My Inquiry
My Account
Microchip Technology 1N2818BU3
- Part No.:
- 1N2818BU3
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- 3-SMD, No Lead
- Datasheet:
-
1N2818BU3.pdf
- Description:
- DIODE ZENER 20V 50W U3
- Quantity:
- Payment:
- Shipping:
Inventory:9,930
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
1N2818BU3 from Microsemi is a 50 W, 20 V ±5% Zener diode in TO-204AD (TO-3) package, qualified to MIL-PRF-19500/114 JANTXV level, with 2.0 °C/W thermal resistance junction-to-case and 10 µA reverse leakage at 15.2 V. It delivers stable voltage regulation in high-reliability power supply and reference circuits requiring ruggedized, hermetically sealed components.
For engineers reviewing the 1N2818BU3 datasheet, 1N2818BU3 pinout, 1N2818BU3 application, or 1N2818BU3 equivalent, this part supports precision DC voltage clamping, overvoltage protection, and programmable reference design in aerospace, defense, and industrial systems where thermal stability, radiation hardness, and military qualification are mandatory.
Technical Context
This device operates as a high-power, temperature-stable Zener regulator with a nominal breakdown voltage of 20 V at 630 mA test current (IZT), exhibiting a typical temperature coefficient of +0.086 %/°C and dynamic impedance of 1.2 Ω at IZT. Its low RθJC (2.0 °C/W) enables full 50 W dissipation when mounted on a heatsink at TC ≥ 75 °C.
The 1N2818BU3 uses internal solder bond construction and is hermetically sealed via welding per MIL-PRF-19500/114. Polarity is standard (anode-to-case); the "U3" suffix indicates JANTXV qualification and RoHS-compliant matte-tin plating - confirmed by Microsemi's nomenclature guide and T4-LDS-0076 Rev. 3.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 20 V ±5% at IZT = 630 mA - ensures tight regulation tolerance for critical reference applications. |
| Power Dissipation | 50 W average @ TC ≥ 75 °C - supports high-energy transient suppression without derating below 75 °C case temp. |
| Thermal Resistance | RθJC = 2.0 °C/W - enables efficient heat transfer to heatsink; allows full 50 W operation with modest thermal interface. |
| Dynamic Impedance | ZZT = 1.2 Ω @ IZT - maintains low output impedance near regulation knee for stable voltage under load variation. |
| Reverse Leakage | IR = 10 µA @ VR = 15.2 V - guarantees minimal standby current in clamp circuits at 76% of VZ. |
| Temp Coefficient | αVZ = +0.086 %/°C - predictable positive drift aids temperature-compensated reference designs. |
| Junction Temp Range | TJ = –65 to +175 °C - supports operation in extreme environments including space-grade thermal cycling. |
Pinout & Package
Package: TO-204AD (TO-3), hermetically sealed metal can with 0.052″ diameter pins; weight ≈ 15 g; anode internally connected to case (standard polarity); pins 1 and 2 internally shorted per Microsemi Package Dimensions (Page 7, Note 4).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Case (Metal Can) | Anode | Primary current path and thermal conduction surface; must be electrically grounded or referenced per circuit topology. |
| Pin 1 / Pin 2 | Cathode | Electrically common terminals (internally jumpered); provide low-inductance cathode connection for high-current regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic weld seal | Prevents moisture ingress and long-term parameter drift in humid or corrosive environments per MIL-PRF-19500/114. |
| JANTXV qualification | Validated reliability for mission-critical aerospace/defense systems, including screening per MIL-STD-750. |
| Internal solder bond | Enhances mechanical robustness and thermal cycle endurance vs. wire-bonded alternatives. |
| Radiation hardness | Inherently radiation-tolerant per Microsemi MicroNote 050 - suitable for low-dose space applications without shielding. |
| RoHS-compliant plating | Matte-tin finish (U3 suffix) meets commercial-grade environmental compliance without compromising solderability. |
Applications
| Aerospace Power Conditioning | Defense System Reference |
|---|---|
|
Use Scenario: Regulating auxiliary 20 V rail in satellite power distribution units exposed to thermal cycling and radiation. IC Role / Device Role / Timing Role: Primary Zener shunt regulator providing stable 20 V reference for ADCs and DACs. Use Value: Maintains ±5% regulation across –65 to +175 °C with <10 µA leakage at 76% VZ, ensuring data converter accuracy. |
Use Scenario: Overvoltage clamp in radar transmitter bias supplies subject to ESD and lightning-induced transients. IC Role / Device Role / Timing Role: High-energy crowbar element absorbing >50 W surges without parametric shift. Use Value: 2.0 °C/W RθJC and hermetic seal prevent thermal runaway or corrosion-induced failure during repeated surge events. |
| Industrial PLC Analog Input | Nuclear Instrumentation Reference |
|
Use Scenario: Precision 20 V reference for 16-bit analog input modules operating in factory-floor cabinets (70 °C ambient). IC Role / Device Role / Timing Role: Temperature-compensated voltage reference stabilizing front-end signal conditioning. Use Value: +0.086 %/°C αVZ enables predictable drift compensation; JANTXV screening ensures field longevity. |
Use Scenario: Stable bias source for radiation detector preamplifiers in nuclear monitoring equipment. IC Role / Device Role / Timing Role: Low-noise, radiation-hardened Zener establishing calibrated gain-setting voltage. Use Value: Inherent radiation tolerance (MicroNote 050) eliminates need for external shielding; 10 µA IR minimizes detector current error. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N2818B | No U3 suffix: non-RoHS tin-lead plating; JANTX (not JANTXV) qualification; same VZ, IZT, RθJC. | Lacks JANTXV screening and RoHS compliance - unsuitable for new aerospace designs requiring full MIL-PRF-19500/114 Class V. | Select 1N2818B only for legacy repair or cost-sensitive commercial programs where RoHS and enhanced screening are not required. |
| 1N2818RB | Reverse polarity (cathode-to-case); identical electrical specs and JANTXV qualification; same TO-3 package. | Requires inverted mounting orientation and PCB layout revision - incompatible with anode-to-case thermal/mechanical interfaces. | Choose 1N2818RB only when system architecture mandates cathode-grounded configuration and mechanical redesign is feasible. |
Compared with 1N2818B and 1N2818RB, the 1N2818BU3 uniquely combines JANTXV reliability screening, RoHS-compliant matte-tin plating, and standard anode-to-case polarity - making it the sole option for new high-reliability designs requiring both environmental compliance and full military qualification.
