Nexperia USA Inc. BZX84W-C51X

Overview

BZX84W-C51X from Nexperia is a ±5% tolerance Zener voltage regulator diode in SOT323 (SC-70) package, rated for 51 V nominal Zener voltage at 2 mA test current, 400 Ω typical differential resistance, and 51.0 mV/K temperature coefficient - used for precision voltage reference and overvoltage clamping in power supply feedback loops and sensor signal conditioning circuits.

For engineers reviewing the BZX84W-C51X datasheet, BZX84W-C51X pinout, BZX84W-C51X application, or BZX84W-C51X equivalent, this page delivers verified Zener parameters, thermal derating guidance, SOT323 terminal mapping, and direct alternatives for 51 V regulation with ±5% tolerance in high-frequency, space-constrained designs.

Technical Context

This Zener diode operates in reverse breakdown mode with a specified 51 V nominal working voltage at I_Z = 2 mA, exhibiting a positive temperature coefficient of +51.0 mV/K - indicating increasing Zener voltage with junction temperature rise. Its 400 Ω differential resistance at 2 mA defines output impedance under dynamic load conditions.

Designed for surface-mount use on FR4 PCBs with single-sided copper, it supports 275 mW total power dissipation at 25 °C ambient and withstands non-repetitive peak reverse power up to 40 W for 100 µs pulses - enabling transient suppression in low-energy surge scenarios.

Key Specifications

Pinout & Package

SOT323 (SC-70) leadless plastic surface-mount package with 3 terminals; compact 2.2 mm × 1.35 mm footprint and 0.65 mm pitch; optimized for reflow soldering using standard land pattern (2.65 mm × 2.35 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5259BLT1G and BZX84-C51-TP, BZX84W-C51X offers identical Zener voltage and differential resistance in a 25% smaller SOT323 package with lower thermal resistance (455 K/W vs. ~500 K/W typical for SOT23), improving power density and thermal margin in space-constrained designs.

Availability

BZX84W-C51X is available at Aetrix Electronics and suitable for power supply feedback reference, overvoltage clamp protection, and sensor signal conditioning requiring stable component supply and consistent ±5% Zener tolerance across production lots.

Supply support for BZX84W-C51X 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 semiconductor expert focused on high-volume, high-reliability discrete and logic devices, serving automotive, industrial, and consumer markets with ISO/TS 16949-certified manufacturing.

The BZX84W series belongs to Nexperia's general-purpose Zener diode product line, engineered for compact, high-frequency voltage regulation and clamping in space-constrained SMD applications - emphasizing low capacitance, tight tolerance options, and robust surge capability.

FAQ

What is the maximum continuous reverse current the BZX84W-C51X can handle at 51 V?

The BZX84W-C51X is not rated for continuous reverse current at its Zener voltage. Its maximum continuous power dissipation is 275 mW at 25 °C ambient, limiting sustained reverse current to approximately 5.4 mA (275 mW ÷ 51 V). Exceeding this requires thermal derating per the 455 K/W R_th(j-a) value.

Can BZX84W-C51X be used in place of a BZX84-C51 in an existing design?

Yes, BZX84W-C51X replaces BZX84-C51 with identical electrical specifications (51 V, ±5%, 400 Ω r_dif) but in the smaller SOT323 package instead of SOT23. PCB footprint and stencil must be updated to match the 2.2 mm × 1.35 mm outline and 0.65 mm pitch - no circuit changes are needed.

Does the "n.c." pin on BZX84W-C51X require grounding or routing?

No - Pin 2 is internally not connected and must remain unconnected on the PCB. Routing a trace to it introduces unnecessary parasitic capacitance and mechanical stress risk. The SOT323 footprint should omit any pad or solder mask opening for Pin 2 per Nexperia's recommended land pattern.

How does temperature affect the 51 V Zener voltage in practical operation?

With a +51.0 mV/K temperature coefficient, the Zener voltage increases by approximately 51 mV per °C rise in junction temperature. At 100 °C junction temperature (75 °C above 25 °C ambient), V_Z rises by ~3.8 V - reaching ~54.8 V. This must be accounted for in overvoltage protection margins and reference stability budgets.