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onsemi MC7818ACT
- Part No.:
- MC7818ACT
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC7818ACT.pdf
- Description:
- IC REG LINEAR 18V 1A TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:2,007
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Product details
Overview
MC7818ACT from onsemi is a fixed-output linear voltage regulator delivering +18 V 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 supports input voltages up to 35 V DC.
For engineers reviewing the MC7818ACT datasheet, pinout, applications, or equivalent options, this page provides verified electrical specs, TO-220 package layout, thermal performance data, and validated alternative parts for design-in and supply chain continuity.
Technical Context
The MC7818ACT uses a monolithic bipolar pass transistor architecture with built-in protection circuitry: thermal overload sensing triggers shutdown before junction temperature exceeds +150°C, while short-circuit current limiting holds output current below 0.2 A under fault conditions. Safe-area compensation dynamically reduces short-circuit current as input-to-output differential increases.
It requires no external components for basic operation but benefits from a 0.33 µF input bypass capacitor when located 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 (±3% tolerance at TJ = 25°C; 17.3–18.7 V over full load/temperature range) |
| Output Current | 1.0 A continuous (2.2 A peak); internally limited and thermally protected |
| Dropout Voltage | 2.0 V at 1.0 A and TJ = 25°C - defines minimum input headroom required for regulation |
| Ripple Rejection | 53–57 dB at 120 Hz (22–32 VIN, IO = 500 mA) - suppresses AC line noise on unregulated rails |
| Quiescent Current | 3.5–6.0 mA (typical 3.5 mA) - low bias draw enables efficient standby operation |
| Thermal Resistance | RθJA = 92°C/W (TO-220, no heatsink); RθJC = 5.0°C/W - dictates heatsink sizing for >500 mW dissipation |
| Operating Junction Temp | +150°C max - enables use in high-ambient environments with proper thermal management |
Pinout & Package
MC7818ACT is housed in a TO-220 package (Case 221AB), with the metal tab electrically connected to Pin 2 (Ground). The package is through-hole mounted and requires mechanical attachment to a heatsink via the tab for operation above ~500 mW.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Input | Unregulated DC input (21–33 V typical operating range); must exceed output by ≥2.0 V |
| Pin 2 | Ground | Common reference for input and output; tied to heatsink surface - critical for thermal and noise integrity |
| Pin 3 | Output | Stable +18 V regulated output; capable of sourcing 1.0 A with adequate heatsinking |
Key Features
| Feature | Design Value |
|---|---|
| Fixed +18 V output | Eliminates external feedback resistors and trimming - simplifies BOM and layout for single-rail systems |
| Internal thermal shutdown | Automatically disables output if junction temperature exceeds +150°C - prevents permanent damage during overload or poor heatsinking |
| Short-circuit current limit | Holds output current ≤0.2 A during hard shorts - protects both regulator and upstream supply without fuse reliance |
| No external capacitors required | Enables minimal footprint designs; input bypass (0.33 µF) recommended only for long trace runs or high-noise environments |
| Safe-area compensated pass transistor | Reduces short-circuit current as VIN−VOUT increases - maintains SOA compliance across full input range |
Applications
| Industrial PLC Power Supply | Automotive Body Control Module |
|---|---|
|
Use Scenario: Local +18 V rail generation for analog sensor interfaces and relay drivers in programmable logic controllers. IC Role / Device Role / Timing Role: Primary linear regulator supplying stable voltage to op-amps, ADC references, and discrete power switches. Use Value: 1.0 A output current and ±3% output tolerance ensure consistent sensor excitation and actuator control across temperature and load variations. |
Use Scenario: Regulated +18 V supply for microcontroller peripherals and CAN transceivers in vehicle body electronics. IC Role / Device Role / Timing Role: Fixed-voltage post-regulator downstream of switching DC/DC converter, providing low-noise bias for communication ICs. Use Value: 57 dB ripple rejection at 120 Hz suppresses switching noise from upstream converters, ensuring reliable CAN bus signaling. |
| Test Equipment Power Rail | Legacy Industrial Motor Drive Control |
|
Use Scenario: Precision +18 V source for calibration-grade DMM front-end amplifiers and reference buffers. IC Role / Device Role / Timing Role: Low-drift, low-noise linear regulator replacing custom discrete designs in metrology-grade instruments. Use Value: −1.5 mV/°C average temperature coefficient and 10 µV/V output noise enable sub-0.1% measurement accuracy over 0–70°C. |
Use Scenario: On-board +18 V supply for gate drivers and optocoupler isolators in older motor drive control boards. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete 7818 variants in field-repair and obsolescence mitigation programs. Use Value: TO-220 pinout and identical electrical behavior allow direct PCB reuse without layout changes or firmware updates. |
