Diodes Incorporated MMSZ5254B-7

Overview

MMSZ5254B-7 from Diodes Incorporated is a 27 V, 500 mW surface-mount Zener diode in SOD123 package, rated for 5.0 mA test current, with 41 Ω dynamic impedance at 1 kHz and ≤0.1 µA reverse leakage at 21 V, widely used for voltage regulation and overvoltage protection in power supply feedback loops and reference circuits.

For engineers reviewing the MMSZ5254B-7 datasheet, MMSZ5254B-7 pinout, MMSZ5254B-7 application, or MMSZ5254B-7 equivalent, key selection criteria include nominal Zener voltage tolerance (±3.5%), thermal resistance (338 °C/W), AEC-Q101 qualification status, SOD123 footprint compatibility, and low-capacitance operation (<4 pF typical) for stable DC reference performance.

Technical Context

This Zener diode operates in reverse breakdown to maintain a stable 27 V reference across varying load currents, with a temperature coefficient of +0.08 %/°C near its nominal voltage-enabling predictable drift compensation in precision analog circuits. Its 500 mW power rating applies at lead temperature (TL = +75°C), derating linearly to 370 mW at ambient (TA = +25°C) on FR-4 PCB with 1-inch copper pad.

The device features a cathode band polarity marker, matte tin-plated Alloy 42 leadframe, and green molding compound compliant with UL 94V-0 and RoHS directives. It exhibits low capacitance (≈3.5 pF at 0 V) and is qualified to AEC-Q101 for automotive-grade reliability under -65°C to +150°C operating range.

Key Specifications

Pinout & Package

Package: SOD123 - molded plastic case with cathode band marking; dimensions: L = 0.30 mm (lead length), D = 1.55 mm (width), E = 2.65 mm (length), He = 3.65 mm (height); weight ≈ 0.01 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX584C27LT1G and MMBZ5254BS, MMSZ5254B-7 offers superior power handling (370 mW vs. 300/350 mW), tighter voltage tolerance (±3.5% vs. ±5%), and lower thermal resistance-making it preferred for automotive and industrial applications demanding long-term stability under thermal stress.

Availability

MMSZ5254B-7 is available at Aetrix Electronics and suitable for automotive engine control units, industrial programmable logic controllers, medical battery monitors, and DC-DC converter feedback circuits requiring stable component supply with AEC-Q101 compliance and full traceability.

Supply support for MMSZ5254B-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 North America.

The MMSZ52xxB series belongs to Diodes' general-purpose Zener diode product line, engineered specifically for cost-sensitive, high-volume voltage regulation and protection in automotive, industrial, and consumer power systems.

FAQ

What is the maximum steady-state power dissipation for MMSZ5254B-7 on a standard FR-4 PCB?

The MMSZ5254B-7 dissipates up to 370 mW continuously at ambient temperature (T_A = +25°C) when mounted on FR-4 with a 1-inch copper pad layout. Derating begins above +25°C at 3.0 mW/°C, reaching 500 mW only at lead temperature T_L = +75°C-requiring careful thermal design for sustained operation.

Is MMSZ5254B-7 suitable for automotive applications?

Yes-MMSZ5254B-7 is explicitly qualified to AEC-Q101 standards, with guaranteed operation from -65°C to +150°C, halogen-free green packaging, and traceable lot-controlled manufacturing. It is approved for use in engine control modules, body electronics, and ADAS power domains where reliability and thermal resilience are mandatory.

How does the Zener impedance affect regulation accuracy in feedback circuits?

With Z_ZT = 41 Ω at 5.0 mA and 1 kHz, MMSZ5254B-7 introduces minimal dynamic error under varying load current-e.g., a 1 mA change causes only ~41 mV shift in output voltage. This low impedance ensures stable reference behavior in closed-loop feedback paths, especially when paired with high-gain error amplifiers or optocouplers.

Can MMSZ5254B-7 replace older MMSZ5254 devices without layout changes?

Yes-MMSZ5254B-7 uses the identical SOD123 package, pinout, and soldering profile as prior revisions. The "B" suffix denotes tightened voltage tolerance (±3.5% vs. ±5% in non-B versions), while electrical characteristics, thermal performance, and mechanical dimensions remain fully compatible with existing footprints and reflow profiles.