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onsemi MC78M20CTG
- Part No.:
- MC78M20CTG
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC78M20CTG.pdf
- Description:
- IC REG LINEAR 20V 500MA TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:4,053
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Product details
Overview
MC78M20CTG from onsemi is a 500 mA, +20 V fixed-output linear voltage regulator in TO-220 package with internal thermal shutdown, short-circuit current limiting, and safe-area compensation. It delivers stable 20 V output across 5.0 mA–500 mA load range with ±4% initial accuracy (20 V ±0.8 V), 2.0 V dropout, and 52 dB ripple rejection at 120 Hz under 300 mA load - used for local on-card regulation in industrial power supplies and embedded control modules.
For engineers reviewing the MC78M20CTG datasheet, pinout, applications, or equivalent options, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific use cases, and two confirmed alternative parts with documented functional trade-offs.
Technical Context
The MC78M20CTG implements a monolithic series pass transistor architecture with built-in current limiting and thermal protection circuitry that automatically disables output when junction temperature exceeds +150°C or short-circuit current exceeds 350 mA. Its internal safe-area compensation dynamically reduces short-circuit current as input-to-output differential increases, preventing secondary breakdown.
It operates over an input voltage range of 23–35 V DC to maintain regulated 20 V output, with line regulation ≤10 mV and load regulation ≤400 mV (5–500 mA). The device requires no external components for basic operation but benefits from ≥0.33 µF input bypass capacitance when connected via long traces or driving large capacitive loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 20 V ±0.8 V (±4%) at TJ = 25°C; ensures compatibility with 20 V nominal systems requiring tight tolerance |
| Max Output Current | 500 mA continuous with adequate heatsinking; supports mid-power analog/digital subsystems |
| Dropout Voltage | 2.0 V typical at 350 mA; mandates minimum 22 V input for stable 20 V output under full load |
| Ripple Rejection | 52 dB at 120 Hz, 300 mA load; suppresses AC line noise in unregulated DC bus applications |
| Thermal Shutdown | Activates at TJ ≥ +150°C; protects against sustained overload or inadequate heatsink mounting |
| Short-Circuit Limit | 350 mA typical; limits fault current to prevent PCB trace damage during output shorts |
| Operating Temp Range | 0°C to +125°C junction; suitable for industrial environments without extended automotive qualification |
Pinout & Package
MC78M20CTG uses the TO-220 (Case 221AB) package with heatsink surface electrically connected to Pin 2 (Ground). The plastic body has three leads and is Pb-free (RoHS compliant).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Input | Unregulated DC input (23–35 V); 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 +20 V output; capable of sourcing up to 500 mA with proper thermal management |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Self-contained regulation enables minimal BOM count and simplified layout for point-of-load use |
| Internal thermal overload protection | Automatic shutdown at +150°C junction temperature prevents permanent damage during transient overloads |
| Internal short-circuit current limiting | Clamps output current to ~350 mA during hard shorts, protecting both IC and downstream circuitry |
| Safe-area compensated pass transistor | Reduces short-circuit current as VI–VO increases, avoiding second breakdown in high-differential scenarios |
| Pb-free TO-220 package | RoHS-compliant construction with industry-standard footprint and thermal interface for mechanical mounting |
Applications
| Industrial Power Supply | Embedded Control Module |
|---|---|
|
Use Scenario: Local regulation of 24 V rail to 20 V for analog sensor front-ends and microcontroller peripherals in factory automation PLCs. IC Role / Device Role / Timing Role: Fixed-output linear regulator providing low-noise, stable DC bias for precision ADC references and op-amp rails. Use Value: 52 dB ripple rejection maintains signal integrity; ±4% output tolerance ensures reliable logic-level compatibility with 20 V-tolerant I/O. |
Use Scenario: On-board voltage regulation for motor driver gate bias and MCU core supply in HVAC control boards. IC Role / Device Role / Timing Role: Primary 20 V source for isolated gate drivers and auxiliary logic, replacing discrete Zener-based solutions. Use Value: Integrated thermal shutdown eliminates need for external thermal sensors; 500 mA output supports multi-channel driver ICs. |
| Test Equipment Power Stage | Legacy System Retrofit |
|
Use Scenario: Replacement regulator in aging bench power supplies where original 20 V LDO failed due to thermal stress. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete 20 V regulators in calibrated instrument power sections. Use Value: Identical TO-220 footprint and pinout allows direct PCB reuse; 2.0 V dropout preserves existing input voltage margins. |
Use Scenario: Upgrading vintage industrial controllers using discrete 20 V Zener+transistor regulators to modern single-chip solution. IC Role / Device Role / Timing Role: Monolithic replacement reducing component count, improving reliability, and simplifying compliance testing. Use Value: Eliminates 3–5 discrete parts per channel; built-in protections reduce field failure rates in unattended operation. |
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 |
|---|---|---|---|
| LM78M20CDT-TR | ±5% output tolerance (vs. ±4% for MC78M20CTG); same 500 mA rating, TO-220 package, and 2.0 V dropout | Lacks AEC-Q100 qualification; not recommended for automotive-adjacent industrial environments requiring extended temp validation | Select when cost sensitivity outweighs minor accuracy loss and automotive-grade validation is unnecessary |
| NCV78M20BDTG | Automotive-grade variant with −40°C to +125°C operating range and AEC-Q100 qualification; identical electrical specs and TO-220 package | Qualified for automotive ECUs and ADAS subsystems; higher screening cost and longer lead times than commercial-grade MC78M20CTG | Select when deployment requires guaranteed performance across extended temperature extremes and automotive PPAP compliance |
Compared with LM78M20CDT-TR, MC78M20CTG offers tighter initial accuracy and broader commercial availability; versus NCV78M20BDTG, it trades automotive qualification for lower cost and faster fulfillment in non-automotive industrial designs.
