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

Taiwan Semiconductor Corporation 1SMA4746

Name: 1SMA4746
Brand: Taiwan Semiconductor Corporation
SKU: 1SMA4746
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1SMA4746

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-214AC, SMA

Datasheet:: 1SMA4746.pdf

Description:: DIODE ZENER 18V 1.25W DO214AC

Quantity:: RFQ Add To RFQ list

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Inventory:2,490

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Product details

Overview

1SMA4746 from Taiwan Semiconductor is a 1W surface-mount Zener diode with nominal zener voltage 18V ±5%, test current 14.0mA, dynamic impedance 20Ω at IZT, maximum leakage current 1μA at 13.7V, and DO-214AC (SMA) package. It provides precise voltage regulation and transient overvoltage protection in compact power supply and interface circuits.

For engineers reviewing the 1SMA4746 datasheet, 1SMA4746 pinout, 1SMA4746 application, or 1SMA4746 equivalent, key selection criteria include its 18V nominal breakdown, 20Ω zener impedance at 14mA, 1W steady-state power rating, -55°C to +175°C junction temperature range, and SMA package compatibility with automated SMT assembly.

Technical Context

The 1SMA4746 operates as a single-die, unidirectional Zener diode with glass-passivated junction for stable reverse-breakdown characteristics. Its electrical behavior is defined by specified V_Z tolerance (±5%), low inductance construction, and guaranteed leakage current ≤1μA at 13.7V (80% of nominal V_Z).

Thermal performance is characterized by a maximum junction temperature of 175°C and power derating above 25°C ambient - delivering 1.25W at 60°C with R_THJA <76.8 K/W. Non-repetitive peak surge capability reaches 60W for 100μs pulses, supporting transient suppression in DC rails.

Key Specifications

Parameter	Value and Actual Design Meaning
Nominal Zener Voltage	18V ±5% - defines regulated output voltage under 14.0mA test current
Test Current (I_ZT)	14.0mA - operating point where V_Z and Z_ZT are guaranteed
Zener Impedance (Z_ZT)	20Ω at I_ZT - determines regulation stiffness and output ripple rejection
Maximum Leakage Current	1μA at 13.7V - ensures minimal standby power loss below breakdown threshold
Power Dissipation (P_D)	1W at 25°C - sets continuous thermal limit on PCB with standard copper pad
Junction Temperature Range	-55°C to +175°C - supports operation in industrial and automotive under-hood environments
Surge Current (I_FSM)	30A (8.3ms half-sine) - enables robust ESD/line-transient clamping without failure

Pinout & Package

DO-214AC (SMA) surface-mount package with cathode indicated by band-marked end. Matte tin-plated leads meet J-STD-002 solderability; weight ≈0.060g; UL 94V-0 molding compound.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / low-voltage reference node	Connected to lower-potential rail during regulation or clamping
Cathode	Zener breakdown terminal / regulated output node	Provides stable 18V reference when reverse-biased above V_Z

Key Features

Feature	Design Value
Glass-passivated chip junction	Ensures long-term stability of V_Z and low parameter drift across temperature and life cycles
Low inductance construction	Minimizes voltage overshoot during fast transients, improving clamping fidelity
Moisture sensitivity level 1	Eliminates bake requirements before reflow, streamlining SMT manufacturing
RoHS and halogen-free compliance	Meets IEC 61249-2-21 and global environmental directives for commercial and industrial use

Applications

Power Supply Regulation	Overvoltage Protection
Use Scenario: Stabilizing 18V bias rail in isolated DC-DC converter feedback loop. IC Role / Device Role / Timing Role: Zener reference element providing precision voltage setpoint for error amplifier. Use Value: 20Ω dynamic impedance ensures <1% output deviation under 10–100mA load step changes.	Use Scenario: Clamping 24V industrial I/O line against induced surges and ESD events. IC Role / Device Role / Timing Role: Transient voltage suppressor shunting excess energy to ground. Use Value: 30A surge current rating and 60W non-repetitive peak power withstand protect downstream logic inputs.
Reference Voltage Source	Signal Level Translation
Use Scenario: Generating stable 18V reference for ADC input scaling in sensor signal conditioning. IC Role / Device Role / Timing Role: Precision voltage reference with low temperature coefficient (≈+3.5mV/°C). Use Value: ±5% V_Z tolerance and <1μA leakage at 13.7V ensure accurate analog front-end calibration.	Use Scenario: Shifting 3.3V logic signals to 18V levels for driving high-side gate drivers. IC Role / Device Role / Timing Role: Clamp diode limiting negative swing and defining positive rail offset. Use Value: Low forward voltage (~0.8V) and fast recovery enable clean level translation without latch-up risk.

Power Supply Regulation

Overvoltage Protection

Use Scenario: Stabilizing 18V bias rail in isolated DC-DC converter feedback loop.

IC Role / Device Role / Timing Role: Zener reference element providing precision voltage setpoint for error amplifier.

Use Value: 20Ω dynamic impedance ensures <1% output deviation under 10–100mA load step changes.

Use Scenario: Clamping 24V industrial I/O line against induced surges and ESD events.

