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onsemi MC7818ACTG
- Part No.:
- MC7818ACTG
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC7818ACTG.pdf
- Description:
- IC REG LINEAR 18V 1A TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:3,589
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Product details
Overview
MC7818ACTG from onsemi is a fixed-output linear voltage regulator delivering +18 V DC at up to 1.0 A, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for robust local regulation in industrial and automotive power supplies. It operates with a 2.0 V dropout voltage at 1.0 A and maintains ±2% output tolerance over temperature and load.
For engineers reviewing the MC7818ACTG datasheet, pinout, applications, or equivalent options, this page provides verified specifications, TO-220 package layout, real-world use cases in 12–24 V systems, and validated alternative parts for supply chain continuity and design flexibility.
Technical Context
The MC7818ACTG implements a monolithic NPN pass transistor architecture with built-in protection circuitry - including thermal overload sensing that disables output above +150°C junction temperature and current-limiting that caps peak short-circuit current at 0.2 A. Its safe-area compensation dynamically reduces output current as input-to-output differential increases, preventing second breakdown during transient overloads.
It requires no external components for basic operation but benefits from a 0.33 µF input bypass capacitor when placed remotely from bulk filtering. Output stability is maintained without an output capacitor, though a ≥0.1 µF ceramic improves transient response - unlike LDOs, it does not require ESR-tuned output capacitance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | +18.0 V nominal, ±2% tolerance (17.64 V to 18.36 V at TJ = 25°C), stable across 5 mA–1.0 A load |
| Maximum Output Current | 1.0 A continuous (with adequate heatsinking); peak current up to 2.2 A for short durations |
| Dropout Voltage | 2.0 V at 1.0 A and TJ = 25°C - requires minimum 20 V input for regulated 18 V output |
| Ripple Rejection | 53 dB at 120 Hz (22–32 VIN, IO = 500 mA) - suppresses line-frequency noise in AC/DC-derived supplies |
| Quiescent Current | 3.5 mA typical (max 6.0 mA), low static draw ideal for always-on subsystems |
| Thermal Protection | Internal shutdown activates at +150°C junction temperature; auto-recovery after cooldown |
| Short-Circuit Limit | 0.2 A typical (at VIN = 35 V), prevents destructive fault currents in wiring faults |
Pinout & Package
MC7818ACTG uses the industry-standard TO-220 package (Case 221AB), with the metal tab electrically connected to Pin 2 (Ground). The heatsink surface must be isolated from other potentials unless intentionally tied to ground.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Input | Unregulated DC input (21–33 V recommended); connects to bulk filter capacitor |
| Pin 2 | Ground | Common reference for input, output, and heatsink; critical for thermal and noise performance |
| Pin 3 | Output | Regulated +18 V output; routed directly to load with minimal trace inductance |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Enables plug-and-play integration into PCBs without feedback resistors, compensation networks, or startup sequencing |
| Internal thermal overload protection | Prevents permanent damage during sustained overloads or poor heatsinking - eliminates need for external thermal cutoff |
| Safe-area compensated pass transistor | Automatically derates output current under high VIN–VOUT conditions, avoiding SOA violations during input surges |
| 1.0 A continuous output capability | Supports mid-power analog circuits, microcontroller peripherals, and sensor signal chains without parallel devices |
| Pb-free and RoHS-compliant | Meets global environmental compliance requirements for industrial and automotive end equipment |
Applications
| Industrial PLC Power Rails | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Providing stable +18 V bias to analog I/O modules, relay drivers, and isolation amplifiers in programmable logic controllers. IC Role / Device Role / Timing Role: Primary local regulator converting 24 V system rail to precision 18 V for analog front-ends and actuator interfaces. Use Value: Maintains ±2% output accuracy across –40°C to +125°C ambient, ensuring consistent ADC reference and op-amp headroom despite thermal cycling. | Use Scenario: Supplying +18 V to window lift motor controllers, seat position sensors, and interior lighting drivers in 12 V/24 V dual-battery vehicles. IC Role / Device Role / Timing Role: Fixed-voltage post-regulator downstream of DC/DC converter, rejecting ripple from alternator and battery transients. Use Value: 53 dB ripple rejection at 120 Hz suppresses alternator whine; thermal shutdown protects against latch-up during motor stall events. |
| Test Equipment Power Supply | Legacy Industrial Instrumentation |
Use Scenario: Generating clean +18 V for benchtop multimeters, oscilloscope analog boards, and calibration references where low noise and stability are critical. IC Role / Device Role / Timing Role: Low-noise linear regulator stage following switching pre-regulation, minimizing switching artifacts in measurement paths. Use Value: 10 µV/V output noise (10 Hz–100 kHz) ensures sub-mV RMS noise floor - essential for 5½-digit DMM accuracy. | Use Scenario: Replacing obsolete 7818 regulators in aging factory automation panels, CNC controllers, and process monitors requiring long-term component availability. IC Role / Device Role / Timing Role: Direct drop-in replacement for legacy TO-220 18 V regulators, maintaining identical footprint and electrical behavior. Use Value: Pin-compatible with MC7818C/AC variants and backward-compatible with decades-old schematics and layouts. |
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 |
|---|---|---|---|
| LM7818CD2T | Same 18 V output, 1.0 A rating, TO-263 (D2PAK) package; higher RJA (65°C/W vs. 92°C/W for TO-220), lower quiescent current (4.5 mA max) | Suitable for surface-mount designs with thermal pads; less tolerant of high ambient temperatures without copper area | Select when board space is constrained and thermal vias/pads are available; verify PCB copper mass meets RJA requirement. |
| NCV7818ABDTKR | Automotive-grade variant (AEC-Q100 qualified); same electrical specs but tighter temp range (–40°C to +150°C), enhanced ESD (2 kV HBM) | Required for safety-critical vehicle subsystems; includes PPAP documentation and extended reliability testing | Choose for new automotive designs where qualification and traceability are mandatory - not a direct replacement in non-automotive contexts. |
Compared with LM7818CD2T and NCV7818ABDTKR, the MC7818ACTG offers lowest cost and widest commercial temperature support (0°C to +125°C), while retaining full compatibility with legacy TO-220 heatsinks and through-hole assembly - making it optimal for industrial retrofit and general-purpose power rails.
