscillation and improve transient response per the Applications Information section.
Can the MC78M12BDT be used in automotive applications?
The MC78M12BDT operates across −40°C to +125°C and includes automotive-grade features like thermal shutdown and short-circuit protection, making it suitable for many automotive subsystems. However, for OEM programs requiring formal qualification, the NCV78M12BDTRKG variant - which is AEC-Q100 qualified and PPAP capable - should be selected instead of the MC78M12BDT.
What is the thermal resistance of the MC78M12BDT in DPAK-3 package?
The MC78M12BDT 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. Effective thermal performance depends on PCB copper area - Figure 2 shows that ≥20 mm² of 2 oz. copper reduces θJA significantly for 500 mA operation.
How does the MC78M12BDT handle short-circuit conditions?
The MC78M12BDT limits short-circuit current to approximately 350 mA when the input voltage is 35 V, as measured at 25°C junction temperature. This internal current limiting, combined with thermal shutdown at +150°C, allows the device to survive indefinite output shorts while protecting upstream circuitry - no external foldback or sensing components are needed.
MC78M12BDT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Packaging:
- Tube
- 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):
- -
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 80dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DPAK
MC78M12BDT FAQ
1.How can I place an order for MC78M12BDT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC78M12BDT 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 MC78M12BDT reliable?
The price and inventory of MC78M12BDT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC78M12BDT is usually 5 days.
3.What payment methods are accepted for MC78M12BDT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC78M12BDT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC78M12BDT?
MC78M12BDT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC78M12BDT 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 MC78M12BDT?
For technical support, including MC78M12BDT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC78M12BDT requirements.
6.How does Aetrix verify that MC78M12BDT is sourced from the original manufacturer or authorized distributors?
All MC78M12BDT 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 MC78M12BDT meets industry standards.
7.What is the process for return or replacement of MC78M12BDT?
All MC78M12BDT units undergo pre-shipment inspection (PSI). If there is an issue with MC78M12BDT, 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 MC78M12BDT part is unused and in its original packaging.
Return procedure for MC78M12BDT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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