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Microchip Technology 1N4985US/TR
- Part No.:
- 1N4985US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, E
- Datasheet:
-
1N4985US/TR.pdf
- Description:
- DIODE ZENER 130V 5W E-MELF
- Quantity:
- Payment:
- Shipping:
Inventory:95
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Product details
Overview
1N4985US/TR from Microsemi is a surface-mount, voidless-hermetically-sealed glass Zener diode rated for 5 W power dissipation at TEC = 125 °C, with nominal Zener voltage of 130 V at 10 mA test current, ±5% tolerance, and maximum dynamic impedance of 190 Ω at IZT. It serves as a precision voltage reference or overvoltage clamp in high-reliability aerospace, defense, and industrial power regulation circuits.
For engineers reviewing the 1N4985US/TR datasheet, 1N4985US/TR pinout, 1N4985US/TR application, or 1N4985US/TR equivalent, key selection criteria include its hermetic glass package, -65 °C to +175 °C operating temperature range, 1.5 V forward voltage at 1.0 A, 2 μA reverse leakage at 104 V, and radiation-hardened construction per MicroNote 050.
Technical Context
This device belongs to the MIL-PRF-19500/356-qualified 1N4954US–1N4996US series, employing triple-layer passivation and Category I internal metallurgical bonds for long-term stability under thermal cycling and mechanical stress. Its voidless-glass construction eliminates moisture ingress pathways and supports operation across extreme ambient conditions without derating until 125 °C end-cap temperature.
The 1N4985US/TR exhibits a Zener voltage temperature coefficient of +0.105 %/°C, enabling predictable drift behavior in wide-temperature designs. Its surge capability includes 1.8 A non-repetitive 8.3 ms square-wave current (IZSM) and 1250 W peak surge power at 1 ms, validated per Figure 1 in SD44A.pdf.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage VZ | 130 V at IZT = 10 mA - stable regulation point for high-voltage reference or clamping |
| Power Dissipation | 5 W @ TEC = 125 °C - requires heatsinking or thermal pad design for sustained operation |
| Dynamic Impedance ZZ | 190 Ω at IZT - low AC impedance ensures minimal output voltage variation under load transients |
| Reverse Leakage IR | 2 μA at VR = 104 V - enables low-power standby modes without significant quiescent loss |
| Forward Voltage VF | 1.50 V at IF = 1.0 A - defines conduction loss when used in bidirectional protection configurations |
| Temp Coefficient αVZ | +0.105 %/°C - quantifies predictable positive drift for compensation in precision references |
| Surge Current IZSM | 1.8 A (8.3 ms) - withstands transient overvoltage events without degradation |
Pinout & Package
Package: Hermetically sealed voidless hard glass case with tungsten slugs; "E" package (also designated D-5B), surface-mount, cathode indicated by band; weight 539 mg; terminations: copper end caps with Sn/Pb finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal in forward bias | Connected to lower-potential node; must handle 1.0 A continuous forward current |
| Cathode | Current exit terminal in forward bias; Zener breakdown terminal | Banded end; connected to higher-potential node during regulation; defines 130 V reference level |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Eliminates moisture-induced parameter shift and corrosion failure in humid or vacuum environments |
| Category I metallurgical bond | Ensures mechanical integrity and thermal cycle reliability up to 1000 cycles between -65 °C and +175 °C |
| Triple-layer passivation | Prevents surface leakage and contamination-induced breakdown instability over lifetime |
| Nonsensitive to ESD | Qualified per MIL-STD-750 Method 1020 - no special handling required during assembly |
| Radiation hardness | Validated per Microsemi MicroNote 050 - suitable for space-grade and nuclear instrumentation applications |
Applications
| Avionics Power Monitoring | Military Radar Bias Supply |
|---|---|
|
Use Scenario: Regulating auxiliary 130 V rail in airborne radar receiver front-end modules subject to wide thermal excursions and vibration. IC Role / Device Role / Timing Role: Zener diode acting as shunt voltage reference and overvoltage clamp. Use Value: Maintains stable 130 V reference despite -55 °C to +125 °C ambient swings and meets DO-160 Section 22 lightning-induced transient immunity. |
Use Scenario: Providing precise bias voltage for GaN RF power amplifier stages in ground-based tactical radar transmitters. IC Role / Device Role / Timing Role: High-reliability shunt regulator ensuring consistent gate bias under pulsed RF load conditions. Use Value: Delivers <2 μA leakage at 104 V and survives 1.8 A surge events inherent in radar pulse modulation. |
| Satellite Power Distribution Unit | Nuclear Instrumentation Signal Conditioning |
|
Use Scenario: Voltage clamping on DC-DC converter outputs in LEO satellite EPS subsystems exposed to total ionizing dose (TID). IC Role / Device Role / Timing Role: Radiation-hardened Zener clamp protecting downstream ADC references from bus transients. Use Value: Leverages inherent radiation hardness per MicroNote 050 and hermetic seal to prevent parametric drift after 100 krad(Si) exposure. |
