onsemi BZX79C4V3-T50A

Overview

BZX79C4V3-T50A from ON Semiconductor is a 4.3 V, 5% tolerance Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 90 Ω dynamic impedance at 5 mA test current and ±3.5 mV/°C temperature coefficient - used for precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the BZX79C4V3-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal coefficient, leakage current at rated VR (10 μA max at 1 V), junction capacitance (160 pF at 0 V, 1 MHz), and DO-35 mechanical compatibility in space-constrained PCB layouts.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain stable voltage regulation across varying load and temperature conditions. Its -3.5 mV/°C temperature coefficient indicates predictable negative drift, enabling compensation in reference designs where thermal stability is critical.

The device exhibits 10 μA maximum leakage current at 1 V reverse bias and 90 Ω dynamic impedance measured at 5 mA zener test current - parameters directly defining regulation accuracy and noise rejection in feedback networks and clamp circuits.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; two-terminal device requiring no orientation-specific PCB footprint beyond standard axial lead spacing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4733A and BZX55C4V3, the BZX79C4V3-T50A offers tighter leakage control and superior thermal coefficient for precision analog references, though all three share DO-35 mounting and basic shunt regulation function.

Availability

BZX79C4V3-T50A is available at Aetrix Electronics and suitable for low-power voltage reference, I/O protection, and analog sensor conditioning requiring stable component supply across automotive infotainment, industrial PLC modules, and medical wearable devices.

Supply support for BZX79C4V3-T50A 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 communications markets.

The BZX79C series is designed for general-purpose voltage regulation and transient suppression in cost-sensitive, space-constrained applications using standard DO-35 packaging.

FAQ

What is the nominal Zener voltage of the BZX79C4V3-T50A?

The BZX79C4V3-T50A has a nominal Zener voltage of 4.3 V, with a guaranteed range of 4.0 V to 4.6 V at 5 mA test current and 25°C ambient. This tolerance band supports reliable operation in circuits where ±5% regulation accuracy is acceptable, such as non-critical biasing or clamping functions. The BZX79C4V3-T50A achieves this specification using silicon process controls defined in ON Semiconductor's BZX79C family datasheet Rev. 3.

What is the maximum power dissipation for the BZX79C4V3-T50A?

The BZX79C4V3-T50A is rated for 500 mW maximum power dissipation at lead temperature (T_L) ≤ 75°C with 3/8″ lead length. Above 75°C, it derates linearly at 4.0 mW/°C. This thermal limit ensures safe operation in enclosed enclosures or high-ambient environments when mounted with specified lead length. The BZX79C4V3-T50A must be derated accordingly in applications exceeding 75°C ambient to avoid junction overheating.

Does the BZX79C4V3-T50A have a specified temperature coefficient?

Yes, the BZX79C4V3-T50A has a temperature coefficient of -3.5 mV/°C, indicating its Zener voltage decreases predictably with rising temperature. This value is measured under controlled thermal equilibrium conditions and enables accurate drift modeling in reference circuits. The BZX79C4V3-T50A's negative TC contrasts with higher-voltage Zeners that exhibit positive coefficients, making it suitable for compensation schemes in mixed-TC reference designs.

What is the dynamic impedance of the BZX79C4V3-T50A at its test current?

The BZX79C4V3-T50A exhibits a maximum dynamic impedance (Z_Z) of 90 Ω at I_Z = 5 mA and 25°C. This parameter reflects how tightly the device maintains its Zener voltage under small-signal AC variations or load transients. Lower Z_Z values improve regulation performance, and the BZX79C4V3-T50A's 90 Ω rating supports stable reference behavior in feedback paths where load current may vary by ±1 mA.

Is the BZX79C4V3-T50A packaged in a DO-35 case?

Yes, the BZX79C4V3-T50A uses a DO-35 glass axial package with cathode identified by a color band. This hermetically sealed package provides long-term parameter stability and moisture resistance, supporting reliability in industrial and automotive environments. The DO-35 form factor allows manual or automated insertion into standard 0.4″ pitch through-hole footprints, and the BZX79C4V3-T50A shares mechanical compatibility with other BZX79C-series diodes.