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Microchip Technology 1N485A
- Part No.:
- 1N485A
- Manufacturer:
- Microchip Technology
- Category:
- Single Diodes
- Package:
- DO-204AA, DO-7, Axial
- Datasheet:
-
1N485A.pdf
- Description:
- DIODE GEN PURP 180V 100MA DO7
- Quantity:
- Payment:
- Shipping:
Inventory:2,126
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Product details
Overview
1N485A from Microsemi is a hermetically sealed glass-packaged switching diode with 180 V DC reverse voltage rating, 200 mA maximum operating current at 25°C, and 500 mW total power dissipation. It features metallurgically bonded double-plug construction and is rated for operation from –65°C to +175°C, commonly used in high-reliability military timing and pulse conditioning circuits.
For engineers reviewing the 1N485A datasheet, 1N485A pinout, 1N485A application, or 1N485A equivalent, key selection factors include its MIL-PRF-19500/118 compliance, DO-7 hermetic glass package, thermal impedance of 70°C/W, and guaranteed low leakage (≤0.025 µA at 180 V, 25°C).
Technical Context
The 1N485A is a silicon switching diode built using metallurgical bonding and double-plug construction inside a hermetically sealed DO-7 glass package. Its design supports fast recovery and stable leakage performance across extreme temperatures.
It operates with a forward voltage of 0.8–1.0 V at 100 mA and 25°C, and exhibits reverse leakage ≤0.025 µA at VRWM = 180 V and 25°C. Thermal impedance is specified at ≤70°C/W, enabling reliable power handling up to 500 mW at ambient 25°C with linear derating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Package | DO-7 hermetically sealed glass per MIL-PRF-19500/118 |
| VRWM | 180 V - maximum continuous reverse voltage before significant leakage |
| IF(max) @ 25°C | 200 mA - max DC forward current without exceeding thermal limits |
| Ptot @ 25°C | 500 mW - total power dissipation limit at ambient 25°C |
| ZθJX | 70°C/W - junction-to-ambient thermal resistance, critical for thermal design margin |
| IR @ 180 V, 25°C | ≤0.025 µA - ultra-low reverse leakage ensures signal integrity in high-impedance bias networks |
Pinout & Package
Hermetically sealed DO-7 glass package with axial leads; cathode identified by blue body coat and black band marking. Lead material is copper-clad steel with tin/lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry point | Connected to lower-potential node in series-switching or clamping configuration |
| Cathode | Forward current exit / reverse-blocking terminal | Banded end; connects to higher-potential node or ground return in pulse shaping circuits |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic DO-7 package | Enables operation from –65°C to +175°C with no moisture-induced parameter drift |
| Metallurgically bonded junction | Improves thermal cycling reliability and reduces interfacial resistance vs. alloyed junctions |
| Double-plug construction | Enhances mechanical robustness and die attachment stability under shock/vibration |
| MIL-PRF-19500/118 compliance | Qualified for high-reliability aerospace, defense, and downhole applications |
Applications
| High-Voltage Pulse Clamping | Military Timing Reference Circuits |
|---|---|
|
Use Scenario: Protecting precision timing comparators from transient overvoltage in radar pulse generators. IC Role / Device Role / Timing Role: Fast-switching clamp diode limiting input swing to ±0.8 V while blocking 180 V reverse bias. Use Value: Maintains comparator accuracy by preventing latch-up via sub-1.0 V VF and <0.025 µA IR at 180 V. |
Use Scenario: Biasing crystal oscillator buffer stages in airborne navigation systems operating at –55°C to +125°C. IC Role / Device Role / Timing Role: DC path stabilizer providing temperature-stable reverse-biased isolation between oscillator core and output driver. Use Value: Hermetic DO-7 package ensures no parameter shift across thermal cycling; leakage remains ≤5.0 µA even at +150°C. |
| Downhole Instrumentation Power Rails | Avionics Signal Conditioning |
|
Use Scenario: Reverse-polarity protection and transient suppression on 28 V DC power inputs in oilfield logging tools. IC Role / Device Role / Timing Role: Series-connected switching diode providing fail-safe isolation during hot-swap events. Use Value: Withstands 2 A surge (8.3 ms sine) and maintains 50 mA forward current capability at +150°C ambient. |
Use Scenario: Waveform shaping in analog-to-digital converter front-end sample-and-hold circuits. IC Role / Device Role / Timing Role: Precision clipping element defining signal amplitude boundaries prior to ADC sampling. Use Value: Tight VF tolerance (0.8–1.0 V) and low ZθJX (70°C/W) ensure consistent clipping threshold across temperature and load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N485 | No JAN/JANTX/JANTXV qualification; same electrical specs and DO-7 package as 1N485A | Lacks MIL-PRF-19500/118 screening; unsuitable for Class H/K/Q military procurement | Select 1N485 only for commercial-grade replacements where extended temperature testing is not required |
| 1N485B | Identical DO-7 package and thermal specs; rated for 200 mA @ 25°C but with tighter IR spec (≤0.01 µA @ 180 V) | Available in JAN/JANTX/JANTXV grades; preferred for space-grade timing references requiring lowest leakage | Choose 1N485B when sub-0.025 µA leakage is mandatory; otherwise 1N485A offers optimal cost/performance balance |
Compared with 1N485 and 1N485B, the 1N485A delivers MIL-qualified reliability at standard leakage performance-making it the default choice for defense-grade pulse conditioning where full JANTXV screening is unnecessary but hermetic integrity is essential.
