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Diodes Incorporated 1N5255B-T
- Part No.:
- 1N5255B-T
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
1N5255B-T.pdf
- Description:
- DIODE ZENER 28V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:3,186
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Product details
Overview
1N5255B-T from Diodes Incorporated is a 28 V, ±5% tolerance, 500 mW surface-mount Zener diode in DO-35 glass package, designed for precision voltage regulation and reference in low-power analog circuits, power supply feedback loops, and overvoltage protection. It delivers 44 Ω dynamic impedance at 4.5 mA test current, -0.091 %/°C temperature coefficient, and operates across -65°C to +175°C.
For engineers reviewing the 1N5255B-T datasheet, 1N5255B-T pinout, 1N5255B-T application, or 1N5255B-T equivalent, this page provides verified electrical specs, thermal derating guidance, DO-35 terminal polarity, RoHS-compliant Sn96.5Ag3.5 termination, and direct replacement options for legacy 1N52xxB-series designs.
Technical Context
This Zener diode operates in reverse breakdown with tightly controlled VZ = 28 V (26.6–29.4 V), specified at IZT = 4.5 mA and validated under thermal equilibrium conditions (lead length = 9.5 mm). Its hermetic glass DO-35 case ensures long-term stability and moisture resistance (J-STD-020 Level 1).
The device exhibits a negative temperature coefficient of -0.091 %/°C, enabling predictable drift compensation in reference circuits. Forward voltage is 1.1 V at 200 mA, supporting dual-use as clamp or regulator, while RθJA = 300 °C/W defines its ambient thermal limit under standard mounting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 28 V nominal, 26.6–29.4 V range at 4.5 mA - sets precise regulation threshold for feedback or clamping |
| Power Dissipation (PD) | 500 mW - limits continuous DC power in compact DO-35 layout without heatsink |
| Zener Impedance (ZZT) | 44 Ω at 4.5 mA - determines output voltage ripple sensitivity in regulated supplies |
| Temperature Coefficient | -0.091 %/°C - enables predictable VZ drift compensation in wide-temperature environments |
| Reverse Leakage (IR) | 0.1 µA at 21 V - ensures minimal quiescent current in high-impedance bias networks |
| Forward Voltage (VF) | 1.1 V at 200 mA - supports use as bidirectional clamp or low-drop rectifier in signal paths |
| Operating Temperature | -65°C to +175°C - qualified for automotive under-hood and industrial control applications |
Pinout & Package
DO-35 glass axial package with cathode band marking; two-terminal device with unidirectional polarity. Leads are Sn96.5Ag3.5 solderable per MIL-STD-202 Method 208; weight ≈ 0.13 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference ground | Connected to circuit ground or lower-potential node in shunt regulation |
| Cathode | Reverse-bias input / Zener breakdown terminal | Connected to regulated voltage node; marked by visible band on glass body |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic Glass Encapsulation | Ensures long-term parameter stability and immunity to humidity-induced leakage drift |
| ±5% Zener Tolerance | Reduces binning requirements in production while maintaining tight regulation accuracy |
| Lead-Free & RoHS Compliant | Sn96.5Ag3.5 termination meets EU Directive 2015/863/EU without exemptions needed |
| High Thermal Stability | Rated for operation up to +175°C junction temperature with defined derating above 75°C |
Applications
| Power Supply Feedback | Overvoltage Clamp |
|---|---|
Use Scenario: Regulating output voltage in isolated flyback or buck-derived auxiliary supplies. IC Role / Device Role: Shunt reference in optocoupler feedback loop controlling primary-side PWM controller. Use Value: 28 V Zener point sets stable secondary-side reference; 44 Ω ZZT minimizes load-induced output variation. |
Use Scenario: Protecting microcontroller I/O pins from transient surges exceeding 21 V. IC Role / Device Role: Bidirectional clamp limiting voltage swing between GND and 28 V rail. Use Value: 0.1 µA reverse leakage preserves high-impedance input integrity; 1.1 V forward drop enables low-threshold clamping. |
| Voltage Reference | Current Source Bias |
Use Scenario: Generating stable bias for op-amp comparators in battery-monitoring circuits. IC Role / Device Role: Precision shunt reference establishing fixed 28 V reference node. Use Value: -0.091 %/°C TC enables <±20 mV drift over -40°C to +85°C ambient range. |
