Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Taiwan Semiconductor Corporation 1SMA4742

Name: 1SMA4742
Brand: Taiwan Semiconductor Corporation
SKU: 1SMA4742
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 1SMA4742

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-214AC, SMA

Datasheet:: 1SMA4742.pdf

Description:: DIODE ZENER 12V 1.25W DO214AC

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:6,949

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

1SMA4742 from Taiwan Semiconductor is a surface-mount 12 V, 1 W Zener diode in DO-214AC (SMA) package, with 21 mA test current, 9 Ω dynamic impedance at IZT, 0.25 µA leakage at 9.1 V, and junction temperature rating up to +175°C. It serves as a precision voltage reference and overvoltage clamp in power supply regulation and ESD protection circuits.

For engineers reviewing the 1SMA4742 datasheet, 1SMA4742 pinout, 1SMA4742 application, or 1SMA4742 equivalent, key selection criteria include nominal Zener voltage tolerance (±5%), low leakage performance below 1 µA, thermal stability across –55°C to +175°C, and surge capability up to 380 A peak forward current.

Technical Context

The 1SMA4742 operates as a single-die, glass-passivated Zener diode optimized for stable reverse-bias breakdown at 12 V ±5% under 21 mA test current. Its 9 Ω Zener impedance at IZT and 700 Ω at knee current support tight regulation in low-noise analog references and feedback loops.

Designed for surface-mount automation, it features matte tin-plated leads compliant with J-STD-002 solderability, moisture sensitivity level 1 per J-STD-020, and UL 94V-0 molding compound. Polarity is marked by a cathode band on the DO-214AC body.

Key Specifications

Parameter	Value and Actual Design Meaning
V_Z @ I_ZT	12 V ±5% - precise clamping/reference voltage at 21 mA test current
I_ZT	21 mA - standardized operating point for guaranteed V_Z and Z_ZT
Z_ZT @ I_ZT	9 Ω - low dynamic impedance ensures minimal voltage deviation under load variation
I_R @ V_R = 9.1 V	0.25 µA - ultra-low leakage preserves accuracy in high-impedance bias networks
P_D	1 W - continuous power dissipation rating at T_A = 25°C with R_THJA < 76.8 K/W
T_J max	+175°C - extended junction temperature enables use in automotive under-hood and industrial power modules
I_FSM	30 A - 8.3 ms half-sine surge withstand supports transient suppression in DC input stages

Pinout & Package

DO-214AC (SMA) surface-mount package with axial polarity marking: cathode indicated by a distinct band on the molded body. Leads are matte tin-plated and solderable per J-STD-002.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / low-side connection in shunt regulator	Connected to ground or lower-potential node during Zener operation; carries forward current up to 30 A surge
Cathode	Zener breakdown terminal / high-side connection in shunt regulator	Connected to regulated voltage node; maintains 12 V reference under reverse bias; marked by visible band

Key Features

Feature	Design Value
Glass passivated junction	Enhances long-term reliability and stability of V_Z under thermal cycling and humidity exposure
Low inductance construction	Minimizes voltage overshoot during fast transients, critical for ESD and surge clamp response
Moisture sensitivity level 1	Eliminates need for dry-pack handling or bake-out prior to reflow, reducing manufacturing cost
RoHS and halogen-free compliance	Meets IEC 61249-2-21 and global environmental directives without compromising electrical performance

Applications

Switching Power Supply Feedback	Industrial Sensor Signal Conditioning
Use Scenario: Voltage reference in optocoupler-coupled feedback loop of 12 V output AC/DC adapter. IC Role / Device Role / Timing Role: Shunt regulator providing stable 12 V reference to TL431 or similar error amplifier. Use Value: Tight ±5% V_Z tolerance and 9 Ω Z_ZT ensure output regulation within ±1.5% across line/load/temperature.	Use Scenario: Bias voltage stabilization for 4–20 mA current-loop transmitter front-end op-amps. IC Role / Device Role / Timing Role: Precision Zener reference supplying clean 12 V to instrumentation amplifiers and DACs. Use Value: 0.25 µA leakage at 9.1 V prevents loading errors in high-impedance sensor bias networks.
Automotive Body Control Module Clamp	Programmable Logic Controller Input Protection
Use Scenario: Reverse-polarity and load-dump transient suppression on 12 V battery rail in BCM microcontroller supply. IC Role / Device Role / Timing Role: Standby shunt clamp activated during overvoltage events exceeding 13.2 V. Use Value: +175°C T_J max and 30 A I_FSM enable reliable operation in under-hood environments with JEDEC-compliant surge immunity.	Use Scenario: Input-stage overvoltage protection for 24 V digital I/O channels in PLC backplane modules. IC Role / Device Role / Timing Role: Parallel-connected Zener limiting voltage spikes before Schottky clamps and current-limiting resistors. Use Value: Low 9 Ω Z_ZT ensures clamping voltage stays within safe margin of downstream logic thresholds during fast transients.

Switching Power Supply Feedback

Industrial Sensor Signal Conditioning

Use Scenario: Voltage reference in optocoupler-coupled feedback loop of 12 V output AC/DC adapter.

IC Role / Device Role / Timing Role: Shunt regulator providing stable 12 V reference to TL431 or similar error amplifier.

Use Value: Tight ±5% V_Z tolerance and 9 Ω Z_ZT ensure output regulation within ±1.5% across line/load/temperature.

