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onsemi 1N5257B_T50R
- Part No.:
- 1N5257B_T50R
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N5257B_T50R.pdf
- Description:
- DIODE ZENER 33V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:9,239
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Product details
Overview
1N5257B_T50R from ON Semiconductor is a 33 V ±5% Zener diode in DO-35 glass package, rated for 500 mW power dissipation at 25°C, with 58 Ω dynamic impedance at 14 mA test current and 0.25 μA reverse leakage at 25.2 V. It provides precision voltage regulation in low-power analog reference and overvoltage protection circuits.
For engineers reviewing the 1N5257B_T50R datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal derating behavior, cathode identification, and direct-fit alternatives for legacy Fairchild-designated designs requiring stable 33 V Zener clamping.
Technical Context
The 1N5257B_T50R operates as a two-terminal silicon Zener diode optimized for voltage regulation and reference applications in linear power supplies, sensor biasing, and signal conditioning. Its DO-35 hermetically sealed glass package ensures long-term stability and low leakage under ambient conditions.
It exhibits a positive temperature coefficient of +0.092 %/°C and maintains 33 V nominal breakdown within ±5% tolerance at IZ = 14 mA. Reverse leakage remains ≤0.25 μA up to 25.2 V (76% of VZ), supporting low-current standby operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 33 V nominal, min 31.35 V / max 34.65 V at IZ = 14 mA - defines precise clamping threshold for voltage reference design |
| Power Dissipation (PD) | 500 mW at TA = 25°C, derates 4.0 mW/°C above 50°C - sets maximum continuous power handling in PCB layout |
| Dynamic Impedance (ZZ) | 58 Ω at IZ = 14 mA - determines regulation stiffness and output voltage variation under load changes |
| Reverse Leakage (IR) | ≤0.25 μA at VR = 25.2 V - enables ultra-low quiescent current in battery-powered sensing nodes |
| Temperature Coefficient | +0.092 %/°C - quantifies VZ drift per degree Celsius for thermal error budgeting in precision references |
| Forward Voltage (VF) | ≤1.2 V at IF = 200 mA - supports use as low-drop rectifier or ESD clamp in bidirectional protection schemes |
Pinout & Package
DO-35 glass axial package with cathode identified by color band; no active pin numbering - device has two terminals: anode and cathode. Cathode terminal connects to banded end; anode is unmarked lead.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Zener breakdown terminal | Connected to regulated node; reverse-biased to maintain fixed voltage drop across load |
| Anode (unmarked end) | Reference return path | Typically tied to ground or lower-potential rail; completes current path during regulation |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables tight regulation without external trimming in cost-sensitive industrial controls |
| Hermetically sealed DO-35 glass case | Ensures long-term parameter stability and moisture resistance in harsh environments |
| Low 0.25 μA leakage at 76% VZ | Permits use in micropower circuits where standby current must remain below 1 μA |
| Positive TC of +0.092 %/°C | Allows predictable compensation when paired with negative-TC components in reference ICs |
Applications
| Industrial Sensor Biasing | Linear Power Supply Reference |
|---|---|
Use Scenario: Providing stable excitation voltage to resistive temperature detectors (RTDs) in factory automation systems. IC Role / Device Role / Timing Role: Zener diode acts as two-terminal shunt voltage reference, regulating bias current independent of supply fluctuations. Use Value: Maintains <±0.5% output stability over -40°C to +85°C due to known TC and low leakage, reducing calibration drift. | Use Scenario: Setting feedback threshold in discrete 78xx-style linear regulators for embedded control modules. IC Role / Device Role / Timing Role: Functions as precision voltage reference in op-amp-based error amplifier circuitry. Use Value: Delivers 33 V reference with 58 Ω ZZ, minimizing load-induced error in 10–100 mA output stages. |
| Overvoltage Clamp Protection | Microcontroller I/O Protection |
Use Scenario: Safeguarding analog inputs of PLC analog input cards against transient surges on 24 V field wiring. IC Role / Device Role / Timing Role: Shunt clamping device that conducts excess energy to ground when line voltage exceeds 33 V. Use Value: Limits peak voltage to ≤34.65 V with fast response (<10 ns), preventing damage to downstream ADC front-ends. | Use Scenario: Protecting GPIO pins of ARM Cortex-M microcontrollers from ESD and accidental 24 V miswiring. IC Role / Device Role / Timing Role: Bidirectional clamp (with series resistor) leveraging forward conduction (VF ≤1.2 V) and reverse Zener action. Use Value: Clamps both positive transients to 34.65 V and negative spikes to -1.2 V, meeting IEC 61000-4-2 Level 4 requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5257BRLG | Same electrical specs; tape-and-reel packaging (T50R = bulk, RL = reel); identical DO-35 package and marking | No functional difference; reel format preferred for automated SMT placement with axial lead formers | Select 1N5257BRLG for high-volume production requiring pick-and-place compatibility |
| BZX55C33 | Same 33 V ±5%, but higher ZZ (70 Ω), higher leakage (0.5 μA), and different DO-35 mechanical tolerances per Philips spec | Suitable for non-critical clamping where tighter regulation not required; not recommended for precision references | Choose BZX55C33 only if cost sensitivity outweighs regulation accuracy and leakage constraints |
Compared with 1N5257B_T50R, 1N5257BRLG offers identical performance in reel format for automated assembly, while BZX55C33 trades regulation precision and leakage for broader vendor availability - making the original optimal for stable 33 V reference design where parameter consistency is critical.
