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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

Diodes Incorporated 1N5238B-T

Name: 1N5238B-T
Brand: Diodes Incorporated
SKU: 1N5238B-T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N5238B-T

Manufacturer:: Diodes Incorporated

Category:: Single Zener Diodes

Package:: DO-204AH, DO-35, Axial

Datasheet:: 1N5238B-T.pdf

Description:: DIODE ZENER 8.7V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:10,000

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Product details

Overview

1N5238B-T from Diodes Incorporated is a 500mW, 8.7V ±5% tolerance surface-mount Zener diode in a hermetic DO-35 glass package, rated for -65°C to +175°C operation, with 8.0Ω zener impedance at 20mA and +0.065%/°C temperature coefficient-used for precision voltage reference and overvoltage protection in power supply feedback loops.

For engineers reviewing the 1N5238B-T datasheet, 1N5238B-T pinout, 1N5238B-T application, or 1N5238B-T equivalent, key selection criteria include its tight V_Z tolerance, low Z_ZT, RoHS-compliant Sn96.5Ag3.5 terminations, and thermal stability across industrial temperature ranges.

Technical Context

This Zener diode operates in reverse breakdown mode with a nominal zener voltage of 8.7V at 20mA test current (I_ZT). Its 8.0Ω dynamic impedance (Z_ZT) ensures stable regulation under varying load conditions, while the +0.065%/°C temperature coefficient enables predictable drift compensation in analog reference circuits.

The device uses an epitaxial construction for high stability and low noise, housed in a hermetic DO-35 glass package with cathode band polarity marking. It meets MIL-STD-202 solderability requirements and is rated for 500mW power dissipation with 300°C/W junction-to-ambient thermal resistance when leads are maintained ≤75°C.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	8.7V nominal, 8.27–9.14V range at 20mA - defines precise clamping/reference level
Power Dissipation (P_D)	500mW - limits continuous reverse-bias energy handling in compact layouts
Zener Impedance (Z_ZT)	8.0Ω at I_ZT = 20mA - ensures minimal output voltage variation under load transients
Temperature Coefficient	+0.065%/°C - quantifies positive V_Z drift per degree, critical for temp-compensated references
Reverse Leakage (I_R)	3.0µA max at V_R = 6.5V - guarantees low standby current in high-impedance bias networks
Operating Temp Range	-65°C to +175°C - supports deployment in automotive under-hood and industrial control environments

Pinout & Package

Package: Hermetic DO-35 glass case with axial leads, cathode identified by a single black band; dimensions: length 25.4mm max, body diameter 0.6–2.0mm, weight ≈0.13g.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Reverse-bias reference ground node	Connected to circuit common or lower-potential rail during Zener operation
Cathode	Reverse-bias voltage reference terminal	Marked with black band; connected to regulated voltage node or feedback point

Key Features

Feature	Design Value
Hermetic Glass Package	Ensures long-term parameter stability and moisture immunity without conformal coating
±5% V_Z Tolerance	Reduces binning requirements and simplifies calibration in voltage reference designs
Lead-Free & RoHS Compliant	Sn96.5Ag3.5 terminations meet EU directives and support Pb-free reflow profiles
High Thermal Stability	Operates reliably up to +175°C ambient-enables use in engine control and power converter modules

Applications

Switching Power Supply Feedback

Industrial Sensor Reference

Use Scenario: Regulates output voltage in flyback or buck converter feedback paths via optocoupler-coupled error amplifier.

IC Role / Device Role / Timing Role: Zener provides stable 8.7V reference to set feedback threshold and maintain ±1% output accuracy.

Use Value: Low Z_ZT minimizes load-induced ripple on reference node, improving transient response and line regulation.

Use Scenario: Supplies excitation voltage to bridge-based pressure/temperature sensors in factory automation systems.

IC Role / Device Role / Timing Role: Acts as precision shunt reference for ratiometric ADC biasing and signal conditioning front-ends.

Use Value: Tight V_Z tolerance and low tempco ensure <±0.5% reference drift over -40°C to +85°C operating range.

Overvoltage Clamp Protection

Microcontroller I/O Protection

Use Scenario: Clamps transient surges on 9V rail inputs in telecom line cards exposed to lightning-induced spikes.

