onsemi BZX84C4V7

Overview

BZX84C4V7 from ON Semiconductor (formerly Fairchild) is a 4.7 V ±5% Zener diode in SOT-23 package, rated for 250 mW power dissipation at 25°C ambient, with typical zener impedance of 15 Ω at 20 mA and reverse leakage current ≤3 µA at 2.0 V, used for precision voltage regulation and overvoltage protection in low-power analog circuits.

For engineers reviewing the BZX84C4V7 datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, dynamic impedance at operating current, thermal resistance (R_JA = 465°C/W), reverse leakage at specified VR, and SOT-23 footprint compatibility in space-constrained PCB designs.

Technical Context

The BZX84C4V7 operates as a silicon planar epitaxial Zener diode optimized for stable voltage reference and clamping in DC bias networks. Its 4.7 V nominal breakdown voltage is specified at test currents of 1.0 mA, 5.0 mA, and 20 mA, with corresponding zener impedances of 500 Ω, 80 Ω, and 15 Ω - indicating strong regulation performance above 5 mA.

Thermal design relies on its junction-to-ambient thermal resistance of 465°C/W (FR-4 board, 76.2 mm × 114.3 mm), limiting continuous power handling to 250 mW at 25°C ambient; derating is required above 25°C per the 1.5 mW/°C slope implied by R_JA.

Key Specifications

Pinout & Package

Package: SOT-23 (TO-236AB), surface-mount, 3-terminal plastic package with cathode marked by color band. Standard pin assignment: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Not connected (NC) - confirmed per ON Semiconductor BZX84C series mechanical drawings and footprint standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84C4V7, MMBZ4685 offers higher power margin and lower impedance for demanding clamping, while BZX84-B4V7 adds automotive qualification and tighter leakage - both retain SOT-23 compatibility but differ in thermal and reliability envelope.

Availability

BZX84C4V7 is available at Aetrix Electronics and suitable for power supply rail clamping, ADC reference stabilization, and signal line ESD protection requiring stable component supply and long-term obsolescence management.

Supply support for BZX84C4V7 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 manufacturer specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and cloud power applications.

The BZX84C4V7 belongs to ON Semiconductor's legacy Zener diode portfolio, designed for cost-sensitive, space-constrained voltage regulation and protection in consumer, computing, and industrial electronics.

FAQ

What is the nominal zener voltage and tolerance of the BZX84C4V7?

The BZX84C4V7 has a nominal zener voltage of 4.7 V with a tolerance of ±5%, meaning its actual breakdown voltage falls between 4.4 V and 5.0 V when tested at 5 mA. This tolerance is confirmed in the Electrical Characteristics table of the official ON Semiconductor datasheet Rev. 1.10. The BZX84C4V7 achieves this specification using silicon planar epitaxial process technology, ensuring consistency across production lots.

What is the maximum power dissipation rating for the BZX84C4V7 and under what conditions?

The BZX84C4V7 is rated for 250 mW power dissipation at an ambient temperature of 25°C when mounted on a standard FR-4 PCB (76.2 mm × 114.3 mm). This rating assumes no forced airflow and follows a linear derating slope of 1.5 mW/°C above 25°C, based on its junction-to-ambient thermal resistance of 465°C/W. The BZX84C4V7 must not exceed this limit to maintain reliability and avoid thermal runaway.

How does the zener impedance of the BZX84C4V7 vary with test current, and why does it matter?

The BZX84C4V7 exhibits zener impedance of 500 Ω at 1.0 mA, 80 Ω at 5.0 mA, and 15 Ω at 20 mA - showing strong improvement with increasing bias current. This matters because lower impedance yields tighter voltage regulation under varying load conditions. For stable reference use, the BZX84C4V7 should be biased near 5–20 mA; using it below 1 mA risks excessive voltage drift and poor noise rejection in the BZX84C4V7 circuit.

Can the BZX84C4V7 be used for bidirectional ESD protection, and what limits its effectiveness?

Yes, the BZX84C4V7 can provide bidirectional ESD protection: its forward voltage is ≤0.9 V at 10 mA, and reverse breakdown is centered at 4.7 V. However, its effectiveness is limited by relatively high capacitance (260 pF) and moderate peak pulse power capability. It is suitable for IEC 61000-4-2 Level 2 (±4 kV) protection but not recommended for high-speed data lines or Level 4 (±8 kV) without series impedance. The BZX84C4V7 remains effective only when paired with appropriate current-limiting resistors in the BZX84C4V7 protection network.

Is the BZX84C4V7 RoHS compliant and halogen-free?

Yes, the BZX84C4V7 is RoHS compliant and halogen-free per ON Semiconductor's product change notices and material declarations. The device meets EU Directive 2011/65/EU and contains ≤900 ppm bromine and ≤900 ppm chlorine in homogeneous materials. This compliance is verified through standardized testing and applies to all currently shipped lots of the BZX84C4V7, supporting environmentally regulated industrial and medical end equipment.