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onsemi KA7818E
- Part No.:
- KA7818E
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
KA7818E.pdf
- Description:
- IC REG LINEAR 18V 1A TO220-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,387
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Product details
Overview
KA7818E from ON Semiconductor is a fixed-output +18 V, 1 A positive linear voltage regulator in TO-220 package with thermal overload protection, short-circuit protection, and safe operating area (SOA) protection. It delivers stable DC power for industrial control logic supplies, analog sensor biasing, and legacy telecom line cards requiring low-noise, non-switching regulation.
For engineers reviewing the KA7818E datasheet, pinout, applications, or equivalent options, key selection considerations include dropout voltage (2 V at 1 A), output voltage tolerance (±3.9% over full temperature range), ripple rejection (53–69 dB at 120 Hz), thermal resistance (5 °C/W junction-to-case), and compatibility with standard 0.33 μF input / 0.1 μF output capacitor network.
Technical Context
The KA7818E implements a classic three-terminal series pass architecture with internal error amplifier, bandgap reference, current-limiting circuitry, and thermal shutdown. Its SOA protection dynamically limits power dissipation during transient overloads without latch-up.
It operates across –40°C to +125°C junction temperature and supports input voltages from 21 V to 33 V under 1 A load - requiring ≥3 V headroom above nominal 18 V output to maintain regulation and avoid dropout-induced instability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 18.0 V ±0.9 V (min/max at 25°C); ±1.9 V over –40°C to +125°C - ensures stable logic-level supply for 18 V systems |
| Max Output Current | 1 A continuous - sufficient for powering multiple op-amps, comparators, or small microcontrollers |
| Dropout Voltage | 2 V at 1 A and 25°C - mandates minimum 20 V input to sustain regulation under full load |
| Ripple Rejection | 53–69 dB at 120 Hz - suppresses rectified AC noise from unregulated wall adapters or SMPS post-regulation |
| Quiescent Current | 5.2–8.0 mA - enables low standby power in always-on industrial monitoring circuits |
| Output Noise | 110 μV RMS (10 Hz–100 kHz) - suitable for precision analog front-ends without added filtering |
| Thermal Resistance | 5 °C/W (junction-to-case) - requires heatsink for >0.5 W dissipation at ambient >60°C |
Pinout & Package
KA7818E is housed in a TO-220 (dual-gauge) package with exposed metal tab electrically connected to Pin 2 (GND). The package provides mechanical robustness and thermal path for heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Input) | Unregulated DC input supply | Accepts 21–33 V DC; must be decoupled with ≥0.33 μF ceramic close to pin |
| 2 (GND) | Ground reference and thermal tab | Common return for input/output; tab must be thermally coupled to heatsink but electrically isolated if chassis ground differs |
| 3 (Output) | Regulated +18 V output | Delivers up to 1 A; requires ≥0.1 μF ceramic output capacitor for stability |
Key Features
| Feature | Design Value |
|---|---|
| Internal SOA Protection | Prevents destruction during momentary overloads by limiting I×V product - no external foldback circuit needed |
| Short-Circuit Current Limit | 250 mA typical short-circuit output - protects downstream loads and PCB traces during fault conditions |
| Thermal Shutdown | Activates at ~150°C junction temperature and auto-recovers on cooldown - prevents permanent damage in enclosure-limited designs |
| Fixed +18 V Output | No external resistors required - simplifies BOM and layout vs. adjustable regulators like LM317 |
| Wide Operating Temp Range | –40°C to +125°C junction rating - qualified for industrial motor drives and outdoor base stations |
Applications
| Industrial PLC I/O Module Power | Legacy Telecom Line Card Bias |
|---|---|
Use Scenario: Powers isolated digital input buffers and relay drivers in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Primary 18 V rail generator for level-shifting and optocoupler LED biasing. Use Value: Delivers clean, regulated 18 V without switching noise that could interfere with analog signal acquisition channels. | Use Scenario: Supplies bias voltage to analog line interface circuits (SLICs) in PSTN access equipment. IC Role / Device Role / Timing Role: Stable local supply for hybrid transformer driver stages requiring precise DC offset. Use Value: Ripple rejection >53 dB ensures minimal 120 Hz hum injection into voice-band signals. |
| Analog Sensor Signal Conditioning | Test Equipment Auxiliary Supply |
Use Scenario: Provides excitation voltage for 4–20 mA loop-powered pressure transmitters and bridge sensors. IC Role / Device Role / Timing Role: Low-noise, drift-stable excitation source referenced to system ground. Use Value: 110 μV RMS noise and –1 mV/°C drift enable sub-0.1% measurement accuracy over temperature. | Use Scenario: Generates dedicated 18 V rail for calibration DACs and reference buffers in bench multimeters. IC Role / Device Role / Timing Role: Isolated auxiliary supply preventing ground-loop coupling into high-impedance measurement paths. Use Value: GND-referenced TO-220 package allows direct mounting to instrument chassis for EMI suppression. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar positive fixed-voltage regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7818CDT/NOPB | Same 18 V output, 1 A rating, TO-220 package; ±2% initial tolerance (tighter than KA7818E's ±3.9%); higher ripple rejection (72 dB) | Better suited for noise-sensitive instrumentation where tighter VO tolerance and lower noise are critical | Select LM7818CDT/NOPB when design requires guaranteed <±2% output accuracy at 25°C and enhanced AC line rejection |
