onsemi BZX84C33LT1

Overview

BZX84C33LT1 from onsemi is a 33 V, ±5% tolerance Zener diode in SOT-23 package, rated for 225 mW power dissipation at 25°C on FR-5 board, with 325 Ω dynamic impedance at 20 mA test current and 55 µA maximum reverse leakage at 24.8 V, used for voltage regulation in space-constrained portable electronics.

For engineers reviewing the BZX84C33LT1 datasheet, pinout, applications, or equivalent options, this page delivers verified Zener voltage, impedance, leakage, temperature coefficient, and SOT-23 terminal mapping - critical for low-power biasing, reference, and overvoltage protection design validation.

Technical Context

The BZX84C33LT1 operates as a two-terminal voltage reference device with cathode-anode polarity, relying on controlled reverse breakdown to maintain stable 33 V output across 5–20 mA Zener test currents. Its thermal resistance of 556 °C/W (FR-5) and junction temperature range of −65°C to +150°C define its derating envelope.

It exhibits a positive temperature coefficient of +23.1 mV/°C at 5 mA, indicating voltage increases with temperature - a key factor when used in temperature-sensitive references. Capacitance is 70 pF at 0 V bias and 1 MHz, limiting high-frequency noise filtering capability.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package (Case 318, Style 8), void-free thermosetting body with corrosion-resistant finish, rated for 260°C soldering (10 s), UL 94 V-0 flammability, and cathode marked by band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84C33LT1, MMBZ5265BLT1 offers identical voltage but reduced power margin, while BZX84C33-7-F delivers higher thermal headroom on ceramic substrates - both retain SOT-23 compatibility but differ in derating behavior and substrate dependency.

Availability

BZX84C33LT1 is available at Aetrix Electronics and suitable for cellular phone power management, USB peripheral voltage reference, and industrial sensor signal conditioning requiring stable component supply with full traceability and lifecycle support.

Supply support for BZX84C33LT1 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 silicon solutions for automotive, industrial, cloud, and IoT applications.

The BZX84CxxxLT1 series is part of onsemi's discrete Zener regulator portfolio, engineered for compact, reliable voltage reference and clamping in high-density portable and embedded systems.

FAQ

What is the exact Zener voltage range for BZX84C33LT1 at 5 mA test current?

The BZX84C33LT1 has a guaranteed Zener voltage range of 31.0 V to 35.0 V when measured at I_ZT = 5 mA and T_A = 25°C, per the official onsemi datasheet revision 7. This ±5% tolerance reflects manufacturing spread and ensures predictable regulation within this band under specified test conditions. The nominal value is 33 V, and the device is not binned tighter than this range.

Does BZX84C33LT1 have a connection on pin 2, and what happens if it's grounded?

No, pin 2 of the BZX84C33LT1 is internally unconnected (NC) - it serves only as a mechanical lead and carries no electrical function. Grounding or routing pin 2 creates no electrical effect but risks mechanical stress or solder bridging. The datasheet explicitly states "2-No Connection", and grounding it violates recommended layout practice without benefit or functional impact on BZX84C33LT1 operation.

What is the maximum reverse leakage current for BZX84C33LT1, and at what voltage is it specified?

The BZX84C33LT1 has a maximum reverse leakage current of 55 µA, specified at a reverse voltage (V_R) of 24.8 V - which is 75% of its nominal 33 V Zener voltage. This value is measured at T_A = 25°C and defines the upper bound of off-state current in bias networks, directly affecting power budget calculations in ultra-low-power IoT nodes using BZX84C33LT1 as a reference.

Can BZX84C33LT1 be used on FR-4 board, and how does its power rating change?

Yes, BZX84C33LT1 is qualified for FR-4 boards, with a rated power dissipation of 225 mW at 25°C ambient - identical to its FR-5 rating. Derating follows 1.8 mW/°C above 25°C, yielding ~180 mW at 50°C. Thermal resistance remains 556 °C/W. No FR-4-specific derating factor is applied; the 225 mW rating applies directly to standard FR-4 PCBs meeting minimum copper area guidelines in the BZX84C33LT1 datasheet.

Is BZX84C33LT1 RoHS-compliant, and does it carry a Pb-Free designation?

The standard BZX84C33LT1 is not inherently Pb-Free; however, the Pb-Free variant is designated BZX84C33LT1G (with 'G' suffix). Both share identical electrical specs and SOT-23 packaging, but only BZX84C33LT1G complies with RoHS Directive 2011/65/EU. Aetrix Electronics stocks both versions, and material declarations confirm BZX84C33LT1G meets JEDEC J-STD-609A Class 1 moisture sensitivity and lead-free soldering requirements.