IC Role / Device Role / Timing Role: Transient voltage suppressor shunting excess energy to ground.

Use Value: 30A surge current rating and 60W non-repetitive peak power withstand protect downstream logic inputs.

Reference Voltage Source

Signal Level Translation

Use Scenario: Generating stable 18V reference for ADC input scaling in sensor signal conditioning.

IC Role / Device Role / Timing Role: Precision voltage reference with low temperature coefficient (≈+3.5mV/°C).

Use Value: ±5% V_Z tolerance and <1μA leakage at 13.7V ensure accurate analog front-end calibration.

Use Scenario: Shifting 3.3V logic signals to 18V levels for driving high-side gate drivers.

IC Role / Device Role / Timing Role: Clamp diode limiting negative swing and defining positive rail offset.

Use Value: Low forward voltage (~0.8V) and fast recovery enable clean level translation without latch-up risk.

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 1N4746A	Same 18V ±5% V_Z, 1W rating, DO-41 through-hole package (not surface-mount)	Requires PCB layout change; unsuitable for automated SMT lines	Select 1N4746A only if through-hole assembly or legacy board redesign is acceptable
Vishay 1SMA4746-G3-08	Identical 18V V_Z, 14mA I_ZT, 20Ω Z_ZT, DO-214AC package, AEC-Q200 qualified	Qualified for automotive applications; higher screening cost but same footprint	Choose Vishay variant when automotive qualification or extended reliability testing is required

Compared with 1N4746A and Vishay 1SMA4746-G3-08, the Taiwan Semiconductor 1SMA4746 offers identical electrical specs and SMA packaging for SMT compatibility, while differing in qualification status and mechanical form factor - making it optimal for cost-sensitive industrial SMT designs without automotive requirements.

Availability

1SMA4746 is available at Aetrix Electronics and suitable for power supply regulation, overvoltage protection, and reference voltage generation requiring stable component supply and full RoHS/halogen-free compliance.

Supply support for 1SMA4746 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, Zener diodes, and TVS components for industrial and consumer markets.

The 1SMA47xx series was designed specifically for surface-mount voltage regulation and transient suppression in space-constrained, high-reliability DC power systems - emphasizing automation readiness, thermal robustness, and JEDEC-compliant surge handling.

FAQ

What is the nominal zener voltage and tolerance of the 1SMA4746?

The 1SMA4746 has a nominal zener voltage of 18V with a standard tolerance of ±5%, measured at 14.0mA test current and 30°C lead temperature. This specification is guaranteed per Taiwan Semiconductor's P2102 datasheet revision and applies across the full operating temperature range of -55°C to +175°C.

Does the 1SMA4746 support automated SMT placement?

Yes, the 1SMA4746 is explicitly designed for automated placement: it uses the DO-214AC (SMA) package with matte tin-plated leads compliant with J-STD-002, moisture sensitivity level 1 (no bake required), and glass-passivated junction for process stability - all confirmed in the official Taiwan Semiconductor datasheet.

What is the maximum leakage current specification for the 1SMA4746?

The 1SMA4746 specifies a maximum leakage current of 1μA at 13.7V (80% of nominal V_Z), tested at 25°C ambient. This value ensures minimal quiescent power loss in always-on regulation or protection circuits, and is verified in the Electrical Specifications table of the Taiwan Semiconductor P2102 document.

Can the 1SMA4746 be used for transient voltage suppression?

Yes, the 1SMA4746 supports transient suppression with a non-repetitive peak surge power rating of 60W (100μs pulse) and peak forward surge current of 30A (8.3ms half-sine). These ratings are validated in the Absolute Maximum Ratings section and enable reliable clamping of ESD and line-induced spikes in industrial interfaces.

What is the thermal derating behavior of the 1SMA4746 above 25°C?

The 1SMA4746 maintains 1W power dissipation up to 25°C ambient, then derates linearly to 1.25W at 60°C when mounted on a PCB with R_THJA <76.8 K/W. This behavior is documented in the Absolute Maximum Ratings table and reflects its suitability for enclosed or thermally demanding environments.

1SMA4746 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):: 18 V

Tolerance:: ±5%

Power - Max:: 1.25 W

Impedance (Max) (Zzt):: 20 Ohms

Current - Reverse Leakage @ Vr:: 1 µA @ 13.7 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)

1SMA4746 FAQ

1.How can I place an order for 1SMA4746 through Aetrix?

Please submit a Request for Quotation (RFQ) for 1SMA4746 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 1SMA4746 reliable?

The price and inventory of 1SMA4746 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA4746 is usually 5 days.

3.What payment methods are accepted for 1SMA4746?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA4746 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1SMA4746?

1SMA4746 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1SMA4746 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 1SMA4746?

For technical support, including 1SMA4746 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA4746 requirements.

6.How does Aetrix verify that 1SMA4746 is sourced from the original manufacturer or authorized distributors?

All 1SMA4746 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 1SMA4746 meets industry standards.

7.What is the process for return or replacement of 1SMA4746?

All 1SMA4746 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA4746, 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 1SMA4746 part is unused and in its original packaging.

Return procedure for 1SMA4746:

1.Submit a request within 90 days.

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

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