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

Taiwan Semiconductor Corporation ZM4749A

Name: ZM4749A
Brand: Taiwan Semiconductor Corporation
SKU: ZM4749A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ZM4749A

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Zener Diodes

Package:: DO-213AB, MELF

Datasheet:: ZM4749A.pdf

Description:: DIODE ZENER 24V 1W MELF

Quantity:: RFQ Add To RFQ list

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Inventory:6,143

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Product details

Overview

ZM4749A from Taiwan Semiconductor is a 1 W, 24 V ±5% surface-mount Zener diode in MELF glass package, with 10.5 mA test current (IZT), 25 Ω dynamic impedance (ZZT) at IZT, and 18.2 V reverse voltage (VR) at 5 µA leakage current - used for precision voltage reference and low-power stabilization in DC/DC converters.

For engineers reviewing the ZM4749A datasheet, ZM4749A pinout, ZM4749A application, or ZM4749A equivalent, key selection factors include its ±5% VZ tolerance, 170 °C/W junction-to-ambient thermal resistance, MELF mechanical robustness, and compliance with J-STD-002 solderability standards for high-reliability board assembly.

Technical Context

The ZM4749A operates as a single-die, hermetically sealed glass Zener diode optimized for stable voltage regulation under steady-state DC bias. Its 24 V nominal breakdown voltage is specified at 10.5 mA test current, with 25 Ω dynamic impedance ensuring tight regulation across load variations.

Designed for operation from –65 °C to +175 °C junction temperature, it delivers 1 W power dissipation capability with a 170 °C/W R_θJA, requiring minimal PCB copper area for thermal management in space-constrained adapters and on-board converters.

Key Specifications

Parameter	Value and Actual Design Meaning
V_Z Nominal	24 V ±5% - defines precise clamping/reference level for feedback loops
I_ZT	10.5 mA - standardized test current for V_Z measurement and regulation stability
Z_zt	25 Ω - low dynamic impedance ensures minimal output voltage shift under current variation
P_D	1 W - maximum continuous power dissipation at T_A = 25 °C
T_J Max	+175 °C - enables use in high-temperature industrial and automotive under-hood environments
R_θJA	170 °C/W - determines required PCB thermal relief for safe 1 W operation without heatsink
V_R @ I_R	18.2 V @ 5 µA - specifies reverse blocking threshold before significant leakage onset

Pinout & Package

Package: MELF (DO-213AB), hermetically sealed glass cylindrical body with matte tin-plated axial leads; cathode indicated by black band; weight ≈129.9 mg.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / low-voltage reference node	Connected to ground or lower-potential rail in shunt regulator configuration
Cathode	Zener breakdown terminal / regulated output node	Connected to input supply via series resistor; provides stable 24 V reference to feedback network

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables predictable regulation without post-production trimming in cost-sensitive power supplies
Hermetically sealed glass construction	Ensures long-term parameter stability and moisture resistance in harsh environments
RoHS-compliant matte tin plating	Supports lead-free reflow soldering per J-STD-002, eliminating post-solder cleaning
MELF mechanical form factor	Provides superior thermal cycling reliability vs. SOD-123, especially in high-vibration applications

Applications

Low-Voltage Stabilizers	AC/DC Adapters
Use Scenario: Providing stable 24 V reference for op-amp comparators and error amplifiers in linear regulators. IC Role / Device Role / Timing Role: Shunt voltage reference maintaining feedback node accuracy within ±5%. Use Value: Enables consistent output regulation despite input ripple and load transients due to 25 Ω Z_zt.	Use Scenario: Clamping transient overvoltage on secondary-side rectifier outputs in wall-wart adapters. IC Role / Device Role / Timing Role: Overvoltage protection element absorbing surge energy during no-load or short-circuit events. Use Value: Withstands 1 W peak dissipation and operates up to +175 °C, preventing adapter failure during thermal stress.
On-Board DC/DC Converters	Industrial Sensor Signal Conditioning
Use Scenario: Generating isolated 24 V bias for gate drivers or optocouplers in buck converter auxiliary rails. IC Role / Device Role / Timing Role: Precision voltage source for isolated feedback path referencing. Use Value: Low 25 Ω impedance minimizes voltage droop under dynamic load steps, preserving control loop stability.	Use Scenario: Supplying calibrated excitation voltage to 4–20 mA transmitter bridge sensors. IC Role / Device Role / Timing Role: Stable analog reference replacing higher-cost IC references where ±5% tolerance suffices. Use Value: Hermetic glass package prevents parameter drift in humid factory environments over 10+ year service life.

Low-Voltage Stabilizers

AC/DC Adapters

Use Scenario: Providing stable 24 V reference for op-amp comparators and error amplifiers in linear regulators.

IC Role / Device Role / Timing Role: Shunt voltage reference maintaining feedback node accuracy within ±5%.

Use Value: Enables consistent output regulation despite input ripple and load transients due to 25 Ω Z_zt.

Use Scenario: Clamping transient overvoltage on secondary-side rectifier outputs in wall-wart adapters.

IC Role / Device Role / Timing Role: Overvoltage protection element absorbing surge energy during no-load or short-circuit events.

Use Value: Withstands 1 W peak dissipation and operates up to +175 °C, preventing adapter failure during thermal stress.

