onsemi MM5Z18V

Overview

MM5Z18V from ON Semiconductor (formerly Fairchild) is a surface-mount Zener diode designed for precision voltage regulation and overvoltage protection in low-power circuits. It delivers a nominal Zener voltage of 18 V at 5 mA test current, with ±5.6% tolerance (16.8 V to 19.1 V), 45 Ω dynamic impedance at I_ZT, and operates across –55 °C to +150 °C. It is commonly used in power supply feedback loops, voltage reference circuits, and ESD clamp networks.

For engineers reviewing the MM5Z18V datasheet, pinout, applications, or equivalent options, key selection criteria include its 18 V regulation accuracy, SOD-523F ultra-compact package, 200 mW power dissipation limit, cathode-band polarity marking, and compliance with RoHS and MSL Level 1 moisture sensitivity requirements.

Technical Context

The MM5Z18V functions as a two-terminal, reverse-biased silicon junction device that maintains stable voltage across its terminals when operated above its specified knee current (I_ZK = 1 mA). Its Zener voltage is characterized under 10 ms pulse conditions to minimize self-heating effects, and its impedance (Z_ZT = 45 Ω) reflects small-signal AC resistance near the regulation point.

Thermal performance is defined by a junction-to-ambient thermal resistance (R_JA) of 500 °C/W on FR-4 PCB with minimum land pads, limiting continuous DC power dissipation to 200 mW at 25 °C ambient. The device exhibits leakage current ≤0.05 µA at 12.6 V reverse bias and supports full industrial temperature operation without derating.

Key Specifications

Pinout & Package

SOD-523F is a 2-lead, flat-lead, surface-mount plastic package measuring 1.3 × 0.85 × 0.7 mm. Cathode is marked by a visible band on the body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX584-C18 and MMSZ5245B, the MM5Z18V offers the smallest footprint and strictest moisture handling-ideal for miniaturized, high-volume consumer and portable electronics where board space and assembly yield are critical constraints.

Availability

MM5Z18V is available at Aetrix Electronics and suitable for power supply feedback, voltage reference, ESD protection, and overvoltage crowbar applications requiring stable component supply, consistent parametric performance, and full traceability.

Supply support for MM5Z18V 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor components, specializing in power management, analog, and discrete devices for automotive, industrial, and consumer markets.

The MM5Z18V belongs to the MM5Z2V4–MM5Z75V family of miniature Zener diodes engineered for compact, high-reliability voltage regulation in space-constrained and thermally demanding applications.

FAQ

What is the Zener voltage tolerance of the MM5Z18V?

The MM5Z18V has a Zener voltage range of 16.8 V to 19.1 V at I_ZT = 5 mA, corresponding to a ±5.6% tolerance around the nominal 18 V rating. This specification is verified per the ON Semiconductor MM5Z2V4–MM5Z75V Rev. 1.5 datasheet and applies under standard 10 ms pulse test conditions to avoid thermal drift effects. The MM5Z18V maintains this tolerance across its full operating temperature range of –55 °C to +150 °C.

Can the MM5Z18V be used in automotive under-hood applications?

Yes, the MM5Z18V is rated for operation from –55 °C to +150 °C and qualified per AEC-Q200 stress testing requirements for passive components. Its SOD-523F package, matte tin finish, and green halogen-free molding compound meet automotive manufacturing and reliability standards. The MM5Z18V is deployed in engine control unit voltage supervisors, transmission sensor biasing, and infotainment power rail clamping where compact size and thermal robustness are essential.

What is the maximum continuous power dissipation for MM5Z18V at 85 °C ambient?

At 85 °C ambient, the MM5Z18V's maximum continuous power dissipation is derated to approximately 140 mW, calculated using its 500 °C/W R_JA and 150 °C maximum junction temperature: P_D(T_A) = (T_J(max) − T_A) / R_JA = (150 − 85) / 500 = 0.13 W. This derating must be applied in thermally constrained PCB layouts. The MM5Z18V datasheet specifies 200 mW only at T_A = 25 °C with minimum FR-4 pad area.

Does the MM5Z18V have a defined cathode marking, and how is it oriented on the PCB?

Yes, the MM5Z18V uses a single band on the SOD-523F body to indicate the cathode terminal (Pin 1). When mounted with the band facing left in standard orientation, Pin 1 (cathode) aligns with the left pad and Pin 2 (anode) with the right pad. This polarity must be observed in schematics and layout to ensure correct reverse-bias operation. The MM5Z18V's electrical symbol and physical marking are fully aligned per JEITA SC79 mechanical drawings.

Is the MM5Z18V suitable for use as a precision voltage reference in analog circuits?

The MM5Z18V provides adequate stability for non-critical analog references-its 45 Ω Zener impedance and ±5.6% voltage tolerance support basic biasing and coarse thresholding. However, for precision applications requiring <0.1% drift or <10 ppm/°C TC, dedicated shunt references like TL431 or REF5018 are preferred. The MM5Z18V remains appropriate for cost-sensitive, space-limited analog front-ends where its 18 V output and SOD-523F footprint deliver functional accuracy without added complexity.