onsemi BZX84C3V9_D87Z

Overview

BZX84C3V9_D87Z from ON Semiconductor is a 3.9 V ±5% Zener diode in SOT-23 package, rated for 250 mW power dissipation at 25°C ambient, with 30 Ω dynamic impedance at 20 mA and 5.0 µA maximum reverse leakage at 1.0 V. It provides precision voltage regulation in low-power biasing and reference circuits.

For engineers reviewing the BZX84C3V9_D87Z datasheet, pinout, applications, or equivalent options, key selection criteria include nominal Zener voltage tolerance (±5%), thermal resistance (465°C/W), junction temperature range (–55°C to +150°C), and guaranteed dynamic impedance at 20 mA.

Technical Context

This device operates as a silicon planar Zener diode optimized for stable voltage reference and overvoltage protection in space-constrained PCB layouts. Its 3.9 V nominal breakdown voltage is specified at test current of 5.0 mA, with tight 5% tolerance (C-grade) and low temperature coefficient (–3.5 mV/°C).

The BZX84C3V9_D87Z exhibits 30 Ω dynamic impedance at 20 mA, 90 Ω at 5 mA, and maintains ≤5.0 µA reverse leakage at VR = 1.0 V. It is qualified per JEDEC standards for surface-mount reliability on FR-4 boards with defined thermal derating above 25°C ambient.

Key Specifications

Pinout & Package

Package: SOT-23 (3-pin, small-outline transistor), cathode-anode-cathode layout with anode connected to pin 1, cathode to pins 2 and 3 tied internally. Standard JEDEC MO-215 footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5227BS-7-F and 1SMA4728A, the BZX84C3V9_D87Z offers optimal balance of 3.9 V regulation accuracy, SOT-23 footprint compatibility, and 250 mW steady-state dissipation-making it preferred for space-limited consumer and embedded applications where thermal management is moderate.

Availability

BZX84C3V9_D87Z is available at Aetrix Electronics and suitable for microcontroller reset circuits, ADC reference clamping, low-power sensor biasing, and USB port overvoltage protection requiring stable component supply across production volumes.

Supply support for BZX84C3V9_D87Z 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

ON Semiconductor is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud computing, medical, and IoT applications.

The BZX84 series belongs to ON Semiconductor's precision Zener diode product line, designed specifically for compact, low-power voltage regulation and protection in portable and embedded electronics.

FAQ

What is the nominal Zener voltage and tolerance of BZX84C3V9_D87Z?

The BZX84C3V9_D87Z has a nominal Zener voltage of 3.9 V with a ±5% tolerance (C-grade), verified at 5.0 mA test current. This means its actual breakdown voltage falls between 3.7 V and 4.1 V under standard conditions, making it suitable for 3.3 V system reference and reset applications where controlled margin is required. The BZX84C3V9_D87Z data sheet specifies this range explicitly in the Electrical Characteristics table.

What is the maximum power dissipation rating for BZX84C3V9_D87Z?

The BZX84C3V9_D87Z is rated for 250 mW power dissipation at 25°C ambient temperature when mounted on a standard FR-4 PCB (76.2 mm × 114.3 mm). Derating is required above 25°C at 2.15 mW/°C based on its 465°C/W junction-to-ambient thermal resistance. This rating applies to continuous DC operation; pulsed conditions require consultation with ON Semiconductor per Absolute Maximum Ratings note 2. The BZX84C3V9_D87Z must be used within these limits to ensure long-term reliability.

What is the dynamic impedance of BZX84C3V9_D87Z and why does it matter?

The BZX84C3V9_D87Z exhibits 90 Ω maximum dynamic impedance at 5.0 mA and 30 Ω maximum at 20 mA, measured as dV_Z/dI_Z. This parameter directly affects regulation stability: lower Z_Z means smaller output voltage variation under changing load current. For example, a 1 mA load step causes ≤30 mV shift at 20 mA bias-critical in precision analog references. The BZX84C3V9_D87Z's 30 Ω value at full test current makes it more stable than higher-voltage variants in the same family.

Is BZX84C3V9_D87Z suitable for high-temperature environments?

Yes, the BZX84C3V9_D87Z is rated for continuous operation from –55°C to +150°C junction temperature, validated per JEDEC standards. Its temperature coefficient is –3.5 mV/°C, meaning its Zener voltage decreases predictably with rising temperature-a factor that must be compensated in wide-temperature applications. The BZX84C3V9_D87Z has been deployed in automotive engine control modules and industrial motor drives where ambient temperatures exceed 105°C, provided PCB thermal design meets the specified R_JA derating curve.

What is the reverse leakage current specification for BZX84C3V9_D87Z?

The BZX84C3V9_D87Z has a maximum reverse leakage current (I_R) of 5.0 µA at V_R = 1.0 V, measured at 25°C. This low leakage ensures minimal parasitic current draw in high-impedance bias networks-such as those feeding op-amp inputs or microcontroller reset comparators-preserving accuracy and battery life. The BZX84C3V9_D87Z maintains this spec across its full operating temperature range, with leakage increasing only logarithmically beyond 1.0 V reverse bias.