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

Taiwan Semiconductor Corporation 1SMB5942H

Name: 1SMB5942H
Brand: Taiwan Semiconductor Corporation
SKU: 1SMB5942H
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1SMB5942H

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-214AA, SMB

Datasheet:: 1SMB5942H.pdf

Description:: DIODE ZENER 51V 3W DO214AA

Quantity:: RFQ Add To RFQ list

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Inventory:7,940

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Product details

Overview

1SMB5942H from Taiwan Semiconductor is a surface-mount silicon Zener diode rated for 3 W power dissipation, with a nominal Zener voltage of 51 V (±5%), test current of 7.3 mA, and maximum DC Zener current of 29 mA. It features glass passivated junction, AEC-Q101 qualification, and DO-214AA (SMB) package - used in automotive voltage reference and overvoltage protection circuits.

For engineers reviewing the 1SMB5942H datasheet, 1SMB5942H pinout, 1SMB5942H application, or 1SMB5942H equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (R_θJA = 226 °C/W), leakage current (≤0.25 μA at 38.8 V), surge capability, and AEC-Q101 compliance for automotive-grade reliability.

Technical Context

The 1SMB5942H operates as a single-die, unidirectional Zener diode optimized for stable voltage regulation and clamping in DC power rails. Its 51 V nominal breakdown voltage is specified at 7.3 mA test current, with dynamic impedance of 1100 Ω at I_ZT and 70 Ω at I_ZK, enabling precise reference performance under low-current bias.

Thermally, it supports junction temperatures from –55 °C to +150 °C, with derated power dissipation above 25 °C (4.4 mW/°C) and a junction-to-ambient thermal resistance of 226 °C/W. The DO-214AA package provides low inductance and meets UL 94V-0 flammability rating.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	48.45–53.55 V (±5% tolerance at 7.3 mA; defines clamping threshold)
Power Dissipation (P_TOT)	3 W (max at T_L = 75 °C; requires PCB copper pad for thermal management)
Zener Impedance (Z_ZT)	1100 Ω (at 7.3 mA; impacts regulation stability under load variation)
Leakage Current (I_R)	≤0.25 μA at 38.8 V (ensures minimal standby power loss in high-impedance reference paths)
Junction Temperature Range	–55 °C to +150 °C (supports operation in under-hood automotive environments)
Package	DO-214AA (SMB); surface-mount, cathode band polarity marking, 0.100 g weight

Pinout & Package

DO-214AA (SMB) package: molded plastic case with matte tin-plated leads, polarity indicated by cathode band. Designed for automated placement and solderable per J-STD-002.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Zener cathode reference ground	Connected to lower-potential node in reverse-biased configuration; forms reference return path
Cathode	Zener breakdown terminal / voltage clamp input	Connected to protected or regulated node; conducts when voltage exceeds 48.45–53.55 V

Key Features

Feature	Design Value
AEC-Q101 qualification	Validated for automotive electronics use, including temperature cycling, humidity, and mechanical shock testing
Glass passivated chip junction	Enhances long-term stability and reduces parameter drift under thermal stress and humidity exposure
Low inductance construction	Minimizes voltage overshoot during fast transient suppression (e.g., ISO 7637-2 pulse 1/2a)
Moisture sensitivity level 1	Enables standard SMT reflow without baking; eliminates moisture-related popcorning risk
Halogen-free & RoHS compliant	Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for environmentally restricted materials

Applications

Automotive ECU Power Rail Protection	Industrial Sensor Reference Voltage
Use Scenario: Clamping transients on 48 V battery-supplied control modules exposed to load dump and jump-start conditions. IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to limit voltage spikes to ≤53.55 V. Use Value: Prevents damage to downstream 5 V/3.3 V LDOs and microcontrollers by absorbing up to 3 W surge energy.	Use Scenario: Providing stable 51 V reference for precision analog front-ends in pressure or temperature transmitters. IC Role / Device Role / Timing Role: Passive voltage reference element with ±5% tolerance and low tempco (from curve data). Use Value: Enables accurate ADC calibration without active regulators; leakage <0.25 μA minimizes error in high-Z dividers.
Telecom DC-DC Converter Feedback	LED Driver Overvoltage Clamp
Use Scenario: Secondary-side voltage sensing in isolated flyback converters where optocoupler feedback uses Zener-derived reference. IC Role / Device Role / Timing Role: Precision shunt reference defining output regulation point via TL431 or similar comparator input. Use Value: Tight 5% V_Z tolerance ensures ±1.5% output accuracy; 1100 Ω Z_ZT maintains loop stability across line/load changes.	Use Scenario: Protecting constant-current LED strings against open-circuit overvoltage during driver failure or wiring disconnect. IC Role / Device Role / Timing Role: Fail-safe shunt clamp activated when string voltage exceeds 53.55 V. Use Value: Absorbs 3 W continuously or higher peak surges (per Fig.2), preventing MOSFET or IC destruction without adding active circuitry.

Automotive ECU Power Rail Protection

Industrial Sensor Reference Voltage

Use Scenario: Clamping transients on 48 V battery-supplied control modules exposed to load dump and jump-start conditions.

IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to limit voltage spikes to ≤53.55 V.

Use Value: Prevents damage to downstream 5 V/3.3 V LDOs and microcontrollers by absorbing up to 3 W surge energy.

Use Scenario: Providing stable 51 V reference for precision analog front-ends in pressure or temperature transmitters.

IC Role / Device Role / Timing Role: Passive voltage reference element with ±5% tolerance and low tempco (from curve data).

Use Value: Enables accurate ADC calibration without active regulators; leakage <0.25 μA minimizes error in high-Z dividers.

