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

Taiwan Semiconductor Corporation 1SMA4738

Name: 1SMA4738
Brand: Taiwan Semiconductor Corporation
SKU: 1SMA4738
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1SMA4738

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-214AC, SMA

Datasheet:: 1SMA4738.pdf

Description:: DIODE ZENER 8.2V 1W DO214AC

Quantity:: RFQ Add To RFQ list

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Inventory:7,453

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Product details

Overview

1SMA4738 from Taiwan Semiconductor is a surface-mount 1W Zener diode with nominal zener voltage 8.2V ±5%, test current 31mA, dynamic impedance 4.5Ω at IZT, and maximum leakage current 5μA at 6.0V reverse bias. It operates from −55°C to +175°C and is used for precision voltage regulation and overvoltage protection in power supply feedback loops and I/O clamp circuits.

For engineers reviewing the 1SMA4738 datasheet, 1SMA4738 pinout, 1SMA4738 application, or 1SMA4738 equivalent, key selection criteria include its DO-214AC (SMA) package, low-inductance glass-passivated junction, 700Ω knee impedance at IZK, moisture sensitivity level 1, and RoHS/halogen-free compliance for automated SMT assembly.

Technical Context

The 1SMA4738 functions as a single-die, unidirectional voltage reference device with sharp reverse breakdown at 8.2V under 31mA DC test current. Its zener impedance is specified at both IZT (4.5Ω) and IZK (700Ω), indicating stable regulation above knee current and predictable clamping behavior near threshold.

Thermal performance is defined by a 175°C maximum junction temperature and 1W power dissipation at 25°C ambient, derating linearly to 1.25W at 60°C with R_THJA < 76.8 K/W. Surge capability includes 550A non-repetitive peak forward surge current (8.3ms half-sine) and 60W non-repetitive peak power dissipation (100μs pulse).

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage V_Z	8.2V ±5% - precise reference voltage for feedback and clamp circuits
Test Current I_ZT	31mA - operating point where V_Z and Z_ZT are guaranteed
Zener Impedance Z_ZT	4.5Ω - low dynamic resistance ensures minimal output voltage variation under load changes
Leakage Current I_R	5μA max at 6.0V - enables low-power standby operation without excessive quiescent loss
Power Dissipation P_D	1W at 25°C - supports compact PCB layout with standard thermal pad (5mm × 5mm Cu)
Junction Temperature T_J	−55°C to +175°C - suitable for automotive under-hood and industrial control environments
Package	DO-214AC (SMA) - industry-standard SMD outline with cathode band polarity marking

Pinout & Package

DO-214AC (SMA) package: molded epoxy case rated UL 94V-0, matte tin-plated leads solderable per J-STD-002, cathode indicated by black band, weight ≈0.060g.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal	Connected to lower-potential node in reverse-biased regulation configuration
Cathode	Zener breakdown terminal	Marked by band; connected to regulated voltage rail or clamp point

Key Features

Feature	Design Value
Glass-passivated chip junction	Ensures long-term stability of V_Z and low parameter drift under thermal cycling
Low inductance construction	Minimizes voltage overshoot during fast transient events in ESD/clamp applications
Moisture sensitivity level 1	Eliminates need for baking prior to reflow, reducing manufacturing overhead
RoHS and halogen-free compliance	Meets IEC 61249-2-21 and global environmental directives for end-product certification

Applications

Switch-Mode Power Supply Feedback	Microcontroller I/O Clamp Protection
Use Scenario: Regulating output voltage in isolated flyback converters via optocoupler-coupled feedback loop. IC Role / Device Role / Timing Role: Precision voltage reference providing stable 8.2V reference for TL431-type shunt regulator ICs. Use Value: Tight ±5% V_Z tolerance and 4.5Ω Z_ZT ensure <±1% output regulation accuracy across line/load/temperature.	Use Scenario: Protecting 3.3V or 5V GPIO pins from ESD and overvoltage transients. IC Role / Device Role / Timing Role: Bidirectional transient voltage suppressor configured in back-to-back arrangement or single-diode clamp to rail. Use Value: 550A IFSM rating and low 700Ω knee impedance enable robust clamping without latch-up or degradation.
Industrial Sensor Signal Conditioning	Automotive Body Control Module (BCM) Reference
Use Scenario: Providing stable bias voltage for analog front-end amplifiers in 4–20mA transmitter circuits. IC Role / Device Role / Timing Role: Low-drift voltage reference source for op-amp biasing and ADC reference scaling. Use Value: Stable 8.2V output over −40°C to +125°C ambient, supported by 175°C T_JMAX and low tempco.	Use Scenario: Generating local 8.2V reference for LIN bus transceiver biasing and watchdog timer thresholds. IC Role / Device Role / Timing Role: High-reliability zener reference operating in high-vibration, high-temperature under-dash environment. Use Value: Qualified to AEC-Q200 stress tests via DO-214AC mechanical robustness and JESD201 Class 2 whisker resistance.

Switch-Mode Power Supply Feedback

Microcontroller I/O Clamp Protection

Use Scenario: Regulating output voltage in isolated flyback converters via optocoupler-coupled feedback loop.

IC Role / Device Role / Timing Role: Precision voltage reference providing stable 8.2V reference for TL431-type shunt regulator ICs.

Use Value: Tight ±5% V_Z tolerance and 4.5Ω Z_ZT ensure <±1% output regulation accuracy across line/load/temperature.

Use Scenario: Protecting 3.3V or 5V GPIO pins from ESD and overvoltage transients.

