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onsemi 1N975B_T50R
- Part No.:
- 1N975B_T50R
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N975B_T50R.pdf
- Description:
- DIODE ZENER 39V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:7,755
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Product details
Overview
1N975B_T50R from Fairchild Semiconductor is a 39 V, ±5% tolerance, 500 mW glass-encapsulated Zener diode in DO-35 package, designed for precision voltage regulation and reference applications in power supply feedback loops, overvoltage protection circuits, and analog signal conditioning stages.
For engineers reviewing the 1N975B_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage accuracy (37.05–40.95 V), dynamic impedance (7.8 Ω at 32 mA), leakage current (≤0.25 μA at 31.5 V), thermal stability (−65 to +200°C), and DO-35 mechanical compatibility with legacy through-hole designs.
Technical Context
This Zener diode operates in reverse breakdown mode with tightly controlled voltage regulation across its specified test current range (IZ = 32 mA). Its 5% tolerance and low dynamic impedance ensure stable reference performance under varying load and temperature conditions.
The device uses a planar-diffused junction in a hermetically sealed DO-35 glass package, enabling reliable operation up to 200°C junction temperature and supporting long-term stability in industrial and automotive environments where thermal cycling and humidity resistance are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 37.05–40.95 V at IZ = 32 mA; defines precise regulation point for feedback or clamping circuits |
| Zener Impedance (ZZ) | 7.8 Ω at IZ = 32 mA; ensures minimal output voltage variation under load transients |
| Power Dissipation (PD) | 500 mW at TL ≤ 75°C; supports continuous operation in compact PCB layouts with standard lead length |
| Leakage Current (IR) | ≤0.25 μA at VR = 31.5 V; guarantees negligible standby current in high-impedance bias networks |
| Operating Temperature | −65 to +200°C; enables deployment in under-hood automotive, industrial motor controls, and aerospace systems |
| Tolerance | ±5%; meets MIL-PRF-19500/105 Class B requirements for voltage reference consistency |
| Package | DO-35 glass case with cathode band; provides hermetic sealing and proven reliability in legacy designs |
Pinout & Package
DO-35 glass axial package with cathode indicated by color band; leads are tinned copper alloy, suitable for wave or hand soldering per J-STD-001.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Reverse-biased reference node | Connected to lower-potential side in Zener regulation; forms reference ground return path |
| Cathode | Zener breakdown terminal / Voltage reference output | Connected to regulated node; delivers stable 39 V reference when reverse biased above VZ |
Key Features
| Feature | Design Value |
|---|---|
| ±5% VZ tolerance | Enables single-bin selection without post-assembly trimming in cost-sensitive power supplies |
| Low ZZ = 7.8 Ω | Maintains <1% output deviation during 10–90% load steps in 5–12 V SMPS feedback paths |
| Hermetic DO-35 glass | Prevents moisture ingress and parameter drift in humid environments (e.g., outdoor lighting, HVAC controls) |
| 200°C max TJ | Supports placement near heat-generating components like MOSFETs or transformers without derating |
| 0.25 μA IR @ 31.5 V | Eliminates measurable error in high-resistance voltage divider networks used in sensor biasing |
Applications
| Switch-Mode Power Supply Feedback | Overvoltage Protection Clamp |
|---|---|
Use Scenario: Regulating output voltage in isolated flyback converters using optocoupler-coupled feedback. IC Role / Device Role / Timing Role: Zener reference providing stable 39 V threshold to TL431 shunt regulator input or directly to optocoupler LED anode. Use Value: Tight 5% VZ tolerance and low ZZ ensure ±1.5% output regulation accuracy across line/load/temperature. | Use Scenario: Protecting microcontroller I/O pins from transient surges on 24 V industrial fieldbus lines. IC Role / Device Role / Timing Role: Clamping voltage to 39 V before it reaches ESD-sensitive inputs of STM32 or PIC microcontrollers. Use Value: Sub-μA leakage preserves signal integrity in high-impedance sensing nodes while absorbing >100 V spikes. |
| Programmable Voltage Reference | Analog Sensor Biasing |
Use Scenario: Setting precise reference for 12-bit ADCs in data acquisition modules requiring calibrated 39 V full-scale input. IC Role / Device Role / Timing Role: Primary voltage reference source feeding resistor-divider network that scales down higher-voltage signals. Use Value: 200°C operating range allows placement near analog front-end ICs without thermal-induced drift. | Use Scenario: Providing stable excitation voltage to RTD or strain gauge bridges in process control transmitters. IC Role / Device Role / Timing Role: Low-noise, low-drift bias source replacing less stable resistive dividers powered from unregulated rails. Use Value: 0.25 μA leakage avoids loading bridge outputs, preserving measurement resolution below 0.1% FS. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4739A | 39 V nominal, ±5%, 1 W rating, DO-41 package; 10 Ω ZZ at 32 mA | Higher power handling but larger footprint; requires PCB layout change | Select when >500 mW dissipation is needed or DO-41 is already standardized |
| BZX55-C39 | 39 V nominal, ±5%, 500 mW, DO-35; 10 Ω ZZ at 32 mA, 0.5 μA IR at 31.5 V | Slightly higher leakage and impedance; same package and mounting | Acceptable drop-in replacement where 0.25 μA leakage is not critical |
Compared with 1N975B_T50R, the 1N4739A offers higher power margin but demands board rework, while the BZX55-C39 matches the DO-35 form factor but trades off tighter leakage and lower impedance-critical for precision analog references.
