onsemi BZX84C68LT1

Overview

BZX84C68LT1 from onsemi is a 68 V, ±5% tolerance Zener diode in SOT-23 package, rated for 225 mW power dissipation at 25°C on FR-5 board, with 240 Ω dynamic impedance at 5 mA test current and 130 µA reverse leakage at 54.4 V. It provides precise voltage regulation in space-constrained portable electronics.

For engineers reviewing the BZX84C68LT1 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal derating behavior, ESD robustness (Class 3, >16 kV HBM), and direct alternative part comparisons for reliable overvoltage protection and reference design.

Technical Context

The BZX84C68LT1 operates as a two-terminal voltage reference device with cathode-anode polarity, where reverse breakdown occurs at nominal 68 V with ±5% tolerance. Its Zener impedance of 240 Ω at 5 mA and temperature coefficient of +47.6 mV/°C indicate stable regulation above 6.2 V, requiring thermal derating beyond 25°C per 1.8 mW/°C on FR-5 substrate.

It features no internal connection on pin 2, making it a true 2-pin active device in a 3-lead SOT-23 package. The device exhibits 35 pF capacitance at 0 V bias and 1 MHz, low forward voltage (≤0.90 V at 10 mA), and Class 3 ESD rating-critical for handheld and battery-powered systems exposed to human handling.

Key Specifications

Pinout & Package

SOT-23 surface-mount plastic package (Case 318, Style 8), void-free thermosetting material, UL 94 V-0 flammability rating, 260°C max soldering temperature for 10 seconds. Cathode identified by band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5267BLT1, BZX84C68LT1 offers 12.5% higher power margin and 20% lower Zener impedance-critical for industrial power rail stabilization. Versus BZX84C68ET1G, it provides identical regulation performance at lower cost and shorter lead time, though without AEC-Q200 qualification.

Availability

BZX84C68LT1 is available at Aetrix Electronics and suitable for USB protection, battery monitoring, industrial sensor conditioning, and IoT node clamping requiring stable component supply across high-mix production runs.

Supply support for BZX84C68LT1 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 delivering energy-efficient silicon solutions for automotive, industrial, cloud, medical, and edge applications.

The BZX84C68LT1 belongs to the BZX84CxxxLT1 series of standard-tolerance Zener diodes designed specifically for space-constrained, cost-sensitive voltage regulation in portable and high-density electronics.

FAQ

What is the maximum reverse voltage the BZX84C68LT1 can safely clamp without damage?

The BZX84C68LT1 is rated for a maximum reverse voltage of 72 V at 5 mA test current, with guaranteed operation within 64–72 V. Exceeding 72 V risks irreversible breakdown. Its absolute maximum junction temperature is +150°C, and thermal derating begins at 1.8 mW/°C above 25°C on FR-5 board-so sustained clamping above 68 V requires careful power budgeting. Always verify worst-case transient energy against the 225 mW rating in your BZX84C68LT1 application.

Does the BZX84C68LT1 have a built-in capacitor or require external filtering?

No, the BZX84C68LT1 is a discrete Zener diode with no integrated capacitor. It exhibits 35 pF junction capacitance at 0 V bias and 1 MHz, which is inherent to its PN junction-not a designed filter element. For noise-sensitive applications like ADC references, designers must add external RC filtering; the BZX84C68LT1 itself provides only DC voltage regulation and transient clamping. Its capacitance value is fixed and cannot be adjusted.

Can the BZX84C68LT1 replace a 62 V Zener in an existing circuit?

No-the BZX84C68LT1 has a nominal 68 V Zener voltage (64–72 V range), while a 62 V Zener operates at 58–66 V. Substituting BZX84C68LT1 would raise the clamping threshold by ~6 V, potentially allowing damaging overvoltage to reach downstream components. Always match nominal Zener voltage and tolerance band. If upgrading protection level is intended, recalculate power dissipation, thermal margins, and system response time for the new 68 V threshold in your BZX84C68LT1 implementation.

Is pin 2 of the BZX84C68LT1 electrically connected internally?

No, pin 2 of the BZX84C68LT1 is explicitly designated "No Connection" in the official datasheet and package drawing. It is not bonded to any die structure and must remain unconnected on the PCB. Routing traces or placing solder paste on pin 2 violates the mechanical and electrical specification and may cause assembly defects or latent reliability issues. Only pins 1 (anode) and 3 (cathode) are functional terminals in the BZX84C68LT1 device.

How does the +47.6 mV/°C temperature coefficient affect BZX84C68LT1 performance in automotive environments?

The +47.6 mV/°C temperature coefficient means the BZX84C68LT1's Zener voltage increases by approximately 47.6 mV per degree Celsius rise in junction temperature. Over a −40°C to +125°C automotive ambient range, this causes a total shift of ~7.8 V-shifting the regulation point from ~65.2 V to ~73.0 V. System designers must account for this drift in overvoltage thresholds; for tighter stability, consider temperature-compensated references or feedback compensation. This coefficient is confirmed in the BZX84C68LT1 datasheet's Figure 1 and Electrical Characteristics table.