Nexperia USA Inc. BZX79-C39,143

Overview

BZX79-C39,143 from Nexperia is a ±5% tolerance Zener voltage regulator diode with nominal 39 V breakdown voltage at 2 mA test current, 80 Ω typical differential resistance, and −2.5 mV/K temperature coefficient. It operates as a low-power voltage reference in bias networks, overvoltage clamping circuits, and analog signal conditioning stages where stable 39 V regulation is required under ≤500 mW dissipation.

For engineers reviewing the BZX79-C39,143 datasheet, BZX79-C39,143 pinout, BZX79-C39,143 application, or BZX79-C39,143 equivalent, this page delivers verified electrical parameters, thermal behavior, SOD27 package geometry, cathode-marked axial lead configuration, and direct alternatives for precision voltage reference design.

Technical Context

This Zener diode functions in reverse-biased breakdown mode, delivering stable 39 V regulation across a 0.5–2 mA operating range. Its 80 Ω typical dynamic impedance ensures minimal output voltage variation under load shifts, while its negative temperature coefficient (−2.5 mV/K) enables predictable drift compensation in multi-diode reference strings.

The device uses hermetically sealed glass SOD27 (DO-35) construction with axial leads and a cathode band marking. Thermal resistance from junction to ambient is 380 K/W (unmounted), limiting continuous power dissipation to 400 mW at 50 °C ambient per IEC 60134 absolute maximum ratings.

Key Specifications

Pinout & Package

Hermetically sealed glass SOD27 (DO-35) package with axial leads; cathode identified by a dark band on the glass body. Leads are tinned copper alloy, suitable for wave or hand soldering per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX79-C39,143, the 1N4739A offers higher power and lower impedance but requires more board area and exhibits opposite temperature drift; the BZX84-C39 matches tempco and tolerance but trades surge robustness for miniaturization.

Availability

BZX79-C39,143 is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, consumer appliance control boards, and test equipment requiring stable component supply with traceable Nexperia manufacturing lineage.

Supply support for BZX79-C39,143 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 semiconductors, formed in 2017 from the former NXP Standard Products division, specializing in high-volume, high-reliability components for automotive, industrial, and computing markets.

The BZX79 series belongs to Nexperia's legacy Zener diode portfolio designed for cost-sensitive, low-power voltage regulation and clamping in general-purpose electronics-emphasizing manufacturability, consistency, and long-term availability.

FAQ

What is the maximum continuous reverse current for reliable operation?

The BZX79-C39,143 is rated for 2 mA test current, but its absolute maximum continuous reverse current is limited by power dissipation: at 50 °C ambient, 500 mW total power allows up to ~12.8 mA (500 mW ÷ 39 V). Derating is required above 50 °C per the 380 K/W thermal resistance specification.

How does the −2.5 mV/K temperature coefficient affect circuit performance?

This negative coefficient means the Zener voltage decreases by 2.5 mV per Kelvin rise in junction temperature. In a 39 V reference, a 50 °C rise causes ~125 mV drop-critical for precision applications. Compensation techniques (e.g., series diodes with positive tempco) are used where drift must be minimized.

Can BZX79-C39,143 replace BZX79-B39 in existing designs?

Yes, but with trade-offs: the "C" version has ±5% tolerance versus ±2% for the "B" variant, resulting in wider V_Z spread (37.0–41.0 V vs. 38.2–39.8 V). Differential resistance is identical (80 Ω typ), so regulation accuracy degrades only due to initial tolerance-not dynamic behavior.

Is the SOD27 package RoHS compliant and lead-free?

Yes-Nexperia confirms the BZX79-C39,143 meets RoHS Directive 2011/65/EU and is manufactured with lead-free terminations. The glass body contains no restricted substances, and the tinned copper leads comply with JEDEC J-STD-609A Class 1 marking for lead-free finish.