onsemi BZX84C27ET3

Overview

BZX84C27ET3 from onsemi is a 27 V, 225 mW surface-mount Zener diode in SOT-23 package, rated for 5 mA test current with ±10% tolerance (25.1–28.9 V), 80 Ω dynamic impedance at 5 mA, and 0.05 µA reverse leakage at 20.3 V. It provides precision voltage regulation in space-constrained power supply rails and reference circuits for portable electronics.

For engineers reviewing the BZX84C27ET3 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage accuracy at 5 mA, thermal resistance (556 °C/W on FR-5 board), ESD robustness (>16 kV HBM), junction temperature range (−65 to +150 °C), and Pb-free SOT-23 compatibility with automated assembly.

Technical Context

This device operates as a two-terminal voltage reference diode, conducting in reverse breakdown to clamp or regulate voltage across load circuits. Its Zener mechanism delivers stable 27 V regulation under controlled current conditions, with temperature coefficient of +21.4 mV/°C enabling predictable drift compensation in mid-voltage references.

Designed for low-power, high-density applications, it features a no-connection terminal (Pin 2) to isolate unused internal structure, and relies on thermal conduction through the SOT-23 leads and PCB copper for dissipation. The 225 W peak pulse rating (8 × 20 µs) supports transient overvoltage suppression without permanent degradation.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package (Case 318, Style 8), void-free thermosetting body, corrosion-resistant finish, UL 94 V-0 flammability rating, and 260°C maximum soldering temperature for 10 seconds.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5254ET1G, BZX84C27ET3 offers tighter board area usage and lower cost per unit in high-volume production, while BZX84-C27LT1G serves identical electrical roles with different logistics packaging-neither is pin-compatible in the sense of shared part number interchangeability, but both satisfy the same circuit function.

Availability

BZX84C27ET3 is available at Aetrix Electronics and suitable for portable power management, industrial sensor reference, automotive body control modules, and consumer audio DC-DC feedback requiring stable component supply, consistent parametric performance, and RoHS-compliant sourcing.

Supply support for BZX84C27ET3 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 management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BZX84C27ET3 belongs to the BZX84CxxxET1 Zener regulator family, designed specifically for space-constrained, high-density voltage reference and overvoltage protection in portable and automotive electronics.

FAQ

What is the Zener voltage tolerance of BZX84C27ET3 at 5 mA test current?

The BZX84C27ET3 has a Zener voltage range of 25.1 V to 28.9 V at I_ZT = 5 mA, corresponding to ±10% tolerance around the nominal 27 V rating. This tolerance is verified per the onsemi datasheet Rev. 7, page 3, and applies under ambient temperature conditions of 25°C. Designers should account for this spread when sizing series resistors and verifying regulation margins across operating temperature.

Does BZX84C27ET3 have a functional connection on Pin 2?

No, Pin 2 of the BZX84C27ET3 is explicitly designated as "No Connection" in the official onsemi datasheet (page 2, marking diagram and pinout table). It is internally unconnected and must remain floating-tying it to ground, V_CC, or any other node may compromise device reliability or violate the specified SOT-23 mechanical and thermal behavior. The active terminals are Pin 1 (Anode) and Pin 3 (Cathode).

What is the maximum reverse leakage current for BZX84C27ET3, and at what voltage is it specified?

The maximum reverse leakage current for BZX84C27ET3 is 0.05 µA, measured at a reverse voltage of 20.3 V (85% of nominal V_Z). This value is confirmed in the Electrical Characteristics table on page 3 of the onsemi datasheet. It reflects the diode's ability to block current below breakdown and is critical for low-power standby circuits where quiescent current must be minimized.

Is BZX84C27ET3 qualified for automotive applications?

Yes, BZX84C27ET3 is AEC-Q101 qualified and PPAP capable, as stated in the "Specification Features" section of the onsemi datasheet (page 1). This qualification covers stress testing for temperature cycling, humidity, mechanical shock, and high-temperature operating life-making it suitable for non-safety-critical automotive subsystems such as body control modules, infotainment power supplies, and sensor interfaces.

How does the temperature coefficient of BZX84C27ET3 affect its regulation accuracy over −40°C to +125°C?

The BZX84C27ET3 has a temperature coefficient of +21.4 mV/°C at I_ZT = 5 mA, meaning its Zener voltage increases by approximately 21.4 mV per degree Celsius rise. Over a 165°C range (−40°C to +125°C), this results in a total drift of ~3.5 V-requiring system-level compensation if sub-1% absolute accuracy is needed. The coefficient is derived from the datasheet's typical TC curve (Figure 1) and confirmed in the Electrical Characteristics table.