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

Taiwan Semiconductor Corporation 1SMA4742H

Name: 1SMA4742H
Brand: Taiwan Semiconductor Corporation
SKU: 1SMA4742H
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1SMA4742H

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-214AC, SMA

Datasheet:: 1SMA4742H.pdf

Description:: DIODE ZENER 12V 1.25W DO214AC

Quantity:: RFQ Add To RFQ list

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Inventory:3,008

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Product details

Overview

1SMA4742H from Taiwan Semiconductor is a 1W surface-mount Zener diode with nominal zener voltage 12 V, test current 21 mA, dynamic impedance 9 Ω, and maximum leakage current 1 µA at 9.1 V reverse bias. It features glass passivated junction, AEC-Q101 qualification, and DO-214AC (SMA) package for automotive-grade voltage regulation and overvoltage protection in power supply rails.

For engineers reviewing the 1SMA4742H datasheet, 1SMA4742H pinout, 1SMA4742H application, or 1SMA4742H equivalent, key selection criteria include zener voltage tolerance (±5%), surge current rating (380 mA), thermal derating above 25°C, and compliance with JESD201 Class 2 whisker resistance and J-STD-020 moisture sensitivity level 1.

Technical Context

The 1SMA4742H operates as a single-die, unidirectional voltage reference device with sharp reverse breakdown at 12 V under 21 mA test current. Its 9 Ω dynamic impedance at IZT and 700 Ω knee impedance at IZK support stable regulation across load variations, while low inductance and glass passivation ensure robust transient response and long-term reliability.

Designed for surface-mount assembly on PCBs with 5 mm × 5 mm copper pads, it sustains non-repetitive peak surge power up to 60 W (100 µs pulse) and continuous dissipation of 1 W at 25°C, derating linearly to 1.25 W at 60°C per R_THJA < 76.8 K/W thermal path.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener voltage V_Z	12 V ±5% - precise DC reference for feedback loops and clamp thresholds
Test current I_ZT	21 mA - operating point where V_Z and Z_ZT are specified
Zener impedance Z_ZT	9 Ω - low AC impedance ensures minimal output voltage variation under dynamic load
Max leakage current I_R	1 µA at 9.1 V - guarantees negligible standby power loss in high-impedance bias networks
Power dissipation P_D	1 W at 25°C - defines maximum continuous DC power handling on standard PCB layout
Junction temperature T_J	−55°C to +175°C - supports operation in under-hood automotive and industrial environments
Surge current I_FSM	30 A (8.3 ms half-sine) - withstands inrush and ESD-induced transients without degradation

Pinout & Package

Package: DO-214AC (SMA), surface-mount, single-ended configuration with cathode band marking. Weight: 0.060 g. Molding compound meets UL 94V-0 flammability rating; matte tin-plated leads comply with J-STD-002 solderability.

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 higher-potential rail for clamping or reference generation

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive electronics per stress test requirements including temperature cycling and HTRB
Glass passivated junction	Prevents moisture ingress and surface contamination, enabling >10-year field reliability in humid environments
Low inductance construction	Minimizes voltage overshoot during fast transients, critical for ESD and surge suppression
J-STD-020 Level 1 moisture sensitivity	Allows unlimited floor life before reflow; no baking required prior to assembly
RoHS and halogen-free	Complies with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for green manufacturing

Applications

Automotive Power Rail Clamp	Industrial Sensor Reference
Use Scenario: Clamping 12 V battery-supplied microcontroller I/O lines against load dump transients up to 40 V. IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to shunt excess energy to ground. Use Value: Limits voltage to ≤12.6 V (12 V × 1.05) with 1 µA leakage, preserving signal integrity without loading the sensor interface.	Use Scenario: Providing stable 12 V reference for analog-to-digital conversion in a 4–20 mA loop transmitter. IC Role / Device Role / Timing Role: Precision voltage reference source with ±5% tolerance and 9 Ω dynamic impedance. Use Value: Enables 0.5% full-scale accuracy in 12-bit ADC systems by minimizing reference drift under varying load currents.
DC-DC Feedback Divider	Overvoltage Protection Circuit
Use Scenario: Setting regulated output voltage in isolated flyback converter using TL431 secondary-side feedback. IC Role / Device Role / Timing Role: Zener diode biasing optocoupler LED to maintain closed-loop stability. Use Value: Delivers consistent 21 mA bias current with <1% variation across −40°C to +125°C ambient, ensuring tight output regulation.	Use Scenario: Protecting FPGA configuration pins from accidental 15 V misconnection during board bring-up. IC Role / Device Role / Timing Role: Standby clamping device activated only above 12.6 V threshold. Use Value: Absorbs 60 W non-repetitive surge (100 µs) without failure, preventing latch-up or gate oxide damage.

Automotive Power Rail Clamp

Industrial Sensor Reference

Use Scenario: Clamping 12 V battery-supplied microcontroller I/O lines against load dump transients up to 40 V.

IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to shunt excess energy to ground.

Use Value: Limits voltage to ≤12.6 V (12 V × 1.05) with 1 µA leakage, preserving signal integrity without loading the sensor interface.

Use Scenario: Providing stable 12 V reference for analog-to-digital conversion in a 4–20 mA loop transmitter.

IC Role / Device Role / Timing Role: Precision voltage reference source with ±5% tolerance and 9 Ω dynamic impedance.

