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Microchip Technology 1N987A
- Part No.:
- 1N987A
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-204AA, DO-7, Axial
- Datasheet:
-
1N987A.pdf
- Description:
- DIODE ZENER 120V 500MW DO7
- Quantity:
- Payment:
- Shipping:
Inventory:4,369
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Product details
Overview
1N987A from Microsemi is a silicon 500 mW axial-leaded Zener diode in DO-35 (DO-204AH) package, rated for 120 V nominal Zener voltage with ±10% tolerance (A suffix), 1.0 mA Zener test current, 900 Ω Zener impedance at IZT, and maximum reverse leakage of 5 μA at 91.2 V. It operates across –65 °C to +175 °C and is used for precision voltage reference and overvoltage protection in industrial power supplies.
For engineers reviewing the 1N987A datasheet, 1N987A pinout, 1N987A application, or 1N987A equivalent, key selection factors include its 120 V regulation point, ±10% voltage tolerance, DO-35 mechanical compatibility, thermal resistance of 250 °C/W (junction-to-lead), and compliance with JEDEC 1N987 series specifications.
Technical Context
The 1N987A functions as a two-terminal voltage reference device operating in reverse breakdown mode, where regulation occurs when cathode voltage exceeds anode by ≥120 V. Its Zener impedance of 900 Ω at 1.0 mA reflects dynamic resistance near the knee of the breakdown curve, directly impacting output stability under varying load currents.
It exhibits a positive temperature coefficient of +0.11 %/°C, meaning its Zener voltage increases with temperature - critical for designs requiring thermal drift compensation. The device is rated for 400 mW steady-state dissipation at 75 °C lead temperature and supports surge currents up to 15 mA (1/120 sec pulse).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Zener Voltage | 120 V ±10% - defines primary regulation threshold; actual VZ falls between 108 V and 132 V at IZT = 1.0 mA |
| Zener Test Current | 1.0 mA - standardized bias point for measuring VZ; operation below this may yield unstable regulation |
| Zener Impedance | 900 Ω at IZT - indicates dynamic resistance affecting voltage deviation under load transients |
| Max Reverse Leakage | 5 μA at 91.2 V - ensures minimal standby current in high-impedance bias networks |
| Power Dissipation | 500 mW at TL ≤ 50 °C (3/8″ lead length) - derates linearly above 50 °C per Figure 1 |
| Operating Temperature | –65 °C to +175 °C - enables use in aerospace, downhole, and military environments without derating |
| Thermal Resistance | 250 °C/W junction-to-lead - determines temperature rise under given power; critical for thermal design margin |
Pinout & Package
Package: DO-35 (DO-204AH), hermetically sealed glass axial-leaded case with tin-lead or RoHS-compliant matte-tin plating; cathode identified by color band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Reference ground node | Connected to system ground or lower-potential rail; reverse-biased operation requires cathode > anode |
| Cathode | Regulated output node | Banded end; provides stable 120 V reference when reverse-biased; must be held >108 V for regulation |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC-registered Zener series | Guarantees interoperability and standardized test conditions across manufacturers' 1N987A equivalents |
| ±10% voltage tolerance (A suffix) | Enables cost-effective regulation where tight accuracy is not required, e.g., coarse overvoltage clamping |
| Nonsensitive to ESD (MIL-STD-750 Method 1020) | Eliminates need for external ESD protection in handling and board-level assembly |
| Hermetic glass DO-35 package | Provides long-term reliability in humid or corrosive environments; no moisture ingress degradation |
| Minimal capacitance (typ. <2 pF) | Preserves high-frequency signal integrity in RF bias networks and fast transient suppression circuits |
Applications
| Industrial Power Supply Regulation | Overvoltage Protection Circuit |
|---|---|
Use Scenario: Stabilizing reference voltage for feedback loops in 120 V DC-DC converters and linear regulators. IC Role / Device Role / Timing Role: Two-terminal passive voltage reference providing fixed 120 V threshold for error amplifier biasing. Use Value: Maintains output regulation within ±10% across –40 °C to +85 °C ambient, supporting MIL-PRF-28804 Class B compliance. |
Use Scenario: Clamping transient surges on 100 V bus lines in motor drive inverters and PLC I/O modules. IC Role / Device Role / Timing Role: Shunt protection element that conducts only above 108 V, diverting excess energy to ground. Use Value: Limits peak voltage to ≤132 V with 15 mA surge capability, preventing damage to downstream MOSFET gate drivers. |
| High-Temperature Sensor Biasing | Aerospace Voltage Reference |
Use Scenario: Providing stable bias current to RTD or thermocouple signal conditioners in engine control units. IC Role / Device Role / Timing Role: Precision current source via series resistor + 120 V Zener drop, enabling ratiometric measurement. Use Value: Operates reliably at +150 °C junction temperature with <0.11 %/°C drift, minimizing sensor offset error. |
Use Scenario: Generating flight-critical reference voltages in satellite power distribution units exposed to radiation. IC Role / Device Role / Timing Role: Radiation-hardened voltage standard replacing active references in analog telemetry chains. Use Value: Inherent radiation hardness (per MicroNote 050) eliminates need for shielding or redundancy in LEO missions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N987B | ±5% tolerance (B suffix) vs. ±10% for 1N987A; identical VZ = 120 V, IZT = 1.0 mA, ZZT = 900 Ω | Used where tighter regulation is required, e.g., calibration equipment or metrology-grade references | Select 1N987B when ±5% VZ accuracy is mandatory; otherwise 1N987A offers cost advantage for general-purpose clamping |
| 1N5242B | Lower voltage (12 V), higher IZT (20 mA), lower ZZT (30 Ω); same DO-35 package but non-JEDEC 1N9xx family | Suitable for low-voltage logic rail clamping, not direct replacement for 120 V systems | Choose 1N5242B only for 12 V applications; not interchangeable with 1N987A due to voltage and impedance mismatch |
Compared with 1N987B and 1N5242B, the 1N987A balances cost and performance for mid-voltage (100–150 V) industrial clamping, offering JEDEC-standardized 120 V regulation with relaxed tolerance - ideal where absolute precision is secondary to ruggedness and wide-temperature operation.
