onsemi BZX84C24ET3

Overview

BZX84C24ET3 from onsemi is a 24 V, 225 mW surface-mount Zener diode in SOT-23 package, designed for precision voltage regulation and reference in space-constrained circuits. It delivers nominal Zener voltage of 24 V at 5 mA test current, with dynamic impedance of 70 Ω, ±5% tolerance, and −65 °C to +150 °C operating temperature range. It is used in voltage clamping, overvoltage protection, and low-power reference circuits in portable electronics.

For engineers reviewing the BZX84C24ET3 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage accuracy (22.8–25.6 V), thermal coefficient (+16.8 mV/°C), leakage current (≤0.05 µA @ 19.2 V), and ESD robustness (>16 kV HBM).

Technical Context

This device operates as a two-terminal voltage reference, conducting in reverse breakdown when cathode voltage exceeds anode by ≥24 V. Its Zener mechanism provides stable regulation under DC or low-frequency transient conditions, with minimal dependence on current within its specified 1–20 mA operating range.

The SOT-23 package enables automated placement and reflow compatibility, while its 225 mW power rating on FR-5 board and 300 mW on alumina substrate supports thermal management in high-density layouts. The unconnected Pin 2 isolates internal structure and confirms mechanical symmetry-not functional use.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5242BS-7-F, BZX84C24ET3 offers tighter production lot consistency and lower cost for low-power (<225 mW) applications; compared with BZX84-C24LT1G, it provides higher-volume reel packaging and identical performance with no design or layout impact.

Availability

BZX84C24ET3 is available at Aetrix Electronics and suitable for portable power rail clamping, low-power voltage reference, ESD protection node, and microcontroller reset circuit applications requiring stable component supply and RoHS-compliant sourcing.

Supply support for BZX84C24ET3 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 BZX84C24ET3 belongs to the BZX84CxxxET1 Series Zener voltage regulators - designed specifically for space-constrained, surface-mount voltage reference and clamping in portable, handheld, and high-density PCB applications.

FAQ

What is the Zener voltage tolerance of BZX84C24ET3?

The BZX84C24ET3 has a nominal Zener voltage of 24 V with a guaranteed range of 22.8 V to 25.6 V at 5 mA test current, corresponding to ±5% tolerance. This specification is verified per the onsemi datasheet Rev. 6 (July 2009) and applies under standard test conditions (T_A = 25°C). The BZX84C24ET3 maintains this tolerance across its qualified operating temperature range.

Does BZX84C24ET3 have a functional Pin 2?

No, Pin 2 of the BZX84C24ET3 is internally unconnected and serves no electrical function. Per the official onsemi datasheet, the pinout is Anode (Pin 1), No Connection (Pin 2), Cathode (Pin 3). Leaving Pin 2 unconnected on the PCB is mandatory - routing or terminating it may compromise mechanical stability or cause unintended parasitic coupling.

What is the maximum reverse leakage current for BZX84C24ET3?

The maximum reverse leakage current for BZX84C24ET3 is 0.05 µA at 19.2 V (80% of nominal V_Z), as specified in the Electrical Characteristics table of the onsemi datasheet. This value is measured at T_A = 25°C and reflects worst-case leakage under sub-breakdown bias - critical for ultra-low-power reference and bias networks where leakage directly impacts accuracy.

Is BZX84C24ET3 RoHS compliant?

Yes, BZX84C24ET3 is RoHS compliant and lead-free. The "ET3" suffix denotes the standard lead-free version; the "G" suffix variant (BZX84C24ET3G) explicitly confirms Pb-free packaging per J-STD-609. Both meet EU RoHS Directive 2011/65/EU and are suitable for environmentally regulated production without exemption requests.

What is the thermal resistance junction-to-ambient for BZX84C24ET3 on FR-5 board?

The thermal resistance junction-to-ambient (R_JA) for BZX84C24ET3 is 556 °C/W when mounted on FR-5 board, as stated in the Maximum Ratings table. This value assumes standard JEDEC test conditions (1.0 × 0.75 × 0.62 inch board) and governs allowable power dissipation: at 25°C ambient, full 225 mW is permitted; above 25°C, derating is 1.8 mW/°C.