Nexperia USA Inc. BZX84-B20,235

Overview

BZX84-B20,235 from Nexperia is a ±2 % tolerance Zener voltage regulator diode in SOT23 (TO-236AB) package, rated for 20 V nominal breakdown voltage at 5 mA, 250 mW total power dissipation, and 40 W non-repetitive peak reverse power. It serves as a precision reference or overvoltage clamp in low-power analog supply rails and sensor biasing circuits.

For engineers reviewing the BZX84-B20,235 datasheet, BZX84-B20,235 pinout, BZX84-B20,235 application, or BZX84-B20,235 equivalent, key selection criteria include Zener voltage tolerance (±2 %), thermal resistance (330 K/W junction-to-solder point), differential resistance (≤225 Ω at IZ = 5 mA), and non-repetitive surge capability (1.5 A peak at 100 μs).

Technical Context

This Zener diode operates in reverse-biased breakdown mode to maintain stable voltage across its terminals under varying load or input conditions. Its 20 V nominal Zener voltage is specified at 5 mA test current with ±2 % tolerance, and exhibits a positive temperature coefficient of +14 mV/K at that current.

The device features low dynamic impedance (≤225 Ω), low reverse leakage (<0.05 μA at VR = 15 V), and robust transient handling-capable of absorbing 40 W non-repetitive reverse power surges for 100 μs pulses while maintaining junction temperature below 150 °C.

Key Specifications

Pinout & Package

Package: SOT23 (TO-236AB), surface-mount plastic package with 3 leads, 1.9 mm × 1.1 mm footprint, 0.45 mm nominal thickness.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-B20,235, MMBZ5243B offers higher power headroom but sacrifices voltage stability, while BZX84-C20 matches form-factor and power but trades ±2 % tolerance and lower impedance for lower unit cost-making it suitable only where tighter regulation is not required.

Availability

BZX84-B20,235 is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable medical monitors, and automotive body-control modules requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for BZX84-B20,235 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 semiconductor expert delivering high-performance, reliable discrete, logic, and MOSFET devices with focus on efficiency, miniaturization, and sustainability.

The BZX84 series belongs to Nexperia's precision Zener regulator portfolio, engineered for low-power voltage reference and protection in space-constrained, cost-sensitive applications across consumer, industrial, and communications markets.

FAQ

What is the maximum continuous reverse current this diode can sustain at 20 V?

The BZX84-B20,235 is not rated for continuous reverse conduction at 20 V-it operates in Zener breakdown mode with controlled current. At V_R = 20 V, typical reverse current is ~1.5 mA (per Fig. 9), well below the 200 mA absolute maximum forward current limit. Continuous operation requires current limiting via series resistor to stay within 250 mW dissipation.

Can this part replace BZX84-A20 in a precision reference circuit?

No-BZX84-A20 has ±1 % tolerance (19.8–20.2 V), while BZX84-B20,235 has ±2 % (19.6–20.4 V). The wider tolerance increases initial voltage error by up to 0.4 V, and its +14 mV/K temperature coefficient is less favorable than A-series' +12 mV/K. Use only if system-level calibration accommodates the added uncertainty.

Is Pin 2 truly unconnected, or does it serve a mechanical function?

Pin 2 is electrically isolated (n.c.) per Table 2 and confirmed in the internal construction diagram. It serves solely as a mechanical support tab for die attachment and package integrity-no PCB trace or copper pour should connect to it, and solder mask must fully cover it to prevent accidental shorts.

How does thermal resistance change when mounted on 2-layer vs. 4-layer PCBs?

R_th(j-a) drops from 500 K/W (FR4, single-sided, 70 µm Cu) to ~200–250 K/W on 2-layer boards with thermal vias, and further to ~120–150 K/W on 4-layer boards with internal ground/power planes. R_th(j-sp) remains 330 K/W regardless, as it measures directly from junction to cathode solder joint-not ambient.