onsemi SZBZX84B18LT1G

Overview

SZBZX84B18LT1G from onsemi is a tight-tolerance Zener diode in SOT-23 package, delivering 18 V nominal Zener voltage at 5 mA test current with ±2% tolerance (17.6–18.4 V), 45 Ω dynamic impedance, and 0.05 μA reverse leakage at 12.6 V. It provides precision voltage regulation for low-power biasing, reference, and overvoltage protection in space-constrained portable electronics.

For engineers reviewing the SZBZX84B18LT1G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance, thermal coefficient (12.6 mV/°C), junction-to-ambient thermal resistance (500 °C/W), and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This device operates as a two-terminal voltage reference using controlled reverse-biased avalanche breakdown. Its tight 2% V_Z tolerance and low temperature coefficient (12.6 mV/°C) enable stable regulation across −55°C to +150°C ambient range without external trimming.

The SOT-23 package features an isolated terminal 2 (no connection), enabling unambiguous anode–cathode orientation. With 250 mW power dissipation on FR-5 board and ESD rating >16 kV (HBM), it supports automated assembly and robust operation in noisy, high-density PCB environments.

Key Specifications

Pinout & Package

SOT-23 (TO-236) surface-mount package: 2.90 mm × 1.30 mm × 1.00 mm body, 1.90 mm lead pitch, Pb-free, RoHS compliant. Cathode identified by band; terminal 2 is internally unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84B18LT1G and SZBZX84C18LT1G, the SZBZX84B18LT1G uniquely combines automotive qualification, tight ±2% tolerance, and low 45 Ω impedance - making it the sole option for AEC-Q101–mandated 18 V reference designs requiring both accuracy and reliability.

Availability

SZBZX84B18LT1G is available at Aetrix Electronics and suitable for automotive sensor modules, portable power monitors, industrial I/O protection, and medical wearable references requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for SZBZX84B18LT1G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and IoT markets.

The BZX84/SZBZX84 series was designed for compact, high-reliability voltage regulation in space-constrained, high-volume applications - particularly where AEC-Q101 compliance, low leakage, and tight Zener tolerance are essential.

FAQ

What is the exact Zener voltage range for SZBZX84B18LT1G at 5 mA test current?

The SZBZX84B18LT1G has a guaranteed Zener voltage range of 17.6 V to 18.4 V at I_ZT = 5 mA and T_A = 25°C, reflecting its ±2% tight tolerance specification. This range is explicitly defined in the "ELECTRICAL CHARACTERISTICS − BZX84BxxxL (Tight Tolerance Series)" table on page 4 of the official onsemi datasheet. The SZBZX84B18LT1G maintains this tolerance across its qualified operating temperature range.

Is SZBZX84B18LT1G pin-compatible with standard BZX84C18LT1G?

Yes - the SZBZX84B18LT1G uses identical SOT-23 pinout (Pin 1: Anode, Pin 2: No Connection, Pin 3: Cathode) and mechanical dimensions as BZX84C18LT1G and all BZX84/SZBZX84 LT1G variants. However, it is not a drop-in replacement due to differences in Zener tolerance (±2% vs. ±5%), impedance (45 Ω vs. 200 Ω), and AEC-Q101 qualification status. The SZBZX84B18LT1G requires explicit validation in safety-critical systems.

Does SZBZX84B18LT1G support reflow soldering, and what is its maximum solder temperature?

Yes, the SZBZX84B18LT1G is qualified for standard Pb-free reflow soldering. Its maximum case temperature for soldering is 260°C for 10 seconds, as specified in the "Mechanical Characteristics" section of the datasheet. The device uses a corrosion-resistant, easily solderable finish and meets UL 94 V-0 flammability rating - ensuring compatibility with IPC/JEDEC J-STD-020-compliant thermal profiles.

What is the reverse leakage current specification for SZBZX84B18LT1G, and at what voltage is it measured?

The SZBZX84B18LT1G specifies a maximum reverse leakage current (I_R) of 0.05 μA, measured at a reverse voltage (V_R) of 12.6 V - which corresponds to 70% of its nominal 18 V Zener voltage. This low leakage value is confirmed in the "ELECTRICAL CHARACTERISTICS − BZX84BxxxL" table on page 4 and directly supports ultra-low-power operation in battery-backed or energy-harvesting applications.

How does the temperature coefficient of SZBZX84B18LT1G affect its regulation stability over temperature?

The SZBZX84B18LT1G has a nominal temperature coefficient of +12.6 mV/°C at I_ZT = 5 mA, meaning its Zener voltage increases by approximately 12.6 mV per degree Celsius rise in junction temperature. This predictable positive drift allows designers to implement first-order thermal compensation in precision reference circuits - a key advantage over non-specified or widely varying coefficients found in standard-tolerance Zeners like the BZX84C18LT1G.