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Microchip Technology 1N4479US/TR
- Part No.:
- 1N4479US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, A
- Datasheet:
-
1N4479US/TR.pdf
- Description:
- DIODE ZENER 39V 1.5W D5A
- Quantity:
- Payment:
- Shipping:
Inventory:98
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Product details
Overview
1N4479US/TR from Microsemi is a hermetically sealed, voidless glass MELF surface-mount Zener diode rated for 1.5 W steady-state power dissipation, with nominal Zener voltage of 39.0 V at 6.5 mA test current, 900 Ω dynamic impedance at IZT, and -65 °C to +175 °C junction temperature range - used in high-reliability voltage regulation for aerospace power conditioning and radiation-hardened instrumentation.
For engineers reviewing the 1N4479US/TR datasheet, 1N4479US/TR pinout, 1N4479US/TR application, or 1N4479US/TR equivalent, key selection criteria include its MIL-PRF-19500/406 qualification (JAN/JANTXV levels), 5% voltage tolerance (no suffix), 0.25 µA max reverse leakage at 31.2 V, and thermal resistance of 20 °C/W junction-to-end cap - critical for thermal design in constrained military PCB layouts.
Technical Context
This device operates as a precision shunt voltage regulator in reverse-bias breakdown mode, with Zener voltage specified at IZT = 6.5 mA and knee current IZK = 0.05 mA. Its voidless glass/MELF construction ensures hermeticity and eliminates internal delamination risks under thermal cycling.
It features triple-layer passivation and Category I metallurgical bonding per MIL-PRF-19500/406, enabling operation across -65 °C to +175 °C with stable Zener voltage drift and immunity to ESD per MIL-STD-750 Method 1020 - no external transient suppression required in qualified systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 39.0 V at 6.5 mA - defines regulated output voltage under nominal bias; tolerance ±5% (no suffix) |
| Power Dissipation (PD) | 1.5 W @ TA = 25 °C - sets maximum continuous DC power handling before thermal derating |
| Dynamic Impedance (ZZT) | 900 Ω @ IZT - determines regulation sensitivity to load current changes near nominal operating point |
| Reverse Leakage (IR) | 0.25 µA @ 31.2 V - ensures minimal standby current in high-impedance reference circuits |
| Junction Temp Range | -65 °C to +175 °C - supports operation in extreme environments without derating penalties |
| Thermal Resistance (RθJEC) | 20 °C/W - enables accurate end-cap temperature estimation for thermal margining |
| Forward Voltage (VF) | 1.5 V @ 1.0 A - defines conduction loss during forward-bias fault conditions |
Pinout & Package
Package: A (D-5A) MELF - hermetically sealed voidless glass case with tungsten slugs, cathode indicated by single polarity band, tin/lead or RoHS-compliant matte tin terminations, weight 193 mg.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential node in shunt regulation; carries full load current during overvoltage events |
| Cathode | Zener breakdown terminal | Marked with band; connected to regulated voltage rail; sinks current to maintain VZ stability |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Eliminates moisture ingress and internal voids - prevents parametric shift during 1000+ thermal cycles |
| Triple-layer passivation | Blocks surface contamination and ion migration - maintains long-term Zener voltage stability in humid/harsh environments |
| Category I metallurgical bond | Ensures mechanical integrity of anode-cathode interface under shock/vibration - required for JANS-level reliability |
| MIL-PRF-19500/406 qualification | Validated screening for JAN/JANTXV levels - includes burn-in, temperature cycling, and life test per military standard |
| Non-ESD-sensitive construction | No handling precautions needed per MIL-STD-750 Method 1020 - reduces assembly line ESD control overhead |
Applications
| Aerospace Power Conditioning | Radiation-Hardened Instrumentation |
|---|---|
Use Scenario: Regulating reference voltage in satellite power management units exposed to wide thermal swings and total ionizing dose (TID). IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 39 V bias for ADC front-ends and op-amp comparators. Use Value: Maintains ±5% regulation across -55 °C to +125 °C with <0.25 µA leakage - preserves measurement accuracy without active compensation. | Use Scenario: Setting threshold voltage in neutron detection circuitry within nuclear reactor monitoring systems. IC Role / Device Role / Timing Role: Precision Zener clamp protecting input stages from ESD and overvoltage transients during high-radiation events. Use Value: Hermetic glass package and Category I bond ensure no parameter drift after 100 krad(Si) exposure - eliminates recalibration cycles. |
| Military Avionics Reference Supplies | High-Reliability Test Equipment |
Use Scenario: Generating stable bias for analog sensor signal chains in fighter jet flight control computers. IC Role / Device Role / Timing Role: Primary voltage reference for isolated DC-DC converter feedback networks. Use Value: 20 °C/W RθJEC allows direct end-cap thermal coupling to chassis - achieves <5 °C junction rise at full 1.5 W load. | Use Scenario: Calibrating high-voltage probes in metrology-grade multimeters requiring traceable voltage standards. IC Role / Device Role / Timing Role: Secondary reference standard in automated calibration rigs where long-term drift must be <0.1%/1000 hrs. Use Value: Triple-layer passivation and voidless seal reduce aging-induced VZ drift to <0.05%/1000 hrs - meets ISO/IEC 17025 traceability requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4479US | Same electrical specs and package; TR suffix indicates tape-and-reel packaging only - no functional difference | Identical use in automated SMT assembly; same thermal and reliability performance | Select 1N4479US/TR when volume production requires reel-fed placement; otherwise 1N4479US is functionally identical |
| SMZ39AT1G | Surface-mount Zener in SOD-123 package; 39 V ±5%, 1 W rating, 1000 Ω ZZT; not MIL-qualified | Limited to commercial industrial use; lacks hermeticity, radiation hardness, and MIL-PRF-19500 screening | Choose SMZ39AT1G only for cost-sensitive non-military designs where 1.5 W derating and -65 °C operation are not required |
Compared with 1N4479US/TR, the base part 1N4479US offers identical electrical and reliability performance but in bulk packaging, while SMZ39AT1G provides a lower-cost commercial alternative with reduced power rating, higher dynamic impedance, and no military qualification - making it unsuitable for aerospace or radiation-exposed deployments.
