Nexperia USA Inc. BZX84W-C18F

Overview

BZX84W-C18F from Nexperia is a ±5 % tolerance Zener voltage regulator diode in SOT323 (SC-70) package, providing 18 V nominal regulation at 5 mA, with 225 Ω differential resistance and 14.4 mV/K temperature coefficient. It delivers stable reference voltage for low-power analog circuits, power supply feedback loops, and overvoltage protection in consumer and industrial electronics.

For engineers reviewing the BZX84W-C18F datasheet, BZX84W-C18F pinout, BZX84W-C18F application, or BZX84W-C18F equivalent, this page provides verified Zener voltage, tolerance, thermal resistance, reverse leakage, and package-specific mounting data required for precision biasing, voltage clamping, and reference design validation.

Technical Context

This Zener diode operates in reverse breakdown to maintain a stable 18 V reference across load variations and temperature shifts. Its ±5 % tolerance (C-series), 225 Ω dynamic impedance at 5 mA, and +14.4 mV/K positive temperature coefficient define its regulation accuracy and thermal drift behavior in real-world circuits.

Designed for surface-mount use on FR4 PCBs with single-sided copper, it supports 275 mW total power dissipation and withstands non-repetitive 40 W surge pulses (100 µs). The SOT323 package enables high-density placement while maintaining thermal performance up to 150 °C junction temperature.

Key Specifications

Pinout & Package

SOT323 (SC-70) leadless surface-mount plastic package with 3 terminals; compact 2.2 mm × 1.35 mm footprint optimized for automated reflow assembly and space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84W-C18F, MMBZ5245BS offers higher power margin but larger size, while BZX84-C18 matches voltage and tolerance but demands SOT-23 footprint adaptation-BZX84W-C18F uniquely balances 275 mW rating, SOT323 miniaturization, and Nexperia's traceable wafer-level quality control.

Availability

BZX84W-C18F is available at Aetrix Electronics and suitable for power supply feedback, overvoltage protection, and reference voltage source applications requiring stable component supply, consistent parametric performance, and long-term obsolescence management.

Supply support for BZX84W-C18F 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

Nexperia is a global semiconductor expert focused on high-volume, high-reliability discrete and logic devices, with leadership in automotive-qualified and industrial-grade components.

BZX84W series belongs to Nexperia's general-purpose Zener diode product line, engineered for cost-effective, space-efficient voltage regulation in consumer, industrial, and computing applications where precision and thermal stability are balanced against footprint and bill-of-materials constraints.

FAQ

What is the maximum continuous Zener current for BZX84W-C18F at 25 °C ambient?

The maximum continuous Zener current is calculated from P_tot = 275 mW and V_Z = 18 V, yielding I_Z(max) ≈ 15.3 mA under ideal thermal conditions. Derating is required above 25 °C ambient due to R_th(j-a) = 455 K/W; at 70 °C ambient, usable current drops to ~9 mA to maintain T_j ≤ 150 °C.

Does BZX84W-C18F have a connected third pin, and how should Pin 2 be handled?

No-Pin 2 is explicitly marked "n.c." (not connected) in the official Nexperia datasheet and internal die construction. It must remain electrically floating: no PCB trace, solder mask opening, or thermal pad connection is permitted, as any coupling may induce parasitic leakage or thermal imbalance affecting regulation stability.

How does the +14.4 mV/K temperature coefficient impact regulation accuracy over −40 °C to +85 °C?

Over a 125 K span, the coefficient causes a ΔV_Z ≈ +1.8 V shift (14.4 mV/K × 125 K), resulting in a total regulation range of ~16.2 V to 19.8 V. This is within the ±5 % initial tolerance band (17.1 V–18.9 V) only near room temperature; full-range designs must include compensation or accept wider output variation.

Can BZX84W-C18F be used in place of a 1N4746A in an existing design?

No-1N4746A is a through-hole 18 V, 1 W Zener in DO-41 package with 10 Ω r_dif and different thermal behavior. BZX84W-C18F has higher impedance (225 Ω), lower power (275 mW), and SMT-only mounting. Direct substitution would cause excessive voltage droop under load and potential thermal failure; redesign of current limiting and PCB layout is mandatory.