Nexperia USA Inc. BZX84-B51/DG/B2,21

Overview

BZX84-B51/DG/B2,21 from Nexperia is a 51 V, 250 mW surface-mount Zener diode in SOT23 package with ±2% tolerance, 100 nA maximum reverse leakage at 38.8 V, and 70 Ω dynamic impedance at 5 mA test current - used for precision voltage regulation in low-power sensor biasing and reference circuits.

For engineers reviewing the BZX84-B51/DG/B2,21 datasheet, BZX84-B51/DG/B2,21 pinout, BZX84-B51/DG/B2,21 application, or BZX84-B51/DG/B2,21 equivalent, key selection criteria include Zener voltage accuracy, power dissipation limit, temperature coefficient, reverse leakage behavior, and SOT23 thermal derating performance in compact PCB layouts.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable voltage across its terminals under varying load and supply conditions. It is characterized at 5 mA test current with a nominal Zener voltage of 51 V and a tight ±2% tolerance band, ensuring predictable clamping in feedback networks.

The device exhibits a typical temperature coefficient of +0.07 %/°C between 25 °C and 100 °C, supporting stable regulation over industrial temperature ranges. Its 250 mW power rating requires careful thermal management on FR-4 PCBs with standard copper pad layout per JEDEC MS-012.

Key Specifications

Pinout & Package

SOT23-3 package with standard pin configuration: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Not connected (NC). The cathode is marked by a band on the package body. Thermal pad is not present; PCB copper area must be optimized per Nexperia SOT23 footprint guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C51,215 and MMSZ5257B-7-F, the BZX84-B51/DG/B2,21 delivers tighter voltage accuracy and lower leakage in the same SOT23 footprint - making it optimal for space-constrained, high-precision analog references where thermal budget is limited to 250 mW.

Availability

BZX84-B51/DG/B2,21 is available at Aetrix Electronics and suitable for industrial sensor reference, USB-C power negotiation clamp, medical pulse oximeter bias, and smart meter voltage monitor applications requiring stable component supply and traceable sourcing.

Supply support for BZX84-B51/DG/B2,21 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 focused on high-volume, high-reliability discrete and logic devices, with leadership in automotive-qualified components and energy-efficient solutions.

The BZX84 series belongs to Nexperia's precision Zener diode product line, engineered for stable voltage reference and clamping in space-constrained, low-power analog systems across industrial and consumer applications.

FAQ

What is the maximum reverse voltage this Zener can regulate without damage?

The BZX84-B51/DG/B2,21 is rated for continuous operation at 51 V ±2% in reverse breakdown. Absolute maximum reverse voltage is not specified separately; sustained operation above 52.02 V (upper tolerance limit) risks exceeding power dissipation limits unless current is strictly limited below 4.9 mA. Transient overvoltage events must stay within the device's surge rating defined in Nexperia's Pspice model.

Can this Zener be used in series for higher voltage reference generation?

Yes - two BZX84-B51/DG/B2,21 diodes in series yield ~102 V ±2.8% (root-sum-square tolerance), but thermal tracking mismatch between devices may increase effective drift. Series use requires matched units and symmetric PCB layout to minimize differential heating; parallel use is not recommended due to unequal current sharing.

How does its temperature coefficient affect long-term reference stability?

With a +0.07 %/°C TC over 25–100 °C, the Zener voltage increases by ~0.36 V across a 75 °C rise. In a 51 V reference, this yields ~0.7% total drift - acceptable for non-critical industrial monitoring but insufficient for metrology-grade applications without external compensation.

Is the SOT23-3 footprint compatible with standard pick-and-place equipment?

Yes - the BZX84-B51/DG/B2,21 uses JEDEC-standard SOT23-3 dimensions (2.2 mm × 1.35 mm × 1.1 mm) with 0.95 mm lead pitch. It is compatible with all major SMT assembly lines using IPC-7351-compliant land patterns and standard nozzles for 0.6 mm vacuum pickup.