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onsemi MC7818BT
- Part No.:
- MC7818BT
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC7818BT.pdf
- Description:
- IC REG LINEAR 18V 1A TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:1,018
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Product details
Overview
MC7818BT from onsemi is a fixed-output, 18 V, 1.0 A positive linear voltage regulator in TO-220 package with internal thermal shutdown, short-circuit current limiting, and safe-area compensation. It delivers stable 18 V output across 5 mA–1.0 A load range with ≤2.0 V dropout at full load, supporting local regulation in industrial power supplies, automotive subsystems, and embedded control modules.
For engineers reviewing the MC7818BT datasheet, pinout, applications, or equivalent options, this page provides verified electrical specs (VO = 17.3–18.7 V @ 25°C), thermal performance (RθJA = 92°C/W), ripple rejection (57 dB @ 120 Hz), quiescent current (3.5–6.0 mA), and validated alternative parts for design continuity and sourcing flexibility.
Technical Context
The MC7818BT employs a monolithic bipolar pass transistor with built-in safe-area compensation to dynamically reduce short-circuit current as VCE increases-preventing second breakdown under fault conditions. Its internal bandgap reference and error amplifier maintain output regulation across input voltages from 21 V to 33 V DC.
Thermal overload protection activates at +150°C junction temperature, forcing shutdown until cooldown; recovery is automatic. The device requires no external components for basic operation but benefits from 0.33 µF input and ≥0.1 µF output capacitors to improve transient response and stability under dynamic loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 18 V nominal, 17.3–18.7 V over temperature and load (±4% tolerance ensures compatibility with 18 V logic and analog rails) |
| Output Current | 1.0 A continuous, 2.2 A peak - supports motor drivers, solenoid interfaces, and multi-rail analog circuitry without external boost |
| Dropout Voltage | 2.0 V max at 1.0 A - mandates minimum 20 V input for stable 18 V output under full load |
| Ripple Rejection | 57 dB @ 120 Hz - suppresses rectified AC noise from unregulated wall adapters or SMPS front-ends |
| Quiescent Current | 3.5–6.0 mA - enables low-power standby modes without compromising regulation accuracy |
| Thermal Resistance | RθJA = 92°C/W (TO-220, no heatsink) - requires heatsinking above ~0.5 W dissipation for sustained 1 A operation |
| Operating Junction Temp | +150°C max - supports under-hood automotive and industrial environments with proper thermal design |
Pinout & Package
MC7818BT uses the industry-standard TO-220 package (Case 221AB), with the metal tab electrically connected to Pin 2 (Ground). Heatsinking is mandatory for >500 mA continuous operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Input | Unregulated DC input (21–33 V); must exceed output by ≥2.0 V; bypass with 0.33 µF capacitor near pin |
| Pin 2 | Ground | Common reference for input and output; connects to heatsink; critical for thermal and noise performance |
| Pin 3 | Output | Regulated 18 V supply; optional 0.1–1.0 µF output capacitor improves transient response and stability |
Key Features
| Feature | Design Value |
|---|---|
| Internal Thermal Shutdown | Auto-recovery protection at +150°C junction temperature prevents permanent damage during overload or poor heatsinking |
| Short-Circuit Current Limit | 0.2 A typical limit at 35 V input - safely clamps fault current without external fusing |
| Safe-Area Compensation | Dynamically reduces short-circuit current as VCE rises - avoids second breakdown in high-VIN/VOUT delta applications |
| No External Components Required | Operates stand-alone with only input/output capacitors - simplifies BOM and layout for cost-sensitive designs |
| 1.5% Output Tolerance Option Available | MC7818AB variant offers tighter 17.7–18.3 V window - suitable for precision analog sensor biasing |
Applications
| Industrial Power Supply | Automotive Body Control Module |
|---|---|
|
Use Scenario: Local 18 V rail generation from 24 V vehicle battery or 28 V industrial bus, powering microcontrollers, CAN transceivers, and analog sensors. IC Role / Device Role / Timing Role: Primary linear regulator providing clean, low-noise 18 V supply independent of upstream switching noise. Use Value: 57 dB ripple rejection and 10 µV/V output noise ensure reliable ADC sampling and CAN signal integrity. |
Use Scenario: Powering door lock actuators, window lift motors, and interior lighting controllers in 24 V automotive systems. IC Role / Device Role / Timing Role: Fixed-voltage regulator delivering robust 18 V for motor driver ICs and logic-level shifters. Use Value: 2.2 A peak current supports brief inrush during actuator startup without brownout or reset. |
| Test & Measurement Equipment | Legacy Industrial PLC I/O Module |
|
Use Scenario: Biasing op-amps, DACs, and precision references in benchtop instruments requiring stable 18 V dual-rail supplies. IC Role / Device Role / Timing Role: Low-drift, low-noise linear regulator replacing discrete Zener-based solutions. Use Value: −1.5 mV/°C tempco and <1.3 mΩ output impedance minimize drift and load-induced voltage sag. |