Use Scenario: Stabilizing high-voltage detector bias supplies in neutron/gamma spectroscopy systems operating in reactor containment zones. IC Role / Device Role / Timing Role: Precision shunt reference maintaining calibration integrity across extended maintenance intervals. Use Value: Achieves ±5% initial tolerance and <0.105%/°C TC for <±0.5% total drift over -25 °C to +70 °C operational range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4985US | Same electrical specs and package; differs only in packaging format (bulk vs. tape-and-reel) | No functional difference; identical use in PCB assembly | Select 1N4985US/TR for automated SMT placement; choose 1N4985US for manual prototyping or low-volume hand-soldering |
| 1N4985 | Axial-leaded version (no "US" suffix); same VZ, IZM, and thermal ratings but different mechanical form factor | Requires through-hole mounting; incompatible with SMT layout; higher thermal resistance due to leadframe path | Choose 1N4985 only when legacy through-hole assembly is mandated or board rework access is prioritized over density |
Compared with 1N4985US/TR, the 1N4985US offers identical performance in bulk packaging, while the axial 1N4985 trades surface-mount compatibility for easier socketing and thermal inspection-critical for field-serviceable nuclear instrumentation calibrators.
Availability
1N4985US/TR is available at Aetrix Electronics and suitable for avionics power monitoring, military radar bias supply, and satellite power distribution units requiring stable component supply across extended temperature ranges and mission-critical reliability.
Supply support for 1N4985US/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 1N4985US/TR belongs to Microsemi's MIL-PRF-19500/356-qualified Zener family, engineered for fail-safe voltage regulation in systems where parameter stability under radiation, thermal shock, and long-term storage is non-negotiable.
FAQ
What is the Zener voltage tolerance for 1N4985US/TR?
The 1N4985US/TR has a standard ±5% Zener voltage tolerance at IZT = 10 mA, as specified in the Electrical Characteristics table on page 2 of SD44A.pdf. No suffix indicates this standard tolerance; tighter tolerances (e.g., ±2% or ±1%) require C or D suffixes not present in the 1N4985US/TR part number.
Does 1N4985US/TR require derating above 125 °C?
Yes - the 1N4985US/TR is rated for 5 W dissipation only at TEC = 125 °C. Power must be linearly derated to zero at 175 °C junction temperature, per the Maximum Ratings section. This requires thermal design that limits end-cap temperature to ≤125 °C under full load.
Is 1N4985US/TR compatible with lead-free soldering processes?
No - the 1N4985US/TR features Sn/Pb (tin/lead) finish on copper end caps, as stated in the Mechanical and Packaging section. It is not RoHS-compliant and requires eutectic solder profiles; lead-free reflow will compromise termination integrity and voidless seal reliability.
What is the maximum reverse leakage current for 1N4985US/TR?
The maximum reverse leakage current for 1N4985US/TR is 2 μA at VR = 104 V and TA = 25 °C, per the Electrical Characteristics table. This value remains stable across the full -65 °C to +175 °C operating range due to hermetic sealing and triple-layer passivation.
Can 1N4985US/TR be used in radiation-intensive environments?
Yes - the 1N4985US/TR is inherently radiation-hardened, as documented in Microsemi MicroNote 050. Its voidless-glass construction and Category I metallurgical bond provide proven resilience to total ionizing dose (TID) and displacement damage, making it suitable for satellite and nuclear instrumentation applications.
1N4985US/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):
- 130 V
- Tolerance:
- ±5%
- Power - Max:
- 5 W
- Impedance (Max) (Zzt):
- 190 Ohms
- Current - Reverse Leakage @ Vr:
- 2 µA @ 98.8 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
1N4985US/TR FAQ
1.How can I place an order for 1N4985US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4985US/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 1N4985US/TR reliable?
The price and inventory of 1N4985US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4985US/TR is usually 5 days.
3.What payment methods are accepted for 1N4985US/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4985US/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4985US/TR?
1N4985US/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4985US/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 1N4985US/TR?
For technical support, including 1N4985US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4985US/TR requirements.
6.How does Aetrix verify that 1N4985US/TR is sourced from the original manufacturer or authorized distributors?
All 1N4985US/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 1N4985US/TR meets industry standards.
7.What is the process for return or replacement of 1N4985US/TR?
All 1N4985US/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4985US/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 1N4985US/TR part is unused and in its original packaging.
Return procedure for 1N4985US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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