Diodes Incorporated ZMM5255B-7

Overview

ZMM5255B-7 from Diodes Incorporated is a 28 V, 4.5 mA nominal zener current, 500 mW surface-mount silicon zener diode in MiniMELF (DO-213AA) package, with 44 Ω dynamic impedance at test current and +0.091 %/°C temperature coefficient - used for precision voltage reference and overvoltage protection in power supply feedback loops.

For engineers reviewing the ZMM5255B-7 datasheet, ZMM5255B-7 pinout, ZMM5255B-7 application, or ZMM5255B-7 equivalent, key selection criteria include zener voltage tolerance (±3.57%), reverse leakage at rated voltage (≤0.1 µA @ 22.4 V), thermal resistance (300 °C/W), and junction capacitance (~20 pF at 2 V), all critical for stable regulation in low-power analog and embedded power management circuits.

Technical Context

This device operates as a two-terminal voltage reference diode, relying on controlled reverse-biased avalanche breakdown to maintain a stable 28 V across its terminals within ±3.57% tolerance. Its MiniMELF glass package enables high reliability and hermetic sealing suitable for industrial ambient conditions up to +175 °C.

The zener exhibits a positive temperature coefficient of +0.091 %/°C above 20 V, indicating increasing voltage with rising temperature - a key design consideration when cascading references or compensating for thermal drift in feedback networks.

Key Specifications

Pinout & Package

Two-terminal device in MiniMELF (JEDEC DO-213AA) glass package: cylindrical body with cathode band marking; anode and cathode terminals are axial leads solderable per MIL-STD-202, Method 208.

Key Features

Applications

Availability

ZMM5255B-7 is available at Aetrix Electronics and suitable for industrial power supplies, automotive ECUs, medical sensor modules, and portable test equipment requiring stable component supply with full traceability and lifecycle support.

Supply support for ZMM5255B-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.

ZMM52xxB is part of Diodes' legacy MiniMELF zener diode family, engineered for high-reliability voltage reference and clamping in space-constrained, thermally demanding applications.

FAQ

What is the maximum reverse voltage before breakdown for ZMM5255B-7?

The ZMM5255B-7 begins controlled zener breakdown at its nominal 28 V rating, with guaranteed operation between 26.6 V and 29.4 V at 4.5 mA. It is not rated for sustained reverse operation below this range - applying less than 26.6 V results in negligible conduction (<0.1 µA), while exceeding 29.4 V risks entering uncontrolled avalanche unless current-limited.

Can ZMM5255B-7 be used in series for higher voltage references?

Yes, but with caution: series connection increases total dynamic impedance (sum of individual Z_ZT values) and compounds temperature coefficient error (+0.091 %/°C per device). For 56 V, two ZMM5255B-7 units yield ~88 Ω total impedance and ±7.14% combined tolerance - requiring matched units and thermal coupling for best performance.

How does ambient temperature affect power dissipation?

At 25 °C, ZMM5255B-7 supports full 500 mW dissipation. Above that, derating follows R_JA = 300 °C/W: power limit drops linearly by ~1.67 mW/°C. At 75 °C ambient, max allowable power is 417 mW; at 125 °C, it falls to 333 mW - requiring appropriate PCB copper area or airflow for thermal management.

Is ZMM5255B-7 RoHS compliant and halogen-free?

Yes - ZMM5255B-7 meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. The MiniMELF glass package contains no lead in solderable terminations, and material declarations confirm compliance with JEDEC J-STD-609 revision C for marking and reporting.