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 |
|---|---|---|---|
| LM7818CDT/NOPB (Texas Instruments) | Same TO-220-3 package; ±2% initial tolerance (vs. ±3% for MC7818ACT); slightly higher quiescent current (4.2–8.0 mA) | Preferred where tighter initial accuracy is needed for reference-sensitive circuits; identical thermal profile | Select LM7818CDT/NOPB when ±2% output tolerance is required and TI's qualification documentation aligns with program requirements. |
| NCV7818BDTAR4G (onsemi) | AEC-Q100 qualified automotive grade; same electrical specs but rated for −40°C to +150°C junction; Pb-free, halogen-free | Required for automotive ECUs and safety-critical modules; supports PPAP and extended temperature validation | Choose NCV7818BDTAR4G for automotive production programs requiring AEC-Q100 compliance and zero-defect manufacturing traceability. |
Compared with LM7818CDT/NOPB and NCV7818BDTAR4G, the MC7818ACT offers broader industrial temperature support (0°C to +150°C), lower cost for non-automotive applications, and proven legacy compatibility - making it optimal for industrial controls, test equipment, and legacy system refreshes where AEC-Q100 is not mandated.
Availability
MC7818ACT is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control modules, test instrumentation, and legacy motor drive systems requiring stable component supply and long-term obsolescence management.
Supply support for MC7818ACT 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 focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications, with leadership in power management, analog, and sensor technologies.
The MC7800 series - including MC7818ACT - was designed as a rugged, drop-in fixed-voltage linear regulator family for local board-level regulation in harsh environments, emphasizing reliability, integrated protection, and ease of use without external compensation.
FAQ
What is the maximum input voltage rating for MC7818ACT?
The absolute maximum input voltage for MC7818ACT is 35 V DC, as specified in the "Maximum Ratings" table of the onsemi datasheet. Operation above this voltage risks permanent device failure due to junction breakdown. For reliable long-term use, the recommended maximum continuous input is 33 V DC, aligned with its specified operating range of 21–33 V for 1.0 A output.
Does MC7818ACT require an output capacitor for stability?
No, MC7818ACT 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 improves transient response to load steps. Unlike LDOs, it has no minimum ESR requirement, making it compatible with ceramic, tantalum, or electrolytic types.
Can MC7818ACT be used in parallel to increase current capacity?
No, MC7818ACT is not designed for parallel operation. Its output voltage tolerance (±3%) and lack of current-sharing features mean paralleling units will cause unequal current distribution and possible thermal runaway. To deliver >1.0 A, use a higher-current regulator (e.g., MC7818CD2T) or implement an external current-boost circuit per Figure 11 in the datasheet.
What thermal considerations apply when using MC7818ACT at full 1.0 A load?
At 1.0 A with a 21 V input (3 V dropout), MC7818ACT dissipates 3 W. With RθJA = 92°C/W and ambient at 50°C, junction temperature would reach ~326°C - far beyond the +150°C limit. A heatsink reducing RθJA to ≤33°C/W is mandatory. Use RθJC = 5.0°C/W to size the interface between device tab and heatsink (e.g., thermal pad + mounting pressure).
Is MC7818ACT RoHS compliant and lead-free?
Yes, MC7818ACT is a Pb-free device, as explicitly stated in the onsemi datasheet (Rev. 29, November 2021): "These are Pb−Free Devices." It complies with RoHS Directive 2011/65/EU and meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for TO-220 packages.
MC7818ACT 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
MC7818ACT FAQ
1.How can I place an order for MC7818ACT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC7818ACT 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 MC7818ACT reliable?
The price and inventory of MC7818ACT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC7818ACT is usually 5 days.
3.What payment methods are accepted for MC7818ACT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC7818ACT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC7818ACT?
MC7818ACT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC7818ACT 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 MC7818ACT?
For technical support, including MC7818ACT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC7818ACT requirements.
6.How does Aetrix verify that MC7818ACT is sourced from the original manufacturer or authorized distributors?
All MC7818ACT 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 MC7818ACT meets industry standards.
7.What is the process for return or replacement of MC7818ACT?
All MC7818ACT units undergo pre-shipment inspection (PSI). If there is an issue with MC7818ACT, 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 MC7818ACT part is unused and in its original packaging.
Return procedure for MC7818ACT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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