Nexperia USA Inc. BZX84W-B33X

Overview

BZX84W-B33X from Nexperia is a ±2% tolerance Zener voltage regulator diode with nominal 33 V breakdown voltage, 32.3 V to 33.7 V regulation range at I_Z = 2 mA, 325 Ω differential resistance, and 29.7 mV/K temperature coefficient - used for precision voltage reference and overvoltage clamping in power supply feedback loops and analog sensor signal conditioning.

For engineers reviewing the BZX84W-B33X datasheet, BZX84W-B33X pinout, BZX84W-B33X application, or BZX84W-B33X equivalent, this page delivers verified electrical parameters, SOT323 package layout, thermal derating guidance, and direct substitution options for industrial power management and high-frequency regulation designs.

Technical Context

This Zener diode operates in reverse-biased breakdown mode with a specified 33 V nominal Zener voltage at 2 mA test current, exhibiting a positive temperature coefficient of +29.7 mV/K - indicating increasing breakdown voltage with junction temperature rise. Its low 325 Ω dynamic impedance ensures stable regulation under small-signal load variations.

Designed for surface-mount use in SOT323 (SC-70) packaging, it supports continuous power dissipation up to 275 mW on FR4 PCBs and withstands non-repetitive peak reverse power surges of 40 W for 100 µs pulses - enabling robust transient suppression in compact DC-DC converter feedback networks.

Key Specifications

Pinout & Package

SOT323 (SC-70) leadless surface-mount plastic package with 3 terminals; 1.3 mm × 1.8 mm footprint, 0.95 mm height, and tin-plated terminations compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84W-C33 and MMSZ5261B, BZX84W-B33X delivers tighter voltage control and lower dynamic impedance in the smallest available footprint - making it optimal for space-constrained, high-accuracy regulation where thermal stability and board area are critical.

Availability

BZX84W-B33X is available at Aetrix Electronics and suitable for industrial power supplies, sensor interface circuits, and overvoltage protection systems requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for BZX84W-B33X 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 precision voltage regulation and transient suppression in cost-sensitive, space-constrained industrial and consumer electronics.

FAQ

What is the maximum continuous Zener current for BZX84W-B33X at 25 °C ambient?

The maximum continuous Zener current is calculated from P_tot = 275 mW and V_Z ≈ 33 V, yielding I_Zmax = 275 mW / 33 V ≈ 8.3 mA. This assumes mounting on FR4 PCB with single-sided copper and standard footprint per datasheet condition [2]. Derating is required above 25 °C using R_th(j-a) = 455 K/W.

Does BZX84W-B33X have a connected pin 2, and what happens if it's soldered?

No - pin 2 is internally not connected (n.c.) and must remain unconnected in the PCB layout. Soldering or routing to pin 2 introduces parasitic capacitance and potential leakage paths, degrading regulation accuracy and transient response. The device outline graphic and Table 2 explicitly confirm "n.c." designation.

How does the +29.7 mV/K temperature coefficient affect regulation accuracy over −40 °C to +125 °C?

Over that 165 °C range, total drift is 165 K × 29.7 mV/K ≈ 4.9 V - shifting nominal 33 V regulation to ~28.1 V at −40 °C and ~37.9 V at +125 °C. For stable operation, designers must either limit ambient rise, use temperature-compensated topologies, or select Zeners with near-zero TC (e.g., 5.6 V types) where possible.

Can BZX84W-B33X replace BZX84W-C33 in an existing design without layout changes?

Yes - both share identical SOT323 package, pinout, and thermal characteristics. Substitution requires only verification that the tighter ±2% tolerance meets system-level voltage margin requirements; no PCB modification is needed since footprint, solder mask, and reflow profile are fully compatible.