Nexperia USA Inc. BZX84W-B20X

Overview

BZX84W-B20X from Nexperia is a ±2 % tolerance Zener voltage regulator diode in SOT323 (SC-70) package, rated for 20 V nominal Zener voltage at 5 mA, 275 mW total power dissipation, and 150 °C maximum junction temperature. It provides precision voltage reference and regulation in compact high-frequency signal conditioning and low-power supply rail stabilization circuits.

For engineers reviewing the BZX84W-B20X datasheet, BZX84W-B20X pinout, BZX84W-B20X application, or BZX84W-B20X equivalent, key selection criteria include Zener voltage tolerance (±2 %), differential resistance (55 Ω at I_Z = 5 mA), temperature coefficient (+16.4 mV/K), reverse leakage current (50 nA at 0.7 × V_Znom), and thermal resistance (455 K/W).

Technical Context

This device operates as a two-terminal shunt voltage regulator, maintaining stable output voltage across its cathode–anode terminals under reverse-biased conditions. Its Zener breakdown mechanism delivers predictable regulation with low dynamic impedance (55 Ω) and controlled temperature drift (+16.4 mV/K) over 25–150 °C.

The SOT323 package enables surface-mount integration in space-constrained designs while supporting reflow and wave soldering per defined footprints. Thermal performance is characterized with R_th(j-a) = 455 K/W on FR4 PCB with single-sided copper, defining safe operating limits under continuous and pulsed load conditions.

Key Specifications

Pinout & Package

SOT323 (SC-70) leadless surface-mount plastic package with 3 terminals: anode (Pin 1), not connected (Pin 2), cathode (Pin 3). Dimensions: 2.2 mm × 1.35 mm × 0.95 mm (L × W × H); footprint optimized for reflow soldering per Figure 9.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84W-B20X, MMBZ5242B offers higher power but sacrifices voltage accuracy and thermal predictability, while BZX84-C20 matches mechanical fit and most electrical specs but trades ±2 % tolerance for cost-driven ±5 % grading-making BZX84W-B20X optimal for precision 20 V references requiring long-term stability.

Availability

BZX84W-B20X is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable instrumentation power rails, and embedded system voltage reference circuits requiring stable component supply, consistent parametric performance, and long-lifecycle availability.

Supply support for BZX84W-B20X 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.

The BZX84W series belongs to Nexperia's general-purpose Zener diode product line, engineered for compact, stable voltage regulation in space-constrained consumer, industrial, and computing applications where SOT323 packaging and tight tolerances are essential.

FAQ

What is the maximum continuous reverse current the BZX84W-B20X can sustain at 25 °C ambient?

The device supports up to 13.75 mA continuous reverse current at 25 °C ambient, calculated from its 275 mW power rating and 20 V Zener voltage (P_tot/V_Z). This assumes no additional thermal derating and operation on a standard FR4 PCB with single-sided copper. At elevated ambient temperatures, current must be reduced per the thermal resistance (455 K/W) and junction temperature limit (150 °C).

Does the 'n.c.' pin (Pin 2) require PCB routing or grounding?

No, Pin 2 is internally not connected and must remain electrically floating-no PCB trace, pad, or solder mask should be applied to it. The SOT323 footprint design intentionally isolates this terminal; connecting it risks mechanical stress or unintended parasitic coupling. Reference Figure 8 and Figure 9 in the Nexperia datasheet for correct land pattern implementation.

How does the +16.4 mV/K temperature coefficient affect regulation accuracy over temperature?

At 20 V nominal Zener voltage, the +16.4 mV/K coefficient causes approximately +1.15 V drift over a 70 °C rise (e.g., 25 °C to 95 °C), resulting in a +5.75 % relative change. For applications requiring tighter thermal stability, this drift must be compensated via circuit design (e.g., paired with negative-tempco components) or limited to narrower ambient ranges where absolute error remains within system tolerance.

Can BZX84W-B20X replace BZX84-C20 in existing designs without layout changes?

Yes-both share identical SOT323 package dimensions, pinout (anode/cathode/n.c.), and thermal footprint. However, BZX84W-B20X offers ±2 % tolerance versus ±5 % for BZX84-C20, delivering tighter voltage control. No PCB modification is needed, but system-level validation is recommended to confirm improved regulation margin meets functional requirements without over-specifying.