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Microchip Technology 1N4485US/TR
- Part No.:
- 1N4485US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, A
- Datasheet:
-
1N4485US/TR.pdf
- Description:
- DIODE ZENER 68V 1.5W D5A
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
1N4485US/TR from Microsemi is a hermetically sealed, voidless glass MELF surface-mount Zener diode rated for 1.5 W steady-state power dissipation, with a nominal Zener voltage of 68.0 V at 3.7 mA test current, ±5% tolerance, and maximum dynamic impedance of 100 Ω at IZT. It is qualified to MIL-PRF-19500/406 (JAN/JANTXV levels) and used in high-reliability voltage regulation for aerospace power conditioning circuits.
For engineers reviewing the 1N4485US/TR datasheet, 1N4485US/TR pinout, 1N4485US/TR application, or 1N4485US/TR equivalent, this page delivers verified military-grade Zener specifications, thermal derating behavior, junction-to-end-cap resistance, reverse leakage limits, and RoHS-compliant commercial availability - all critical for radiation-hardened, high-temperature, and fail-safe analog design.
Technical Context
This device operates as a precision shunt voltage regulator in the reverse breakdown region, with Zener voltage defined at IZT = 3.7 mA and knee current IZK = 0.25 mA. Its 100 Ω dynamic impedance at IZT and 1700 Ω at IZK ensures stable regulation across wide current ranges.
Thermal performance is characterized by RθJEC = 20 °C/W and a junction temperature range of –65 °C to +175 °C. The device uses internal Category III metallurgical bonds and triple-layer passivation, enabling operation under extreme thermal cycling and radiation exposure per MicroNote 050.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 68.0 V at IZT = 3.7 mA - defines nominal regulation point for stable reference in feedback loops |
| Power Dissipation (PD) | 1.5 W @ TA = 25 °C - sets maximum continuous DC power handling before thermal derating applies |
| Dynamic Impedance (ZZT) | 100 Ω @ IZT - determines output voltage variation under load current changes |
| Max Reverse Current (IR) | 0.25 µA @ VR = 54.4 V - specifies leakage below regulation threshold, critical for low-power standby circuits |
| Junction Temperature Range | –65 °C to +175 °C - enables deployment in avionics, downhole tools, and space-qualified systems |
| Thermal Resistance (RθJEC) | 20 °C/W - quantifies heat transfer efficiency from junction to end cap, guiding heatsink or PCB copper design |
| Forward Voltage (VF) | 1.0 V @ 200 mA - defines conduction loss during forward-biased transient protection or clamping |
Pinout & Package
Package: A (D-5A) MELF - hermetically sealed voidless glass body with tungsten slugs; cathode indicated by single polarity band; weight 193 mg; dimensions BD = 0.091–0.103 in, BL = 0.168–0.200 in.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-side connection in shunt regulator | Connected to system ground or lower potential node; carries full load current during regulation |
| Cathode | Zener breakdown terminal / high-side connection | Connected to regulated voltage rail; reverse-biased to maintain precise VZ under varying load |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass construction | Eliminates moisture ingress and internal delamination, ensuring long-term stability in humid or vacuum environments |
| Category III internal metallurgical bond | Provides mechanical robustness against thermal shock and vibration in launch-critical aerospace systems |
| MIL-PRF-19500/406 qualification (JAN/JANTXV) | Validates reliability for mission-critical applications requiring zero-failure probability over extended lifetimes |
| Triple-layer passivation | Reduces surface leakage and enhances long-term parameter drift immunity under ionizing radiation |
| Non-sensitive to ESD (MIL-STD-750 Method 1020) | Enables safe handling and assembly without special grounding protocols or ESD-safe workstations |
Applications
| Avionics Power Conditioning | Satellite Voltage Reference |
|---|---|
Use Scenario: Regulating auxiliary 28 V DC bus in flight control electronics under wide temperature (-55 °C to +125 °C) and radiation exposure. IC Role / Device Role / Timing Role: Shunt voltage reference providing stable bias for op-amps and ADC references. Use Value: Maintains ±5% regulation accuracy across 0.25–3.7 mA operating range while surviving 100 krad(Si) total ionizing dose. |
Use Scenario: Establishing precision bias points in star tracker analog front-ends aboard LEO satellites. IC Role / Device Role / Timing Role: Low-drift Zener reference for sensor signal conditioning circuitry. Use Value: Delivers <0.25 µA reverse leakage at 54.4 V, minimizing current draw from constrained battery systems. |
| Downhole Oilfield Instrumentation | Military Radar Bias Supply |
Use Scenario: Stabilizing high-voltage bias rails (>60 V) in logging-while-drilling (LWD) tools operating at 175 °C ambient. IC Role / Device Role / Timing Role: Primary shunt regulator in isolated DC-DC feedback path. Use Value: Sustains regulation integrity up to +175 °C junction temperature with no parameter shift beyond spec limits. |