Availability
1N485A is available at Aetrix Electronics and suitable for high-reliability pulse clamping, military timing reference circuits, and downhole instrumentation requiring stable component supply across extended temperature ranges.
Supply support for 1N485A 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) designs high-reliability analog and discrete semiconductors for aerospace, defense, and industrial applications.
The 1N485A belongs to Microsemi's legacy MIL-PRF-19500/118 qualified switching diode family, engineered specifically for extreme-environment signal integrity and power rail protection.
FAQ
What is the maximum reverse voltage rating for the 1N485A?
The 1N485A has a DC reverse voltage (VRWM) rating of 180 V. This value represents the maximum continuous reverse-bias voltage the device can withstand without exceeding specified leakage current limits. At 25°C, reverse leakage is guaranteed ≤0.025 µA at this voltage, making the 1N485A suitable for high-voltage clamping and isolation in precision analog circuits.
Does the 1N485A meet MIL-PRF-19500/118 specifications?
Yes, the 1N485A is manufactured and tested per MIL-PRF-19500/118 for switching diodes. It complies with the DO-7 hermetic glass package requirements, including environmental testing, surge current capability (2 A, 8.3 ms), and extended temperature operation (–65°C to +175°C). The 1N485A is distinct from the non-qualified 1N485 variant.
What is the thermal impedance of the 1N485A and how does it affect layout?
The 1N485A has a maximum junction-to-ambient thermal impedance (ZθJX) of 70°C/W. This means each watt of dissipated power raises the junction temperature by up to 70°C above ambient. For reliable operation at 500 mW, PCB layout must minimize local heating-avoid enclosing the DO-7 package in thermally insulating enclosures and ensure adequate airflow or heatsinking if ambient exceeds 25°C.
How does the 1N485A differ from the 1N485B variant?
The 1N485B shares the same DO-7 package and basic ratings as the 1N485A but offers tighter reverse leakage (≤0.01 µA vs. ≤0.025 µA at 180 V, 25°C) and is available in JAN/JANTX/JANTXV screening levels. The 1N485A is qualified to MIL-PRF-19500/118 but lacks the enhanced screening of the 1N485B, making it appropriate for applications needing hermetic reliability without full space-grade leakage specs.
What is the forward voltage range of the 1N485A at 100 mA and 25°C?
The 1N485A exhibits a forward voltage (VF) between 0.8 V and 1.0 V when conducting 100 mA at 25°C ambient. This tight VF window ensures predictable voltage drop in series-switching and biasing applications. At –55°C, VF may rise to 1.2 V, which must be accounted for in low-temperature circuit margin analysis.
1N485A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- DO-204AA, DO-7, Axial
- Packaging:
- Bulk
- Product Status:
- Active
- Technology:
- Standard
- Voltage - DC Reverse (Vr) (Max):
- 180 V
- Current - Average Rectified (Io):
- 100mA
- Voltage - Forward (Vf) (Max) @ If:
- 1 V @ 100 mA
- Speed:
- Small Signal =< 200mA (Io), Any Speed
- Reverse Recovery Time (trr):
- -
- Current - Reverse Leakage @ Vr:
- 25 nA @ 180 V
- Capacitance @ Vr, F:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-7
- Operating Temperature - Junction:
- -65°C ~ 175°C
1N485A FAQ
1.How can I place an order for 1N485A through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N485A 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 1N485A reliable?
The price and inventory of 1N485A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N485A is usually 5 days.
3.What payment methods are accepted for 1N485A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N485A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N485A?
1N485A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N485A 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 1N485A?
For technical support, including 1N485A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N485A requirements.
6.How does Aetrix verify that 1N485A is sourced from the original manufacturer or authorized distributors?
All 1N485A 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 1N485A meets industry standards.
7.What is the process for return or replacement of 1N485A?
All 1N485A units undergo pre-shipment inspection (PSI). If there is an issue with 1N485A, 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 1N485A part is unused and in its original packaging.
Return procedure for 1N485A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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