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Microchip Technology 1N974A
- Part No.:
- 1N974A
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-204AA, DO-7, Axial
- Datasheet:
-
1N974A.pdf
- Description:
- DIODE ZENER 36V 500MW DO7
- Quantity:
- Payment:
- Shipping:
Inventory:8,167
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Product details
Overview
1N974A from Microsemi is a silicon 500 mW axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 36 V nominal Zener voltage with ±10% tolerance (A suffix), 3.4 mA Zener test current, 700 Ω dynamic impedance at IZT, and maximum 10 mA DC Zener current. It operates across –65 °C to +175 °C and serves as a precision voltage reference or shunt regulator in low-power analog circuits.
For engineers reviewing the 1N974A datasheet, 1N974A pinout, 1N974A application, or 1N974A equivalent, key selection criteria include its 36 V regulation point, ±10% tolerance, DO-35 glass-body construction, thermal resistance of 250 °C/W (junction-to-lead), and compatibility with through-hole PCB assembly requiring stable low-power voltage clamping.
Technical Context
The 1N974A functions as a shunt-connected voltage regulator, maintaining a stable 36 V across its terminals when reverse-biased above its breakdown threshold. Its Zener impedance of 700 Ω at 3.4 mA ensures predictable regulation under moderate load variation, while its 0.5 W power rating is derated linearly above 50 °C lead temperature.
It exhibits a positive temperature coefficient of +0.093 %/°C, indicating Zener voltage increases with junction temperature - a critical factor in high-temperature designs. The device uses a hermetically sealed glass DO-35 package with tin-lead or RoHS-compliant matte-tin plating, cathode identified by a band, and polarity-sensitive mounting (banded end positive for regulation).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Zener Voltage | 36 V ±10% - defines primary regulation setpoint for voltage reference or overvoltage clamp circuits |
| Zener Test Current | 3.4 mA - operating point at which VZ and ZZT are specified; used for calibration and biasing |
| Zener Impedance | 700 Ω @ IZT - quantifies AC voltage variation under changing load; impacts regulation accuracy |
| Max DC Zener Current | 10 mA - maximum continuous reverse current before exceeding 400 mW dissipation at 75 °C lead temp |
| Power Dissipation | 500 mW @ TL ≤ 50 °C (3/8″ from body) - sets thermal design margin for PCB trace width and copper area |
| Temp Coefficient | +0.093 %/°C - enables temperature-compensated reference design when paired with negative-TC components |
| Reverse Leakage | 5 μA @ 27.4 V - defines minimum bias current required to maintain regulation onset; affects low-current stability |
Pinout & Package
Package: DO-35 (DO-204AH), hermetically sealed glass axial-leaded case with cathode band marking. Tin-lead or RoHS-compliant matte-tin plating; weight 0.2 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Non-banded lead | Connected to lower-potential node; forward voltage ≤1.3 V @ 200 mA; not used in Zener regulation mode |
| Cathode | Banded lead | Connected to higher-potential node during reverse-bias regulation; carries full Zener current and heat |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC-registered Zener series | Ensures standardized electrical behavior and interchangeability across qualified suppliers |
| ±10% voltage tolerance (A suffix) | Supports cost-sensitive applications where tight regulation is not required, reducing BOM cost |
| –65 °C to +175 °C operating range | Enables deployment in automotive engine compartments, industrial controls, and aerospace subsystems |
| Nonsensitive to ESD (MIL-STD-750 Method 1020) | Eliminates need for external ESD protection in handling and board-level assembly |
| Minimal capacitance (typ. <2 pF) | Preserves high-frequency signal integrity in RF bias networks and fast-switching clamp circuits |
Applications
| Industrial Power Supply Monitoring | Automotive Sensor Reference |
|---|---|
Use Scenario: Monitoring 48 V DC bus voltage in programmable logic controller (PLC) backplanes using resistive divider + comparator. IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 36 V threshold for overvoltage detection circuitry. Use Value: Enables accurate trip point despite ambient temperature swings up to 125 °C due to +0.093 %/°C TC and wide operating range. |
Use Scenario: Biasing a pressure transducer bridge in an engine control unit (ECU) under under-hood conditions. IC Role / Device Role / Timing Role: Precision analog reference source for ratiometric sensor excitation and ADC reference scaling. Use Value: Maintains reference stability across –40 °C to +150 °C without active compensation, leveraging hermetic DO-35 reliability. |
| Telecom Line Card Protection | Medical Instrument Calibration |
Use Scenario: Clamping transient surges on -48 V telecom distribution rails during lightning-induced events. IC Role / Device Role / Timing Role: Low-energy shunt protector absorbing brief overvoltage spikes while limiting rail excursion to ≤36 V. Use Value: Survives repeated 100 mA surge pulses (1/120 sec) per JEDEC spec, with no parameter shift after 10⁴ cycles. |
Use Scenario: Factory calibration of portable blood glucose meter analog front-end gain stages. IC Role / Device Role / Timing Role: Traceable voltage standard used during production test to set 36 V reference points. Use Value: Delivers ±10% initial accuracy and <0.5% long-term drift over 5 years, meeting ISO 13485 calibration requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N974B | Same 36 V nominal voltage but ±5% tolerance (B suffix); lower ZZT = 700 Ω at 3.4 mA; identical package and thermal specs | Preferred where tighter regulation accuracy is required, e.g., precision instrumentation references | Select 1N974B when ±5% tolerance justifies higher unit cost; otherwise 1N974A suffices for general-purpose clamping |
| 1N4738A | 33 V nominal voltage, ±5% tolerance, 1 W power rating, DO-41 package; ZZT = 25 Ω @ 76 mA; higher surge capability | Suitable for higher-power regulation or where 33 V setpoint aligns with system architecture | Choose 1N4738A only if 33 V is acceptable and 1 W dissipation is needed; not a direct replacement due to voltage and package mismatch |
Compared with 1N974B and 1N4738A, the 1N974A offers the lowest cost for 36 V ±10% regulation in DO-35, balancing accuracy, thermal robustness, and legacy compatibility - ideal for cost-constrained industrial controls where ±10% is sufficient.
