Diodes Incorporated ZMM5251B-7

Overview

ZMM5251B-7 from Diodes Incorporated is a 22 V, 500 mW surface-mount Zener diode in MiniMELF (DO-213AA) glass package, designed for precision voltage regulation and reference applications at I_ZT = 5.6 mA. It exhibits 600 Ω maximum zener impedance at test current, ±5% zener voltage tolerance (20.9–23.1 V), and +0.087 %/°C temperature coefficient - enabling stable biasing in power supply feedback loops and analog sensor conditioning circuits.

For engineers reviewing the ZMM5251B-7 datasheet, ZMM5251B-7 pinout, ZMM5251B-7 application, or ZMM5251B-7 equivalent, key selection criteria include its 22 V nominal zener voltage, 500 mW power rating, MiniMELF thermal resistance (300 °C/W), low leakage (<0.1 µA at 17 V), and RoHS-compliant Sn97.5Ag2.5 termination - critical for space-constrained, thermally sensitive, or high-reliability industrial designs.

Technical Context

This device operates as a two-terminal voltage reference diode with reverse-biased avalanche breakdown at 22 V. Its junction capacitance is ~4 pF at 0 V (inferred from Fig. 2), and differential zener impedance is 29 Ω at I_ZT = 5.6 mA per electrical characteristics table.

The MiniMELF glass package enables hermetic sealing and high-temperature operation (–65 to +175 °C), while the 300 °C/W junction-to-ambient thermal resistance limits continuous power dissipation to 500 mW only when leads are held at ambient temperature - requiring careful PCB copper area design for thermal management.

Key Specifications

Pinout & Package

MiniMELF (DO-213AA) cylindrical glass package with axial cathode band marking; no internal leads - terminals are the metallized ends of the glass body. Cathode is identified by a single dark band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZMM5251B-7, MMSZ5251T1G trades thermal robustness for compactness and cost, while BZX55C22 retains glass hermeticity but sacrifices regulation precision - making ZMM5251B-7 optimal for new designs demanding both stability and high-temperature resilience.

Availability

ZMM5251B-7 is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor modules, medical instrumentation, and test equipment requiring stable component supply with full traceability and lifecycle support.

Supply support for ZMM5251B-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 semiconductor company specializing in discrete, analog, and mixed-signal devices, with manufacturing and distribution infrastructure across Asia, the Americas, and Europe.

ZMM52xx belongs to Diodes' legacy MiniMELF Zener diode product line, engineered for high-reliability voltage reference and regulation in harsh-environment applications where hermetic sealing and wide temperature operation are essential.

FAQ

What is the maximum continuous power dissipation for ZMM5251B-7?

The ZMM5251B-7 has a rated power dissipation of 500 mW at 25 °C ambient, derating linearly above 25 °C at 1.67 mW/°C (based on R_JA = 300 °C/W). This assumes leads are maintained at ambient temperature - actual PCB copper area directly impacts achievable power handling.

Is ZMM5251B-7 suitable for new designs despite the "NOT RECOMMENDED FOR NEW DESIGN" note?

No - Diodes Incorporated explicitly marks ZMM5251B-7 as not recommended for new designs due to obsolescence risk and superior alternatives like MMSZ5251T1G. The note reflects strategic phase-out; Aetrix recommends evaluating MMSZ52xx for all new schematics while supporting ZMM5251B-7 for legacy production and repair.

How does the +0.087 %/°C temperature coefficient affect long-term voltage stability?

A +0.087 %/°C TC means the zener voltage increases by 19.14 mV per °C rise (0.087% × 22 V). Over a 100 °C range (–25 to +75 °C), this yields ~1.9 V total drift - requiring compensation in precision references, but acceptable for non-critical biasing where absolute accuracy is secondary to repeatability.

Can ZMM5251B-7 be used in place of ZMM5250B or ZMM5252B without circuit modification?

Yes - ZMM5251B-7 shares identical MiniMELF package, power rating, and thermal specs with adjacent parts in the series. Substitution requires verifying that the 22 V zener voltage meets system margin requirements, as ZMM5250B (20 V) and ZMM5252B (24 V) differ by ±2 V - potentially affecting regulation headroom or feedback loop gain.