Diodes Incorporated MMSZ5221BS-7-F

Overview

MMSZ5221BS-7-F from Diodes Incorporated is a surface-mount Zener diode with nominal 2.4 V zener voltage, 20 mA test current, and 200 mW power dissipation in SOD-323 package. It provides precise voltage regulation for low-power biasing, reference, and protection circuits in space-constrained consumer and industrial electronics.

For engineers reviewing the MMSZ5221BS-7-F datasheet, MMSZ5221BS-7-F pinout, MMSZ5221BS-7-F application, or MMSZ5221BS-7-F equivalent, key selection criteria include zener voltage tolerance (±5%), dynamic impedance (30 Ω at 20 mA), reverse leakage (100 µA at 1.0 V), thermal resistance (625 °C/W), and RoHS-compliant lead-free plating.

Technical Context

This Zener diode uses planar die construction to ensure stable breakdown characteristics and low temperature coefficient. Its operation relies on controlled avalanche and Zener mechanisms depending on voltage range, with specified performance at 25 °C ambient and validated under short-duration pulse testing to minimize self-heating effects.

The device is rated for continuous operation from –65 °C to +150 °C and exhibits typical zener impedance of 30 Ω at 20 mA and 1200 Ω at 0.25 mA, supporting both precision reference and general-purpose clamping applications where low forward voltage (0.9 V @ 10 mA) and tight voltage tolerance are required.

Key Specifications

Pinout & Package

Package: SOD-323 - ultra-small plastic surface-mount case (2.3–2.7 mm length, 1.2–1.4 mm width, 0.25–0.35 mm thickness), UL 94V-0 rated, moisture sensitivity level 1, cathode indicated by band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX384-B2V4,115 and MMBZ5221BS-7-F, the MMSZ5221BS-7-F offers optimal balance of size, regulation accuracy, and thermal derating for space-constrained 2.4 V reference designs - its 30 Ω impedance at 20 mA delivers tighter voltage control than the Nexperia part, while its SOD-323 footprint saves >40% board area versus the SOT-23 alternative.

Availability

MMSZ5221BS-7-F is available at Aetrix Electronics and suitable for low-voltage reference generation, ESD protection clamping, and power rail limiting requiring stable component supply in high-mix, low-volume production.

Supply support for MMSZ5221BS-7-F 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The MMSZ52xxBS series belongs to Diodes' general-purpose Zener diode product line, engineered for cost-sensitive, high-reliability voltage regulation and protection in consumer, computing, and industrial applications.

FAQ

What is the maximum continuous reverse voltage this Zener can withstand without breakdown?

The MMSZ5221BS-7-F has a nominal zener voltage of 2.4 V with a guaranteed breakdown range of 2.28–2.52 V at 20 mA. Below 1.0 V reverse bias, leakage remains ≤100 µA; sustained reverse voltage above 2.52 V will cause conduction. It is not rated for blocking voltages beyond its zener specification.

Can this device be used in series to achieve higher regulated voltage?

Yes - multiple MMSZ5221BS-7-F diodes may be stacked anode-to-cathode in series to sum zener voltages (e.g., four units yield ~9.6 V). However, mismatched unit tolerances (±5%) and differing temperature coefficients will reduce overall regulation accuracy and require individual current balancing resistors.

Is the SOD-323 package compatible with standard automated pick-and-place equipment?

Yes - the SOD-323 package (2.5 × 1.3 × 0.9 mm) is supported by industry-standard feeders and vision systems. Its cathode band and symmetrical geometry enable reliable orientation detection; recommended pad layout per AP02001 ensures ≥75% solder paste coverage and coplanarity <0.1 mm.

How does its 625 °C/W thermal resistance affect PCB layout?

A R_θJA of 625 °C/W means a 200 mW dissipation raises junction temperature by 125 °C above ambient. To stay within the 150 °C max rating at 25 °C ambient, the PCB must provide ≥25 mm² of 1-oz copper connected to both terminals - verified via the AP02001 recommended pad pattern.