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Diodes Incorporated 1N4738A-T
- Part No.:
- 1N4738A-T
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- DO-204AL, DO-41, Axial
- Datasheet:
-
1N4738A-T.pdf
- Description:
- DIODE ZENER 8.2V 1W DO41
- Quantity:
- Payment:
- Shipping:
Inventory:9,754
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Product details
Overview
1N4738A-T from Diodes Incorporated is a 1.0 W, 8.2 V ±5% Zener diode in DO-41 glass package, designed for voltage regulation and reference applications with 4.5 Ω zener impedance at 31 mA test current and -65°C to +175°C operating temperature range. It delivers stable clamping in power supply feedback loops and overvoltage protection circuits.
For engineers reviewing the 1N4738A-T datasheet, 1N4738A-T pinout, 1N4738A-T application, or 1N4738A-T equivalent, key selection criteria include nominal zener voltage (8.2 V), power dissipation (1.0 W), zener impedance (4.5 Ω), reverse leakage (10 µA @ 6.0 V), and thermal resistance (175 °C/W).
Technical Context
This device operates as a silicon planar Zener diode with sharp breakdown knee, optimized for DC voltage regulation where precise, low-drift references are required. Its 8.2 V nominal zener voltage exhibits a positive temperature coefficient (+0.03 to +0.07 %/°C), enabling predictable drift behavior in temperature-varying environments.
The DO-41 glass package provides hermetic sealing and UL 94V-0 flammability rating, supporting reliable operation under thermal stress. With 175 °C/W junction-to-ambient thermal resistance and 6.67 mW/°C derating above 50°C, thermal management requires lead length control per MIL-STD-202.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 8.2 V ±5% at 31 mA - defines regulated output voltage with tight tolerance for precision reference use |
| Power Dissipation (Pd) | 1.0 W at 25°C - sets maximum continuous power handling before thermal derating begins |
| Zener Impedance (ZZT) | 4.5 Ω at IZT = 31 mA - indicates low dynamic resistance for minimal regulation error under load variation |
| Reverse Leakage (IR) | 10 µA max at VR = 6.0 V - ensures low standby current in high-impedance bias networks |
| Surge Current (IZS) | 550 mA for 8.3 ms - supports transient overvoltage clamping without failure |
| Temperature Coefficient | +0.03 to +0.07 %/°C at IZT - enables predictable, monotonic voltage drift with temperature rise |
| Operating Temperature | -65°C to +175°C - allows deployment in automotive under-hood and industrial harsh-environment systems |
Pinout & Package
Package: DO-41 glass axial-leaded case with cathode band marking; UL 94V-0 rated; Sn96.5Ag3.5 solderable terminations; weight ≈ 0.35 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Zener cathode reference ground | Connected to circuit ground or lower-potential node when used in reverse-bias regulation |
| Cathode | Zener breakdown terminal / voltage reference output | Provides stable 8.2 V reference relative to anode; marked with visible band on glass body |
Key Features
| Feature | Design Value |
|---|---|
| 1.0 W Power Rating | Enables robust voltage clamping in mid-power supply rails without external heat sinking |
| ±5% Zener Tolerance | Reduces binning requirements and simplifies design margining for 8.2 V reference accuracy |
| Low 4.5 Ω Zener Impedance | Minimizes output voltage deviation under varying load currents in feedback networks |
| DO-41 Glass Hermetic Package | Ensures long-term parameter stability and moisture resistance in humid or high-reliability environments |
| RoHS-Compliant Finish | Meets EU Directive 2002/95/EC with Sn96.5Ag3.5 terminations compatible with lead-free reflow |
Applications
| Switch-Mode Power Supply Feedback | Overvoltage Protection Clamp |
|---|---|
Use Scenario: Regulating output voltage in isolated flyback converters via optocoupler-coupled feedback loop. IC Role / Device Role / Timing Role: Zener diode provides precise 8.2 V reference to TL431 shunt regulator input, setting primary-side feedback threshold. Use Value: Tight 8.2 V ±5% tolerance and low 4.5 Ω impedance ensure <±1% output regulation across line/load/temperature. | Use Scenario: Protecting microcontroller I/O pins from ESD or inductive kickback in motor drive circuits. IC Role / Device Role / Timing Role: Acts as bidirectional transient voltage suppressor, clamping negative transients to ground and positive transients to 8.2 V rail. Use Value: 550 mA 8.3 ms surge rating absorbs repetitive 100 V/1 A spikes without degradation, extending system lifetime. |
| Industrial Sensor Reference | Linear Regulator Shunt |
