Taiwan Semiconductor Corporation 1SMA4751

Overview

1SMA4751 from Taiwan Semiconductor is a 1 W, 30 V ±5% surface-mount Zener diode in DO-214AC (SMA) package, with 8.5 mA test current, 40 Ω dynamic impedance at IZT, 1 μA leakage at 22.8 V, and rated for -55°C to +175°C junction operation. It provides precise voltage regulation and transient overvoltage protection in compact power supply rails and I/O interface circuits.

For engineers reviewing the 1SMA4751 datasheet, 1SMA4751 pinout, 1SMA4751 application, or 1SMA4751 equivalent, key selection criteria include nominal Zener voltage tolerance, surge current capability (150 A), thermal derating behavior, and DO-214AC mechanical compatibility with automated SMT assembly lines.

Technical Context

The 1SMA4751 operates as a single-die, glass-passivated Zener diode optimized for stable reverse-biased breakdown regulation. Its 30 V nominal Zener voltage exhibits a positive temperature coefficient above ~5 V, with typical leakage <1 μA at 80% VR and dynamic impedance measured under 10% AC ripple superimposed on 8.5 mA DC test current.

Designed for surface-mount use, it features matte tin-plated leads compliant with J-STD-002 solderability, meets JESD201 Class 2 whisker resistance, and carries moisture sensitivity level 1 per J-STD-020 - enabling reflow without baking. Polarity is marked by a cathode band on the DO-214AC body.

Key Specifications

Pinout & Package

Package: DO-214AC (SMA), surface-mount, single-anode/single-cathode configuration. Cathode identified by molded band on body. Weight ≈ 0.060 g. UL 94V-0 rated molding compound.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4751A and SZ1SMA4751-TP, the 1SMA4751 offers optimal balance of SMT manufacturability, 40 Ω regulation stiffness, and commercial-grade qualification - making it ideal for high-volume consumer and industrial power management where footprint and thermal performance are prioritized over automotive certification.

Availability

1SMA4751 is available at Aetrix Electronics and suitable for industrial power supplies, sensor interface modules, and automotive body electronics requiring stable component supply, consistent parametric performance, and DO-214AC footprint compatibility.

Supply support for 1SMA4751 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, analog ICs, and protection components for industrial, computing, and consumer markets.

The 1SMA47xx series was developed to deliver high-reliability, low-cost Zener regulation in standardized SMT packages - targeting cost-sensitive, high-volume applications where precision, thermal robustness, and automated assembly compatibility are essential.

FAQ

What is the Zener voltage tolerance for 1SMA4751?

The 1SMA4751 has a nominal Zener voltage of 30 V with a standard tolerance of ±5%, meaning the actual measured VZ at 8.5 mA test current falls between 28.5 V and 31.5 V. This tolerance is guaranteed per JEDEC registration and applies across the full operating temperature range of -55°C to +175°C. The 1SMA4751 achieves this via tightly controlled diffusion and passivation processes during wafer fabrication.

Can 1SMA4751 be used in place of 1N4751A?

No - the 1SMA4751 cannot serve as a direct replacement for the 1N4751A due to fundamental package incompatibility: 1SMA4751 uses DO-214AC (SMA) surface-mount packaging, while 1N4751A uses DO-41 through-hole packaging. Although both share identical electrical specifications (30 V ±5%, 1 W), PCB layout, reflow profile, and mechanical mounting differ significantly. Substitution requires redesign of land patterns and assembly process.

What is the maximum non-repetitive surge current rating for 1SMA4751?

The 1SMA4751 is rated for a non-repetitive peak forward surge current (IFSM) of 30 A per 8.3 ms single half-sine wave, and a peak reverse surge current of 150 A under the same waveform condition. These values are defined in the Absolute Maximum Ratings table and validated per JEDEC standards. Actual clamping performance depends on PCB copper area and thermal mass, with recommended 5 mm × 5 mm Cu pad for full 1 W dissipation.

Does 1SMA4751 meet RoHS and halogen-free requirements?

Yes, the 1SMA4751 complies with EU RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. The molding compound contains no brominated flame retardants (BFRs), chlorinated flame retardants (CFRs), antimony trioxide, or phosphorus-based flame retardants above threshold limits. Certificate of Compliance is available upon request from Taiwan Semiconductor's official distribution channel.

How does temperature affect the Zener voltage of 1SMA4751?

The 1SMA4751 exhibits a positive temperature coefficient of approximately +6.5 mV/°C near its 30 V operating point, as shown in Figure 6 of the datasheet. This means VZ increases linearly with junction temperature - e.g., a +50°C rise above 25°C raises VZ by ~325 mV. Designers must account for this drift in precision reference applications, especially when operating above 85°C ambient or under high-power dissipation conditions.