Diodes Incorporated SMAZ18-13

Overview

SMAZ18-13 from Diodes Incorporated is a 1.0W surface-mount Zener diode with a nominal zener voltage of 18.0V (range: 17.1–18.9V), ±5% tolerance, 25mA test current, and 150Ω maximum zener impedance at I_ZT. It features a molded SMA package, cathode band polarity marking, and is rated for operation from −65°C to +150°C. It is used for precision voltage regulation and overvoltage protection in DC power rails of industrial control modules.

For engineers reviewing the SMAZ18-13 datasheet, SMAZ18-13 pinout, SMAZ18-13 application, or SMAZ18-13 equivalent, key selection criteria include zener voltage accuracy at 25mA, thermal resistance (R_θJA = 100°C/W), power derating above +50°C, and compliance with RoHS, halogen-free, and antimony-free "Green" requirements.

Technical Context

This device operates as a two-terminal voltage reference, maintaining stable reverse-bias breakdown across its specified current range (1.0–15mA typical operating zone). Its 18.0V nominal regulation point targets mid-range supply monitoring and clamping in 24V industrial systems.

The SMA package enables automated SMT assembly with JEDEC-standard footprint and moisture sensitivity level 1. Thermal performance is defined on FR-4 PCB per Diodes Inc.'s recommended pad layout, delivering 1.0W dissipation at +25°C and linearly derated by 10mW/°C above +50°C.

Key Specifications

Pinout & Package

Package: SMA (Surface Mount Axial), molded plastic case (UL 94V-0), cathode identified by band marking. Dimensions: 4.00–4.60mm length (B), 2.29–2.92mm width (A), 1.27–1.63mm height (C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C18LT1G and 1N4744A, SMAZ18-13 uniquely combines 1.0W SMT capability, full RoHS/halogen-free compliance, and industry-standard SMA footprint-making it optimal for new industrial and automotive designs requiring automated assembly and environmental certification.

Availability

SMAZ18-13 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, 24V DC power rail clamping, and automotive body control unit sensor reference circuits requiring stable component supply, long-term lifecycle support, and full environmental compliance.

Supply support for SMAZ18-13 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, serving industrial, computing, consumer, and communications markets since 1966.

The SMAZ series belongs to Diodes Inc.'s surface-mount Zener diode product line, engineered specifically for high-reliability voltage regulation and transient suppression in automated SMT environments with strict environmental compliance requirements.

FAQ

What is the maximum continuous reverse current (I_ZM) for SMAZ18-13?

The maximum zener current I_ZM is calculated as P_D/V_Z = 1.0W / 18.0V ≈ 55.6mA. This represents the absolute upper limit for continuous DC operation at 25°C ambient; derating applies above +50°C per the datasheet's 10mW/°C slope. Operation beyond this risks thermal runaway and permanent degradation.

Does SMAZ18-13 have a specified capacitance value?

No specific capacitance is listed in the DS18015 datasheet for SMAZ18-13. However, Figure 2 shows typical total capacitance for related devices (e.g., SMAZ12, SMAZ27) ranging from ~10pF to ~100pF at 1MHz and low reverse bias (<5V). At its 18V operating point, capacitance is expected to be ≤20pF - suitable for DC and low-frequency regulation but not RF bypassing.

Can SMAZ18-13 be used in place of a 1N4744A?

Electrically, yes - both are 18V, ±5%, 1.0W Zeners. Mechanically, no: SMAZ18-13 uses SMA surface-mount packaging while 1N4744A uses DO-41 through-hole. Substitution requires PCB redesign and process change from wave to reflow soldering. Also, SMAZ18-13 meets RoHS and halogen-free standards; 1N4744A does not.

What is the meaning of the "-13" suffix in SMAZ18-13?

The "-13" denotes tape-and-reel packaging: 5,000 units per reel, compatible with standard pick-and-place equipment. It follows Diodes Inc.'s ordering convention where "x-13-F" indicates commercial-grade, lead-free, RoHS-compliant, tape-and-reel packaging - distinct from bulk ("-BULK") or ammo-pack ("-AP") variants.