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Microchip Technology JANTX1N4978US/TR
- Part No.:
- JANTX1N4978US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, E
- Datasheet:
-
JANTX1N4978US/TR.pdf
- Description:
- DIODE ZENER 68V 5W E-MELF
- Quantity:
- Payment:
- Shipping:
Inventory:7,288
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Product details
Overview
JANTX1N4978US/TR from Microsemi is a military-grade, hermetically sealed surface-mount Zener diode with 68 V nominal zener voltage, 5 W power rating at 140 °C end-cap temperature, and ±5% tolerance. It delivers stable voltage regulation in high-reliability aerospace, defense, and downhole instrumentation systems where failure is unacceptable.
For engineers reviewing the JANTX1N4978US/TR datasheet, JANTX1N4978US/TR pinout, JANTX1N4978US/TR application, or JANTX1N4978US/TR equivalent, this part is selected for extreme-temperature operation (–65 °C to +175 °C), radiation-hardened environments, and ESD-insensitive power rail stabilization requiring voidless-glass reliability.
Technical Context
This device operates as a precision shunt voltage regulator in reverse-biased breakdown mode, maintaining 68 V across its terminals over a continuous current range of 2.2 mA to 930 mA. Its dynamic impedance is 50 Ω at 20 mA test current and 500 Ω near the knee (1 mA), enabling low-noise reference stability under varying load conditions.
The JANTX1N4978US/TR uses a Category I internal metallurgical bond within a voidless hard-glass package with tungsten slugs and copper end caps (Sn/Pb finish), meeting MIL-PRF-19500/356 Class JANTX requirements. Thermal resistance is 7 °C/W junction-to-end-cap, supporting robust thermal management in conduction-cooled PCB layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 68 V ±5% at 20 mA - defines regulated output voltage under standard bias; used for precision reference generation |
| Power Dissipation | 5 W @ TEC = 140 °C - maximum steady-state power handling before thermal derating begins |
| Operating Temperature | –65 °C to +175 °C - enables deployment in jet engine bays, space avionics, and oilfield electronics |
| Dynamic Impedance (ZZT) | 50 Ω @ IZT = 20 mA - low AC impedance ensures minimal output voltage variation under ripple or transient load changes |
| Reverse Leakage (IR) | 2 μA @ VR = 54.4 V - guarantees negligible standby current in high-impedance sensing circuits |
| Surge Current (IZSM) | 18.7 A @ 8.3 ms - withstands short-duration transients such as lightning-induced surges or inductive switch-off spikes |
| Forward Voltage (VF) | 1.5 V @ 1.0 A - supports use as a forward-conducting clamp or series protection element when needed |
Pinout & Package
Package: Hermetically sealed voidless hard-glass "E" package (also designated D-5B), surface-mount, two-terminal device with cathode band marking. End caps are copper with Sn/Pb finish; weight 539 mg.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Reference ground node | Connected to system ground or lowest potential point; establishes return path for zener current |
| Cathode | Regulated output node | Connected to voltage rail being stabilized; polarity marked by visible band on glass body |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Eliminates moisture ingress and internal delamination risk over 20+ year field life in humid or corrosive environments |
| Category I metallurgical bond | Ensures mechanical integrity and thermal cycling reliability exceeding 1000 cycles between –65 °C and +175 °C |
| Nonsensitive to ESD | Qualified per MIL-STD-750 Method 1020 - no special handling required during assembly or field maintenance |
| Inherent radiation hardness | Validated per Microsemi MicroNote 050 - suitable for low-earth orbit and nuclear instrumentation without shielding |
| Tape-and-reel packaging | EIA-481-B compliant - enables automated SMT placement without manual handling or contamination risk |
Applications
| Aerospace Power Conditioning | Downhole Telemetry Systems |
|---|---|
|
Use Scenario: Regulating auxiliary 28 V DC bus in satellite power distribution units exposed to thermal vacuum and total ionizing dose. IC Role / Device Role / Timing Role: Shunt voltage regulator providing stable reference for DC-DC converter feedback loops and telemetry sensor excitation. Use Value: Maintains regulation accuracy within ±5% across –65 °C to +125 °C operating range while surviving 100 krad(Si) TID exposure. |
Use Scenario: Stabilizing bias voltage for piezoelectric pressure sensors deployed at 175 °C in oil/gas well logging tools. IC Role / Device Role / Timing Role: Precision voltage reference source for analog front-end amplifiers and ADC drivers in high-temperature ASICs. Use Value: Delivers <2 μA leakage at 54.4 V and 175 °C, minimizing sensor offset drift and extending calibration intervals. |
| Military Radar Transmitter Bias | Nuclear Instrumentation Front-Ends |
|
Use Scenario: Providing stable gate bias for GaN RF power amplifiers in airborne radar modules subject to vibration and EMI. IC Role / Device Role / Timing Role: High-reliability shunt regulator protecting amplifier bias rails from supply ripple and switching noise. Use Value: 50 Ω dynamic impedance suppresses 100 kHz–1 MHz ripple; 18.7 A surge rating absorbs pulsed EMI events. |
Use Scenario: Generating reference voltage for pulse-height analyzers in reactor monitoring systems requiring long-term stability. IC Role / Device Role / Timing Role: Radiation-hardened voltage reference ensuring consistent gain calibration across decades of service. Use Value: Inherent radiation hardness eliminates need for periodic recalibration or shielding mass in containment zones. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| JANTXV1N4978US | Higher screening level (JANTXV vs JANTX); tighter ΔVZ spec (±2.5% vs ±5%) and extended burn-in | Required for mission-critical flight hardware where parametric drift must be minimized over 15+ year service life | Select JANTXV1N4978US when full MIL-PRF-19500/356 Class JANTXV compliance and enhanced lot traceability are mandated |
| 1N4978US | Commercial-grade version; same electrical specs but no MIL-qualified screening, no radiation hardness validation | Suitable for industrial test equipment or non-safety-critical avionics where cost and lead time outweigh radiation/longevity needs | Choose 1N4978US for prototyping or commercial derivatives where military qualification is not contractually required |
Compared with JANTX1N4978US/TR, JANTXV1N4978US offers superior parametric stability for flight-critical systems, while 1N4978US provides identical electrical behavior at lower cost and shorter lead time for non-military designs.