Use Scenario: Providing stable excitation voltage for resistive bridge sensors in process control transmitters. IC Role / Device Role / Timing Role: Serves as low-noise, low-drift voltage reference for Wheatstone bridge biasing and ADC reference scaling. Use Value: +0.03 to +0.07 %/°C tempco enables <0.5% full-scale error over -40°C to +85°C ambient range. | Use Scenario: Improving regulation in low-dropout linear regulators by shunting excess current from pass transistor base. IC Role / Device Role / Timing Role: Functions as programmable current sink to stabilize base-emitter voltage of series pass transistor. Use Value: 1.0 W power rating supports up to 120 mA shunt current at 8.2 V, enabling stable 5 V/3.3 V outputs under variable loads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DFLZ8.2-7 | Surface-mount SOD-123 package; 8.2 V ±5%; 500 mW rating; 10 Ω ZZT at 5 mA | Lower power, higher impedance, and SMT footprint - suited for space-constrained PCBs but not direct 1W replacement | Select for new designs prioritizing board density and automated assembly; verify thermal margin at target current |
| 1N4738A-A | Identical electrical specs and DO-41 package; differs only in ammo-pack packaging (vs. tape-and-reel) | No functional difference - identical performance and mounting; packaging affects reel-based SMT placement compatibility | Choose based on assembly method: -T for pick-and-place machines, -A for manual or wave-soldered through-hole production |
Compared with DFLZ8.2-7 and 1N4738A-A, the 1N4738A-T offers higher power headroom (1.0 W vs. 0.5 W), lower dynamic impedance (4.5 Ω vs. 10 Ω), and proven reliability in legacy through-hole designs - making it optimal for repair, industrial retrofits, and applications requiring sustained 31 mA regulation current.
Availability
1N4738A-T is available at Aetrix Electronics and suitable for switch-mode power supplies, overvoltage protection circuits, industrial sensor references, and linear regulator shunt applications requiring stable component supply and long-lifecycle support.
Supply support for 1N4738A-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 automotive, industrial, and computing markets.
The 1N47xxA series belongs to Diodes' standard Zener diode product line, engineered for cost-effective, high-volume voltage regulation and reference functions in power management and protection circuits.
FAQ
What is the maximum continuous Zener current for 1N4738A-T at 25°C?
The maximum continuous Zener current is calculated as Pd/VZ = 1.0 W / 8.2 V ≈ 122 mA. However, the recommended test current is 31 mA per datasheet, and operation above this level requires thermal derating per the 6.67 mW/°C curve and lead-length-controlled layout to avoid junction overheating.
Is 1N4738A-T suitable for surface-mount assembly?
No - the 1N4738A-T uses a DO-41 axial glass package with leads intended for through-hole mounting. It is not compatible with reflow or wave soldering processes designed for SMT components. For surface-mount equivalents, consider the DFLZ8.2-7 in SOD-123 package.
How does the temperature coefficient affect regulation accuracy over temperature?
With a +0.03 to +0.07 %/°C coefficient, the 1N4738A-T's zener voltage increases by approximately 2.5–5.8 mV/°C. Over a 100°C range (e.g., -25°C to +75°C), this results in a total shift of +0.25 V to +0.58 V - requiring system-level compensation if sub-1% absolute accuracy is needed across that span.
Why is 1N4738A-T marked "Not Recommended for New Design"?
This designation reflects Diodes Incorporated's strategic shift toward surface-mount alternatives like the DFLZ series, which offer better thermal performance, smaller footprint, and automated assembly compatibility. The 1N4738A-T remains fully qualified and supported for legacy designs, repairs, and applications where through-hole construction is mandated.
1N4738A-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- DO-204AL, DO-41, Axial
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- 1.2 V @ 200 mA
- Operating Temperature:
- -65°C ~ 175°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-41
1N4738A-T FAQ
1.How can I place an order for 1N4738A-T through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4738A-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 1N4738A-T reliable?
The price and inventory of 1N4738A-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4738A-T is usually 5 days.
3.What payment methods are accepted for 1N4738A-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4738A-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4738A-T?
1N4738A-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4738A-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 1N4738A-T?
For technical support, including 1N4738A-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4738A-T requirements.
6.How does Aetrix verify that 1N4738A-T is sourced from the original manufacturer or authorized distributors?
All 1N4738A-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 1N4738A-T meets industry standards.
7.What is the process for return or replacement of 1N4738A-T?
All 1N4738A-T units undergo pre-shipment inspection (PSI). If there is an issue with 1N4738A-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 1N4738A-T part is unused and in its original packaging.
Return procedure for 1N4738A-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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