Use Scenario: Setting constant current for LED driver or sensor excitation circuits. IC Role / Device Role: Zener-based current source with series resistor defining IOUT. Use Value: 500 mW rating allows ≥17.9 mA at 28 V before thermal shutdown; DO-35 fits space-constrained layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMSZ5255B | Surface-mount SOD-123 package; same 28 V, ±5%, 500 mW rating; ZZT = 44 Ω at 5 mA | Lower profile (1.3 mm height vs. DO-35's 2.0 mm); automated placement compatible; no axial leads | Select for PCB assembly automation and space-constrained designs where DO-35 lead forming is impractical |
| 1N4752A | Through-hole DO-41 package; 27 V nominal, ±5%; PD = 1 W; ZZT = 35 Ω at 12.5 mA | Higher power handling and lower impedance, but larger footprint and different thermal path | Select when >500 mW dissipation or lower dynamic impedance is required, accepting larger board area |
Compared with MMSZ5255B, the 1N5255B-T offers identical regulation performance in a legacy axial form factor suitable for hand-soldered prototypes or through-hole retrofits; versus 1N4752A, it trades power headroom for smaller size and tighter thermal coupling in low-power feedback nodes.
Availability
1N5255B-T is available at Aetrix Electronics and suitable for power supply feedback, overvoltage protection, voltage reference, and current source bias applications requiring stable component supply and long-lifecycle support.
Supply support for 1N5255B-T 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.
The 1N52xxB series belongs to Diodes' legacy Zener diode product line, engineered for cost-sensitive, high-reliability voltage reference and regulation in consumer, industrial, and computing power systems.
FAQ
What is the maximum continuous power dissipation for 1N5255B-T at 75°C ambient?
At ambient temperatures ≤75°C, the 1N5255B-T sustains full 500 mW dissipation provided leads are held at TL ≤75°C with 9.5 mm length from case. Above 75°C, linear derating applies at 1.67 mW/°C based on RθJA = 300 °C/W, reducing max power to 417 mW at 125°C ambient.
How does the cathode band orientation affect circuit connection?
The cathode band marks the Zener's cathode terminal, which must connect to the higher-potential node in shunt regulation or clamping configurations. Reversing polarity causes forward conduction at ~1.1 V instead of 28 V breakdown, risking incorrect regulation or excessive current if not current-limited.
Is 1N5255B-T suitable for automotive under-hood applications?
Yes - its -65°C to +175°C operating range, hermetic glass construction, and J-STD-020 Level 1 moisture sensitivity meet baseline requirements for non-safety-critical under-hood functions like sensor biasing or auxiliary supply regulation, though system-level qualification remains customer responsibility.
Why is the MMSZ5255B recommended as a direct alternative?
MMSZ5255B matches 1N5255B-T's 28 V Zener voltage, ±5% tolerance, 500 mW rating, and 44 Ω impedance at nearly identical test current (5 mA vs. 4.5 mA), while offering SOD-123 packaging for modern SMT lines - making it a functionally and electrically aligned upgrade path without circuit redesign.
1N5255B-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 28 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 44 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 21 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.1 V @ 200 mA
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
1N5255B-T FAQ
1.How can I place an order for 1N5255B-T through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N5255B-T 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 1N5255B-T reliable?
The price and inventory of 1N5255B-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5255B-T is usually 5 days.
3.What payment methods are accepted for 1N5255B-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5255B-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N5255B-T?
1N5255B-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N5255B-T 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 1N5255B-T?
For technical support, including 1N5255B-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5255B-T requirements.
6.How does Aetrix verify that 1N5255B-T is sourced from the original manufacturer or authorized distributors?
All 1N5255B-T 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 1N5255B-T meets industry standards.
7.What is the process for return or replacement of 1N5255B-T?
All 1N5255B-T units undergo pre-shipment inspection (PSI). If there is an issue with 1N5255B-T, 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 1N5255B-T part is unused and in its original packaging.
Return procedure for 1N5255B-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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