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Microchip Technology 1N4994US/TR
- Part No.:
- 1N4994US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, E
- Datasheet:
-
1N4994US/TR.pdf
- Description:
- DIODE ZENER 330V 5W E-MELF
- Quantity:
- Payment:
- Shipping:
Inventory:98
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Product details
Overview
1N4994US/TR from Microsemi is a surface-mount, hermetically sealed, voidless-glass 5 W Zener diode with nominal Zener voltage of 330 V, ±5% tolerance, 2 mA maximum reverse leakage at 252 V, and 1175 Ω dynamic impedance at 4 mA test current. It operates from −65 °C to +175 °C and is qualified to MIL-PRF-19500/356 for high-reliability power regulation in aerospace and defense systems.
For engineers reviewing the 1N4994US/TR datasheet, 1N4994US/TR pinout, 1N4994US/TR application, or 1N4994US/TR equivalent, this part serves as a rugged, radiation-hardened voltage reference and overvoltage clamp in mission-critical DC power rails where long-term stability and zero-failure tolerance are mandatory.
Technical Context
This device functions as a precision shunt voltage regulator in reverse-biased breakdown mode, maintaining stable output voltage across wide current (4 mA to 32 mA) and temperature (−65 °C to +175 °C) ranges. Its voidless-glass hermetic seal and Category I metallurgical bond ensure immunity to moisture ingress and mechanical stress.
It exhibits a positive temperature coefficient of +0.120 %/°C at 4 mA, enabling predictable thermal drift compensation in series-regulated supplies. The 1.5 V forward voltage at 1 A supports use in bidirectional protection configurations when paired with complementary devices.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 330 V nominal at 4 mA - sets precise clamping threshold for 300–360 V DC bus protection |
| Power Dissipation | 5 W @ TEC = 140 °C - enables sustained regulation without heatsinking in compact military enclosures |
| Dynamic Impedance (ZZ) | 1175 Ω at 4 mA - defines voltage regulation sensitivity to load current transients |
| Reverse Leakage (IR) | 2 μA max at 252 V - ensures minimal standby power loss in high-impedance bias networks |
| Temp Coefficient (αVZ) | +0.120 %/°C - allows accurate thermal drift modeling in wide-temperature avionics designs |
| Surge Current (IZSM) | 32 A @ 8.3 ms - withstands lightning-induced transients per MIL-STD-461/464 |
| Operating Temperature | −65 °C to +175 °C - supports operation in jet engine bays and space-grade electronics |
Pinout & Package
Package: Hermetically sealed voidless glass "E" package (also designated D-5B), with copper end caps and Sn/Pb finish; cathode indicated by band; weight 539 mg; tape-and-reel compliant per EIA-481-B.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-side reference node | Connected to system ground or lowest potential rail in shunt regulation topology |
| Cathode | Zener breakdown terminal / regulated output node | Connected to input rail; maintains 330 V relative to anode during overvoltage events |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Eliminates internal delamination risk under thermal cycling and humidity exposure |
| Category I metallurgical bond | Guarantees mechanical integrity of die-to-leadframe interface per MIL-PRF-19500/356 |
| Nonsensitive to ESD | Withstands >4 kV HBM per MIL-STD-750 Method 1020 without parameter shift |
| Inherent radiation hardness | Qualified per MicroNote 050 for total ionizing dose (TID) up to 100 krad(Si) |
| Triple-layer passivation | Prevents surface conduction paths and leakage growth in high-voltage bias conditions |
Applications
| Aerospace Power Distribution | Defense Radar Transmitter Bias |
|---|---|
|
Use Scenario: Regulating high-voltage bias supply for traveling-wave tube (TWT) collectors in airborne radar systems. IC Role / Device Role / Timing Role: Shunt Zener regulator maintaining stable 330 V collector rail despite input ripple and load step changes. Use Value: Prevents TWT gain collapse and arcing by holding voltage within ±1.5 V over −55 °C to +125 °C ambient. |
Use Scenario: Overvoltage protection for pulse modulator charging circuits in ground-based missile guidance radars. IC Role / Device Role / Timing Role: Clamping transient spikes above 330 V during capacitor bank switching events. Use Value: Absorbs 32 A surge currents without degradation, preserving downstream GaN switch reliability. |
| Satellite Solar Array Regulation | Nuclear Instrumentation Supply |
|
Use Scenario: Reference stabilization in MPPT controllers for high-voltage solar array strings (200–400 V). IC Role / Device Role / Timing Role: Precision voltage reference for ADC feedback loop in radiation-hardened DC-DC converters. Use Value: Maintains <±0.5% voltage accuracy after 100 krad(Si) TID exposure, ensuring consistent power harvesting. |