Availability
MC78M20CTG is available at Aetrix Electronics and suitable for industrial power supplies, embedded control modules, test equipment power stages, and legacy system retrofits requiring stable component supply and long-term manufacturability.
Supply support for MC78M20CTG 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 manufacturer specializing in energy-efficient power management, analog, and sensing technologies for automotive, industrial, and cloud infrastructure markets.
The MC78Mxx series was designed as a robust, drop-in upgrade to legacy 78xx regulators - delivering enhanced thermal protection, tighter tolerances, and Pb-free packaging for modern industrial and instrumentation applications.
FAQ
What is the maximum input voltage for MC78M20CTG?
The absolute maximum input voltage for MC78M20CTG is 40 V DC, as specified in the Maximum Ratings table. However, for reliable operation within specifications, the recommended input range is 23–35 V DC - ensuring sufficient headroom above the 20 V output while maintaining thermal safety margins under full 500 mA load. Exceeding 35 V risks exceeding power dissipation limits even with heatsinking.
Does MC78M20CTG require an input bypass capacitor?
Yes, MC78M20CTG requires a minimum 0.33 µF input bypass capacitor placed directly across Pins 1 and 2. This capacitor stabilizes operation under dynamic load changes and suppresses high-frequency noise from upstream sources. Tantalum, ceramic, or low-ESR aluminum electrolytic types are acceptable - but placement must minimize lead inductance to prevent oscillation.
Can MC78M20CTG be used in automotive applications?
MC78M20CTG is rated for 0°C to +125°C junction temperature and is not AEC-Q100 qualified. For automotive applications, use the NCV78M20BDTG variant instead - which shares identical electrical characteristics but adds automotive-grade screening, extended temperature validation (−40°C to +125°C), and PPAP documentation support.
What is the thermal resistance of MC78M20CTG in TO-220 package?
The MC78M20CTG TO-220 package has a junction-to-case thermal resistance (θJC) of 5.0°C/W and a junction-to-air thermal resistance (θJA) of 70°C/W in free-air conditions. With a properly mounted heatsink (e.g., 20°C/W), total θJA drops to ~25°C/W - enabling 500 mA continuous operation at ambient temperatures up to +70°C without exceeding +150°C junction limit.
How does MC78M20CTG handle short-circuit conditions?
MC78M20CTG limits short-circuit output current to approximately 350 mA and activates thermal shutdown if sustained fault causes junction temperature to reach +150°C. Its safe-area compensation further reduces short-circuit current as input-to-output differential rises - preventing destructive second breakdown in high-VI–VO fault scenarios. Recovery is automatic after fault removal and cooldown.
MC78M20CTG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 20V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 70dB (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
MC78M20CTG FAQ
1.How can I place an order for MC78M20CTG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC78M20CTG 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 MC78M20CTG reliable?
The price and inventory of MC78M20CTG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC78M20CTG is usually 5 days.
3.What payment methods are accepted for MC78M20CTG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC78M20CTG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC78M20CTG?
MC78M20CTG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC78M20CTG 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 MC78M20CTG?
For technical support, including MC78M20CTG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC78M20CTG requirements.
6.How does Aetrix verify that MC78M20CTG is sourced from the original manufacturer or authorized distributors?
All MC78M20CTG 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 MC78M20CTG meets industry standards.
7.What is the process for return or replacement of MC78M20CTG?
All MC78M20CTG units undergo pre-shipment inspection (PSI). If there is an issue with MC78M20CTG, 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 MC78M20CTG part is unused and in its original packaging.
Return procedure for MC78M20CTG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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