On-Board DC/DC Converters

Industrial Sensor Signal Conditioning

Use Scenario: Generating isolated 24 V bias for gate drivers or optocouplers in buck converter auxiliary rails.

IC Role / Device Role / Timing Role: Precision voltage source for isolated feedback path referencing.

Use Value: Low 25 Ω impedance minimizes voltage droop under dynamic load steps, preserving control loop stability.

Use Scenario: Supplying calibrated excitation voltage to 4–20 mA transmitter bridge sensors.

IC Role / Device Role / Timing Role: Stable analog reference replacing higher-cost IC references where ±5% tolerance suffices.

Use Value: Hermetic glass package prevents parameter drift in humid factory environments over 10+ year service life.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4749A	Same 24 V ±5%, but TO-204AA (DO-41) through-hole package; R_θJA ≈ 125 °C/W	Requires PCB through-holes and wave soldering; less suitable for high-density SMT layouts	Select when legacy through-hole assembly or higher thermal mass is preferred
BZX55-C24	24 V ±5%, DO-35 glass package; 1 W rating; ZZT = 30 Ω at 5 mA (higher than ZM4749A's 25 Ω at 10.5 mA)	Lower test current reduces regulation sensitivity to current variation; slightly higher impedance affects precision	Select when lower-cost DO-35 sourcing is prioritized over MELF reliability and thermal performance

Compared with 1N4749A and BZX55-C24, the ZM4749A offers superior thermal resistance margin (170 °C/W vs. 125 °C/W) and lower dynamic impedance at higher test current, making it optimal for compact, high-reliability SMT DC/DC reference designs.

Availability

ZM4749A is available at Aetrix Electronics and suitable for AC/DC adapters, on-board DC/DC converters, and industrial sensor signal conditioning requiring stable component supply with full traceability and RoHS compliance.

Supply support for ZM4749A 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 industrial, computing, and consumer markets since 1979.

The ZM47xxA series is part of TSC's high-reliability Zener diode product line, engineered for stable voltage reference and overvoltage protection in space-constrained, thermally demanding power systems.

FAQ

What is the Zener voltage tolerance of the ZM4749A?

The ZM4749A has a nominal Zener voltage of 24 V with a standard tolerance of ±5%, meaning its actual breakdown voltage falls between 22.8 V and 25.2 V at the specified test current of 10.5 mA. This tolerance is confirmed in the Electrical Specifications table of the official Taiwan Semiconductor datasheet (Version E2301) and applies to all units shipped under this part number.

What is the maximum power dissipation rating for the ZM4749A?

The ZM4749A is rated for 1 W maximum continuous power dissipation at ambient temperature (T_A = 25 °C). Its junction temperature must not exceed +175 °C, and derating is required above 25 °C at 5.88 mW/°C based on its 170 °C/W thermal resistance - a critical design constraint for sustained operation in enclosed enclosures.

Is the ZM4749A RoHS compliant and lead-free solder compatible?

Yes, the ZM4749A is RoHS compliant and features matte tin-plated leads qualified for lead-free reflow soldering per J-STD-002. The MELF glass package contains no restricted substances, and the device meets JEDEC Level 1 moisture sensitivity requirements - enabling compatibility with standard Pb-free SMT processes without special baking or handling.

What does the "A" suffix in ZM4749A indicate?

The "A" suffix in ZM4749A denotes the standard ±5% Zener voltage tolerance grade, as defined in Taiwan Semiconductor's ordering nomenclature. It distinguishes this variant from tighter-tolerance versions (e.g., "B" for ±2%) and confirms that the ZM4749A meets the electrical specifications published in Version E2301 of the datasheet, including V_Z = 24 V, I_ZT = 10.5 mA, and Z_zt = 25 Ω.

How is polarity marked on the ZM4749A MELF package?

Polarity on the ZM4749A is indicated by a single black cathode band located near one end of the cylindrical MELF glass body. The terminal adjacent to the band is the cathode (Zener breakdown side); the opposite terminal is the anode. This marking aligns with JEDEC DO-213AB standard orientation and is visible under standard optical inspection during automated placement.

ZM4749A Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Series:: -

Package/Case:: DO-213AB, MELF

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 24 V

Tolerance:: ±5%

Power - Max:: 1 W

Impedance (Max) (Zzt):: 25 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 18.2 V

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

Operating Temperature:: -65°C ~ 175°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: MELF

ZM4749A FAQ

1.How can I place an order for ZM4749A through Aetrix?

Please submit a Request for Quotation (RFQ) for ZM4749A 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 ZM4749A reliable?

The price and inventory of ZM4749A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZM4749A is usually 5 days.

3.What payment methods are accepted for ZM4749A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZM4749A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ZM4749A?

ZM4749A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ZM4749A 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 ZM4749A?

For technical support, including ZM4749A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZM4749A requirements.

6.How does Aetrix verify that ZM4749A is sourced from the original manufacturer or authorized distributors?

All ZM4749A 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 ZM4749A meets industry standards.

7.What is the process for return or replacement of ZM4749A?

All ZM4749A units undergo pre-shipment inspection (PSI). If there is an issue with ZM4749A, 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 ZM4749A part is unused and in its original packaging.

Return procedure for ZM4749A:

1.Submit a request within 90 days.

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

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