Nexperia USA Inc. BZX79-B20,133

Overview

BZX79-B20,133 from Nexperia is a ±2% tolerance Zener voltage regulator diode with nominal 20 V breakdown voltage at 5 mA test current, 60 Ω typical differential resistance, and −12.3 mV/K temperature coefficient. It operates as a low-power voltage reference in bias networks, feedback loops, and overvoltage clamping circuits, rated for 500 mW total power dissipation at 50 °C ambient.

For engineers reviewing the BZX79-B20,133 datasheet, BZX79-B20,133 pinout, BZX79-B20,133 application, or BZX79-B20,133 equivalent, key selection criteria include Zener voltage tolerance (±2%), thermal coefficient (−12.3 mV/K), junction-to-ambient thermal resistance (380 K/W), reverse leakage (≤1.5 μA at 14 V), and DO-35 glass package compatibility with through-hole PCB assembly.

Technical Context

This Zener diode functions via controlled reverse-biased avalanche breakdown, delivering stable DC reference voltage under regulated current conditions. Its −12.3 mV/K temperature coefficient indicates predictable negative drift across operating temperature, enabling compensation in precision analog circuits.

The device uses a hermetically sealed SOD27 (DO-35) axial glass package with cathode band marking, supporting continuous forward current up to 250 mA and non-repetitive peak reverse power of 40 W for 100 μs pulses. Junction temperature range spans −65 °C to +200 °C.

Key Specifications

Pinout & Package

Hermetically sealed axial-lead SOD27 (DO-35) glass package with cathode indicated by a colored band. Leads are tinned copper-clad steel, suitable for wave or hand soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX79-B20,133, the 1N4742A offers tighter dynamic impedance but looser voltage tolerance and larger footprint, while the BZX84-C20 enables miniaturization at the cost of reduced surge robustness and altered thermal management requirements.

Availability

BZX79-B20,133 is available at Aetrix Electronics and suitable for power supply feedback networks, microcontroller reset circuits, overvoltage clamp protection, and precision reference voltage generation requiring stable component supply across industrial, computing, and consumer electronics programs.

Supply support for BZX79-B20,133 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 semiconductors, formed in 2017 from the former NXP Standard Products division, specializing in high-volume, high-reliability components for automotive, industrial, and consumer markets.

The BZX79 series belongs to Nexperia's legacy Zener diode product line, engineered for cost-effective, stable voltage regulation in general-purpose analog circuits where ±2% tolerance and hermetic reliability are critical.

FAQ

What is the maximum continuous reverse voltage this diode can regulate?

The BZX79-B20,133 is specified for nominal 20 V Zener voltage at 5 mA test current, with guaranteed range 19.6 V to 20.4 V. It maintains regulation up to its maximum power limit: at 50 °C ambient, it sustains 20 V × 25 mA = 500 mW continuously. Exceeding this causes thermal runaway.

How does the temperature coefficient affect circuit performance?

With a −12.3 mV/K coefficient at 5 mA, the Zener voltage decreases by approximately 12.3 mV per degree Celsius rise. In a 0–70 °C operating range, this yields ~0.86 V total drift - critical for precision references but usable for compensated designs or moderate-accuracy applications.

Can this diode be used in forward conduction mode?

Yes - it supports up to 250 mA continuous forward current with 0.9 V typical forward voltage at 10 mA. However, its primary design intent is reverse-bias regulation; forward use is limited to low-voltage clamping or LED driver biasing where 0.9 V drop is acceptable.

Is the DO-35 package compatible with automated through-hole insertion?

Yes - the SOD27 (DO-35) package has standardized 25.4 mm lead spacing and 0.56 mm max lead diameter, meeting IPC-7351B requirements for axial-leaded components. Its hermetic glass body withstands standard wave solder thermal profiles without cracking or parameter shift.