Nexperia USA Inc. NZX18B,133

Overview

NZX18B,133 from Nexperia is a single Zener diode in a hermetically sealed SOD27 (SC-40) glass package, designed for precision voltage regulation at 18 V nominal Zener voltage with ±5% tolerance. It delivers 55 Ω differential resistance at I_Z = 5 mA, supports up to 250 mA forward current, and maintains ≤0.05 µA reverse leakage at rated voltage - deployed in low-power reference and overvoltage clamp circuits within industrial sensor signal conditioning modules.

For engineers reviewing the NZX18B,133 datasheet, NZX18B,133 pinout, NZX18B,133 application, or NZX18B,133 equivalent, this device is selected for stable 18 V regulation under low-current bias (5 mA), where low thermal resistance (R_th(j-a) = 380 K/W), axial-leaded mechanical robustness, and tight V_Z tolerance are critical for analog front-end protection and calibration-critical power rails.

Technical Context

This Zener operates in reverse breakdown mode with a specified working voltage of 17.5 V to 18.3 V at I_Z = 5 mA, exhibiting a temperature coefficient near zero at that bias point per typical curves. Its hermetic glass package ensures long-term stability and minimal parameter drift across −55 °C to +175 °C ambient range.

The device follows IEC 60134 absolute maximum rating conventions: P_tot ≤ 500 mW at T_tp ≤ 25 °C, junction temperature limited to 175 °C, and thermal resistance from junction to ambient measured at 380 K/W on FR4 PCB without copper pour - defining its safe operating area under pulsed and DC conditions.

Key Specifications

Pinout & Package

Package: SOD27 (SC-40), hermetically sealed axial-leaded glass package with 25.4 mm minimum lead length and 4.25 mm max body diameter; cathode identified by black band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX55-C18 and 1N4746A, NZX18B,133 offers superior long-term V_Z stability via hermetic sealing and lower leakage for precision references, while occupying minimal board area - making it optimal for space-constrained, high-reliability analog subsystems.

Availability

NZX18B,133 is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, microcontroller reset protection, low-power analog reference sources, and LED driver current sense clamps requiring stable component supply and traceable sourcing.

Supply support for NZX18B,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 semiconductor expert delivering high-performance logic, discrete, and MOSFET devices with focus on reliability, efficiency, and miniaturization for industrial, automotive, and consumer markets.

NZX series Zeners are part of Nexperia's general-purpose discrete portfolio, engineered for stable voltage reference and overvoltage protection in cost-sensitive, high-volume applications demanding hermetic reliability and tight parametric control.

FAQ

What is the maximum continuous Zener current for NZX18B,133 at 25 °C ambient?

The device supports up to 27.8 mA continuous Zener current at 25 °C ambient, calculated from P_tot = 500 mW and V_Z ≈ 18 V (500 mW ÷ 18 V). Derating is required above 25 °C per the 380 K/W thermal resistance; at 70 °C ambient, max I_Z drops to ~18.5 mA to maintain T_j ≤ 175 °C.

How does the cathode marking appear on the NZX18B,133 package?

The cathode is marked by a distinct black band located near one end of the SOD27 glass body. This band aligns with Pin 1 in the standardized pinning diagram and must be oriented toward the more positive node in reverse-bias configuration to enable Zener conduction.

Can NZX18B,133 be used in place of a 1N4746A in existing designs?

No - although both regulate near 18 V, NZX18B,133 has lower power rating (500 mW vs. 1 W), smaller SOD27 package (vs. DO-41), and significantly lower leakage (<0.05 µA vs. ≤5 µA). Substitution requires verifying thermal margin, board layout compatibility, and whether low-leakage performance is essential for circuit accuracy.

What is the temperature coefficient behavior of NZX18B,133 around its nominal Zener voltage?

At I_Z = 5 mA, NZX18B,133 exhibits near-zero temperature coefficient (≈0 mV/K), as confirmed by Figure 4 in the datasheet for the 18 V variant. This minimizes V_Z drift over −55 °C to +150 °C, making it suitable for applications where reference stability across wide temperature ranges is mandatory.