Nexperia USA Inc. BZX384-A3V9X

Overview

BZX384-A3V9X from Nexperia is a ±1 % tolerance Zener voltage regulator diode in SOD323 (SC-76) package, providing precise 3.9 V nominal breakdown voltage at 5 mA test current, 90 Ω maximum differential resistance, and ≤3 μA reverse current at 1 V. It delivers stable reference voltage for low-power biasing, overvoltage protection, and signal clamping in space-constrained consumer and industrial PCBs.

For engineers reviewing the BZX384-A3V9X datasheet, BZX384-A3V9X pinout, BZX384-A3V9X application, or BZX384-A3V9X equivalent, key selection criteria include its tight ±1 % tolerance, 300 mW total power dissipation at 25 °C ambient, 415 K/W junction-to-ambient thermal resistance, and cathode/anode polarity marking per IEC 60747-2.

Technical Context

This discrete Zener diode operates in reverse-biased breakdown mode to maintain a stable 3.9 V reference across load variations. Its 90 Ω differential resistance ensures minimal voltage shift under 1 mA to 10 mA operating current, while the −3.5 mV/K temperature coefficient indicates predictable negative drift with rising junction temperature.

Designed for surface-mount use on FR4 PCBs with single-sided copper, it supports pulsed non-repetitive peak reverse power up to 40 W (100 μs, square wave), and exhibits 450 pF capacitance at 0 V reverse bias-critical for noise-sensitive analog reference and timing circuits.

Key Specifications

Pinout & Package

Two-terminal SOD323 (SC-76) plastic surface-mount package with cathode marked by a bar on the device body. Mounting requires reflow-compatible footprint per Figure 12 (0.5 mm pad width, 1.35 mm pad length, 2.2 mm center-to-center).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX384-A3V9X, MMBZ5227BS-7-F trades 4× tighter tolerance and 40 % lower impedance for lower cost and larger package, while BZX384-C3V9 retains identical form factor but sacrifices regulation precision and leakage performance for broader production yield.

Availability

BZX384-A3V9X is available at Aetrix Electronics and suitable for power supply reference, overvoltage clamp, and signal level shifting requiring stable component supply in high-mix consumer electronics manufacturing.

Supply support for BZX384-A3V9X 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 logic, discrete, and MOSFET solutions for automotive, industrial, and consumer markets.

The BZX384 series belongs to Nexperia's precision Zener diode product line, engineered for accurate voltage regulation in compact SMD applications where board space and parametric consistency are critical.

FAQ

What is the maximum continuous reverse current the BZX384-A3V9X can handle?

The device supports a maximum continuous forward current of 250 mA, but as a Zener diode, it operates in reverse breakdown. Its rated Zener test current is 5 mA, and sustained reverse current must remain within the 300 mW power limit-yielding ~77 mA at 3.9 V. Exceeding this risks thermal runaway due to its 415 K/W junction-to-ambient resistance.

How does the −3.5 mV/K temperature coefficient affect circuit performance?

This coefficient means the Zener voltage decreases by 3.5 mV per Kelvin rise in junction temperature. At 100 °C junction temperature (75 K above 25 °C), the voltage drops by ~263 mV-to approximately 3.64 V. Designers must account for this drift in temperature-critical references, especially when combined with self-heating from >10 mA bias currents.

Can BZX384-A3V9X be used in place of a 3.3 V Zener diode?

No-it is specified for 3.9 V nominal breakdown and will not regulate reliably at 3.3 V. Attempting to force conduction below its knee voltage results in high dynamic impedance and unstable voltage. For 3.3 V regulation, use BZX384-A3V3 (3.3 V ±1 %) or BZX384-B3V3 (3.3 V ±2 %), which share identical package and thermal characteristics.

Is the SOD323 package compatible with standard reflow soldering profiles?

Yes-the SOD323 package is qualified for lead-free reflow per JEDEC J-STD-020. The recommended profile uses peak temperatures of 260 °C for ≤10 seconds, with ramp rates ≤3 °C/s. Figure 12 in the datasheet specifies a 0.5 mm pad width and 1.35 mm pad length footprint optimized for controlled wetting and minimal tombstoning risk.