Availability
1N2818BU3 is available at Aetrix Electronics and suitable for aerospace power conditioning, defense system reference, and industrial PLC analog input applications requiring stable component supply, long-term obsolescence management, and traceable military-grade sourcing.
Supply support for 1N2818BU3 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 Corporation (now part of Microchip Technology) is a U.S.-based semiconductor manufacturer specializing in high-reliability, radiation-hardened, and military-qualified analog and mixed-signal components.
The 1N2818BU3 belongs to Microsemi's legacy 50 W MIL-PRF-19500/114 Zener family, engineered for voltage regulation in harsh-environment systems where parameter stability, hermetic integrity, and extended temperature operation are non-negotiable.
FAQ
What is the Zener voltage tolerance and test current for the 1N2818BU3?
The 1N2818BU3 has a nominal Zener voltage of 20 V with a ±5% tolerance (B grade), measured at a Zener test current (IZT) of 630 mA. This test condition ensures 12.5 W dissipation at 30 °C base temperature, per Microsemi T4-LDS-0076 Rev. 3, Page 3.
Is the 1N2818BU3 RoHS compliant, and what does the 'U3' suffix indicate?
Yes, the 1N2818BU3 is RoHS compliant: the 'U3' suffix denotes matte-tin plating and JANTXV qualification per MIL-PRF-19500/114. This replaces the standard tin-lead finish and adds enhanced screening for aerospace and defense use, as defined in the Part Nomenclature section (Page 2).
What is the maximum power dissipation and thermal resistance of the 1N2818BU3?
The 1N2818BU3 delivers 50 W average power dissipation when case temperature (TC) is ≥75 °C, with a thermal resistance junction-to-case (RθJC) of 2.0 °C/W. Derating begins at 0.5 W/°C above 75 °C, per Maximum Ratings table (Page 1).
Does the 1N2818BU3 have radiation hardness, and is it documented?
Yes, the 1N2818BU3 exhibits inherent radiation hardness as described in Microsemi MicroNote 050, cited in the Applications/Benefits section (Page 1). This property stems from its hermetic TO-3 construction and silicon process - no additional hardening is required for low-dose space applications.
How is polarity configured on the 1N2818BU3, and how are the pins connected?
The 1N2818BU3 uses standard polarity: the metal case is the anode, and both pins (1 and 2) are internally shorted to form the cathode terminal. This configuration is confirmed in the Mechanical and Packaging section and Package Dimensions Note 4 (Pages 2 and 7).
1N2818BU3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 3-SMD, No Lead
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 20 V
- Tolerance:
- ±5%
- Power - Max:
- 50 W
- Impedance (Max) (Zzt):
- 2.4 Ohms
- Current - Reverse Leakage @ Vr:
- 10 µA @ 15.2 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 10 A
- Operating Temperature:
- -65°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- U3 (SMD-0.5)
1N2818BU3 FAQ
1.How can I place an order for 1N2818BU3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N2818BU3 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 1N2818BU3 reliable?
The price and inventory of 1N2818BU3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N2818BU3 is usually 5 days.
3.What payment methods are accepted for 1N2818BU3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N2818BU3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N2818BU3?
1N2818BU3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N2818BU3 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 1N2818BU3?
For technical support, including 1N2818BU3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N2818BU3 requirements.
6.How does Aetrix verify that 1N2818BU3 is sourced from the original manufacturer or authorized distributors?
All 1N2818BU3 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 1N2818BU3 meets industry standards.
7.What is the process for return or replacement of 1N2818BU3?
All 1N2818BU3 units undergo pre-shipment inspection (PSI). If there is an issue with 1N2818BU3, 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 1N2818BU3 part is unused and in its original packaging.
Return procedure for 1N2818BU3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N2818BU3 Tags
-
MMBZ5240B-7-F
Diodes Incorporated
-
BZT52C5V6T-7
Diodes Incorporated
-
MMSZ5231B-7-F
Diodes Incorporated
-
BZT52C15-7-F
Diodes Incorporated
-
BZX84C3V3LT1G
onsemi
-
MMSZ5245BS-7-F
Diodes Incorporated
-
MMSZ4682T1G
onsemi
-
BZT52C15S-7-F
Diodes Incorporated
-
MM5Z5V1ST1G
onsemi
-
SMAJ4744A-TP
Micro Commercial Co
-
BZT52C3V6LP-7
Diodes Incorporated
-
SMAZ12-13-F
Diodes Incorporated
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
