onsemi BZX84C75LT3G

Overview

BZX84C75LT3G from onsemi is a 75 V, ±5% tolerance Zener diode in SOT-23 package, rated for 250 mW power dissipation at 25°C on FR-5 board, with 500 Ω maximum Zener impedance at 5 mA test current and 140 µA max reverse leakage at 60 V. It provides precise voltage regulation in space-constrained power rail protection circuits.

For engineers reviewing the BZX84C75LT3G datasheet, pinout, applications, or equivalent options, key selection criteria include nominal Zener voltage (75 V), tight thermal coefficient (±52.5 mV/°C), low capacitance (35 pF @ 0 V), ESD robustness (>16 kV HBM), and SOT-23 compatibility with automated assembly.

Technical Context

This device operates as a two-terminal voltage reference using avalanche breakdown at 75 V nominal, with specified test conditions at IZT = 5 mA (IZT1), IZT = 1 mA (IZT2), and IZT = 20 mA (IZT3). Its temperature coefficient of +52.5 mV/°C indicates positive drift above 6 V, consistent with high-voltage Zener behavior.

The SOT-23 package features pin 1 (anode), pin 2 (no connection), and pin 3 (cathode), with cathode polarity marked by a band. Thermal resistance is 500 °C/W junction-to-ambient on FR-5 board, derating linearly at 2.0 mW/°C above 25°C.

Key Specifications

Pinout & Package

SOT-23 (TO-236) surface-mount plastic package, 2.90 × 1.30 × 1.00 mm, void-free thermosetting case with corrosion-resistant finish, UL 94 V-0 flammability rating, and cathode polarity indicated by band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84C75LT3G, BZX84C75LT1G offers identical performance in a smaller reel format ideal for development, while MMBZ5267BLT1 delivers enhanced regulation stability and power capability at the cost of slightly larger thermal footprint and different manufacturer sourcing.

Availability

BZX84C75LT3G is available at Aetrix Electronics and suitable for battery management systems, industrial sensor interfaces, and RS-485 node protection requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for BZX84C75LT3G 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 (Semiconductor Components Industries, LLC) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BZX84CxxxLTxG series targets cost-optimized, space-constrained voltage regulation in portable and high-density electronics, emphasizing manufacturability, ESD resilience, and broad Zener voltage coverage from 2.4 V to 75 V.

FAQ

What is the maximum power dissipation of the BZX84C75LT3G at 70°C ambient temperature?

The BZX84C75LT3G has a 250 mW power rating at 25°C on FR-5 board, derating linearly at 2.0 mW/°C above that temperature. At 70°C ambient, derating is (70 − 25) × 2.0 = 90 mW, so maximum allowable dissipation is 250 − 90 = 160 mW. This ensures safe operation without exceeding junction temperature limits in typical industrial environments.

Does the BZX84C75LT3G have a connected pin 2, and what happens if it is soldered to PCB?

No, pin 2 of the BZX84C75LT3G is internally unconnected (NC) - it has no bond wire or die attachment. If inadvertently soldered to a trace or pad, it introduces no electrical function but risks mechanical stress or solder bridging. The official marking diagram and mechanical outline (Style 8) confirm pin 2 is NC, and PCB layout must leave it floating per onsemi's design guidance.

How does the temperature coefficient of +52.5 mV/°C affect regulation accuracy of the BZX84C75LT3G across −40°C to +85°C?

Over a 125°C span (−40°C to +85°C), the BZX84C75LT3G's +52.5 mV/°C coefficient causes ~6.56 V total drift (125 × 0.0525). With a nominal 75 V Zener voltage, this yields ±4.4% variation - acceptable for clamping but insufficient for precision references. Designers must account for this drift in overvoltage trip margins or pair with compensation circuits where tight regulation is critical.

Can the BZX84C75LT3G replace the BZX84C75LT1G in an existing design without layout changes?

Yes, the BZX84C75LT3G and BZX84C75LT1G share identical SOT-23 package dimensions, pinout (1-Anode, 2-NC, 3-Cathode), electrical specifications, and marking scheme. Only the tape-and-reel quantity differs (10,000 vs. 3,000 units), so PCB layout, solder paste stencil, and placement files require no modification when switching to BZX84C75LT3G.

What is the reverse leakage current specification for the BZX84C75LT3G at its rated Zener voltage of 75 V?

The BZX84C75LT3G is not tested for reverse leakage at 75 V - its IR specification is defined at VR = 60 V (140 µA max), per the Electrical Characteristics table. At 75 V, leakage exceeds rated limits and enters breakdown region; therefore, 60 V is the maximum recommended reverse voltage for leakage-critical biasing. Operating near or above 75 V relies on controlled Zener conduction, not leakage control.