Availability
JANTX1N4978US/TR is available at Aetrix Electronics and suitable for aerospace power conditioning, downhole telemetry systems, and military radar transmitter bias requiring stable component supply across extended temperature and radiation environments.
Supply support for JANTX1N4978US/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 (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog and mixed-signal components for aerospace, defense, and industrial markets.
The JANTX1N4978US/TR belongs to Microsemi's MIL-PRF-19500/356 qualified Zener diode family, engineered for fail-safe voltage regulation in mission-critical systems where long-term parametric stability and environmental survivability are non-negotiable.
FAQ
What is the Zener voltage tolerance for JANTX1N4978US/TR?
The JANTX1N4978US/TR has a nominal Zener voltage of 68 V with a standard tolerance of ±5%, as specified in the Microsemi SD44A datasheet. This tolerance applies at 20 mA test current and 25 °C ambient, and is maintained across the full military temperature range (–65 °C to +175 °C) per MIL-PRF-19500/356 screening.
Does JANTX1N4978US/TR require derating above 140 °C?
Yes - JANTX1N4978US/TR is rated for 5 W dissipation only at an end-cap temperature (TEC) of 140 °C. Above that, power must be linearly derated to zero at 175 °C, yielding a derating factor of 143 mW/°C. This reflects its 7 °C/W junction-to-end-cap thermal resistance and must be accounted for in thermal design.
Is JANTX1N4978US/TR compatible with lead-free solder reflow profiles?
No - JANTX1N4978US/TR features Sn/Pb (tin/lead) terminations and is not qualified for Pb-free reflow. Its end caps are designed for eutectic solder (183 °C peak). Lead-free processes exceeding 220 °C may compromise the hermetic glass-to-metal seal integrity and voidless construction.
What is the maximum reverse leakage current for JANTX1N4978US/TR?
The maximum reverse leakage current for JANTX1N4978US/TR is 2 μA at 54.4 V (80% of VZ) and 25 °C, per the SD44A datasheet. At 175 °C, leakage remains ≤2 μA due to the device's Category I metallurgical bond and hermetic sealing, making it suitable for high-temperature sensor biasing.
Can JANTX1N4978US/TR be used in forward conduction mode?
Yes - JANTX1N4978US/TR has a maximum forward voltage of 1.5 V at 1.0 A, allowing use as a low-drop series clamp or crowbar element. However, its primary design function is reverse-bias Zener regulation; forward-mode operation should be limited to transient protection or auxiliary biasing, not continuous conduction.
JANTX1N4978US/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- SQ-MELF, E
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 68 V
- Tolerance:
- ±5%
- Power - Max:
- 5 W
- Impedance (Max) (Zzt):
- 50 Ohms
- Current - Reverse Leakage @ Vr:
- 2 µA @ 51.7 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 1 A
- Operating Temperature:
- -65°C ~ 175°C (TJ)
- Grade:
- Military
- Qualification:
- MIL-PRF-19500/356
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- E-MELF
JANTX1N4978US/TR FAQ
1.How can I place an order for JANTX1N4978US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for JANTX1N4978US/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 JANTX1N4978US/TR reliable?
The price and inventory of JANTX1N4978US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for JANTX1N4978US/TR is usually 5 days.
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Once your JANTX1N4978US/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 JANTX1N4978US/TR?
For technical support, including JANTX1N4978US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your JANTX1N4978US/TR requirements.
6.How does Aetrix verify that JANTX1N4978US/TR is sourced from the original manufacturer or authorized distributors?
All JANTX1N4978US/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 JANTX1N4978US/TR meets industry standards.
7.What is the process for return or replacement of JANTX1N4978US/TR?
All JANTX1N4978US/TR units undergo pre-shipment inspection (PSI). If there is an issue with JANTX1N4978US/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 JANTX1N4978US/TR part is unused and in its original packaging.
Return procedure for JANTX1N4978US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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