Nexperia USA Inc. BZX79-B33,113

Overview

BZX79-B33,113 from Nexperia is a ±2% 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 bias networks, power supply feedback loops, and overvoltage protection circuits, rated for 500 mW total power dissipation at 50 °C ambient.

For engineers reviewing the BZX79-B33,113 datasheet, BZX79-B33,113 pinout, BZX79-B33,113 application, or BZX79-B33,113 equivalent, key selection criteria include Zener voltage tolerance (±2%), thermal coefficient behavior across operating current, non-repetitive surge capability (45 A peak reverse current), and DO-35 package compatibility with through-hole PCB layouts.

Technical Context

This device functions as a two-terminal passive voltage reference, relying on controlled avalanche breakdown in silicon to maintain stable reverse-bias voltage under defined current conditions. Its operation requires external current limiting and is specified at T_j = 25 °C, with thermal resistance R_{th j-a} = 380 K/W and R_{th j-tp} = 300 K/W for lead-length–dependent derating.

The BZX79-B33,113 exhibits a negative temperature coefficient of −23.3 mV/K at I_Z = 2 mA, indicating decreasing Zener voltage with rising junction temperature - a critical factor in precision reference designs where thermal drift must be compensated. Its 75 Ω typical dynamic impedance directly impacts regulation accuracy under load transients.

Key Specifications

Pinout & Package

Hermetically sealed glass SOD27 (DO-35) axial-leaded 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 1N4745A and BZX85C33, the BZX79-B33,113 delivers superior voltage accuracy and thermal predictability in space-constrained, long-life applications - critical where calibration cycles are impractical and environmental stability is mandated.

Availability

BZX79-B33,113 is available at Aetrix Electronics and suitable for power supply feedback reference, overvoltage protection clamp, and sensor bias network applications requiring stable component supply, consistent parametric performance, and long-term availability in through-hole form factor.

Supply support for BZX79-B33,113 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, formed in 2017 from the former NXP Standard Products business, with focus on automotive, industrial, computing, and consumer markets.

The BZX79 series belongs to Nexperia's legacy Zener diode product line, engineered for reliable low-power voltage regulation and referencing in cost-sensitive, high-volume applications where hermetic sealing and tight tolerance matter.

FAQ

What is the maximum continuous Zener current for BZX79-B33,113 at 25 °C ambient?

The device does not specify a maximum continuous Zener current directly, but derives it from its 500 mW power rating and 33 V nominal voltage: I_Zmax ≈ 500 mW / 33 V ≈ 15 mA. At this current, junction temperature remains within safe limits only if thermal resistance is managed via PCB layout and lead length - derating applies above 50 °C ambient.

Can BZX79-B33,113 be used in surface-mount designs?

No - BZX79-B33,113 uses an axial-leaded DO-35 (SOD27) glass package designed exclusively for through-hole mounting. It lacks solder pads or terminations compatible with reflow or wave soldering of SMT boards. For SMT equivalents, consider Nexperia's PZM series or ON Semiconductor's MMBZ52xx series.

How does the −23.3 mV/K temperature coefficient affect circuit accuracy?

This coefficient means the Zener voltage decreases by 23.3 mV per Kelvin rise in junction temperature. Over a 50 °C junction swing (e.g., 25 °C to 75 °C), voltage drift totals ~1.165 V - a 3.5% shift relative to 33 V. Designers must either thermally stabilize the diode, compensate in software/firmware, or select higher-V_Z parts with near-zero coefficients (e.g., 5.6 V types).

Is the cathode marking polarity consistent across all BZX79-Bxxx devices?

Yes - all BZX79-Bxxx variants, including BZX79-B33,113, use a single color band (typically black or dark gray) on the glass body to denote the cathode terminal. This marking aligns with JEDEC DO-35 standards and matches Nexperia's official package drawings; reversal will cause forward conduction instead of Zener regulation.