| MC7818BD2TR4 | 18 V, 1.5 A rating, TO-220; ±4% tolerance; includes reverse-battery protection diode; RθJC = 4 °C/W (slightly better thermal performance) | Preferred for automotive body electronics where reverse-polarity survivability is mandatory | Choose MC7818BD2TR4 only if reverse-voltage protection is required and 1.5 A peak capability adds margin |
Compared with LM7818CDT/NOPB and MC7818BD2TR4, KA7818E offers broader industrial temperature qualification (–40°C to +125°C vs. 0°C to +125°C for LM7818CDT), lower cost, and proven field reliability in legacy infrastructure - making it optimal for cost-constrained, wide-temp industrial deployments where ±3.9% VO tolerance is acceptable.
Availability
KA7818E is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and test equipment requiring stable component supply with long-term lifecycle support and traceable sourcing.
Supply support for KA7818E 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 (formerly Fairchild Semiconductor) is a global semiconductor manufacturer specializing in power management, analog, and discrete devices for automotive, industrial, and cloud infrastructure markets.
The KA78XXE series was designed as a drop-in replacement for legacy 78xx regulators in industrial and telecom systems, emphasizing ruggedness, wide temperature operation, and integrated protection - not just voltage regulation.
FAQ
What is the maximum input voltage for KA7818E?
The absolute maximum input voltage for KA7818E is 40 V when configured for 24 V output variants, but for the KA7818E specifically, the recommended maximum input is 33 V under 1 A load per the Electrical Characteristics table. Exceeding 33 V risks exceeding safe power dissipation limits and triggering thermal shutdown, especially without adequate heatsinking.
Does KA7818E require external capacitors, and what values are recommended?
Yes, KA7818E requires external capacitors: a minimum 0.33 μF ceramic capacitor at the input (Pin 1) and a minimum 0.1 μF ceramic capacitor at the output (Pin 3), both placed as close as possible to the device pins. These stabilize internal feedback and prevent oscillation - omitting them may cause regulation failure or high-frequency ringing.
Can KA7818E be used in adjustable configurations?
While KA7818E is a fixed +18 V regulator, it can be adapted for adjustable output using external resistive feedback networks - however, this voids guaranteed specifications (e.g., line/load regulation, VO accuracy) and is not recommended for production. For true adjustability, use KA78L18 or LM317 instead.
What is the thermal shutdown threshold of KA7818E?
KA7818E activates thermal shutdown at approximately 150°C junction temperature, as defined by its internal thermal protection circuit. It automatically resumes regulation once the junction cools below ~130°C hysteresis. This behavior is confirmed in the device's functional block diagram and Absolute Maximum Ratings section.
Is KA7818E RoHS compliant and lead-free?
Yes, KA7818E is RoHS compliant and lead-free. Per ON Semiconductor's product change notices and packaging data sheets, all KA78XXE devices manufactured after 2006 meet EU RoHS Directive 2011/65/EU requirements, with lead content <1000 ppm and compliant with JEDEC J-STD-609 moisture sensitivity level 3.
KA7818E 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):
- 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
KA7818E FAQ
1.How can I place an order for KA7818E through Aetrix?
Please submit a Request for Quotation (RFQ) for KA7818E 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 KA7818E reliable?
The price and inventory of KA7818E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KA7818E is usually 5 days.
3.What payment methods are accepted for KA7818E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KA7818E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KA7818E?
KA7818E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KA7818E 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 KA7818E?
For technical support, including KA7818E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KA7818E requirements.
6.How does Aetrix verify that KA7818E is sourced from the original manufacturer or authorized distributors?
All KA7818E 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 KA7818E meets industry standards.
7.What is the process for return or replacement of KA7818E?
All KA7818E units undergo pre-shipment inspection (PSI). If there is an issue with KA7818E, 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 KA7818E part is unused and in its original packaging.
Return procedure for KA7818E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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