Nexperia USA Inc. BZX79-B51,133

Overview

BZX79-B51,133 from Nexperia is a ±2% tolerance Zener voltage regulator diode with nominal 51 V working voltage at 2 mA test current, 90 Ω typical differential resistance, and −38.6 mV/K temperature coefficient. It operates in low-power stabilization circuits requiring precise reference voltage under ambient temperatures up to +200 °C and handles non-repetitive 40 W peak reverse power surges (100 μs). Used in industrial power supply feedback loops and analog sensor biasing.

For engineers reviewing the BZX79-B51,133 datasheet, BZX79-B51,133 pinout, BZX79-B51,133 application, or BZX79-B51,133 equivalent, this page delivers verified electrical parameters, thermal behavior, package geometry, real-world use cases, and validated alternative parts - all grounded in Nexperia's official 2002 product data sheet.

Technical Context

This Zener diode functions as a two-terminal shunt voltage reference, maintaining stable output by conducting reverse current above its specified breakdown voltage. Its 51 V nominal Zener voltage is defined at I_Ztest = 2 mA, with differential resistance of 90 Ω (typ.) ensuring minimal voltage shift under load variation.

Thermal performance is governed by junction-to-ambient thermal resistance of 380 K/W (lead length ≤8 mm, no PCB metallization), limiting continuous power dissipation to 400 mW at T_amb = 50 °C. Non-repetitive surge capability reaches 40 W for 100 μs pulses, enabling transient overvoltage clamping in low-energy protection circuits.

Key Specifications

Pinout & Package

Hermetically sealed axial-leaded SOD27 (DO-35) glass package with cathode indicated by a black band. Leads are tinned copper-clad steel; 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 BZX79-B51,133, the 1N4733A offers greater power handling but sacrifices precision and thermal compactness, while the BZX85C51 trades tighter thermal resistance for reduced voltage stability - making the BZX79-B51,133 optimal for space-constrained, accuracy-critical 500 mW reference designs.

Availability

BZX79-B51,133 is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor interfaces, programmable logic controller input stages, and portable test equipment requiring stable component supply and long-lifecycle support.

Supply support for BZX79-B51,133 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 and industrial markets.

The BZX79 series belongs to Nexperia's legacy Zener diode portfolio, engineered specifically for low-power voltage regulation and reference applications where precision, thermal stability, and hermetic reliability are critical.

FAQ

What is the maximum continuous power dissipation for BZX79-B51,133 at 70 °C ambient?

At 70 °C ambient, continuous power dissipation must be derated linearly from 500 mW at 50 °C using R_{th j-a} = 380 K/W. The junction temperature limit is +200 °C, so maximum allowable P_tot = (200 − 70) / 380 ≈ 342 mW. Operation above this risks thermal runaway.

Can BZX79-B51,133 replace BZX79-C51 in existing designs?

No - BZX79-C51 has ±5% tolerance (48–54 V range) versus BZX79-B51,133's ±2% (50–52 V). Substituting introduces up to ±3% reference error, potentially violating regulation specs in feedback loops or calibration circuits requiring tight voltage accuracy.

Is the cathode marked on the BZX79-B51,133 package?

Yes - the cathode is identified by a single black band on the glass body of the SOD27 (DO-35) package. This marking aligns with JEDEC DO-35 standards and is visible under standard visual inspection during manual or automated assembly.

What is the typical Zener impedance at 10 mA for BZX79-B51,133?

The datasheet specifies differential resistance only at I_Ztest = 2 mA (90 Ω typ., 400 Ω max). At 10 mA, impedance drops further - extrapolating from Fig.5/Fig.6 trends and comparable BZX79-B parts, typical r_dif is ~65 Ω, but this is not guaranteed and requires characterization in-circuit.