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onsemi 1N4738A-T50A
- Part No.:
- 1N4738A-T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AL, DO-41, Axial
- Datasheet:
-
1N4738A-T50A.pdf
- Description:
- DIODE ZENER 8.2V 1W DO41
- Quantity:
- Payment:
- Shipping:
Inventory:3,159
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Product details
Overview
1N4738A-T50A from ON Semiconductor is a 8.2 V, 1.0 W axial-leaded Zener diode in DO-41 glass package, rated for ±5% tolerance, 31 Ω dynamic impedance at 25 mA test current, and operating from −65 °C to +200 °C - used for precision voltage regulation in power supply feedback loops, overvoltage protection circuits, and reference voltage generation.
For engineers reviewing the 1N4738A-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage accuracy, thermal derating behavior (6.67 mW/°C above 50 °C), peak reverse surge capability (550 mA), and DO-41 mechanical compatibility with through-hole PCB layouts.
Technical Context
The 1N4738A-T50A operates as a silicon planar Zener diode optimized for stable reverse-bias breakdown at 8.2 V nominal, with specified test current IZ = 25 mA and maximum Zener impedance ZZ = 31 Ω at that condition. Its low leakage current (≤0.5 µA at 6.6 V) and tight 5% tolerance support reliable voltage clamping in analog and power control circuits.
It features a DO-41 glass passivated package with cathode band marking, rated for 1.0 W power dissipation at lead temperature ≤50 °C and full operational range from −65 °C to +200 °C - enabling use in industrial and automotive environments where thermal robustness and long-term stability are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 8.2 V nominal, ±5% tolerance - defines precise clamping level for regulated output or reference node. |
| Test Current (IZ) | 25 mA - standard bias point for measuring VZ and ZZ; design must ensure stable 25 mA sourcing for spec-compliant operation. |
| Zener Impedance (ZZ) | 31 Ω max at IZ = 25 mA - determines voltage deviation under load transients; lower value improves regulation fidelity. |
| Power Dissipation (PD) | 1.0 W @ TL ≤ 50 °C - sets maximum continuous power handling; requires thermal management beyond 50 °C per 6.67 mW/°C derating. |
| Leakage Current (IR) | ≤0.5 µA at VR = 6.6 V - ensures minimal error current in high-impedance reference paths or standby circuits. |
| Peak Reverse Surge (IZSM) | 550 mA non-repetitive (8.3 ms) - supports transient overvoltage suppression without failure during line surges or inductive kick events. |
| Operating Temp Range | −65 °C to +200 °C - enables deployment in under-hood automotive, industrial motor drives, and downhole equipment. |
Pinout & Package
DO-41 glass axial package with cathode indicated by a single color band on the case. Leads are tinned copper-clad steel, suitable for wave or hand soldering. Mechanical dimensions conform to JEDEC DO-41 standard: body diameter 2.0–2.7 mm, overall length 4.5–5.5 mm, lead diameter 0.4–0.6 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference ground | Connected to circuit ground or lower-potential node; reverse bias applied between cathode and anode to activate regulation. |
| Cathode | Zener breakdown terminal / regulated output node | Marked with color band; connects to voltage node requiring stabilization; delivers fixed 8.2 V relative to anode when reverse biased ≥VZ. |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables accurate voltage setting without post-assembly trimming in cost-sensitive power supplies and sensor references. |
| Low dynamic impedance (31 Ω) | Maintains <±0.1 V output variation across 5–40 mA load current changes - critical for stable feedback in SMPS controllers. |
| High surge rating (550 mA, 8.3 ms) | Withstands common-mode transients and ESD-induced spikes without degradation - reduces need for external TVS devices. |
| Wide temperature range (−65 °C to +200 °C) | Supports uninterrupted operation in engine control units, industrial PLCs, and aerospace power modules without derating penalties. |
| DO-41 glass package with cathode band | Ensures unambiguous polarity identification during manual assembly and automated optical inspection (AOI) on production lines. |
Applications
| Switch-Mode Power Supply Feedback | Microcontroller Voltage Reference |
|---|---|
Use Scenario: Regulates output voltage in flyback or buck converter feedback path using optocoupler-coupled error amplifier. IC Role / Device Role / Timing Role: Zener reference node establishing precise 8.2 V threshold for TL431 or similar shunt regulator comparison. Use Value: Tight 5% tolerance and low ZZ minimize output drift across line/load/temperature - achieving ±1.5% total output regulation. |
Use Scenario: Provides stable analog reference for ADC input scaling or internal bandgap calibration in MCU-based sensor nodes. IC Role / Device Role / Timing Role: Low-leakage (≤0.5 µA) voltage clamp generating clean 8.2 V reference independent of supply rail fluctuations. Use Value: Enables 12-bit ADC accuracy by limiting reference error to <0.05% FS, even at −40 °C ambient. |
| Overvoltage Protection Circuit | Industrial Sensor Signal Conditioning |
Use Scenario: Clamps input to protection IC or microcontroller GPIO during 24 V field bus transients or wiring faults. IC Role / Device Role / Timing Role: Fast-acting shunt element diverting excess energy before downstream components exceed absolute maximum ratings. Use Value: 550 mA non-repetitive surge rating absorbs 100 V/1 A ring wave events per IEC 61000-4-5 Level 3 without failure. |
Use Scenario: Biases bridge amplifier stages and sets common-mode voltage in 4–20 mA loop transmitter front-ends. IC Role / Device Role / Timing Role: Stable 8.2 V bias source compensating for resistor tolerance drift and temperature coefficient mismatch. Use Value: Reduces zero-point drift to <±2 µV/°C over −25 °C to +75 °C - meeting Class A industrial accuracy requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4738A (no suffix) | Identical electrical specs; same DO-41 package; differs only in packaging format (bulk vs. tape-and-reel T50A). | No functional difference; T50A denotes 500-piece tape-and-reel packaging for SMT-compatible pick-and-place, while bare 1N4738A is bulk-packed. | Select 1N4738A-T50A for automated assembly; choose bulk 1N4738A for prototyping or low-volume hand-soldered builds. |
| BZX55C8V2 | Same 8.2 V, ±5%, DO-35 package; slightly higher ZZ (40 Ω max), lower PD (500 mW), and narrower temp range (−65 °C to +175 °C). | Suitable for space-constrained PCBs but not for >1 W continuous dissipation or >175 °C ambient environments. | Choose BZX55C8V2 only when board area is critical and thermal load remains below 400 mW; otherwise prefer 1N4738A-T50A for robustness. |
Compared with 1N4738A-T50A, the bare 1N4738A offers identical performance in manual assembly contexts, while BZX55C8V2 trades power handling and temperature margin for smaller footprint - making 1N4738A-T50A optimal for high-reliability, thermally demanding applications requiring 1 W regulation.
