Nexperia USA Inc. BZX84W-C18X

Overview

BZX84W-C18X from Nexperia is a ±5 % tolerance Zener voltage regulator diode in SOT323 (SC-70) package, providing 16.8 V to 19.1 V nominal regulation at 5 mA test current, with 225 Ω typical 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-C18X datasheet, BZX84W-C18X pinout, BZX84W-C18X application, or BZX84W-C18X equivalent, key selection factors include its ±5 % Zener voltage tolerance, 275 mW total power dissipation on FR4 PCB, 225 Ω dynamic impedance at 5 mA, 14.4 mV/K temperature coefficient, and SOT323 three-terminal configuration with center pin unconnected.

Technical Context

This Zener diode operates in reverse breakdown to maintain a stable DC reference voltage across its cathode–anode terminals under varying load and input conditions. Its 16.8–19.1 V regulation range targets mid-voltage rail monitoring and precision biasing where moderate accuracy suffices.

Designed for surface-mount assembly on standard FR4 PCBs, it exhibits 455 K/W junction-to-ambient thermal resistance and supports non-repetitive surge currents up to 1.0 A (100 µs pulse), enabling transient overvoltage clamping in compact power management stages.

Key Specifications

Pinout & Package

The BZX84W-C18X is housed in a leadless SOT323 (SC-70) plastic surface-mount package with three terminals: anode (Pin 1), not connected (Pin 2), and cathode (Pin 3). The center pin is internally unconnected and must remain floating in PCB layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5245BS, BZX84W-C18X offers 37 % higher power dissipation and identical dynamic impedance, improving thermal headroom in dense layouts; versus Vishay BZX84-C18, it eliminates Pin 2 connection complexity while maintaining regulation performance, simplifying layout and reducing assembly risk.

Availability

BZX84W-C18X is available at Aetrix Electronics and suitable for power supply feedback, overvoltage clamp, and reference voltage source applications requiring stable component supply, consistent parametric performance, and SMT-compatible packaging.

Supply support for BZX84W-C18X 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 delivering high-performance, reliable discrete, logic, and MOSFET solutions for automotive, industrial, and consumer markets.

The BZX84W series belongs to Nexperia's general-purpose Zener diode product line, engineered for compact, cost-effective voltage regulation in space-constrained SMT designs where ±2 % or ±5 % tolerance meets system accuracy needs.

FAQ

What is the Zener voltage tolerance of BZX84W-C18X?

The BZX84W-C18X has a ±5 % Zener voltage tolerance, meaning its breakdown voltage ranges from 16.8 V to 19.1 V when tested at 5 mA reverse current. This tolerance is confirmed in Table 8 of the Nexperia datasheet Rev. 2 (January 2023) under the "C" series designation and applies across the full operating temperature range.

Is Pin 2 electrically connected inside the BZX84W-C18X package?

No, Pin 2 is internally not connected (n.c.) and must remain unconnected on the PCB. This is explicitly stated in Table 2 ("Pinning information") of the datasheet, which labels Pin 2 as "not connected" and shows no internal bond wire in the simplified outline graphic. Connecting it risks mechanical stress or unintended coupling.

Can BZX84W-C18X replace older BZX84-C18 variants in existing designs?

Yes, BZX84W-C18X is a direct functional replacement for BZX84-C18 with identical Zener voltage, tolerance, and SOT323 package. Key improvements include updated non-automotive qualification status (Rev. 2, 2023) and refined thermal characterization-no layout or schematic changes are needed for drop-in substitution.

What is the maximum allowable ambient temperature for continuous operation?

The BZX84W-C18X supports continuous operation from −55 °C to +150 °C ambient temperature, as specified in Table 5 ("Limiting values"). At the upper limit, derating applies: its 275 mW power dissipation assumes FR4 PCB mounting; actual usable power decreases above 25 °C per the R_th(j-a) = 455 K/W thermal resistance value in Table 6.