IC Role / Device Role / Timing Role: Shunts excess energy above 9.14V to ground before downstream ICs exceed absolute maximum ratings.

Use Value: 500mW rating and fast reverse recovery enable repeated surge absorption without degradation.

Use Scenario: Protects 3.3V/5V GPIO pins from ESD and accidental 12V miswiring in programmable logic controllers.

IC Role / Device Role / Timing Role: Functions as bidirectional clamp (with series resistor) limiting pin voltage to safe levels.

Use Value: Cathode-band polarity and DO-35 form factor allow direct placement adjacent to connector interfaces.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener diode applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMSZ5238B	SMD SOD-123 package, same 8.7V V_Z, 500mW rating, but Z_ZT = 10Ω (vs. 8Ω)	Surface-mount only; no axial leads; requires PCB rework for legacy through-hole designs	Select for new SMT designs requiring automated assembly and smaller footprint
1N4738A	Through-hole DO-41 package, 8.2V V_Z, ±5%, 1.0W rating, Z_ZT = 7.0Ω at 21mA	Higher power handling but different V_Z; not a direct replacement without circuit recalibration	Choose where higher surge capability is needed and 8.2V reference is acceptable

Compared with MMSZ5238B and 1N4738A, the 1N5238B-T offers superior thermal stability in hermetic glass packaging and tighter impedance matching for analog reference use-but requires axial lead mounting and is obsolete, necessitating design migration planning.

Availability

1N5238B-T is available at Aetrix Electronics and suitable for switching power supplies, industrial sensor interfaces, overvoltage protection circuits, and microcontroller I/O protection requiring stable component supply despite end-of-life status.

Supply support for 1N5238B-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, specializing in high-reliability components for power management, signal integrity, and protection applications.

The 1N52xxB series belongs to Diodes' legacy Zener diode product line, engineered for precision voltage regulation and robustness in industrial and automotive environments where hermetic sealing and wide temperature operation are essential.

FAQ

Is the 1N5238B-T still in active production?

No-the 1N5238B-T is officially obsolete and discontinued by Diodes Incorporated, as confirmed in DS18006 Rev. 19. It has been superseded by the MMSZ5238B SOD-123 surface-mount variant. Aetrix Electronics maintains limited legacy stock for design continuity and repair needs.

What is the maximum reverse voltage (V_R) this diode can withstand before breakdown?

The 1N5238B-T exhibits a guaranteed zener breakdown between 8.27V and 9.14V at 20mA. Its maximum reverse voltage prior to breakdown is not specified separately-it is designed to operate continuously in controlled reverse breakdown, not as a blocking diode. For blocking applications, consider a standard rectifier diode instead.

Can this diode be used in place of the 1N5234B-T (6.2V) without circuit changes?

No-replacing the 6.2V 1N5234B-T with the 8.7V 1N5238B-T will raise the regulated voltage by ~40%, altering feedback thresholds, bias points, and potentially causing overvoltage damage. Circuit recalculations for current limiting, power dissipation, and loop stability are required before substitution.

Does the DO-35 package support automated optical inspection (AOI) after soldering?

Yes-the DO-35's cylindrical glass body and distinct cathode band provide sufficient contrast and geometry for AOI systems to verify orientation, coplanarity, and solder joint integrity. However, its axial lead configuration requires compatible placement equipment and may need custom vision algorithms versus SMD packages.

1N5238B-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):: 8.7 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 8 Ohms

Current - Reverse Leakage @ Vr:: 3 µA @ 6.5 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

1N5238B-T FAQ

1.How can I place an order for 1N5238B-T through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N5238B-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 1N5238B-T reliable?

The price and inventory of 1N5238B-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5238B-T is usually 5 days.

3.What payment methods are accepted for 1N5238B-T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5238B-T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N5238B-T?

1N5238B-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N5238B-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 1N5238B-T?

For technical support, including 1N5238B-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5238B-T requirements.

6.How does Aetrix verify that 1N5238B-T is sourced from the original manufacturer or authorized distributors?

All 1N5238B-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 1N5238B-T meets industry standards.

7.What is the process for return or replacement of 1N5238B-T?

All 1N5238B-T units undergo pre-shipment inspection (PSI). If there is an issue with 1N5238B-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 1N5238B-T part is unused and in its original packaging.

Return procedure for 1N5238B-T:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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