Taiwan Semiconductor Corporation ZM4728A L0G

Overview

ZM4728A L0G from Taiwan Semiconductor is a 1W surface-mount Zener diode with a nominal zener voltage of 3.3 V ±5%, 76 mA test current (IZT), 10 Ω dynamic impedance (ZZT), and MELF glass package rated for junction temperatures up to +175°C. It serves as a precision low-voltage reference or stabilizer in compact DC/DC converter circuits.

For engineers reviewing the ZM4728A L0G datasheet, ZM4728A L0G pinout, ZM4728A L0G application, or ZM4728A L0G equivalent, key selection criteria include its ±5% VZ tolerance, 10 Ω Zener impedance at 76 mA, 1 W power rating, MELF mechanical form factor, and cathode-band polarity marking - all critical for stable low-voltage regulation in space-constrained power designs.

Technical Context

The ZM4728A L0G operates as a single-die, hermetically sealed glass Zener diode optimized for low-voltage stabilization where tight regulation and thermal robustness are required. Its 3.3 V nominal breakdown voltage is specified at 76 mA IZT, with 10 Ω dynamic impedance ensuring minimal output variation under load transients.

Designed for surface-mount assembly on standard PCBs, it features matte tin-plated leads compliant with J-STD-002 solderability requirements and a cathode band for unambiguous polarity identification. The MELF package provides superior thermal dissipation (RθJA = 170°C/W) and mechanical reliability versus axial-leaded alternatives.

Key Specifications

Pinout & Package

MELF (DO-213AB) package: hermetically sealed glass cylinder with two axial matte tin-plated leads; cathode identified by black band; weight ≈129.9 mg; RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4728A TR and BZX55C3V3-TP, the ZM4728A L0G offers superior thermal performance in a compact MELF SMT package, enabling higher power density and better regulation stability in modern DC/DC converters and embedded power monitors.

Availability

ZM4728A L0G is available at Aetrix Electronics and suitable for low-voltage reference, DC/DC converter feedback, and adapter stabilization applications requiring stable component supply, consistent ±5% VZ tolerance, and MELF package compatibility with automated placement equipment.

Supply support for ZM4728A L0G 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, specializing in power management, protection, and signal conditioning devices.

The ZM47xxA series was developed specifically for high-reliability, surface-mount Zener regulation in industrial power supplies and compact adapters - emphasizing thermal robustness, hermetic sealing, and tight parametric consistency across voltage grades.

FAQ

What is the Zener voltage tolerance of the ZM4728A L0G?

The ZM4728A L0G has a nominal Zener voltage of 3.3 V with a tolerance of ±5%, meaning the actual breakdown voltage falls between 3.135 V and 3.465 V when measured at the specified test current of 76 mA. This tolerance is guaranteed per the manufacturer's datasheet revision E2301 and applies across the full operating temperature range.

Does the ZM4728A L0G have a defined polarity marking?

Yes, the ZM4728A L0G uses a black cathode band on the glass MELF body to indicate polarity. The banded end is the cathode and must be connected to the higher-potential node in reverse-bias Zener operation. This marking complies with JEDEC DO-213AB and is visible under standard optical inspection during SMT assembly.

What is the maximum power dissipation rating for the ZM4728A L0G?

The ZM4728A L0G is rated for 1 W maximum continuous power dissipation at ambient temperature (TA = 25°C). Derating is required above 25°C per the specified thermal resistance of 170°C/W; for example, at TA = 75°C, the usable power drops to approximately 0.71 W to maintain TJ ≤ +175°C.

Is the ZM4728A L0G RoHS compliant and lead-free?

Yes, the ZM4728A L0G is RoHS compliant and features matte tin-plated leads that meet J-STD-002 solderability requirements. The hermetically sealed glass construction contains no restricted substances per EU Directive 2011/65/EU, and the part is marked "RoHS Compliant" in the official Taiwan Semiconductor documentation (Version E2301).

Can the ZM4728A L0G replace the 1N4728A in existing designs?

The ZM4728A L0G can serve as a functional alternative to the 1N4728A in many applications, but it is not a direct drop-in replacement due to differing packages: ZM4728A L0G uses MELF (SMT), while 1N4728A uses DO-41 (through-hole). Electrical parameters (3.3 V ±5%, 76 mA IZT, 10 Ω ZZT) match closely, but layout and thermal design must accommodate the MELF footprint and superior RθJA of 170°C/W.