Availability
MC7818ACTG is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, test instrumentation, and legacy equipment repair requiring stable component supply and long-term sourcing assurance.
Supply support for MC7818ACTG 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The MC7800 series - including MC7818ACTG - was designed for rugged, cost-sensitive fixed-voltage regulation in harsh environments, emphasizing intrinsic protection, wide input range, and drop-in replaceability across decades of electronic systems.
FAQ
What is the minimum input voltage required for stable operation of the MC7818ACTG?
The MC7818ACTG requires a minimum input voltage of 20.0 V DC to maintain regulation at full 1.0 A load, based on its 2.0 V dropout voltage specification at TJ = 25°C. For reliable operation across temperature and load extremes, a 21 V minimum input is recommended per the datasheet's operating range (21–33 V).
Does the MC7818ACTG require an output capacitor for stability?
No, the MC7818ACTG does not require an output capacitor for stability - it is internally compensated and remains stable with zero output capacitance. However, adding a ≥0.1 µF ceramic capacitor at the output significantly improves transient response to step-load changes, especially in systems driving digital loads or relays.
Can the MC7818ACTG be used in automotive applications?
The standard MC7818ACTG is rated for 0°C to +125°C junction temperature and supports automotive under-hood environments, but it is not AEC-Q100 qualified. For production automotive use, onsemi's NCV7818ABDTKR - the automotive-qualified variant - is required to meet qualification, PPAP, and traceability mandates.
What thermal considerations apply when using the MC7818ACTG at 1.0 A output?
At 1.0 A with a 21 V input (3 V differential), the MC7818ACTG dissipates 3 W. With RJA = 92°C/W (TO-220, no heatsink), junction temperature rise would exceed +276°C - far beyond the +150°C limit. A heatsink reducing RJA to ≤30°C/W (e.g., 25 cm² aluminum finned sink) is mandatory for continuous 1.0 A operation.
How does the MC7818ACTG handle short-circuit conditions?
The MC7818ACTG limits short-circuit current to approximately 0.2 A when VIN = 35 V, per datasheet testing. This current limit is combined with thermal shutdown: if the short persists, junction temperature rises to +150°C and the device disables output. It automatically recovers once temperature falls below the hysteresis threshold (~135°C), providing self-protecting behavior without external circuitry.
MC7818ACTG 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):
- 18V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 2V @ 1A (Typ)
- Current - Output:
- 1A
- Current - Quiescent (Iq):
- 6 mA
- Current - Supply (Max):
- -
- PSRR:
- 57dB (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
MC7818ACTG FAQ
1.How can I place an order for MC7818ACTG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC7818ACTG 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 MC7818ACTG reliable?
The price and inventory of MC7818ACTG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC7818ACTG is usually 5 days.
3.What payment methods are accepted for MC7818ACTG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC7818ACTG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC7818ACTG?
MC7818ACTG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC7818ACTG 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 MC7818ACTG?
For technical support, including MC7818ACTG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC7818ACTG requirements.
6.How does Aetrix verify that MC7818ACTG is sourced from the original manufacturer or authorized distributors?
All MC7818ACTG 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 MC7818ACTG meets industry standards.
7.What is the process for return or replacement of MC7818ACTG?
All MC7818ACTG units undergo pre-shipment inspection (PSI). If there is an issue with MC7818ACTG, 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 MC7818ACTG part is unused and in its original packaging.
Return procedure for MC7818ACTG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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