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

Taiwan Semiconductor Corporation 1SMA5940H

Name: 1SMA5940H
Brand: Taiwan Semiconductor Corporation
SKU: 1SMA5940H
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1SMA5940H

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-214AC, SMA

Datasheet:: 1SMA5940H.pdf

Description:: DIODE ZENER 43V 1.5W DO214AC

Quantity:: RFQ Add To RFQ list

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Inventory:7,219

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Product details

Overview

1SMA5940H from Taiwan Semiconductor is a surface-mount Zener diode with nominal zener voltage of 43 V, 1.5 W power dissipation, and DO-214AC (SMA) package. It delivers regulated voltage reference in DC/DC converters and SMPS feedback loops, featuring low leakage current (<0.5 µA at VR = 32.7 V), 950 Ω dynamic impedance at IZT, and AEC-Q101 qualification for automotive-grade reliability.

For engineers reviewing the 1SMA5940H datasheet, 1SMA5940H pinout, 1SMA5940H application, or 1SMA5940H equivalent, key selection criteria include its ±5% VZ tolerance, 8.7 mA test current, 53.0 Ω knee impedance, 150 °C maximum junction temperature, and compatibility with automated SMT placement on standard PCBs.

Technical Context

The 1SMA5940H operates as a single-die, glass-passivated Zener diode optimized for precision voltage regulation under stable DC bias. Its electrical behavior is defined by a well-characterized breakdown region between 40.85 V (min) and 45.15 V (max) at 8.7 mA, with low inductance and Class 3B HBM ESD rating supporting robust operation in noisy power environments.

Designed for thermal stability in compact layouts, it exhibits a derating curve starting at 75 °C (20 mW/°C reduction), supports peak forward surge current up to 10 A (8.3 ms half-sine), and maintains moisture sensitivity level 1 per J-STD-020-enabling reflow compatibility without baking.

Key Specifications

Parameter	Value and Actual Design Meaning
VZ @ IZT	40.85–45.15 V at 8.7 mA - defines tight regulation window for feedback sensing
P_D	1.5 W - maximum continuous power dissipation at TL = 75 °C on 5 mm × 5 mm Cu pad
Z_ZT @ IZT	950 Ω - dynamic impedance impacting regulation accuracy under load transients
I_R @ V_R	<0.5 µA at 32.7 V - ensures minimal error current in high-impedance reference paths
T_J max	150 °C - enables operation in under-hood automotive and industrial power stages
Package	DO-214AC (SMA) - industry-standard SMD outline with cathode band polarity marking
AEC-Q101	Qualified - validated for automotive electronics per stress test requirements

Pinout & Package

DO-214AC (SMA) package: surface-mount, molded plastic case with matte tin-plated leads, polarity indicated by cathode band, weight ≈ 0.060 g.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal	Connected to lower-potential node in reverse-biased Zener configuration
Cathode	Zener breakdown terminal	Connected to higher-potential node; marked by visible band; carries regulated output voltage

Key Features

Feature	Design Value
Glass passivated junction	Enhances long-term stability and reduces parameter drift under thermal cycling
Low inductance construction	Minimizes voltage overshoot during fast transient events in switching regulators
Class 3B HBM ESD rating	Withstands ≥8 kV human-body-model discharge without degradation
Moisture sensitivity level 1	Allows standard SMT reflow without pre-baking, reducing manufacturing complexity
Halogen-free & RoHS compliant	Meets IEC 61249-2-21 and EU Directive 2011/65/EU environmental requirements

Applications

Switching Mode Power Supply (SMPS)	On-board DC/DC Converter
Use Scenario: Voltage regulation and overvoltage protection in primary-side feedback circuits of AC/DC adapters. IC Role / Device Role / Timing Role: Zener reference element providing stable 43 V clamp for optocoupler-driven feedback loop. Use Value: Tight ±5% VZ tolerance and low IR ensure accurate output voltage setpoint and minimal standby power loss.	Use Scenario: Output voltage stabilization in isolated buck-boost converters for industrial control modules. IC Role / Device Role / Timing Role: Secondary-side shunt regulator maintaining precise 43 V rail for gate driver biasing. Use Value: 950 Ω Z_ZT and 150 °C T_J max support reliable regulation across wide ambient temperature ranges.
Automotive Lighting Control	Industrial Adapter Protection
Use Scenario: Overvoltage clamping in LED driver IC supply rails exposed to load-dump transients. IC Role / Device Role / Timing Role: Transient voltage suppressor placed across input capacitor to limit surge-induced rail excursions. Use Value: AEC-Q101 qualification and 10 A IFSM rating enable survivability during ISO 7637-2 pulse 5a events.	Use Scenario: Input-stage voltage limiting in universal-input wall adapters for consumer electronics. IC Role / Device Role / Timing Role: Precision Zener used in crowbar circuit triggering thyristor-based shutdown on overvoltage fault. Use Value: Low 0.25 µA leakage at 25% below VZ ensures negligible quiescent current in always-on protection logic.

Switching Mode Power Supply (SMPS)

On-board DC/DC Converter

Use Scenario: Voltage regulation and overvoltage protection in primary-side feedback circuits of AC/DC adapters.

IC Role / Device Role / Timing Role: Zener reference element providing stable 43 V clamp for optocoupler-driven feedback loop.

Use Value: Tight ±5% VZ tolerance and low IR ensure accurate output voltage setpoint and minimal standby power loss.

Use Scenario: Output voltage stabilization in isolated buck-boost converters for industrial control modules.

