onsemi BZX55C3V3_T50R

Overview

BZX55C3V3_T50R from Fairchild Semiconductor is a 3.3 V, ±5% tolerance Zener diode in DO-35 glass package, rated for 500 mW power dissipation at 75°C with 85 Ω dynamic impedance at 5 mA test current and 2 μA reverse leakage at 1 V reverse voltage. It serves as a precision voltage reference or overvoltage clamp in low-power analog and digital supply regulation circuits.

For engineers reviewing the BZX55C3V3_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, junction temperature range (–65°C to +200°C), and DO-35 mechanical compatibility in space-constrained PCB layouts.

Technical Context

The BZX55C3V3_T50R operates as a silicon planar Zener diode optimized for stable voltage regulation under reverse bias. Its 3.3 V nominal breakdown voltage is specified at 5 mA test current with tight ±5% tolerance and 85 Ω dynamic impedance, ensuring predictable clamping performance across temperature.

It supports operation from –65°C to +200°C and exhibits 2 μA maximum reverse leakage at 1 V VR, enabling reliable use in battery-powered and industrial environments where low standby current and thermal robustness are critical.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; two-terminal device with no internal complexity or polarity-sensitive mounting beyond standard diode orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4728A and MMSZ4679, the BZX55C3V3_T50R offers DO-35 axial compatibility and proven thermal stability across –65°C to +200°C, making it optimal for repair, legacy replacement, and high-reliability through-hole designs where footprint and heritage matter.

Availability

BZX55C3V3_T50R is available at Aetrix Electronics and suitable for microcontroller power rail protection, low-power sensor biasing, and industrial signal conditioning requiring stable component supply and long-lifecycle support.

Supply support for BZX55C3V3_T50R 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The BZX55 series was developed as a general-purpose, cost-effective Zener diode family targeting voltage reference, regulation, and transient suppression in consumer, industrial, and automotive electronics.

FAQ

What is the exact Zener voltage range for BZX55C3V3_T50R at 25°C?

The BZX55C3V3_T50R has a guaranteed Zener voltage range of 3.1 V to 3.5 V at 5 mA test current and 25°C ambient, per the Fairchild BZX55C2V4–BZX55C56 datasheet Rev. D1. This ±5% tolerance window ensures predictable clamping behavior in 3.3 V system designs without requiring binning or calibration. The BZX55C3V3_T50R maintains this specification across its full operating temperature range when applied within power derating limits.

Does BZX55C3V3_T50R support operation above 125°C?

Yes, the BZX55C3V3_T50R is rated for junction temperatures from –65°C to +200°C, meaning it remains fully functional well above 125°C ambient when properly heat-sinked or mounted with appropriate lead length. Its 500 mW power rating applies up to 75°C lead temperature, with linear derating of 4.0 mW/°C above that point. The BZX55C3V3_T50R's glass DO-35 package contributes to its high-temperature reliability in under-hood or industrial control applications.

What is the reverse leakage current specification for BZX55C3V3_T50R?

The BZX55C3V3_T50R specifies a maximum reverse leakage current (I_R) of 2 μA at 1 V reverse voltage and 25°C, per the official Fairchild datasheet. This low leakage supports energy-efficient operation in battery-backed or always-on circuits. At elevated temperatures (e.g., 125°C), leakage increases but remains within design-safe margins for most low-current reference applications. The BZX55C3V3_T50R's leakage performance is consistent with its role as a stable, low-power Zener reference.

Is BZX55C3V3_T50R compatible with lead-free soldering processes?

Yes, the BZX55C3V3_T50R's DO-35 glass package and metallization are qualified for standard lead-free reflow profiles, including peak temperatures up to 260°C for 10 seconds. Its construction meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for through-hole discrete diodes. When hand-soldering, maintain iron tip temperature below 350°C and contact time under 3 seconds to avoid thermal shock to the glass body. The BZX55C3V3_T50R is widely used in RoHS-compliant manufacturing lines.

How does the dynamic impedance of BZX55C3V3_T50R affect regulation performance?

The BZX55C3V3_T50R exhibits 85 Ω dynamic impedance (Z_Z) at 5 mA test current, indicating moderate voltage regulation stiffness. This means a 1 mA change in Zener current results in approximately 85 mV shift in clamping voltage - acceptable for non-precision biasing or overvoltage limiting but insufficient for high-accuracy references. For tighter regulation, the BZX55C3V3_T50R is best paired with a series resistor to limit current variation; its Z_Z value is stable across temperature and matches other BZX55C-series devices for design consistency.