Diodes Incorporated MMSZ5237B-7

Overview

MMSZ5237B-7 from Diodes Incorporated is a 500mW surface-mount Zener diode with a nominal zener voltage of 8.2V (±5% tolerance), 20mA test current, and 8Ω dynamic impedance at 20mA. It features SOD123 packaging, AEC-Q101 qualification for automotive reliability, and operates across –65°C to +150°C. It serves as a precision voltage reference or overvoltage clamp in low-power power supply regulation circuits.

For engineers reviewing the MMSZ5237B-7 datasheet, MMSZ5237B-7 pinout, MMSZ5237B-7 application, or MMSZ5237B-7 equivalent, key selection criteria include zener voltage accuracy (7.79–8.61V), thermal resistance (338°C/W), reverse leakage (<3.0µA @ 6.5V), and SOD123 footprint compatibility with automated PCB assembly.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable voltage under varying load and temperature conditions. Its 8.2V nominal rating targets mid-range voltage reference needs in analog sensing and regulator feedback paths, with a temperature coefficient near +0.04%/°C per Figure 6 - indicating slight positive drift above 6V.

The device uses alloy 42 leadframe with matte tin plating and green molding compound compliant with RoHS, halogen-free, and antimony-free standards. Its SOD123 package supports high-density layouts and reflow soldering per J-STD-020 Level 1 moisture sensitivity.

Key Specifications

Pinout & Package

Package: SOD123 - surface-mount plastic case with cathode band marking; dimensions: 2.65mm (E) × 1.55mm (D) × 1.20mm (A); weight ≈ 0.01g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX584-C8V2 and 1N4737A, MMSZ5237B-7 offers optimal balance of SMT compatibility, AEC-Q101 reliability, and 370mW–500mW scalable power handling - making it preferred for volume automotive and industrial PCBs requiring zero post-assembly inspection risk.

Availability

MMSZ5237B-7 is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, consumer power adapter feedback loops, and medical portable device references requiring stable component supply and long-term lifecycle support.

Supply support for MMSZ5237B-7 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 the Americas.

The MMSZ52xxB series belongs to Diodes' general-purpose Zener diode product line, engineered specifically for cost-sensitive, high-volume applications demanding AEC-Q101 reliability, tight voltage tolerances, and robust SMT manufacturability.

FAQ

What is the maximum reverse voltage that can be continuously applied without breakdown?

The MMSZ5237B-7 exhibits a sharp reverse breakdown at its nominal 8.2V zener voltage. Below 6.5V, reverse leakage remains below 3.0µA - meaning up to 6.5V may be applied continuously without significant conduction. Exceeding this risks entering the breakdown region and uncontrolled current flow unless properly current-limited.

Is MMSZ5237B-7 suitable for use in high-frequency noise suppression?

No - this device is not optimized for RF or high-frequency bypass. Its typical junction capacitance is ~25pF at 0V (estimated from Figure 4 curve), and its zener impedance rises sharply below 10mA. For noise suppression, dedicated TVS diodes or ceramic capacitors provide superior high-frequency attenuation and lower impedance.

How does the SOD123 package affect thermal performance compared to larger packages?

The SOD123 package has a thermal resistance of 338°C/W (junction-to-ambient on FR-4), significantly higher than DO-41 (≈200°C/W) or SOD-323 (≈450°C/W). This means it reaches thermal limits faster under sustained load - derating to 250mW is recommended above +70°C ambient unless using enhanced copper pour or thermal vias.

Can MMSZ5237B-7 replace MMSZ5236B (7.5V) or MMSZ5238B (8.7V) in existing designs?

Only if the circuit's voltage tolerance allows ±0.5V shift. MMSZ5237B-7's 7.79–8.61V range overlaps partially with both neighbors but introduces measurable error in precision references. Verify regulation margin, power dissipation, and temperature drift impact - especially in feedback loops where 0.5V change alters output by >6%.