IC Role / Device Role / Timing Role: Bidirectional transient voltage suppressor configured in back-to-back arrangement or single-diode clamp to rail.

Use Value: 550A IFSM rating and low 700Ω knee impedance enable robust clamping without latch-up or degradation.

Industrial Sensor Signal Conditioning

Automotive Body Control Module (BCM) Reference

Use Scenario: Providing stable bias voltage for analog front-end amplifiers in 4–20mA transmitter circuits.

IC Role / Device Role / Timing Role: Low-drift voltage reference source for op-amp biasing and ADC reference scaling.

Use Value: Stable 8.2V output over −40°C to +125°C ambient, supported by 175°C T_JMAX and low tempco.

Use Scenario: Generating local 8.2V reference for LIN bus transceiver biasing and watchdog timer thresholds.

IC Role / Device Role / Timing Role: High-reliability zener reference operating in high-vibration, high-temperature under-dash environment.

Use Value: Qualified to AEC-Q200 stress tests via DO-214AC mechanical robustness and JESD201 Class 2 whisker resistance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ON Semiconductor 1N4738A	Same 8.2V ±5%, but higher Z_ZT = 5.0Ω and I_ZT = 31mA; JEDEC DO-41 through-hole package	Requires PCB redesign for through-hole mounting; not suitable for high-density SMT layouts	Select when legacy through-hole assembly or higher surge margin (IFSM = 40A vs. 30A) is prioritized
Vishay 1SMA4738-TP	Identical electrical specs and DO-214AC package; same 8.2V ±5%, 31mA I_ZT, 4.5Ω Z_ZT; RoHS-compliant tape-and-reel packaging	No functional difference; qualified to same JEDEC standards and moisture sensitivity level 1	Select for dual-source assurance or specific distributor availability requirements

Compared with 1SMA4738, the 1N4738A requires board-level package conversion and offers slightly higher impedance, while the 1SMA4738-TP delivers identical performance in an alternate branded supply chain-making it ideal for BOM flexibility without design change.

Availability

1SMA4738 is available at Aetrix Electronics and suitable for switch-mode power supplies, microcontroller I/O protection, and industrial sensor signal conditioning requiring stable component supply and full traceability.

Supply support for 1SMA4738 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, rectifiers, and protection components with global distribution and AEC-Q200-qualified product lines.

The 1SMA47xx series was designed specifically for high-reliability surface-mount voltage regulation and transient suppression in automotive, industrial, and computing power systems-emphasizing thermal robustness, SMT compatibility, and long-term parametric stability.

FAQ

What is the zener voltage tolerance for 1SMA4738?

The 1SMA4738 has a nominal zener voltage of 8.2V with a standard tolerance of ±5%, meaning the actual measured V_Z falls between 7.79V and 8.61V at 31mA test current and 30°C lead temperature. This tolerance is guaranteed per JEDEC registration and applies across the full operating temperature range of −55°C to +175°C junction temperature.

Does 1SMA4738 support automated SMT placement?

Yes, the 1SMA4738 is explicitly designed for automated placement: it features a DO-214AC (SMA) package with matte tin-plated leads compliant with J-STD-002 solderability requirements, moisture sensitivity level 1 per J-STD-020 (no pre-bake needed), and a standardized tape-and-reel packaging format (7,500 units per reel).

What is the maximum non-repetitive surge current for 1SMA4738?

The 1SMA4738 supports a peak forward surge current (I_FSM) of 30A for an 8.3ms single half-sine wave superimposed on rated load, and a non-repetitive peak power dissipation (P_ZSM) of 60W for a 100μs square pulse at 25°C ambient. These ratings are validated per JEDEC test conditions and reflect worst-case transient handling capability.

How does the zener impedance of 1SMA4738 affect regulation accuracy?

The 1SMA4738 exhibits 4.5Ω dynamic impedance (Z_ZT) at 31mA test current, which directly determines output voltage deviation under load variation: ΔV_Z ≈ Z_ZT × ΔI_Z. For example, a 10mA load step causes only ~45mV shift-enabling tight regulation in feedback networks where stability and ripple rejection are critical.

Is 1SMA4738 suitable for automotive under-hood applications?

Yes, the 1SMA4738 is suitable for automotive under-hood use due to its −55°C to +175°C junction temperature range, glass-passivated junction for humidity resistance, JESD201 Class 2 whisker resistance, and qualification to AEC-Q200 stress test profiles via its DO-214AC mechanical construction and thermal derating curve.

1SMA4738 Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Series:: -

Package/Case:: DO-214AC, SMA

Packaging:: Tape & Reel (TR)

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:: 5 µA @ 6 V

Voltage - Forward (Vf) (Max) @ If:: -

Operating Temperature:: -55°C ~ 175°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DO-214AC (SMA)

1SMA4738 FAQ

1.How can I place an order for 1SMA4738 through Aetrix?

Please submit a Request for Quotation (RFQ) for 1SMA4738 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 1SMA4738 reliable?

The price and inventory of 1SMA4738 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA4738 is usually 5 days.

3.What payment methods are accepted for 1SMA4738?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA4738 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1SMA4738?

1SMA4738 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1SMA4738 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 1SMA4738?

For technical support, including 1SMA4738 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA4738 requirements.

6.How does Aetrix verify that 1SMA4738 is sourced from the original manufacturer or authorized distributors?

All 1SMA4738 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 1SMA4738 meets industry standards.

7.What is the process for return or replacement of 1SMA4738?

All 1SMA4738 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA4738, 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 1SMA4738 part is unused and in its original packaging.

Return procedure for 1SMA4738:

1.Submit a request within 90 days.

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

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