Nexperia USA Inc. BZX84W-B27X

Overview

BZX84W-B27X from Nexperia is a ±2% tolerance Zener voltage regulator diode in SOT323 (SC-70) package, rated for 27 V nominal Zener voltage at 2 mA test current, 275 mW total power dissipation, and 150 °C maximum junction temperature. It serves as a precision reference or overvoltage clamp in low-power analog signal conditioning and power rail stabilization circuits.

For engineers reviewing the BZX84W-B27X datasheet, BZX84W-B27X pinout, BZX84W-B27X application, or BZX84W-B27X equivalent, key selection criteria include Zener voltage tolerance (±2%), differential resistance (300 Ω at I_Z = 0.5 mA), temperature coefficient (+23.4 mV/K), reverse leakage (50 nA at 0.7 × V_Znom), and thermal resistance (455 K/W).

Technical Context

This Zener diode operates in reverse breakdown to maintain stable voltage across its cathode-anode terminals under controlled current conditions. Its ±2% tolerance ensures tight regulation accuracy for reference applications, while the 300 Ω differential resistance at low bias reflects moderate dynamic impedance suitable for non-critical feedback paths.

The device exhibits a positive temperature coefficient of +23.4 mV/K at I_Z = 2 mA, indicating increasing Zener voltage with rising junction temperature - a critical factor in thermally sensitive designs. Its 455 K/W junction-to-ambient thermal resistance requires careful PCB copper layout to avoid derating above 25 °C ambient.

Key Specifications

Pinout & Package

SOT323 (SC-70) leadless surface-mount plastic package with 3 terminals; compact footprint (2.2 mm × 1.35 mm × 0.95 mm) optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84W-B27X, BZX84W-C27 trades regulation accuracy for lower unit cost in non-critical clamping, while MMSZ5254B offers higher power handling at the expense of board space and tighter thermal management requirements.

Availability

BZX84W-B27X is available at Aetrix Electronics and suitable for power rail clamping, ADC reference stabilization, and low-power sensor biasing requiring stable component supply, consistent parametric performance, and long-term obsolescence mitigation.

Supply support for BZX84W-B27X 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, headquartered in Nijmegen, Netherlands.

The BZX84W series belongs to Nexperia's general-purpose Zener diode product line, engineered for stable voltage regulation and overvoltage protection in consumer, industrial, and communication equipment with emphasis on SMT manufacturability and thermal robustness.

FAQ

What is the maximum continuous reverse current for reliable Zener operation?

The BZX84W-B27X is rated for 200 mA maximum forward current, but Zener operation uses reverse bias. At 27 V, continuous reverse current must be limited to ≤10.2 mA to stay within the 275 mW power limit (P = V × I). Derating is required above 25 °C ambient due to 455 K/W thermal resistance.

Does Pin 2 require PCB connection or grounding?

No - Pin 2 is explicitly marked "n.c." (not connected) in the official Nexperia datasheet and internal die construction. It must remain electrically floating; no PCB trace, pad, or solder mask opening should be assigned to this terminal to avoid mechanical stress or unintended coupling.

How does the +23.4 mV/K temperature coefficient affect circuit stability?

This positive coefficient means V_Z increases by 23.4 mV per °C rise in junction temperature. In a 50 °C ambient-to-junction rise, V_Z shifts +1.17 V - a 4.3% change. Stable operation requires either thermal isolation, active compensation, or design margin to accommodate this drift in precision references.

Can BZX84W-B27X replace BZX84C27 in existing designs?

Yes, with functional verification: both share identical SOT323 package, pinout, and 27 V nominal rating, but BZX84W-B27X has ±2% tolerance versus ±5% for the 'C' variant. Substitution improves regulation accuracy but may alter bias point in resistor-limited circuits - verify current compliance and thermal margin under worst-case V_Z extremes.