Availability
1N975B_T50R is available at Aetrix Electronics and suitable for switch-mode power supplies, overvoltage protection circuits, and programmable voltage reference designs requiring stable component supply and long-lifecycle support.
Supply support for 1N975B_T50R 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 devices before its acquisition by ON Semiconductor in 2016.
The 1N957B–1N979B series was engineered for high-reliability voltage reference and regulation in industrial, automotive, and military-grade equipment where long-term parametric stability and hermetic packaging were essential.
FAQ
What is the nominal zener voltage of the 1N975B_T50R?
The 1N975B_T50R has a nominal zener voltage of 39 V, with a guaranteed range of 37.05 V to 40.95 V at a test current of 32 mA and ambient temperature of 25°C. This value is measured under thermal equilibrium conditions with 3/8-inch lead length, ensuring repeatability in production testing and design validation.
Does the 1N975B_T50R have a cathode marking?
Yes, the 1N975B_T50R features a visible cathode band on the DO-35 glass body, consistent with industry-standard polarity identification. The band is located adjacent to the cathode lead and must be oriented toward the higher-potential node in reverse-bias applications such as voltage regulation or clamping.
What is the maximum power dissipation for the 1N975B_T50R?
The 1N975B_T50R is rated for 500 mW power dissipation at lead temperature (TL) ≤ 75°C with 3/8-inch lead length. Above 75°C, it derates linearly at 4.0 mW/°C, reaching zero dissipation at 200°C-matching its maximum storage temperature specification.
Is the 1N975B_T50R suitable for high-temperature environments?
Yes, the 1N975B_T50R supports continuous operation from −65°C to +200°C, making it suitable for under-hood automotive electronics, industrial motor drives, and downhole instrumentation. Its DO-35 glass package maintains hermeticity and parameter stability across this full range without external encapsulation.
How does the 1N975B_T50R compare to the 1N4739A in terms of package and performance?
The 1N975B_T50R uses a DO-35 package, while the 1N4739A uses DO-41-requiring PCB redesign for substitution. Electrically, the 1N975B_T50R offers lower dynamic impedance (7.8 Ω vs. 10 Ω) and tighter leakage (0.25 μA vs. 1.0 μA), giving it superior precision in reference applications despite identical nominal voltage and tolerance.
1N975B_T50R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 39 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 80 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 29.7 V
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
1N975B_T50R FAQ
1.How can I place an order for 1N975B_T50R through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N975B_T50R 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 1N975B_T50R reliable?
The price and inventory of 1N975B_T50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N975B_T50R is usually 5 days.
3.What payment methods are accepted for 1N975B_T50R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N975B_T50R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N975B_T50R?
1N975B_T50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N975B_T50R 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 1N975B_T50R?
For technical support, including 1N975B_T50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N975B_T50R requirements.
6.How does Aetrix verify that 1N975B_T50R is sourced from the original manufacturer or authorized distributors?
All 1N975B_T50R 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 1N975B_T50R meets industry standards.
7.What is the process for return or replacement of 1N975B_T50R?
All 1N975B_T50R units undergo pre-shipment inspection (PSI). If there is an issue with 1N975B_T50R, 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 1N975B_T50R part is unused and in its original packaging.
Return procedure for 1N975B_T50R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N975B_T50R Tags
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