Nexperia USA Inc. BZX79-C33,133

Overview

BZX79-C33,133 from Nexperia is a ±5% tolerance Zener voltage regulator diode with nominal 33 V breakdown voltage at 2 mA test current, 75 Ω typical differential resistance, and −23.3 mV/K temperature coefficient. It operates as a low-power voltage reference in biasing, regulation, and overvoltage protection circuits, rated for 500 mW total power dissipation at 50 °C ambient.

For engineers reviewing the BZX79-C33,133 datasheet, BZX79-C33,133 pinout, BZX79-C33,133 application, or BZX79-C33,133 equivalent, this device is selected for precision low-current voltage referencing where ±5% tolerance and stable thermal behavior across −65 °C to +200 °C are required in space-constrained through-hole designs.

Technical Context

This Zener diode functions via controlled reverse-biased avalanche breakdown, delivering stable DC reference voltage under fixed current conditions. Its 33 V nominal Zener voltage is specified at I_Ztest = 2 mA, with 75 Ω typical dynamic impedance ensuring minimal output variation under load shifts.

The device exhibits a negative temperature coefficient of −23.3 mV/K, meaning its Zener voltage decreases linearly with rising junction temperature - a critical factor when designing thermally compensated references or clamping circuits operating across industrial temperature ranges.

Key Specifications

Pinout & Package

Hermetically sealed axial-leaded SOD27 (DO-35) glass package with cathode indicated by a colored band. Leads are tinned copper-clad steel, suitable for wave or hand soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX79-B33,113, the BZX79-C33,133 trades voltage precision and dynamic performance for cost and compatibility with established ±5% design margins; versus 1N4745A, it offers smaller footprint and superior thermal resistance but requires requalification for DO-35 assembly processes.

Availability

BZX79-C33,133 is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor interfaces, programmable logic controller (PLC) input modules, and embedded system voltage monitoring requiring stable component supply across extended temperature and lifecycle requirements.

Supply support for BZX79-C33,133 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

Nexperia is a global leader in discrete, logic, and PowerMOS semiconductors, spun off from NXP in 2017 and focused on high-volume, high-reliability components for automotive, industrial, and computing markets.

The BZX79 series belongs to Nexperia's standard voltage regulator diode product line, engineered for cost-sensitive, space-constrained applications demanding stable Zener performance in hermetic glass packages.

FAQ

What is the maximum continuous reverse current the BZX79-C33,133 can sustain without degradation?

The device is rated for continuous Zener current up to 15 mA at 50 °C ambient, derived from its 500 mW power limit and 33 V nominal voltage (P = V × I → I = 500 mW / 33 V ≈ 15.2 mA). Operation above this current requires thermal derating per the R_{th j-a} = 380 K/W specification to avoid exceeding 200 °C junction temperature.

Can BZX79-C33,133 be used in parallel for higher power dissipation?

No - Zener diodes exhibit negative temperature coefficients and manufacturing spread, causing current hogging when paralleled. One diode will conduct disproportionately, leading to thermal runaway and failure. For higher power, use a single higher-rated Zener or implement active regulation with a transistor pass element.

Is the cathode marking band polarity consistent across all SOD27-packaged Nexperia Zeners?

Yes - Nexperia uses a single-color band (typically black or dark gray) on the cathode end of all SOD27 Zener diodes, including the BZX79 series. This marking aligns with JEDEC DO-35 standards and is verified in the official package outline drawing (SOD27, version A24).

How does the −23.3 mV/K temperature coefficient impact circuit accuracy over −40 °C to +125 °C?

Over this 165 K range, the Zener voltage shifts by approximately −3.85 V (−23.3 mV/K × 165 K), resulting in a 33 V nominal device varying from ~29.15 V to ~33.0 V. Designers must account for this drift in closed-loop systems or pair with positive-TC components for compensation.