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onsemi KA7818ETU-ON
- Part No.:
- KA7818ETU-ON
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
KA7818ETU-ON.pdf
- Description:
- IC REG LIN FIXED POS STD REG 18V
- Quantity:
- Payment:
- Shipping:
Inventory:16,000
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Product details
Overview
KA7818ETU-ON from ON Semiconductor (formerly Fairchild) is a fixed-output, three-terminal positive voltage regulator delivering 18 V at up to 1 A output current in TO-220 (dual gauge) package. It integrates thermal overload protection, short-circuit protection, and safe operating area (SOA) protection for robust linear regulation in industrial power supplies and embedded systems requiring stable 18 V rail.
For engineers reviewing the KA7818ETU-ON datasheet, pinout, applications, or equivalent options, this page provides verified electrical specifications, thermal resistance data, load/line regulation performance, dropout voltage, and real-world use cases - all confirmed from the official KA78XXE family datasheet Rev. 1.8.
Technical Context
The KA7818ETU-ON implements a monolithic series pass transistor with internal error amplifier, reference voltage, current generator, and protection circuitry. Its architecture supports fixed 18 V output without external components while enabling adjustable configurations via external resistors per Figure 11–12 of the datasheet.
It operates across –40°C to +125°C junction temperature range with 2 V dropout voltage at 1 A, 5 °C/W junction-to-case thermal resistance, and ripple rejection of 53–69 dB (120 Hz, VI = 22–32 V), making it suitable for unregulated DC inputs derived from rectified AC or switching pre-regulators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 18.0 V ±0.7 V (min/max at 25°C); maintains regulation across 5–1.0 A load and input 21–33 V |
| Output Current | Up to 1 A continuous; peak current capability of 2.2 A for transient loads |
| Dropout Voltage | 2 V at 1 A and 25°C - requires minimum 20 V input for stable 18 V output under full load |
| Ripple Rejection | 69 dB typical (120 Hz, 22–32 V input) - suppresses low-frequency AC ripple from rectifier stages |
| Thermal Resistance | 5 °C/W junction-to-case - mandates heatsink for >500 mA continuous operation in enclosed environments |
| Quiescent Current | 5.2–8.0 mA - low standby draw enables efficient operation in always-on subsystems |
| Load Regulation | ≤180 mV over 5 mA–1.5 A (25°C) - ensures <1% output deviation across full load range |
Pinout & Package
KA7818ETU-ON uses the TO-220 (dual gauge) package with standard 3-pin configuration: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The metal tab is electrically connected to Pin 2 (GND) and serves as thermal path to heatsink.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Input) | Unregulated DC supply input | Accepts 21–33 V DC; must exceed output by ≥2 V to maintain regulation under load |
| 2 (GND) | Common reference and thermal tab | Electrical ground reference; metal tab is GND-connected and requires insulated mounting if chassis is not grounded |
| 3 (Output) | Regulated 18 V DC output | Delivers up to 1 A; requires 0.1 μF ceramic capacitor (CO) close to pin for stability and transient response |
Key Features
| Feature | Design Value |
|---|---|
| Thermal Overload Protection | Automatic shutdown at safe junction temperature limit prevents damage during sustained overload or poor heatsinking |
| Short-Circuit Protection | Limits output current to ~250 mA during hard short, enabling safe recovery without external current limiting |
| Safe Operating Area (SOA) Protection | Prevents pass transistor failure under simultaneous high voltage and high current stress (e.g., startup into capacitive load) |
| Fixed 18 V Output | Eliminates need for external feedback resistors - simplifies BOM and layout for dedicated 18 V rails |
| Wide Operating Temperature | –40°C to +125°C junction range supports deployment in automotive engine compartments and industrial control cabinets |
Applications
| Industrial PLC I/O Module | Test Equipment Power Supply |
|---|---|
Use Scenario: Providing isolated 18 V bias for analog input signal conditioning circuits in programmable logic controller modules. IC Role / Device Role / Timing Role: Primary linear regulator supplying clean, low-noise 18 V to op-amps and ADC drivers. Use Value: 110 μV RMS output noise and 69 dB ripple rejection ensure ≤0.0006% measurement error in 16-bit data acquisition systems. | Use Scenario: Generating stable 18 V rail for DUT (device under test) interface circuitry in automated benchtop test fixtures. IC Role / Device Role / Timing Role: Fixed-voltage regulator powering relay drivers and level-shifting logic in test sequencers. Use Value: 1 A output current and SOA protection enable reliable operation during hot-plug events and output shorts during fixture reconfiguration. |
| Legacy Industrial Motor Controller | Embedded Security Camera Power |
Use Scenario: Regulating 18 V for gate driver ICs and microcontroller peripherals in retrofit motor control boards using legacy discrete designs. IC Role / Device Role / Timing Role: Main system regulator replacing obsolete 7818 variants with identical pinout and thermal profile. Use Value: TO-220 dual-gauge footprint and 5 °C/W RθJC allow drop-in replacement without PCB or heatsink redesign. | Use Scenario: Delivering 18 V to CMOS image sensor bias and IR LED drivers in outdoor security cameras exposed to wide ambient temperatures. IC Role / Device Role / Timing Role: Primary power regulator supporting both analog sensor bias and pulsed IR illumination. Use Value: –40°C to +125°C operating range and thermal shutdown ensure uninterrupted operation from arctic winters to desert summers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar positive voltage regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7818CDT/NOPB | ±2% output tolerance (vs. ±4% for KA7818ETU-ON); higher quiescent current (6–8 mA vs. 5.2–8.0 mA) | Preferred where tighter initial accuracy is required, e.g., precision analog front-ends | Select LM7818CDT/NOPB when ±2% VO tolerance is mandatory and TI's qualification for extended temperature is needed |
| MC7818BD2TR4 | ±2% tolerance; lower dropout (1.7 V typ.); improved ripple rejection (72 dB min.) | Better suited for marginal input headroom or high-ripple environments like SMPS-derived inputs | Choose MC7818BD2TR4 when input voltage margin is constrained below 20 V or ripple exceeds 100 mVpp |
Compared with LM7818CDT/NOPB and MC7818BD2TR4, KA7818ETU-ON offers broader industrial temperature support (–40°C to +125°C vs. –40°C to +125°C for LM7818CDT but only –40°C to +125°C for MC7818BD2TR4), identical TO-220 packaging, and proven reliability in legacy industrial deployments - making it optimal for cost-sensitive, long-lifecycle replacements.
