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onsemi 1N972B
- Part No.:
- 1N972B
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N972B.pdf
- Description:
- DIODE ZENER 30V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:4,961
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Product details
Overview
1N972B from Fairchild Semiconductor is a 5% tolerance, 30 V nominal Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C with 4.0 mW/°C derating, operating from –65°C to +200°C, used for voltage regulation and reference in low-power analog circuits.
For engineers reviewing the 1N972B datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage (28.5–31.5 V), zener impedance (4.2 Ω @ 49 mA), leakage current (0.25 μA @ 22.8 V), maximum zener current (49 mA), and DO-35 mechanical compatibility.
Technical Context
The 1N972B operates as a silicon planar passivated Zener diode optimized for stable voltage reference in low-current, high-temperature environments. Its 30 V nominal breakdown is specified at 49 mA test current, with tight 5% tolerance and low dynamic impedance enabling precise regulation under varying load conditions.
It features a glass-passivated DO-35 package with cathode band marking, supporting operation up to +200°C junction temperature and exhibiting low leakage (≤0.25 μA at 22.8 V) and consistent knee characteristics defined by ZZK = 10 Ω @ IZK = 5 mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 28.5–31.5 V at IZ = 49 mA - defines stable regulation point across production lot |
| Zener Impedance (ZZ) | 4.2 Ω @ IZ = 49 mA - ensures minimal output voltage variation under load transients |
| Power Dissipation (PD) | 500 mW @ TL ≤ 75°C - sets maximum continuous DC power handling on standard lead length |
| Leakage Current (IR) | ≤0.25 μA @ VR = 22.8 V - guarantees negligible standby current in high-impedance bias networks |
| Operating Temperature | –65°C to +200°C - enables use in automotive under-hood, industrial sensor, and aerospace environments |
| Zener Knee Impedance (ZZK) | 10 Ω @ IZK = 5 mA - supports stable regulation even at low bias currents |
Pinout & Package
DO-35 glass axial package with cathode indicated by color band; two-terminal device with anode and cathode leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal in forward bias; reference node in reverse-bias regulation | Connected to lower-potential side of regulated circuit; establishes polarity for Zener operation |
| Cathode | Current exit terminal in forward bias; Zener breakdown terminal in reverse bias | Marked with color band; connected to higher-potential side to enable controlled reverse conduction |
Key Features
| Feature | Design Value |
|---|---|
| 5% Zener voltage tolerance | Enables predictable regulation without post-production trimming in cost-sensitive designs |
| Low zener impedance (4.2 Ω) | Maintains ±0.2 V output stability over 10–100% load current range at 30 V |
| High-temperature operation (up to +200°C) | Supports placement near heat sources in motor control and power supply feedback loops |
| DO-35 glass package with cathode band | Ensures visual polarity identification and hermetic reliability in humid or corrosive environments |
Applications
| Industrial Sensor Signal Conditioning | Automotive ECU Reference Supply |
|---|---|
Use Scenario: Stabilizing bias voltage for precision op-amp input stages in temperature-transducer interfaces. IC Role / Device Role / Timing Role: Voltage reference element providing fixed 30 V rail for analog front-end scaling. Use Value: Low 4.2 Ω impedance minimizes gain error drift caused by sensor bridge current variations. | Use Scenario: Generating stable reference for microcontroller ADC reference inputs in engine control modules. IC Role / Device Role / Timing Role: Zener shunt regulator supplying clean 30 V to external voltage reference ICs. Use Value: –65°C to +200°C rating ensures functionality during cold cranking and under-hood thermal cycling. |
| Programmable Power Supply Feedback | Overvoltage Protection Clamp |
Use Scenario: Setting adjustable output voltage threshold in lab-grade bench power supplies using TL431-based topology. IC Role / Device Role / Timing Role: Precision Zener reference for optocoupler feedback loop compensation network. Use Value: Tight 5% tolerance reduces calibration burden and improves setpoint repeatability across units. | Use Scenario: Clamping transient surges on 24 V CAN bus power rails in industrial gateways. IC Role / Device Role / Timing Role: Shunt protection device limiting voltage excursions above 31.5 V during ESD or load dump events. Use Value: 0.25 μA leakage at 22.8 V prevents false triggering while maintaining fast response to overvoltage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5254B (ON Semiconductor) | Same 30 V nominal, 5% tolerance, DO-35 package; ZZ = 35 Ω @ 20 mA (higher than 1N972B's 4.2 Ω @ 49 mA) | Higher impedance limits use in high-precision, high-current references; better suited for low-current biasing | Select 1N5254B only when test current is ≤20 mA and impedance sensitivity is low |
| BZX55-C30 (Vishay) | 30 V nominal, 5% tolerance, DO-35; ZZ = 30 Ω @ 20 mA; max PD = 500 mW but derating starts at 50°C (vs. 75°C for 1N972B) | Reduced thermal margin in high-ambient environments; requires tighter layout thermal management | Prefer BZX55-C30 only if sourcing constraints exist and ambient temperature remains <60°C |
Compared with 1N5254B and BZX55-C30, the 1N972B delivers superior regulation stability at higher bias currents due to its 4.2 Ω impedance and extended thermal derating threshold, making it optimal for precision analog and high-temperature embedded systems.