Use Scenario: High-stability bias source for photomultiplier tube (PMT) dynode chains in reactor monitoring systems. IC Role / Device Role / Timing Role: Low-noise, low-drift Zener reference generating cascaded dynode voltages. Use Value: Delivers <2 μA leakage at 252 V, minimizing dark current error in neutron detection signals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4994US | No TR suffix; bulk packaging instead of tape-and-reel | Same electrical specs; unsuitable for automated SMT placement | Select 1N4994US/TR for pick-and-place assembly; choose 1N4994US for manual prototyping or repair |
| JANTXV1N4994US | MIL-PRF-19500/356 JANTXV screening level; full lot traceability and extended testing | Required for Class H/V spaceflight hardware; adds ~35% cost and 8-week lead time | Specify JANTXV1N4994US only when DoD or NASA mission assurance requirements mandate Level V screening |
Compared with 1N4994US/TR, the 1N4994US lacks reel packaging but matches all electrical and environmental specs, while JANTXV1N4994US adds rigorous military screening for flight-critical use-neither is pin-compatible with non-US variants like 1N4994.
Availability
1N4994US/TR is available at Aetrix Electronics and suitable for aerospace power distribution, defense radar transmitter bias, and satellite solar array regulation requiring stable component supply across extended temperature and radiation environments.
Supply support for 1N4994US/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 1N49xxUS series belongs to Microsemi's military-qualified Zener regulator product line, engineered specifically for fail-safe voltage reference and transient suppression in safety-critical power systems.
FAQ
What is the Zener voltage tolerance for 1N4994US/TR?
The 1N4994US/TR has a nominal Zener voltage of 330 V with a standard tolerance of ±5%, as specified in the Microsemi SD44A datasheet. No suffix indicates this default tolerance; tighter tolerances (e.g., ±1% or ±2%) require different part number suffixes (D or C) not present in 1N4994US/TR.
Does 1N4994US/TR meet MIL-PRF-19500/356 requirements?
Yes, the 1N4994US/TR is qualified to MIL-PRF-19500/356 as a JAN-class Zener diode. It undergoes full military screening including temperature cycling, burn-in, and parametric verification per the specification, making it suitable for high-reliability defense and aerospace applications.
What is the maximum continuous Zener current for 1N4994US/TR?
The maximum continuous Zener current (IZM) for 1N4994US/TR is 32 mA at 25 °C, derived from its 5 W power rating and 330 V Zener voltage. Derating applies above 140 °C case temperature, reaching zero at 175 °C per linear thermal derating curve.
Is 1N4994US/TR radiation hardened?
Yes, the 1N4994US/TR is inherently radiation hard per Microsemi MicroNote 050, demonstrating functional stability up to 100 krad(Si) total ionizing dose without parameter shift-critical for satellite and nuclear instrumentation use.
What package type does 1N4994US/TR use?
The 1N4994US/TR uses the "E" package (also known as D-5B): a hermetically sealed voidless glass surface-mount outline with tungsten slugs, copper end caps, and Sn/Pb finish. Cathode polarity is marked by a visible band on the glass body.
1N4994US/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):
- 330 V
- Tolerance:
- ±5%
- Power - Max:
- 5 W
- Impedance (Max) (Zzt):
- 1175 Ohms
- Current - Reverse Leakage @ Vr:
- 2 µA @ 251 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:
- E-MELF
1N4994US/TR FAQ
1.How can I place an order for 1N4994US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4994US/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 1N4994US/TR reliable?
The price and inventory of 1N4994US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4994US/TR is usually 5 days.
3.What payment methods are accepted for 1N4994US/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4994US/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4994US/TR?
1N4994US/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4994US/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 1N4994US/TR?
For technical support, including 1N4994US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4994US/TR requirements.
6.How does Aetrix verify that 1N4994US/TR is sourced from the original manufacturer or authorized distributors?
All 1N4994US/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 1N4994US/TR meets industry standards.
7.What is the process for return or replacement of 1N4994US/TR?
All 1N4994US/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4994US/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 1N4994US/TR part is unused and in its original packaging.
Return procedure for 1N4994US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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