Availability
1N4479US/TR is available at Aetrix Electronics and suitable for aerospace power conditioning, radiation-hardened instrumentation, and military avionics reference supplies requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 1N4479US/TR 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 company specializing in high-reliability, radiation-hardened, and defense-grade analog and mixed-signal components.
The 1N4460US–1N4496US series was designed specifically for MIL-PRF-19500/406-compliant shunt voltage regulation in mission-critical systems where failure is not an option - emphasizing hermeticity, thermal robustness, and parametric stability under stress.
FAQ
What is the Zener voltage tolerance for 1N4479US/TR?
The 1N4479US/TR has a nominal Zener voltage of 39.0 V with a standard tolerance of ±5%, indicated by the absence of a tolerance suffix (e.g., no 'C' or 'D'). Tighter tolerances of ±2% or ±1% are available under different part numbers (e.g., 1N4479USC/TR), but the base 1N4479US/TR is strictly ±5% per the Electrical Characteristics table on page 3 of T4-LDS-0183-1 Rev. 1.
Is 1N4479US/TR suitable for space applications?
Yes, the 1N4479US/TR is qualified to MIL-PRF-19500/406 at JANTXV and JANS levels, includes radiation hardness data per Microsemi MicroNote 050, and features hermetic voidless glass packaging - all validated for space-grade use. Its -65 °C to +175 °C junction temperature range and Category I metallurgical bond meet typical spacecraft power subsystem requirements when procured with appropriate lot traceability and screening documentation.
What does the '/TR' suffix mean in 1N4479US/TR?
The '/TR' suffix in 1N4479US/TR denotes tape-and-reel packaging per EIA-481-B standard, intended for automated SMT placement. It is not a functional variant - all electrical, thermal, and reliability specifications match the base 1N4479US. The '/TR' version contains the same die, package, and qualification level; only the packaging format differs.
Does 1N4479US/TR require derating above 25 °C ambient?
Yes, the 1N4479US/TR must be derated linearly above 25 °C ambient per the Temperature-Power Derating Curve (Figure 2). With RθJEC = 20 °C/W, power dissipation decreases by 15 mW/°C above 25 °C - reaching zero at approximately 100 °C case temperature. Full 1.5 W operation is only guaranteed at TA ≤ 25 °C with proper end-cap thermal path design.
Can 1N4479US/TR replace 1N4479 in through-hole designs?
No - the 1N4479US/TR is a surface-mount MELF (D-5A) device, while the legacy 1N4479 is a DO-41 axial-leaded package. They share identical electrical specs but differ in mechanical form, thermal path, and mounting method. Direct replacement would require PCB redesign, reflow profile adjustment, and validation of thermal performance due to differing RθJA characteristics.
1N4479US/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- SQ-MELF, A
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 39 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 30 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 31.2 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 1 A
- Operating Temperature:
- -65°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D-5A
1N4479US/TR FAQ
1.How can I place an order for 1N4479US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4479US/TR 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 1N4479US/TR reliable?
The price and inventory of 1N4479US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4479US/TR is usually 5 days.
3.What payment methods are accepted for 1N4479US/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4479US/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4479US/TR?
1N4479US/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4479US/TR 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 1N4479US/TR?
For technical support, including 1N4479US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4479US/TR requirements.
6.How does Aetrix verify that 1N4479US/TR is sourced from the original manufacturer or authorized distributors?
All 1N4479US/TR 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 1N4479US/TR meets industry standards.
7.What is the process for return or replacement of 1N4479US/TR?
All 1N4479US/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4479US/TR, 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 1N4479US/TR part is unused and in its original packaging.
Return procedure for 1N4479US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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