Availability
1N972B is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, automotive ECU reference supplies, and programmable power supply feedback requiring stable component supply and long-term lifecycle continuity.
Supply support for 1N972B 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.
The 1N972B belongs to Fairchild's legacy 1N957B–1N979B Zener diode family, designed for general-purpose voltage regulation and reference in cost-sensitive, thermally demanding applications.
FAQ
What is the nominal Zener voltage and tolerance of the 1N972B?
The 1N972B has a nominal Zener voltage of 30 V with a guaranteed tolerance of ±5%, meaning its actual breakdown voltage falls between 28.5 V and 31.5 V when tested at 49 mA. This specification is measured under standardized thermal conditions (lead temperature = 30°C ± 1°C, 3/8″ lead length) per Fairchild's datasheet Rev. F1. The 1N972B maintains this tolerance across its full operating temperature range.
What is the maximum power dissipation and derating behavior of the 1N972B?
The 1N972B is rated for 500 mW power dissipation at lead temperature (TL) ≤ 75°C with 3/8″ lead length. Above 75°C, it derates linearly at 4.0 mW/°C. This means at 100°C lead temperature, its usable power drops to 400 mW. The 1N972B's thermal design allows reliable operation up to +200°C junction temperature, making it suitable for high-ambient environments where the 1N972B remains functional beyond typical commercial-grade devices.
What is the Zener impedance (ZZ) of the 1N972B and why does it matter?
The 1N972B exhibits a Zener impedance of 4.2 Ω when measured at IZ = 49 mA and 60 Hz AC signal. This low dynamic impedance ensures minimal output voltage variation under changing load conditions - critical for precision reference applications. Compared to alternatives like the BZX55-C30 (30 Ω), the 1N972B's lower ZZ directly improves regulation accuracy, especially in circuits where the 1N972B supplies bias to sensitive analog blocks.
How is polarity identified on the 1N972B DO-35 package?
The 1N972B uses a DO-35 glass axial package with a visible cathode band - a painted or etched stripe near one end of the glass body - indicating the cathode terminal. The unmarked end is the anode. This marking follows JEDEC standards and is confirmed in Fairchild's top-marking specification: Line 1 is the Fairchild logo (F), Line 2 is "72", and Line 3 is "B", uniquely identifying the 1N972B among the 1N957B–1N979B series. Correct orientation is essential for proper 1N972B function in reverse-bias regulation.
What are the storage and operating temperature limits for the 1N972B?
The 1N972B is specified for an operating and storage temperature range of –65°C to +200°C, verified per Fairchild's Absolute Maximum Ratings table. This wide range supports deployment in extreme environments such as automotive under-hood locations, industrial furnace controls, and downhole instrumentation. Unlike many commercial Zeners limited to +150°C, the 1N972B retains full electrical performance throughout this span, ensuring long-term reliability where the 1N972B is exposed to thermal cycling or sustained high ambient temperatures.
1N972B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 30 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 49 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 22.8 V
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
1N972B FAQ
1.How can I place an order for 1N972B through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N972B 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 1N972B reliable?
The price and inventory of 1N972B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N972B is usually 5 days.
3.What payment methods are accepted for 1N972B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N972B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N972B?
1N972B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N972B 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 1N972B?
For technical support, including 1N972B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N972B requirements.
6.How does Aetrix verify that 1N972B is sourced from the original manufacturer or authorized distributors?
All 1N972B 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 1N972B meets industry standards.
7.What is the process for return or replacement of 1N972B?
All 1N972B units undergo pre-shipment inspection (PSI). If there is an issue with 1N972B, 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 1N972B part is unused and in its original packaging.
Return procedure for 1N972B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N972B 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
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BZT52C15-7-F
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BZX84C3V3LT1G
onsemi
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MMSZ5245BS-7-F
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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
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SMAZ12-13-F
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