Diodes Incorporated BZX84C39TA

Overview

BZX84C39TA from Diodes Incorporated is a 39V, 350mW surface-mount Zener diode in SOT23 package, designed for precision voltage regulation and overvoltage protection in low-power analog and digital circuits. It delivers a nominal Zener voltage of 39.0V at 2.0mA test current, with ±5.1% tolerance (37.0–41.0V), 130Ω dynamic impedance at 2mA, and 0.1µA maximum reverse leakage at 33.4V.

For engineers reviewing the BZX84C39TA datasheet, BZX84C39TA pinout, BZX84C39TA application, or BZX84C39TA equivalent, key selection criteria include its 39V regulation accuracy, low thermal resistance (357°C/W), AEC-Q101 qualification for automotive use, and compatibility with automated SMT assembly on FR-4 PCBs.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable reference voltage under varying load and temperature conditions. Its planar die construction ensures consistent Zener characteristics, while the SOT23 package enables high-density board layout and reliable thermal dissipation up to 350mW at ambient temperature.

The device exhibits a negative temperature coefficient of –3.5mV/°C near 39V, enabling predictable drift compensation in voltage-reference designs. With 0.1µA reverse current at VR = 33.4V and 130Ω Zener impedance at IZT = 2mA, it supports low-noise, low-current regulation in sensor biasing and power-supply feedback paths.

Key Specifications

Pinout & Package

Package: SOT23 - molded plastic case, UL 94V-0 rated, matte tin-plated alloy 42 leadframe, 0.008g weight. Polarity indicated by cathode band on top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5257BS-7-F and BZX84-C39,115, the BZX84C39TA offers superior low-current regulation stability (0.1µA IR), guaranteed Green compound compliance, and optimized thermal performance (357°C/W) for high-reliability SMT deployment.

Availability

BZX84C39TA is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor signal conditioning, and consumer power adapter feedback loops requiring stable component supply and full AEC-Q101 traceability.

Supply support for BZX84C39TA 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, energy-efficient components for automotive, industrial, and computing markets.

The BZX84 series belongs to Diodes' precision Zener portfolio, engineered specifically for stable voltage reference and overvoltage protection in space-constrained, high-volume SMT applications.

FAQ

What is the maximum continuous reverse voltage the BZX84C39TA can withstand without breakdown?

The BZX84C39TA begins controlled Zener breakdown at its nominal 39V rating, with a guaranteed minimum breakdown voltage of 37.0V at 2.0mA test current. It is not rated for continuous operation above 39V in forward bias; sustained reverse voltage exceeding 41.0V (maximum VZ) may cause thermal runaway unless power dissipation remains within 350mW limits and ambient temperature is controlled.

Is the BZX84C39TA suitable for use in automotive applications?

Yes - the BZX84C39TA is explicitly qualified to AEC-Q101 standards, covering stress tests such as high-temperature reverse bias, temperature cycling, and ESD (HBM ≥8kV). Its Green molding compound and RoHS 3 compliance meet Tier 1 automotive supplier requirements for cabin and chassis control modules operating from –40°C to +125°C ambient.

How does the SOT23 package affect thermal performance in PCB layout?

The SOT23 package achieves 357°C/W junction-to-ambient thermal resistance when mounted on FR-4 with Diodes' recommended pad layout (2.4mm × 1.3mm copper pour per pin). Reducing pad size or omitting thermal vias increases RθJA significantly; adding two 0.3mm thermal vias under the center pad lowers resistance by ~25%, critical for sustained 300mW operation.

Can the BZX84C39TA replace a 36V or 43V Zener in an existing design?

No - the BZX84C39TA has a fixed 39V nominal Zener voltage with ±5.1% tolerance (37.0–41.0V). Substituting it for 36V or 43V variants risks incorrect regulation or insufficient clamping margin. Use BZX84C36TA or BZX84C43TA instead, which share identical SOT23 packaging, thermal specs, and AEC-Q101 qualification but differ only in VZ and impedance values.