Nexperia USA Inc. BZX79-C39,133

Overview

BZX79-C39,133 from Nexperia is a ±5% tolerance Zener voltage regulator diode with nominal working voltage 39 V at 2 mA test current, 80 Ω typical differential resistance, and −28.7 to −41.2 mV/K temperature coefficient. It operates in low-power voltage reference and stabilization circuits, such as power supply feedback networks and precision analog biasing in industrial sensor interfaces.

For engineers reviewing the BZX79-C39,133 datasheet, BZX79-C39,133 pinout, BZX79-C39,133 application, or BZX79-C39,133 equivalent, key selection criteria include Zener voltage tolerance, thermal coefficient sign/magnitude, non-repetitive surge capability (0.7 A peak reverse current), and DO-35 package compatibility with through-hole PCB layouts requiring stable low-current regulation.

Technical Context

This device functions as a passive two-terminal voltage reference, relying on controlled reverse breakdown in silicon PN junction. Its Zener voltage is specified at I_Ztest = 2 mA per Table 2, with differential resistance measured under same condition, enabling predictable dynamic impedance in shunt regulation loops.

The negative temperature coefficient (−28.7 to −41.2 mV/K) indicates decreasing breakdown voltage with rising junction temperature - critical for thermal drift analysis in unregulated environments. Device operation assumes T_j = 25 °C unless otherwise stated, and maximum non-repetitive peak reverse current is validated at t_p = 100 μs square wave.

Key Specifications

Pinout & Package

Hermetically sealed glass axial-leaded SOD27 (DO-35) package with cathode indicated by a colored band. Leads are tinned copper alloy; body diameter 1.85 mm, length 4.25 mm, lead spacing 25.4 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4739A and BZX84-C39, BZX79-C39,133 offers optimal balance of through-hole manufacturability, 500 mW power handling, and DO-35 reliability - making it preferred for industrial control modules requiring field-serviceable components and moderate thermal loads.

Availability

BZX79-C39,133 is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor interfaces, consumer audio DC-DC converters, and medical instrumentation requiring stable component supply with long-lifecycle support.

Supply support for BZX79-C39,133 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

Nexperia is a global leader in discrete, logic, and PowerMOS semiconductors, spun off from NXP in 2017 and focused on automotive, industrial, computing, and consumer markets.

The BZX79 series belongs to Nexperia's standard Zener diode product line, designed specifically for low-power voltage regulation and reference applications where reliability, consistency, and through-hole assembly compatibility are essential.

FAQ

What is the maximum continuous power dissipation for BZX79-C39,133 at 50 °C ambient?

The maximum continuous total power dissipation is 500 mW when mounted on a PCB with 8 mm lead length and ambient temperature maintained at 50 °C. This value drops to 400 mW under less favorable thermal conditions (no metallization pad, same lead length), per the Absolute Maximum Ratings table.

How does the temperature coefficient affect regulation accuracy over temperature?

The temperature coefficient ranges from −28.7 to −41.2 mV/K at I_Z = 2 mA, meaning the Zener voltage decreases by approximately 35 mV per Kelvin rise in junction temperature. Over a 100 K range (−40 °C to +60 °C), this results in ~3.5 V drift - critical for applications requiring <1% regulation stability.

Can BZX79-C39,133 be used in place of BZX79-B39 for tighter voltage tolerance?

No - BZX79-C39,133 has ±5% tolerance (37.0–41.0 V), whereas BZX79-B39 offers ±2% (38.2–39.8 V). Substituting introduces up to 2.0 V additional uncertainty in regulation point, which may violate system-level voltage margin requirements in precision references.

What is the cathode identification method on the DO-35 package?

The cathode is marked by a distinct colored band (typically black or dark gray) located near one end of the glass body. When oriented with the banded end to the left, the left lead is cathode and the right lead is anode - consistent with standard diode polarity marking conventions per SOD27 outline drawing.