Use Value: Enables 0.5% full-scale accuracy in 12-bit ADC systems by minimizing reference drift under varying load currents.

DC-DC Feedback Divider

Overvoltage Protection Circuit

Use Scenario: Setting regulated output voltage in isolated flyback converter using TL431 secondary-side feedback.

IC Role / Device Role / Timing Role: Zener diode biasing optocoupler LED to maintain closed-loop stability.

Use Value: Delivers consistent 21 mA bias current with <1% variation across −40°C to +125°C ambient, ensuring tight output regulation.

Use Scenario: Protecting FPGA configuration pins from accidental 15 V misconnection during board bring-up.

IC Role / Device Role / Timing Role: Standby clamping device activated only above 12.6 V threshold.

Use Value: Absorbs 60 W non-repetitive surge (100 µs) without failure, preventing latch-up or gate oxide damage.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4742A	Same 12 V ±5%, but through-hole DO-41 package; 1 W rating; higher Z_ZT (10 Ω)	Requires PCB through-hole mounting; unsuitable for automated SMT lines	Select when legacy through-hole design or manual prototyping is required
BZX84-C12	SOT-23 package; 12 V ±5%; 300 mW rating; Z_ZT = 25 Ω; max I_R = 100 nA at 8 V	Limited power handling; not rated for AEC-Q101 or automotive use	Select for space-constrained low-power consumer circuits where automotive qualification is unnecessary

Compared with 1SMA4742H, the 1N4742A offers identical electrical specs but lacks SMT compatibility and AEC-Q101 validation, while BZX84-C12 trades power capability and automotive qualification for ultra-small footprint-making 1SMA4742H optimal for production-grade automotive and industrial SMT designs requiring 1 W regulation.

Availability

1SMA4742H is available at Aetrix Electronics and suitable for automotive power management, industrial sensor interfaces, and DC-DC converter feedback networks requiring stable component supply, AEC-Q101 compliance, and DO-214AC packaging.

Supply support for 1SMA4742H 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 ISO/TS 16949 certification.

The 1SMA47xxH series targets high-reliability surface-mount Zener regulation in automotive and industrial systems, emphasizing AEC-Q101 qualification, low-inductance packaging, and extended temperature operation from −55°C to +175°C.

FAQ

What is the zener voltage tolerance for 1SMA4742H?

The 1SMA4742H has a nominal zener voltage of 12 V with a standard tolerance of ±5%, meaning the actual measured V_Z falls between 11.4 V and 12.6 V at 21 mA 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.

Is 1SMA4742H suitable for automotive applications?

Yes, the 1SMA4742H is AEC-Q101 qualified and specifically designed for automotive use. It passes stress tests including high-temperature reverse bias (HTRB), temperature cycling, and mechanical shock. Its DO-214AC package, JESD201 Class 2 whisker resistance, and −55°C to +175°C operating range make it appropriate for engine control units, body electronics, and ADAS power domains.

What is the maximum non-repetitive surge current for 1SMA4742H?

The 1SMA4742H supports a non-repetitive peak forward surge current (I_FSM) of 30 A for an 8.3 ms single half-sine wave, and a non-repetitive peak reverse surge power (P_ZSM) of 60 W for a 100 µs square pulse at 25°C ambient. These ratings are validated per JEDEC standards and reflect real-world capability against load dump and ESD events.

How does the 1SMA4742H compare to 1SMA4741H and 1SMA4743H in terms of zener impedance?

The 1SMA4742H has a zener impedance (Z_ZT) of 9 Ω at 21 mA, which is lower than 1SMA4741H (8 Ω at 23 mA) and higher than 1SMA4743H (10 Ω at 19 mA). This progression reflects the inverse relationship between nominal zener voltage and Z_ZT within the 1SMA47xxH family-lower-voltage parts exhibit lower impedance due to higher doping density and reduced series resistance.

What is the moisture sensitivity level (MSL) for 1SMA4742H?

The 1SMA4742H is rated at Moisture Sensitivity Level 1 per J-STD-020, meaning it has unlimited floor life at ≤30°C/60% RH and requires no baking prior to reflow soldering. This eliminates handling constraints in high-volume SMT production and supports standard JEDEC-compliant reflow profiles without popcorn risk.

1SMA4742H 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):: 12 V

Tolerance:: ±5%

Power - Max:: 1.25 W

Impedance (Max) (Zzt):: 9 Ohms

Current - Reverse Leakage @ Vr:: 1 µA @ 9.1 V

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

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

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

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

1SMA4742H FAQ

1.How can I place an order for 1SMA4742H through Aetrix?

Please submit a Request for Quotation (RFQ) for 1SMA4742H 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 1SMA4742H reliable?

The price and inventory of 1SMA4742H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA4742H is usually 5 days.

3.What payment methods are accepted for 1SMA4742H?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA4742H transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1SMA4742H?

1SMA4742H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1SMA4742H 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 1SMA4742H?

For technical support, including 1SMA4742H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA4742H requirements.

6.How does Aetrix verify that 1SMA4742H is sourced from the original manufacturer or authorized distributors?

All 1SMA4742H 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 1SMA4742H meets industry standards.

7.What is the process for return or replacement of 1SMA4742H?

All 1SMA4742H units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA4742H, 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 1SMA4742H part is unused and in its original packaging.

Return procedure for 1SMA4742H:

1.Submit a request within 90 days.

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

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