Availability
KA7818ETU-ON is available at Aetrix Electronics and suitable for industrial automation, test equipment, and embedded vision systems requiring stable component supply and long-term obsolescence management.
Supply support for KA7818ETU-ON 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
ON Semiconductor is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, communications, and computing markets.
The KA78XXE series was designed as a direct replacement for legacy 78xx regulators, emphasizing ruggedness, integrated protection, and compatibility with existing TO-220-based power supply layouts in industrial control and instrumentation.
FAQ
What is the maximum input voltage for KA7818ETU-ON?
The absolute maximum input voltage for KA7818ETU-ON is 40 V when regulating 24 V output, but for the 18 V variant, the datasheet specifies 35 V as the safe upper limit under normal operating conditions. Exceeding 35 V risks exceeding safe operating area limits even with adequate heatsinking, especially at elevated temperatures.
Does KA7818ETU-ON require input and output capacitors?
Yes - KA7818ETU-ON requires a 0.33 μF ceramic capacitor (CI) on the input and a 0.1 μF ceramic capacitor (CO) on the output, placed as close as possible to their respective pins. These capacitors stabilize regulation, improve transient response, and prevent oscillation, as confirmed in Figures 6–8 of the KA78XXE datasheet Rev. 1.8.
Can KA7818ETU-ON be used in adjustable voltage configurations?
Yes - KA7818ETU-ON can be configured as an adjustable regulator using external resistors per Figure 11 and Figure 12 in the datasheet. The output voltage becomes VO = 18 V × (1 + R2/R1) + IQ × R2, enabling outputs from 7 V to 30 V while retaining built-in protection features.
What is the thermal resistance and heatsink requirement for KA7818ETU-ON at 1 A?
KA7818ETU-ON has RθJC = 5 °C/W and RθJA = 65 °C/W (TO-220, no heatsink). At 1 A with 20 V input (2 V dropout), power dissipation is 2 W. With ambient at 50°C, a heatsink with ≤20 °C/W total thermal resistance (including interface) is required to keep junction temperature below 125°C - verified using θJA = θJC + θCS + θSA.
Is KA7818ETU-ON RoHS compliant and lead-free?
Yes - KA7818ETU-ON is RoHS compliant and lead-free, as confirmed by ON Semiconductor's product change notifications and packaging markings. The "TU" suffix denotes TO-220 package, and "-ON" indicates ON Semiconductor branding post-acquisition of Fairchild, with full compliance maintained across manufacturing transitions.
KA7818ETU-ON Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Bulk
- Product Status:
- Active
- 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:
- 69dB (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-220-3
KA7818ETU-ON FAQ
1.How can I place an order for KA7818ETU-ON through Aetrix?
Please submit a Request for Quotation (RFQ) for KA7818ETU-ON 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 KA7818ETU-ON reliable?
The price and inventory of KA7818ETU-ON are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KA7818ETU-ON is usually 5 days.
3.What payment methods are accepted for KA7818ETU-ON?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KA7818ETU-ON transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KA7818ETU-ON?
KA7818ETU-ON orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KA7818ETU-ON 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 KA7818ETU-ON?
For technical support, including KA7818ETU-ON datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KA7818ETU-ON requirements.
6.How does Aetrix verify that KA7818ETU-ON is sourced from the original manufacturer or authorized distributors?
All KA7818ETU-ON 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 KA7818ETU-ON meets industry standards.
7.What is the process for return or replacement of KA7818ETU-ON?
All KA7818ETU-ON units undergo pre-shipment inspection (PSI). If there is an issue with KA7818ETU-ON, 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 KA7818ETU-ON part is unused and in its original packaging.
Return procedure for KA7818ETU-ON:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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