IC Role / Device Role / Timing Role: Secondary-side shunt regulator maintaining precise 43 V rail for gate driver biasing.

Use Value: 950 Ω Z_ZT and 150 °C T_J max support reliable regulation across wide ambient temperature ranges.

Automotive Lighting Control

Industrial Adapter Protection

Use Scenario: Overvoltage clamping in LED driver IC supply rails exposed to load-dump transients.

IC Role / Device Role / Timing Role: Transient voltage suppressor placed across input capacitor to limit surge-induced rail excursions.

Use Value: AEC-Q101 qualification and 10 A IFSM rating enable survivability during ISO 7637-2 pulse 5a events.

Use Scenario: Input-stage voltage limiting in universal-input wall adapters for consumer electronics.

IC Role / Device Role / Timing Role: Precision Zener used in crowbar circuit triggering thyristor-based shutdown on overvoltage fault.

Use Value: Low 0.25 µA leakage at 25% below VZ ensures negligible quiescent current in always-on protection logic.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84-C43	300 mW rating, SOT-23 package, ±5% VZ, 100 Ω Z_ZT at 5 mA	Limited to low-power signal-level regulation; unsuitable for 1.5 W power handling	Select when board space is constrained and power demand is ≤300 mW
1N4749A	1 W rating, DO-41 through-hole package, ±5% VZ, 150 Ω Z_ZT at 13 mA	Requires through-hole assembly; lacks AEC-Q101 and moisture level 1 certification	Select only for non-automotive, non-SMT legacy designs where reflow compatibility is not required

Compared with BZX84-C43 and 1N4749A, the 1SMA5940H uniquely combines 1.5 W surface-mount capability, AEC-Q101 qualification, and DO-214AC mechanical robustness-making it the only option among the three qualified for automotive-grade DC/DC converter reference and protection roles.

Availability

1SMA5940H is available at Aetrix Electronics and suitable for switching mode power supplies, on-board DC/DC converters, and automotive lighting systems requiring stable component supply, consistent parametric performance, and full traceability.

Supply support for 1SMA5940H 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, serving global automotive, industrial, and consumer markets since 1979.

The 1SMA59xxH series was developed specifically for high-reliability surface-mount voltage regulation in automotive power systems and industrial switch-mode supplies-emphasizing AEC-Q101 compliance, thermal robustness, and SMT process compatibility.

FAQ

What is the nominal zener voltage and tolerance of the 1SMA5940H?

The 1SMA5940H has a nominal zener voltage of 43 V with a guaranteed tolerance of ±5%, corresponding to a minimum VZ of 40.85 V and maximum VZ of 45.15 V when tested at IZT = 8.7 mA. This tolerance is specified per the device's voltage regulation designation and applies under thermal equilibrium conditions as defined in the official Taiwan Semiconductor datasheet revision A2102.

Is the 1SMA5940H suitable for automotive applications?

Yes, the 1SMA5940H is AEC-Q101 qualified and rated for junction temperatures from –55 °C to +150 °C, making it suitable for under-hood and powertrain-adjacent automotive applications. Its glass-passivated junction, Class 3B HBM ESD rating, and moisture sensitivity level 1 further support robust deployment in automotive lighting control and DC/DC converter modules.

What is the maximum DC zener current (IZM) for the 1SMA5940H?

The maximum DC zener current IZM for the 1SMA5940H is 35 mA, calculated from its 1.5 W power rating and nominal 43 V zener voltage (P_D/V_Z ≈ 34.9 mA). This value is confirmed in the Electrical Specifications table of the Taiwan Semiconductor datasheet and represents the highest continuous current the 1SMA5940H can sustain without exceeding its thermal limits at TA = 25 °C.

Does the 1SMA5940H have a specified dynamic impedance, and at what test condition?

Yes, the 1SMA5940H has a typical dynamic impedance Z_ZT of 950 Ω, measured at the specified test current IZT = 8.7 mA. This parameter reflects the small-signal resistance in the breakdown region and directly impacts regulation accuracy during load transients in circuits using the 1SMA5940H as a voltage reference.

What packaging and reel quantity is offered for the 1SMA5940H?

The 1SMA5940H is supplied in DO-214AC (SMA) package format on tape-and-reel, with 7,500 units per reel. The device features matte tin-plated leads compliant with J-STD-002 solderability standards and is marked with code "940A" on the cathode end for traceability and voltage identification.

1SMA5940H 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):: 43 V

Tolerance:: ±5%

Power - Max:: 1.5 W

Impedance (Max) (Zzt):: 53 Ohms

Current - Reverse Leakage @ Vr:: 500 nA @ 32.7 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-214AC (SMA)

1SMA5940H FAQ

1.How can I place an order for 1SMA5940H through Aetrix?

Please submit a Request for Quotation (RFQ) for 1SMA5940H 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 1SMA5940H reliable?

The price and inventory of 1SMA5940H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA5940H is usually 5 days.

3.What payment methods are accepted for 1SMA5940H?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA5940H transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1SMA5940H?

1SMA5940H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1SMA5940H 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 1SMA5940H?

For technical support, including 1SMA5940H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA5940H requirements.

6.How does Aetrix verify that 1SMA5940H is sourced from the original manufacturer or authorized distributors?

All 1SMA5940H 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 1SMA5940H meets industry standards.

7.What is the process for return or replacement of 1SMA5940H?

All 1SMA5940H units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA5940H, 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 1SMA5940H part is unused and in its original packaging.

Return procedure for 1SMA5940H:

1.Submit a request within 90 days.

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

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