Availability
1N4738A-T50A is available at Aetrix Electronics and suitable for switch-mode power supplies, industrial sensor interfaces, overvoltage protection circuits, and microcontroller reference designs requiring stable component supply with full traceability and lifecycle support.
Supply support for 1N4738A-T50A 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 manufacturer specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The 1N47xxA series was designed specifically for general-purpose, high-reliability Zener voltage regulation in cost-sensitive, high-volume power conversion and protection applications - emphasizing thermal stability, surge resilience, and manufacturing consistency.
FAQ
What is the exact Zener voltage tolerance for 1N4738A-T50A?
The 1N4738A-T50A has a guaranteed Zener voltage tolerance of ±5% around its nominal 8.2 V rating, meaning the actual measured VZ falls between 7.79 V and 8.61 V at 25 °C and 25 mA test current. This tolerance is verified per ON Semiconductor's 1N4728A–1N4758A datasheet Rev. 8 and applies to every unit shipped in the 1N4738A-T50A tape-and-reel configuration.
Can 1N4738A-T50A replace 1N4738A in existing designs?
Yes - the 1N4738A-T50A is electrically and mechanically identical to the bulk-packaged 1N4738A, differing only in packaging format (500-piece tape-and-reel). All electrical parameters, DO-41 footprint, thermal characteristics, and marking remain unchanged, so no schematic or layout revision is needed when substituting 1N4738A-T50A into designs originally specifying 1N4738A.
What is the maximum allowable power dissipation for 1N4738A-T50A at 75 °C lead temperature?
At 75 °C lead temperature, the 1N4738A-T50A must be derated from its 1.0 W rating at 50 °C by 6.67 mW/°C for each degree above 50 °C. That yields 1.0 W − (25 °C × 6.67 mW/°C) = 1.0 W − 166.75 mW = 833.25 mW maximum continuous power dissipation - a value confirmed in the Absolute Maximum Ratings table of the official ON Semiconductor datasheet.
Does 1N4738A-T50A meet automotive AEC-Q200 stress testing requirements?
No - the 1N4738A-T50A is not AEC-Q200 qualified. While it operates from −65 °C to +200 °C and withstands 550 mA surge, ON Semiconductor does not list it in their AEC-Q200 qualified portfolio. For automotive applications requiring qualification, consider the AEC-Q200 compliant NZ9F8V2T5G or MMBZ5231BS, which share similar 8.2 V regulation but undergo extended reliability testing.
How is cathode polarity identified on the 1N4738A-T50A DO-41 package?
The cathode of the 1N4738A-T50A is marked by a single distinct color band (typically black or dark gray) located near one end of the DO-41 glass body. This band aligns with the cathode terminal - the lead on the banded side - and must be connected to the higher-potential node in reverse-bias Zener operation. The anode is the unmarked lead.
1N4738A-T50A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AL, DO-41, Axial
- Packaging:
- Cut Tape (CT)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 8.2 V
- Tolerance:
- ±5%
- Power - Max:
- 1 W
- Impedance (Max) (Zzt):
- 4.5 Ohms
- Current - Reverse Leakage @ Vr:
- 10 µA @ 6 V
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-41
1N4738A-T50A FAQ
1.How can I place an order for 1N4738A-T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4738A-T50A 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 1N4738A-T50A reliable?
The price and inventory of 1N4738A-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4738A-T50A is usually 5 days.
3.What payment methods are accepted for 1N4738A-T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4738A-T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4738A-T50A?
1N4738A-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4738A-T50A 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 1N4738A-T50A?
For technical support, including 1N4738A-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4738A-T50A requirements.
6.How does Aetrix verify that 1N4738A-T50A is sourced from the original manufacturer or authorized distributors?
All 1N4738A-T50A 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 1N4738A-T50A meets industry standards.
7.What is the process for return or replacement of 1N4738A-T50A?
All 1N4738A-T50A units undergo pre-shipment inspection (PSI). If there is an issue with 1N4738A-T50A, 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 1N4738A-T50A part is unused and in its original packaging.
Return procedure for 1N4738A-T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N4738A-T50A Tags
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BZX84C3V3LT1G
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MM5Z5V1ST1G
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