Diodes Incorporated BZX84B3V9Q-7-F

Overview

BZX84B3V9Q-7-F from Diodes Incorporated is an AEC-Q101-qualified, ±2% tolerance precision Zener diode in SOT23 package, rated for 350mW power dissipation and 3.9V nominal zener voltage at 5mA test current, with 90Ω maximum zener impedance and 3.0µA maximum reverse leakage at 1.0V. It provides stable voltage reference and overvoltage protection in automotive power management circuits.

For engineers reviewing the BZX84B3V9Q-7-F datasheet, BZX84B3V9Q-7-F pinout, BZX84B3V9Q-7-F application, or BZX84B3V9Q-7-F equivalent, key selection criteria include zener voltage tolerance, thermal resistance (357°C/W), junction temperature range (–65°C to +150°C), and automotive qualification status.

Technical Context

This Zener diode operates in reverse breakdown mode with a nominal 3.9V regulation point at I_ZT = 5mA, exhibiting low dynamic impedance (≤90Ω) and tight ±2% voltage tolerance. Its temperature coefficient is –3.5mV/°C near 3.9V, enabling predictable drift compensation in analog reference designs.

Designed for high-reliability automotive applications, it meets AEC-Q101 stress testing requirements and features halogen- and antimony-free "Green" packaging with matte tin lead finish. Thermal performance is specified under two conditions: 350mW derated to ambient (R_θJA = 357°C/W) and 300mW on FR-4 PCB (R_θJA = 417°C/W).

Key Specifications

Pinout & Package

Package: SOT23 - surface-mount plastic case with 0.008g mass, UL 94V-0 flammability rating, and moisture sensitivity level 1 per J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ4685-TP and BZX84-C3V9, BZX84B3V9Q-7-F delivers superior voltage accuracy (±2% vs. ±5%), higher power margin (350mW vs. 300mW), and verified automotive reliability-critical for safety-critical voltage supervision in ECUs and ADAS subsystems.

Availability

BZX84B3V9Q-7-F 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 with full traceability and long-term lifecycle support.

Supply support for BZX84B3V9Q-7-F 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, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

This device belongs to the BZX84B automotive Zener diode family, engineered specifically for high-reliability voltage regulation and transient suppression in harsh-environment automotive electronics.

FAQ

What is the maximum reverse voltage this Zener can withstand before breakdown?

The BZX84B3V9Q-7-F has a nominal zener voltage of 3.9V at 5mA test current, with a guaranteed breakdown range of 3.82V to 3.98V. It is not rated for forward conduction beyond 0.9V at 10mA, and sustained reverse voltage below 3.82V will not initiate breakdown. The device is designed exclusively for controlled reverse-bias operation.

How does the –3.5mV/°C temperature coefficient affect circuit performance?

The negative temperature coefficient means the zener voltage decreases by approximately 3.5mV per degree Celsius rise in junction temperature. At 125°C ambient (with self-heating), V_Z may drop ~0.35V from its 25°C value-requiring thermal design consideration in high-power or high-ambient applications where regulation stability is critical.

Is this part suitable for use in a 5V logic rail clamp?

No-this 3.9V Zener is unsuitable for clamping a 5V rail because its breakdown begins below the rail's nominal voltage. Clamping would occur prematurely, disrupting normal logic operation. A 5.1V or higher Zener (e.g., BZX84B5V1Q-7-F) is required for effective 5V rail protection.

Can BZX84B3V9Q-7-F replace BZX84C3V9 in an existing design?

Physically yes-the SOT23 footprint and pinout match-but electrically no without validation. The BZX84B3V9Q-7-F offers ±2% tolerance and AEC-Q101 qualification versus ±5% and no automotive qualification for the C-series. Substitution requires rechecking regulation accuracy, thermal margins, and compliance documentation for automotive programs.