Nexperia USA Inc. BZX84W-B3V9X

Overview

BZX84W-B3V9X from Nexperia is a ±2 % tolerance Zener voltage regulator diode in SOT323 (SC-70) package, rated for 3.9 V nominal Zener voltage at 5 mA, 275 mW total power dissipation, and 3 µA reverse current at 1 V reverse bias. It serves as a precision reference or low-power voltage clamp in signal conditioning and power rail stabilization circuits.

For engineers reviewing the BZX84W-B3V9X datasheet, BZX84W-B3V9X pinout, BZX84W-B3V9X application, or BZX84W-B3V9X equivalent, this page delivers verified Zener parameters, thermal resistance (455 K/W), differential resistance (90 Ω), temperature coefficient (−2.5 mV/K), and SC-70 terminal mapping to support accurate circuit modeling and layout integration.

Technical Context

This Zener diode operates in reverse breakdown with a tightly controlled 3.9 V nominal regulation voltage at I_Z = 5 mA, exhibiting −2.5 mV/K temperature coefficient and 90 Ω differential resistance - enabling stable reference generation across ambient temperatures from −55 °C to +150 °C.

Designed for surface-mount use on FR4 PCBs with single-sided copper, it delivers 275 mW steady-state dissipation and withstands non-repetitive 40 W surge pulses (t_p = 100 µs), while maintaining ≤3 µA leakage at V_R = 1 V - critical for low-current biasing and sensing nodes.

Key Specifications

Pinout & Package

SOT323 (SC-70) leadless plastic surface-mount package with 3 terminals, 1.3 mm × 1.8 mm footprint, and 0.65 mm pitch; 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-C3V9, the BZX84W-B3V9X offers tighter voltage control essential for precision references; versus MMSZ4685T1G, it trades power margin for 30 % smaller footprint and lower thermal resistance - favoring compact, thermally constrained designs.

Availability

BZX84W-B3V9X is available at Aetrix Electronics and suitable for power supply rail clamping, microcontroller reset circuits, ADC reference stabilization, and signal level translation requiring stable component supply and consistent Zener performance across production batches.

Supply support for BZX84W-B3V9X 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 cost-effective, space-efficient voltage regulation in consumer, industrial, and computing applications - emphasizing tight tolerance, low leakage, and robust SMT manufacturability.

FAQ

What is the maximum continuous reverse current the BZX84W-B3V9X can sustain at 3.9 V?

The BZX84W-B3V9X is not rated for continuous reverse current at its Zener voltage; instead, it specifies a maximum total power dissipation of 275 mW at 25 °C ambient. At 3.9 V, this corresponds to a maximum average reverse current of approximately 70.5 mA (275 mW ÷ 3.9 V), assuming full power is allocated to Zener operation and thermal limits are observed.

Can the n.c. pin (Pin 2) be used as a heatsink pad or grounded for thermal improvement?

No - Pin 2 is internally not connected to any die structure or substrate. Connecting it to ground or a thermal plane provides no electrical or thermal benefit and may risk solder bridging or mechanical stress. Thermal performance relies solely on the anode (Pin 1) and cathode (Pin 3) thermal paths through the PCB copper.

How does the −2.5 mV/K temperature coefficient affect regulation accuracy over −40 °C to +85 °C?

Across a 125 K temperature span, the Zener voltage shifts by −2.5 mV/K × 125 K = −312.5 mV - resulting in a V_Z range of ~3.59 V to ~3.9 V. This 7.9 % drift is inherent to low-voltage Zeners and must be accommodated in system-level tolerance budgets or mitigated via compensation techniques.

Is the BZX84W-B3V9X suitable for automotive applications?

No - per Nexperia's revision history (Rev. 2, Jan 2023), the BZX84W series is explicitly designated as non-automotive qualified. It lacks AEC-Q101 qualification, automotive-grade testing, and extended reliability validation. For automotive use, Nexperia recommends their separate −Q qualified Zener families.