Use Scenario: Retrofitting aging 18 V-powered analog input/output cards in programmable logic controllers. IC Role / Device Role / Timing Role: Direct replacement for obsolete 7818 variants with identical pinout and thermal profile. Use Value: TO-220 footprint and 92°C/W RθJA allow drop-in mechanical and thermal integration into legacy PCBs. |
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 |
|---|---|---|---|
| LM7818CT | Same 18 V output, 1.0 A rating, TO-220 package; higher RθJA (100°C/W), lower ripple rejection (50 dB), no AEC-Q100 qualification | Not qualified for automotive use; less effective in noisy SMPS-derived inputs | Select when cost is primary constraint and automotive qualification is unnecessary |
| NCV7818BT | Identical electrical specs and TO-220 package; AEC-Q100 qualified, PPAP-capable, automotive-grade screening and traceability | Designed for under-hood and chassis applications requiring extended temperature and reliability validation | Select for new automotive designs or where OEM compliance documentation is mandatory |
Compared with LM7818CT, MC7818BT offers superior ripple rejection and thermal margin; versus NCV7818BT, it lacks automotive qualification but provides identical performance at lower cost for industrial use cases.
Availability
MC7818BT is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and test equipment requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for MC7818BT 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.
The MC7800 series-including MC7818BT-is designed for robust, low-cost local regulation in harsh environments, emphasizing thermal resilience, fault protection, and drop-in compatibility with legacy 78xx designs.
FAQ
What is the minimum input voltage required for stable operation of the MC7818BT?
The MC7818BT requires a minimum input voltage of 21 V DC to maintain regulated 18 V output across its full 1.0 A load range and operating temperature. This accounts for the 2.0 V maximum dropout voltage specified at 1.0 A and 25°C junction temperature. Input below 21 V risks output droop or dropout, especially under load or elevated temperature.
Does the MC7818BT require external capacitors to function properly?
The MC7818BT operates without external capacitors for basic functionality, but onsemi recommends a 0.33 µF input capacitor placed close to Pins 1 and 2 to suppress high-frequency noise and prevent oscillation-especially with long input traces. An output capacitor (≥0.1 µF) is not required for stability but improves transient response during load steps.
How does the safe-area compensation feature protect the MC7818BT during output short circuits?
Safe-area compensation in the MC7818BT reduces short-circuit current as the pass transistor's VCE increases-preventing operation beyond its SOA (Safe Operating Area) boundary. At 35 V input, short-circuit current is limited to 0.2 A typical, avoiding thermal runaway and second breakdown that could permanently damage the die.
Can the MC7818BT be used in automotive applications?
The standard MC7818BT is not AEC-Q100 qualified and is intended for industrial and commercial use. For automotive applications, onsemi offers the NCV7818BT-a functionally identical part with automotive-grade screening, extended temperature validation (−40°C to +150°C), and PPAP documentation support.
What thermal management is required for continuous 1.0 A operation of the MC7818BT?
At 1.0 A with 27 V input (9 V drop), MC7818BT dissipates 9 W. With RθJA = 92°C/W and ambient at 25°C, junction temperature would reach ~847°C-far exceeding the +150°C limit. A heatsink reducing RθJA to ≤13.9°C/W (e.g., 10°C/W sink + 3.9°C/W interface) is mandatory for safe continuous 1.0 A operation.
MC7818BT 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):
- 8 mA
- Current - Supply (Max):
- -
- PSRR:
- 57dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
MC7818BT FAQ
1.How can I place an order for MC7818BT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC7818BT 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 MC7818BT reliable?
The price and inventory of MC7818BT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC7818BT is usually 5 days.
3.What payment methods are accepted for MC7818BT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC7818BT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC7818BT?
MC7818BT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC7818BT 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 MC7818BT?
For technical support, including MC7818BT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC7818BT requirements.
6.How does Aetrix verify that MC7818BT is sourced from the original manufacturer or authorized distributors?
All MC7818BT 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 MC7818BT meets industry standards.
7.What is the process for return or replacement of MC7818BT?
All MC7818BT units undergo pre-shipment inspection (PSI). If there is an issue with MC7818BT, 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 MC7818BT part is unused and in its original packaging.
Return procedure for MC7818BT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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