Availability
1N974A is available at Aetrix Electronics and suitable for industrial power supply monitoring, automotive sensor reference, and telecom line card protection requiring stable component supply and long-lifecycle support.
Supply support for 1N974A 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, RF, and radiation-hardened components for aerospace, defense, and industrial markets.
The 1N957B–1N992B series was designed to deliver JEDEC-standardized, glass-encapsulated Zener regulation with extended temperature range and metallurgical bond options for mission-critical analog subsystems.
FAQ
What is the Zener voltage tolerance for 1N974A?
The 1N974A has a nominal Zener voltage of 36 V with a ±10% tolerance, as indicated by the "A" suffix per Microsemi's documentation. This means the actual measured VZ at 3.4 mA test current falls between 32.4 V and 39.6 V at 25 °C. The tolerance is wider than the B-suffix variant (±5%), making the 1N974A suitable for non-critical voltage clamping where cost optimization is prioritized over precision.
Can 1N974A be used in surface-mount designs?
No, the 1N974A is packaged exclusively in the axial-leaded DO-35 (DO-204AH) glass case and is not a surface-mount device. For SMT equivalents, Microsemi offers the MLL974B series in DO-213AA (MELF) package - but note that MLL974B has ±5% tolerance and different thermal characteristics. Direct substitution requires PCB layout revision and requalification.
What is the maximum allowable surge current for 1N974A?
The 1N974A supports a maximum surge current (IZSM) of 55 mA for a 1/120 second duration square-wave or half-sine pulse, as specified in the Electrical Characteristics table. This value assumes proper PCB thermal design (e.g., 4 mm² copper pads) and is validated per JEDEC test methods. Exceeding this limit risks irreversible junction damage even if average power remains within 500 mW.
How does temperature affect the Zener voltage of 1N974A?
The 1N974A has a positive temperature coefficient of +0.093 %/°C, meaning its Zener voltage increases by approximately 33.5 mV per °C rise in junction temperature. At 100 °C junction temperature, VZ rises ~7.5 V above its 25 °C value. Designers must account for this drift in high-temperature applications or pair the 1N974A with negative-TC components for compensation.
Is 1N974A RoHS compliant?
The base 1N974A is not inherently RoHS compliant; RoHS compliance requires the "e3" suffix (e.g., 1N974Ae3), which denotes annealed matte-tin plating instead of traditional tin-lead. Standard 1N974A uses Sn/Pb terminations per MIL-STD-750 Method 2026. Customers requiring RoHS conformance must specify the e3 variant at time of order - it is not a drop-in replacement without qualification.
1N974A 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):
- 36 V
- Tolerance:
- ±10%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 70 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 27.4 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
1N974A FAQ
1.How can I place an order for 1N974A through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N974A 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 1N974A reliable?
The price and inventory of 1N974A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N974A is usually 5 days.
3.What payment methods are accepted for 1N974A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N974A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N974A?
1N974A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N974A 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 1N974A?
For technical support, including 1N974A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N974A requirements.
6.How does Aetrix verify that 1N974A is sourced from the original manufacturer or authorized distributors?
All 1N974A 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 1N974A meets industry standards.
7.What is the process for return or replacement of 1N974A?
All 1N974A units undergo pre-shipment inspection (PSI). If there is an issue with 1N974A, 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 1N974A part is unused and in its original packaging.
Return procedure for 1N974A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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