Telecom DC-DC Converter Feedback

LED Driver Overvoltage Clamp

Use Scenario: Secondary-side voltage sensing in isolated flyback converters where optocoupler feedback uses Zener-derived reference.

IC Role / Device Role / Timing Role: Precision shunt reference defining output regulation point via TL431 or similar comparator input.

Use Value: Tight 5% V_Z tolerance ensures ±1.5% output accuracy; 1100 Ω Z_ZT maintains loop stability across line/load changes.

Use Scenario: Protecting constant-current LED strings against open-circuit overvoltage during driver failure or wiring disconnect.

IC Role / Device Role / Timing Role: Fail-safe shunt clamp activated when string voltage exceeds 53.55 V.

Use Value: Absorbs 3 W continuously or higher peak surges (per Fig.2), preventing MOSFET or IC destruction without adding active circuitry.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SMF51A (ON Semiconductor)	Same DO-214AA package, 51 V nominal, but 200 W peak pulse rating vs. 3 W continuous; higher I_ZM (32 mA)	Better suited for transient suppression (e.g., IEC 61000-4-5), less ideal for precision reference due to looser tolerance (±10%) and no AEC-Q101 rating	Select for surge-heavy environments where clamping speed and peak energy matter more than DC regulation accuracy
BZX84-C51 (Nexperia)	SOT-23 package (smaller footprint), same 51 V nominal, ±5% tolerance, but only 300 mW P_TOT; higher Z_ZT (1500 Ω)	Targeted at space-constrained portable electronics; insufficient for automotive under-hood thermal loads or sustained 3 W dissipation	Choose only for low-power, non-automotive applications where board area is critical and thermal margin is ample

Compared with SMF51A and BZX84-C51, the 1SMB5942H uniquely combines AEC-Q101 qualification, 3 W continuous power handling in SMB package, and tight ±5% Zener tolerance - making it the preferred choice for automotive and industrial voltage reference and clamping where reliability and thermal robustness are mandatory.

Availability

1SMB5942H is available at Aetrix Electronics and suitable for automotive ECU protection, industrial sensor reference design, and telecom DC-DC feedback circuits requiring stable component supply, long-lifecycle support, and AEC-Q101-compliant sourcing.

Supply support for 1SMB5942H 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-Q101 validation capabilities.

The 1SMB59xxH series was developed specifically for automotive and industrial applications demanding high-reliability Zener regulation in surface-mount form, emphasizing thermal robustness, low leakage, and process-controlled voltage tolerance.

FAQ

What is the Zener voltage tolerance of the 1SMB5942H?

The 1SMB5942H has a Zener voltage tolerance of ±5%, with a nominal value of 51 V and specified range of 48.45 V to 53.55 V at 7.3 mA test current. This tolerance is confirmed in the Electrical Specifications table and applies under standard test conditions (T_A = 25 °C). The 1SMB5942H achieves this via tightly controlled diffusion and passivation processes during wafer fabrication.

Is the 1SMB5942H suitable for automotive applications?

Yes, the 1SMB5942H is AEC-Q101 qualified and designed for automotive use, including engine control units and body electronics. Its –55 °C to +150 °C junction temperature range, glass passivated junction, and moisture sensitivity level 1 rating meet automotive reliability requirements. The 1SMB5942H is explicitly listed in TSC's AEC-Q101 qualified product list for Zener diodes.

What is the maximum continuous power dissipation for the 1SMB5942H?

The 1SMB5942H has a maximum continuous power dissipation of 3 W when measured at lead temperature (T_L) of 75 °C with zero lead length on a 5 mm × 5 mm Cu pad. At ambient temperature (T_A = 25 °C), the rating is 550 mW, derating linearly at 4.4 mW/°C above that point. This thermal behavior is defined in the Absolute Maximum Ratings table.

Does the 1SMB5942H have a specified Zener impedance?

Yes, the 1SMB5942H specifies Zener impedance Z_ZT = 1100 Ω at 7.3 mA test current and Z_ZK = 70 Ω at 1 mA knee current. These values reflect AC dynamic resistance under small-signal conditions and directly impact regulation accuracy in reference and feedback applications. The 1SMB5942H datasheet provides these figures in the Electrical Specifications table.

What packaging and reel quantity is offered for the 1SMB5942H?

The 1SMB5942H is supplied in DO-214AA (SMB) package on 3,000-piece tape-and-reel format, as stated in the Ordering Information section. The reel conforms to EIA-481 standards, and the device marking code "942B" appears on the cathode band. This packaging supports automated SMT placement and complies with J-STD-002 solderability requirements.

1SMB5942H Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Series:: -

Package/Case:: DO-214AA, SMB

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 51 V

Tolerance:: ±5%

Power - Max:: 3 W

Impedance (Max) (Zzt):: 70 Ohms

Current - Reverse Leakage @ Vr:: 1 µA @ 38.8 V

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

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: DO-214AA (SMB)

1SMB5942H FAQ

1.How can I place an order for 1SMB5942H through Aetrix?

Please submit a Request for Quotation (RFQ) for 1SMB5942H 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 1SMB5942H reliable?

The price and inventory of 1SMB5942H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB5942H is usually 5 days.

3.What payment methods are accepted for 1SMB5942H?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB5942H transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1SMB5942H?

1SMB5942H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1SMB5942H 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 1SMB5942H?

For technical support, including 1SMB5942H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB5942H requirements.

6.How does Aetrix verify that 1SMB5942H is sourced from the original manufacturer or authorized distributors?

All 1SMB5942H 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 1SMB5942H meets industry standards.

7.What is the process for return or replacement of 1SMB5942H?

All 1SMB5942H units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB5942H, 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 1SMB5942H part is unused and in its original packaging.

Return procedure for 1SMB5942H:

1.Submit a request within 90 days.

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

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