Use Scenario: Bias voltage stabilization for 4–20 mA current-loop transmitter front-end op-amps.

IC Role / Device Role / Timing Role: Precision Zener reference supplying clean 12 V to instrumentation amplifiers and DACs.

Use Value: 0.25 µA leakage at 9.1 V prevents loading errors in high-impedance sensor bias networks.

Automotive Body Control Module Clamp

Programmable Logic Controller Input Protection

Use Scenario: Reverse-polarity and load-dump transient suppression on 12 V battery rail in BCM microcontroller supply.

IC Role / Device Role / Timing Role: Standby shunt clamp activated during overvoltage events exceeding 13.2 V.

Use Value: +175°C T_J max and 30 A I_FSM enable reliable operation in under-hood environments with JEDEC-compliant surge immunity.

Use Scenario: Input-stage overvoltage protection for 24 V digital I/O channels in PLC backplane modules.

IC Role / Device Role / Timing Role: Parallel-connected Zener limiting voltage spikes before Schottky clamps and current-limiting resistors.

Use Value: Low 9 Ω Z_ZT ensures clamping voltage stays within safe margin of downstream logic thresholds during fast transients.

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 1N4742A	Same 12 V ±5%, 1 W, DO-41 through-hole package; higher Z_ZT (10 Ω vs. 9 Ω); 1 µA leakage at 9.1 V	Requires PCB layout change due to axial leaded DO-41 vs. surface-mount DO-214AC	Select when legacy through-hole assembly or higher surge margin (50 A I_FSM) is prioritized over board space
Vishay 1N5242B	12 V ±5%, 0.5 W, DO-35 glass package; Z_ZT = 23 Ω; 0.1 µA leakage at 9.1 V	Limited to low-power signal-level regulation; not rated for 30 A surge or +175°C operation	Select only for low-current bias references where thermal derating and surge immunity are non-critical

Compared with 1N4742A and 1N5242B, the 1SMA4742 offers superior surface-mount compatibility, lower dynamic impedance, and extended thermal/surge capability-making it optimal for modern compact, high-reliability power and protection designs.

Availability

1SMA4742 is available at Aetrix Electronics and suitable for switching power supplies, industrial sensor interfaces, automotive body control modules, and programmable logic controller input protection requiring stable component supply and RoHS-compliant sourcing.

Supply support for 1SMA4742 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 with global distribution and AEC-Q200 qualified product lines.

The 1SMA47xx series was designed specifically for high-volume, automated SMT applications demanding robust voltage regulation, low leakage, and extended temperature operation in industrial and automotive power systems.

FAQ

What is the Zener voltage tolerance for the 1SMA4742?

The 1SMA4742 has a nominal Zener voltage of 12 V with a standard tolerance of ±5%, meaning its actual breakdown voltage falls between 11.4 V and 12.6 V when measured at 21 mA test current and 30°C lead temperature. This tolerance is confirmed in the Electrical Specifications table of the Taiwan Semiconductor datasheet P2102 and applies across the full operating temperature range.

Does the 1SMA4742 support reflow soldering per J-STD-020?

Yes, the 1SMA4742 is rated at Moisture Sensitivity Level 1 per J-STD-020, meaning it can be subjected to standard Pb-free reflow profiles without baking or dry-pack handling. Its DO-214AC package uses UL 94V-0 compliant molding compound and matte tin-plated leads qualified to J-STD-002 for reliable solder joint formation.

What is the maximum non-repetitive surge current rating for the 1SMA4742?

The 1SMA4742 is rated for a peak forward surge current (I_FSM) of 30 A for an 8.3 ms single half-sine wave at T_A = 25°C. This rating is defined in the Absolute Maximum Ratings table and supports transient suppression in DC input stages without degradation when used within JEDEC-defined test conditions.

How does the 1SMA4742 compare to the 1N4742A in terms of thermal performance?

The 1SMA4742 has a maximum junction temperature of +175°C and is specified for surface-mount thermal derating curves with R_THJA < 76.8 K/W, while the 1N4742A (DO-41) typically limits to +150°C and lacks published board-level thermal resistance data. This makes the 1SMA4742 better suited for high-temperature industrial and automotive applications where sustained power dissipation is required.

Is the 1SMA4742 halogen-free and RoHS compliant?

Yes, the 1SMA4742 meets RoHS Directive 2011/65/EU requirements and is halogen-free in accordance with IEC 61249-2-21. These compliance statements are explicitly declared in the Features section of the Taiwan Semiconductor datasheet P2102 and verified through material declarations and third-party testing.

1SMA4742 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:: -

Qualification:: -

Mounting Type:: Surface Mount

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

1SMA4742 FAQ

1.How can I place an order for 1SMA4742 through Aetrix?

Please submit a Request for Quotation (RFQ) for 1SMA4742 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 1SMA4742 reliable?

The price and inventory of 1SMA4742 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA4742 is usually 5 days.

3.What payment methods are accepted for 1SMA4742?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA4742 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1SMA4742?

1SMA4742 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1SMA4742 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 1SMA4742?

For technical support, including 1SMA4742 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA4742 requirements.

6.How does Aetrix verify that 1SMA4742 is sourced from the original manufacturer or authorized distributors?

All 1SMA4742 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 1SMA4742 meets industry standards.

7.What is the process for return or replacement of 1SMA4742?

All 1SMA4742 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA4742, 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 1SMA4742 part is unused and in its original packaging.

Return procedure for 1SMA4742:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…