Availability
1N987A is available at Aetrix Electronics and suitable for industrial power supply regulation, overvoltage protection circuits, high-temperature sensor biasing, and aerospace voltage reference applications requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 1N987A 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, radiation-hardened, and high-temperature analog components for defense, aerospace, and industrial markets.
The 1N987A belongs to Microsemi's legacy JEDEC-registered 1N957B–1N992B Zener series, designed specifically for robust voltage regulation in harsh-environment applications where long-term stability and extreme temperature operation are mandatory.
FAQ
What is the Zener voltage tolerance for 1N987A?
The 1N987A has a nominal Zener voltage of 120 V with a ±10% tolerance, as indicated by the "A" suffix per JEDEC specification. This means the actual measured Zener voltage at 1.0 mA test current falls between 108 V and 132 V under standard test conditions defined in Microsemi's datasheet Rev C.
Can 1N987A be used in place of 1N987B?
No - the 1N987A and 1N987B are not interchangeable without circuit review. While both share 120 V nominal Zener voltage and DO-35 packaging, the 1N987A has ±10% tolerance versus ±5% for the 1N987B. Substituting 1N987A into a design calibrated for 1N987B may cause regulation errors exceeding system specifications.
What is the maximum power dissipation for 1N987A at 75°C lead temperature?
At a lead temperature of 75 °C (measured 3/8″ from body), the 1N987A is rated for 400 mW maximum steady-state power dissipation, as calculated per Note 4 in the Microsemi datasheet. This is derated from its full 500 mW rating at ≤50 °C lead temperature using the specified thermal resistance of 250 °C/W.
Does 1N987A have RoHS-compliant variants?
Yes - Microsemi offers RoHS-compliant versions of the 1N987A by adding the "e3" suffix (e.g., 1N987Ae3), which denotes annealed matte-tin plating compliant with EU RoHS Directive 2011/65/EU. These retain identical electrical and thermal specifications but meet environmental compliance requirements for modern PCB assembly.
What is the reverse leakage current specification for 1N987A?
The 1N987A has a maximum reverse leakage current of 5 μA when tested at 91.2 V (76% of nominal 120 V), per the Electrical Characteristics table on page 2 of the Microsemi datasheet. This low leakage supports high-impedance bias networks and minimizes standby power loss in always-on circuits.
1N987A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- DO-204AA, DO-7, Axial
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 120 V
- Tolerance:
- ±10%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 900 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 91.2 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.1 V @ 200 mA
- Operating Temperature:
- -65°C ~ 175°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-7
1N987A FAQ
1.How can I place an order for 1N987A through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N987A 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 1N987A reliable?
The price and inventory of 1N987A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N987A is usually 5 days.
3.What payment methods are accepted for 1N987A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N987A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N987A?
1N987A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N987A 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 1N987A?
For technical support, including 1N987A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N987A requirements.
6.How does Aetrix verify that 1N987A is sourced from the original manufacturer or authorized distributors?
All 1N987A 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 1N987A meets industry standards.
7.What is the process for return or replacement of 1N987A?
All 1N987A units undergo pre-shipment inspection (PSI). If there is an issue with 1N987A, 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 1N987A part is unused and in its original packaging.
Return procedure for 1N987A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N987A Tags
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MMBZ5240B-7-F
Diodes Incorporated
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BZT52C5V6T-7
Diodes Incorporated
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MMSZ5231B-7-F
Diodes Incorporated
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BZT52C15-7-F
Diodes Incorporated
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BZX84C3V3LT1G
onsemi
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MMSZ5245BS-7-F
Diodes Incorporated
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
Diodes Incorporated
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MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
Micro Commercial Co
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BZT52C3V6LP-7
Diodes Incorporated
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SMAZ12-13-F
Diodes Incorporated
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