Nexperia USA Inc. BZX84W-B68X

Overview

BZX84W-B68X from Nexperia is a ±2% tolerance Zener voltage regulator diode in SOT323 (SC-70) package, rated for 68 V nominal Zener voltage at 2 mA, 240 Ω differential resistance, and 71.7 mV/K temperature coefficient - used for precision voltage reference and overvoltage protection in low-power analog sensor interfaces and power supply feedback loops.

For engineers reviewing the BZX84W-B68X datasheet, BZX84W-B68X pinout, BZX84W-B68X application, or BZX84W-B68X equivalent, this page delivers verified Zener parameters, thermal derating guidance, SOT323 terminal mapping, and direct substitution options with documented tolerance and temperature coefficient differences.

Technical Context

This device operates as a two-terminal reverse-biased voltage reference, maintaining stable 68 V regulation across 0.5–2 mA test currents with specified 240 Ω dynamic impedance. Its negative-to-positive temperature coefficient transition occurs near 6.2 V; at 68 V, it exhibits +71.7 mV/K drift, requiring thermal compensation in high-stability references.

Designed for surface-mount use on FR4 PCBs with single-sided copper, it sustains 275 mW total power dissipation at 25 °C ambient and withstands non-repetitive 40 W surge pulses (100 µs), enabling transient clamping in low-energy signal lines without external series limiting resistors.

Key Specifications

Pinout & Package

SOT323 (SC-70) plastic surface-mounted package with 3 leads; leadless construction optimized for automated reflow assembly and 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-B68X, BZX84W-C68 trades tighter tolerance for lower unit cost but increases reference uncertainty by 2.5×; MMBZ5263B offers slightly better dynamic impedance but sacrifices 16 % power capability and requires SOT23 layout revision.

Availability

BZX84W-B68X is available at Aetrix Electronics and suitable for industrial sensor conditioning, USB-C power delivery feedback, programmable logic controller input protection, and automotive body control module reference applications requiring stable component supply with full traceability and lifecycle support.

Supply support for BZX84W-B68X 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 manufacturer headquartered in Nijmegen, Netherlands, specializing in high-volume, high-reliability discrete and logic devices for industrial, consumer, and automotive markets.

The BZX84W series belongs to Nexperia's general-purpose Zener diode product line, engineered for stable voltage regulation in space-constrained SMT applications where precision, thermal robustness, and long-term parametric stability are essential.

FAQ

What is the maximum continuous reverse current for BZX84W-B68X at 85 °C ambient?

At 85 °C ambient, the maximum continuous reverse current is 1.2 mA. This is derived from the 275 mW P_tot rating and thermal resistance of 455 K/W: junction temperature rise is 455 × 0.275 = 125 K, so T_j = 85 + 125 = 210 °C - exceeding 150 °C absolute max. Derating to 150 °C allows ΔT = 65 K, yielding P_max = 65 / 455 = 143 mW, and I_Z = 143 mW / 68 V ≈ 2.1 mA; however, Table 8 specifies 2 mA as the test condition, and Table 5 confirms 200 mA forward limit does not apply in reverse bias - thus 1.2 mA is the safe continuous value per thermal constraints.

Can BZX84W-B68X be used in place of a 68 V Zener with ±5 % tolerance?

Yes, BZX84W-B68X can replace ±5 % Zeners like BZX84W-C68 in applications requiring tighter regulation, but only if the circuit accommodates its narrower 66.6–69.4 V window. Its 240 Ω differential resistance and +71.7 mV/K temperature coefficient match the C-series exactly, so no redesign of bias networks or thermal compensation is needed - only verification that system tolerances benefit from the improved ±2 % spec.

Why is Pin 2 marked "n.c." and how should it be handled on the PCB?

Pin 2 is internally not connected and serves only as a mechanical alignment aid during SMT placement. It must remain unconnected - no solder paste, no copper trace, and no solder mask opening required. The SOT323 footprint in Figure 9 shows three separate pads; Pad 2 is intentionally isolated and may be omitted entirely in Gerber files without affecting electrical performance or reliability.

How does the +71.7 mV/K temperature coefficient impact long-term voltage reference stability?

The +71.7 mV/K coefficient means the Zener voltage increases by 71.7 mV per degree Celsius rise in junction temperature. Over a 50 °C operating range (25–75 °C), this causes a +3.585 V shift - approximately 5.3 % of 68 V. For stable references, this requires either active compensation (e.g., opposing TC resistor network) or system-level calibration; it is not suitable for uncompensated high-accuracy metrology without additional drift correction.