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Microchip Technology 1N3318A
- Part No.:
- 1N3318A
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- -
- Datasheet:
-
1N3318A.pdf
- Description:
- DIODE ZENER VOLT DO5-PKG
- Quantity:
- Payment:
- Shipping:
Inventory:3,598
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Product details
Overview
1N3318A from Microsemi is a 50 W hermetically sealed, DO-5 packaged Zener diode with nominal Zener voltage of 19.0 V at 2.2 mA test current, ±10% tolerance (A suffix), 2.0 °C/W max junction-to-base thermal resistance, and rated for operation from –65 °C to +175 °C. It serves as a high-power voltage reference and regulation element in industrial power supply feedback loops, overvoltage protection circuits, and precision shunt regulators requiring stable breakdown under sustained 50 W dissipation.
For engineers reviewing the 1N3318A datasheet, 1N3318A pinout, 1N3318A application, or 1N3318A equivalent, this page delivers verified electrical parameters, mechanical package details, thermal derating behavior, polarity configuration options, and qualified military-grade alternatives - all specific to the 1N3318A variant within the 1N3305–1N3350B family.
Technical Context
This device operates as a silicon planar Zener diode with internal solder bond construction and welded metal-glass hermetic sealing. Its low thermal resistance (2.0 °C/W max) enables full 50 W power dissipation when mounted on a heatsink maintaining case temperature below 75 °C, with linear derating beyond that threshold.
The 1N3318A exhibits a typical temperature coefficient of +0.075 %/°C and dynamic impedance of 660 Ω at IZT = 2.2 mA, confirming stable regulation across wide current and temperature ranges. Standard polarity connects anode to case; reverse polarity (cathode-to-case) requires R suffix (e.g., 1N3318AR).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 19.0 V ±10% at 2.2 mA test current - defines precise regulation point for feedback and clamping circuits. |
| Power Dissipation | 50 W at TC ≤ 75 °C - supports high-energy transient suppression and continuous shunt regulation. |
| Thermal Resistance | 2.0 °C/W max junction-to-hexagonal base - enables predictable thermal design with standard stud-mount heatsinking. |
| Dynamic Impedance | 660 Ω at IZT = 2.2 mA - ensures minimal output voltage variation under load current changes. |
| Max Reverse Current | 10 µA at 13.7 V - guarantees low leakage in high-impedance reference paths. |
| Temp Coefficient | +0.075 %/°C - indicates positive drift, critical for temperature-compensated regulator designs. |
| Junction Temp Range | –65 °C to +175 °C - suitable for aerospace, downhole, and extended-temperature industrial environments. |
Pinout & Package
Package: DO-5 (DO-203AB), hermetically sealed metal-glass case with 11/16″ hexagonal stud and 1/4-28 threaded mounting interface. Anode is internally connected to case in standard polarity units; cathode-to-case configuration requires R suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Case (Stud) | Anode (standard polarity) | Primary current path and thermal conduction surface - must be electrically connected and thermally coupled to heatsink. |
| Lead (Axial) | Cathode | Signal/reference node - connects to regulated rail or error amplifier input in feedback topologies. |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic metal-glass seal | Enables long-term reliability in harsh environments including high humidity, vacuum, and radiation exposure per MicroNote 050. |
| JEDEC-registered 1N33xx series | Ensures standardized parametric definitions, test methods, and interchangeability across qualified suppliers. |
| ±10% Zener tolerance (A suffix) | Provides tighter regulation than ±20% base variants while retaining cost and availability advantages over ±5% (B) grade. |
| Nonsensitive to ESD | Complies with MIL-STD-750 Method 1020 - eliminates need for handling precautions during assembly. |
| Military screening options | JAN/JANTX/JANTXV qualification available via prefix - supports defense and space programs requiring traceable lot control and extended testing. |
Applications
| Industrial Power Supply Regulation | Aerospace Overvoltage Protection |
|---|---|
Use Scenario: Shunt regulation in high-voltage DC-DC converter feedback networks where primary-side sensing demands robustness against transients and thermal cycling. IC Role / Device Role / Timing Role: Precision voltage reference and error signal generator - sets output voltage via optocoupler feedback loop. Use Value: 50 W power rating and 2.0 °C/W thermal resistance allow direct stud-mounting to chassis without auxiliary heatsinks, reducing BOM count and improving long-term stability. |
Use Scenario: Clamp-based overvoltage protection in avionics power distribution units exposed to lightning-induced surges and load dump events. IC Role / Device Role / Timing Role: High-energy transient suppressor - diverts fault current away from sensitive downstream converters and controllers. Use Value: Hermetic DO-5 package and –65 °C to +175 °C operating range ensure survivability in unpressurized bays and engine-mounted electronics. |
| Downhole Oilfield Instrumentation | High-Reliability Test Equipment Reference |
Use Scenario: Voltage reference in borehole logging tools operating at elevated ambient temperatures and high mechanical stress. IC Role / Device Role / Timing Role: Stable Zener reference for ADC biasing and sensor excitation - maintains accuracy despite thermal gradients up to 175 °C. Use Value: +0.075 %/°C tempco and low 10 µA leakage at 13.7 V enable predictable drift compensation in closed-loop calibration algorithms. |