Availability
1N5257B_T50R is available at Aetrix Electronics and suitable for industrial sensor biasing, linear power supply reference, and overvoltage clamp protection requiring stable component supply and consistent Zener voltage matching across production lots.
Supply support for 1N5257B_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
ON Semiconductor is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The 1N52xxB series was designed specifically for general-purpose Zener regulation in cost-sensitive, high-reliability analog circuits - emphasizing tight tolerance, low leakage, and DO-35 mechanical robustness.
FAQ
What is the Zener voltage tolerance of the 1N5257B_T50R?
The 1N5257B_T50R has a Zener voltage tolerance of ±5% at IZ = 14 mA, yielding a guaranteed range of 31.35 V to 34.65 V. This tolerance is specified per ON Semiconductor's 1N5221B–1N5263B datasheet Rev. 3 and applies to all units shipped under the 1N5257B_T50R designation.
Does the 1N5257B_T50R have a defined cathode marking?
Yes, the 1N5257B_T50R uses a single color band on the DO-35 glass body to denote the cathode terminal. The banded end is the cathode; the opposite unmarked lead is the anode. This marking conforms to JEDEC DO-204AH standards and is visible under standard visual inspection.
What is the maximum power dissipation for the 1N5257B_T50R at 75°C ambient?
At 75°C ambient, the 1N5257B_T50R derates from its 500 mW rating at 25°C by 4.0 mW/°C above 50°C. Over the 25°C offset (75°C − 50°C = 25°C), total derating is 100 mW, resulting in a maximum allowable power dissipation of 400 mW - critical for thermal design in enclosed enclosures.
Can the 1N5257B_T50R be used in bidirectional ESD protection?
Yes, the 1N5257B_T50R supports bidirectional clamping: reverse-biased operation provides 33 V Zener clamping, while forward conduction limits negative transients to ≤1.2 V at 200 mA. Used with a current-limiting resistor, it meets basic IEC 61000-4-2 ESD protection requirements for microcontroller I/O lines.
Is the 1N5257B_T50R compatible with lead-free soldering processes?
Yes, the 1N5257B_T50R's DO-35 glass package is rated for lead-free reflow with a maximum lead temperature of +230°C for 10 seconds at 1/16 inch from case - compliant with IPC/JEDEC J-STD-020D moisture sensitivity level 1 and RoHS reflow profiles.
1N5257B_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):
- 33 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 58 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 25 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.2 V @ 200 mA
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
1N5257B_T50R FAQ
1.How can I place an order for 1N5257B_T50R through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N5257B_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 1N5257B_T50R reliable?
The price and inventory of 1N5257B_T50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5257B_T50R is usually 5 days.
3.What payment methods are accepted for 1N5257B_T50R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5257B_T50R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N5257B_T50R?
1N5257B_T50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N5257B_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 1N5257B_T50R?
For technical support, including 1N5257B_T50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5257B_T50R requirements.
6.How does Aetrix verify that 1N5257B_T50R is sourced from the original manufacturer or authorized distributors?
All 1N5257B_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 1N5257B_T50R meets industry standards.
7.What is the process for return or replacement of 1N5257B_T50R?
All 1N5257B_T50R units undergo pre-shipment inspection (PSI). If there is an issue with 1N5257B_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 1N5257B_T50R part is unused and in its original packaging.
Return procedure for 1N5257B_T50R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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