Nexperia USA Inc. BZX38450-B3V9-QX

Overview

BZX38450-B3V9-QX from Nexperia is a low-current Zener voltage regulator diode in SOD323 (SC-76) package, rated for 3.9 V nominal regulation at 50 µA test current, with ±2 % tolerance, 300 mW total power dissipation, and AEC-Q101 qualification for automotive use.

For engineers reviewing the BZX38450-B3V9-QX datasheet, BZX38450-B3V9-QX pinout, BZX38450-B3V9-QX application, or BZX38450-B3V9-QX equivalent, key selection criteria include low-bias operation at 50 µA, thermal resistance of 415 K/W (junction-to-ambient), cathode-anode polarity marking, and automotive-grade reliability per AEC-Q101.

Technical Context

This device operates as a precision shunt voltage reference, maintaining stable 3.9 V regulation under reverse bias with differential resistance ≤600 Ω at I_Z = 50 µA and ≤95 Ω at I_Z = 5 mA. Its temperature coefficient is −2.7 mV/K, minimizing drift across operating temperatures.

Designed for low-power systems, it features intentional leakage optimization for fast switching and noise reduction (per AN90031), and supports operation from −55 °C to +150 °C ambient with junction temperature up to 150 °C.

Key Specifications

Pinout & Package

Package: SOD323 (SC-76), surface-mount plastic package, 1.7 mm × 1.25 mm × 0.95 mm body, 1.3 mm lead pitch, cathode marked by bar on top surface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX38450-B3V9-QX, the BZX384-C3V9-Q trades voltage accuracy for lower cost and enhanced switching performance, while MMSZ4685T1G offers higher power handling but no automotive qualification or SOD323 size advantage.

Availability

BZX38450-B3V9-QX is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, and portable medical diagnostics requiring stable component supply with guaranteed AEC-Q101 compliance and traceable sourcing.

Supply support for BZX38450-B3V9-QX 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 essential efficiency technologies, delivering high-performance, reliable discrete and logic devices for automotive, industrial, and consumer markets.

BZX38450-Q series belongs to Nexperia's automotive-qualified Zener diode product line, engineered specifically for low-current, high-stability voltage regulation in harsh-environment electronic control units and sensor subsystems.

FAQ

What is the maximum reverse voltage this diode can withstand continuously?

The BZX38450-B3V9-QX has a nominal Zener voltage of 3.9 V and is not rated for continuous reverse voltage beyond its specified breakdown range. Its absolute maximum reverse voltage is defined by the non-repetitive peak reverse power dissipation limit of 40 W at 100 µs pulse width, not steady-state operation. Continuous reverse bias must be limited to the 3.9 V regulation band under controlled current conditions.

Does this part support reflow soldering, and what footprint should be used?

Yes, BZX38450-B3V9-QX is qualified for reflow soldering using the SOD323 footprint shown in Figure 10 of the datasheet: 0.5 mm wide solder lands (2×), 0.6 mm solder resist opening (2×), and 1.35 mm center-to-center pad spacing. The recommended stencil aperture matches the land pattern to ensure reliable joint formation without bridging.

How does the −2.7 mV/K temperature coefficient affect circuit performance?

A −2.7 mV/K temperature coefficient means the Zener voltage decreases by 2.7 mV per degree Celsius rise in junction temperature. Over a −40 °C to +125 °C range, this results in approximately ±45 mV drift from nominal 3.9 V - critical for high-accuracy references but acceptable for general-purpose biasing where ±1.2 % variation is tolerable.

Is the cathode marking visible on the physical device, and how is it oriented?

Yes, the cathode is marked by a distinct bar on the top surface of the SOD323 package. When viewed with the marking bar on the left, Pin 1 (cathode) is the left terminal and Pin 2 (anode) is the right terminal - matching the simplified outline in Table 2 of the datasheet and ensuring correct polarity during automated placement.