Use Scenario: Primary shunt reference in benchtop multimeters and calibrators requiring long-term drift stability and low noise. IC Role / Device Role / Timing Role: Low-noise, low-drift voltage standard - supplies reference to precision op-amps and DACs in metrology-grade signal chains. Use Value: 660 Ω dynamic impedance and JEDEC registration guarantee repeatable performance across production lots and calibration cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N3318B | Same 19.0 V nominal voltage and DO-5 package, but ±5% tolerance instead of ±10%. | Higher precision required in metrology or closed-loop control where tighter VZ spread improves system accuracy. | Select 1N3318B when ±5% tolerance justifies higher cost and longer lead time; 1N3318A remains optimal for general-purpose regulation. |
| JANTX1N3318A | Identical electrical specs and packaging, but includes MIL-PRF-19500/358 JANTX screening (extended environmental and life testing). | Mandatory for defense/aerospace programs requiring certified lot traceability, burn-in, and radiation hardness documentation. | Choose JANTX1N3318A only when contractual or program requirements mandate military qualification; 1N3318A satisfies commercial and industrial use cases. |
Compared with 1N3318B and JANTX1N3318A, the 1N3318A offers the optimal balance of cost, availability, and performance for non-military industrial applications - delivering verified 19.0 V regulation with ±10% tolerance and full 50 W capability without over-specifying precision or qualification level.
Availability
1N3318A is available at Aetrix Electronics and suitable for industrial power supply regulation, aerospace overvoltage protection, and downhole instrumentation requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.
Supply support for 1N3318A 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
Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and RF solutions for aerospace, defense, and industrial markets.
The 1N3305–1N3350B series was designed specifically for high-power, high-stability Zener regulation in mission-critical systems where hermetic packaging, wide temperature operation, and MIL-qualified variants are essential.
FAQ
What is the Zener voltage tolerance for 1N3318A?
The 1N3318A has a nominal Zener voltage of 19.0 V with a ±10% tolerance, as indicated by the "A" suffix per Microsemi's documentation. This means the actual measured VZ at 2.2 mA test current falls between 17.1 V and 20.9 V under standard conditions. The tolerance is confirmed in the Electrical Characteristics table on Page 2 of the official datasheet.
Does 1N3318A support reverse polarity configuration?
Yes, 1N3318A supports reverse polarity (cathode-to-case) when ordered with the "R" suffix as 1N3318AR. Standard polarity units have the anode internally bonded to the metal case. The R-suffix variant maintains identical electrical specifications but reverses terminal assignment - critical for designs requiring case-isolated cathode connections.
What is the maximum power dissipation for 1N3318A and how does it derate with temperature?
The 1N3318A is rated for 50 W DC power dissipation at case temperature (TC) ≤ 75 °C. Above 75 °C, power must be linearly derated at 0.5 W/°C, reaching zero dissipation at 175 °C. This derating curve is defined in the Maximum Ratings section and directly tied to its 2.0 °C/W thermal resistance specification.
Is 1N3318A hermetically sealed and what standards does it meet?
Yes, the 1N3318A uses a welded metal-glass hermetic seal compliant with MIL-PRF-19500/358 for JAN/JANTX variants. It is nonsensitive to ESD per MIL-STD-750 Method 1020 and inherently radiation-hardened as documented in Microsemi MicroNote 050 - making it suitable for high-reliability aerospace and nuclear instrumentation applications.
What is the dynamic impedance of 1N3318A and why does it matter?
The 1N3318A has a maximum dynamic impedance (ZZT) of 660 Ω at IZT = 2.2 mA. This value quantifies AC voltage variation per unit change in Zener current - lower impedance yields tighter regulation under varying load conditions. At 660 Ω, the 1N3318A provides stable reference performance in feedback loops and precision shunt regulators.
1N3318A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- *
- Package/Case:
- -
- Packaging:
- Tray
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- -
- Tolerance:
- -
- Power - Max:
- -
- Impedance (Max) (Zzt):
- -
- Current - Reverse Leakage @ Vr:
- -
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
1N3318A FAQ
1.How can I place an order for 1N3318A through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N3318A 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 1N3318A reliable?
The price and inventory of 1N3318A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N3318A is usually 5 days.
3.What payment methods are accepted for 1N3318A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N3318A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N3318A?
1N3318A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N3318A 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 1N3318A?
For technical support, including 1N3318A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N3318A requirements.
6.How does Aetrix verify that 1N3318A is sourced from the original manufacturer or authorized distributors?
All 1N3318A 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 1N3318A meets industry standards.
7.What is the process for return or replacement of 1N3318A?
All 1N3318A units undergo pre-shipment inspection (PSI). If there is an issue with 1N3318A, 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 1N3318A part is unused and in its original packaging.
Return procedure for 1N3318A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N3318A Tags
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