Use Scenario: Providing stable gate bias for GaN RF power amplifiers in ground-based radar transmitters. IC Role / Device Role / Timing Role: High-reliability voltage clamp protecting amplifier input stages from transients. Use Value: Withstands 0.23 A surge current (8.3 ms square wave) and exhibits <100 Ω dynamic impedance for fast transient suppression. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4485US (non-TR) | Same electrical specs and package, but supplied in bulk or ammo pack instead of tape-and-reel | Preferred for prototyping or low-volume manual assembly where reel feeding is unnecessary | Select 1N4485US/TR when automated SMT placement is required; choose 1N4485US for hand-soldered evaluation boards |
| SMF68A (ON Semiconductor) | Surface-mount SOD-123 package, 68 V, 1 W rating, ±5%, 1000 Ω ZZT, non-military qualified | Suitable for commercial industrial controls but lacks MIL-PRF-19500/406 qualification and radiation hardness | Choose SMF68A only for cost-sensitive, non-safety-critical applications where military reliability and TID tolerance are not required |
Compared with 1N4485US/TR, the 1N4485US offers identical performance in non-automated contexts, while SMF68A trades military qualification and thermal robustness for lower cost and smaller footprint - making it viable only where environmental stress and lifetime reliability are secondary to BOM cost.
Availability
1N4485US/TR is available at Aetrix Electronics and suitable for avionics power conditioning, satellite voltage reference, and downhole instrumentation requiring stable component supply with guaranteed traceability and long-term obsolescence management.
Supply support for 1N4485US/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) designs high-reliability analog and mixed-signal semiconductors for aerospace, defense, and industrial markets, with emphasis on radiation-hardened, high-temperature, and MIL-spec components.
The 1N4485US/TR belongs to Microsemi's military-qualified Zener diode family engineered for fail-safe voltage regulation in systems where parameter stability under extreme thermal, mechanical, and radiation stress is non-negotiable.
FAQ
What is the Zener voltage tolerance for 1N4485US/TR?
The 1N4485US/TR has a nominal Zener voltage of 68.0 V with a standard tolerance of ±5%, as specified in the Electrical Characteristics table on page 3 of T4-LDS-0183-1. No suffix indicates 5% tolerance; tighter tolerances (±2% or ±1%) require different part number suffixes (C or D), which do not apply to the 1N4485US/TR variant.
Is 1N4485US/TR RoHS compliant?
Yes, the 1N4485US/TR is available in RoHS-compliant versions (marked with e3 suffix) for commercial-grade use. However, MIL-qualified versions (JAN/JANTXV) retain Sn/Pb terminations per specification requirements. Confirm RoHS compliance via the specific ordering part number's suffix and datasheet revision notes.
What is the maximum surge current rating for 1N4485US/TR?
The 1N4485US/TR supports a non-repetitive peak Zener surge current (IZSM) of 0.21 A for an 8.3 ms square wave pulse, as listed in the Electrical Characteristics table. This value reflects its capability to absorb transient energy without degradation when used in overvoltage protection circuits.
Does 1N4485US/TR require heatsinking in standard operation?
No external heatsink is required for 1N4485US/TR at ambient temperatures ≤25 °C and power dissipation ≤1.5 W. However, thermal derating begins above 25 °C per Figure 2, and PCB copper area or end-cap thermal paths must be designed to maintain RθJEC = 20 °C/W - especially above 85 °C ambient.
How is polarity marked on the 1N4485US/TR package?
The 1N4485US/TR uses a single cathode band on the glass MELF body to indicate polarity. The banded end is the cathode; the unmarked end is the anode. This marking aligns with JEDEC-standard MELF diode orientation and is visible under standard optical inspection during SMT placement verification.
1N4485US/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):
- 68 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 100 Ohms
- Current - Reverse Leakage @ Vr:
- 250 nA @ 54.4 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
1N4485US/TR FAQ
1.How can I place an order for 1N4485US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4485US/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 1N4485US/TR reliable?
The price and inventory of 1N4485US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4485US/TR is usually 5 days.
3.What payment methods are accepted for 1N4485US/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4485US/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4485US/TR?
1N4485US/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4485US/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 1N4485US/TR?
For technical support, including 1N4485US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4485US/TR requirements.
6.How does Aetrix verify that 1N4485US/TR is sourced from the original manufacturer or authorized distributors?
All 1N4485US/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 1N4485US/TR meets industry standards.
7.What is the process for return or replacement of 1N4485US/TR?
All 1N4485US/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4485US/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 1N4485US/TR part is unused and in its original packaging.
Return procedure for 1N4485US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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