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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

Nexperia USA Inc. BZX84-B18/DG/B3,21

Name: BZX84-B18/DG/B3,21
Brand: Nexperia USA Inc.
SKU: BZX84-B18/DG/B3,21
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZX84-B18/DG/B3,21

Manufacturer:: Nexperia USA Inc.

Category:: Single Zener Diodes

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: BZX84-B18/DG/B3,21.pdf

Description:: DIODE ZENER 18V 250MW TO236AB

Quantity:: RFQ Add To RFQ list

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Inventory:3,005

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Product details

Overview

BZX84-B18/DG/B3,21 from Nexperia is a 18 V, 250 mW surface-mount Zener diode with ±2% tolerance, 100 nA maximum reverse leakage at 13.7 V, and 15 Ω dynamic impedance, used for precision voltage regulation in low-power sensor biasing and reference circuits.

For engineers reviewing the BZX84-B18/DG/B3,21 datasheet, BZX84-B18/DG/B3,21 pinout, BZX84-B18/DG/B3,21 application, or BZX84-B18/DG/B3,21 equivalent, key selection criteria include Zener voltage tolerance, power dissipation limit, dynamic impedance at test current, reverse leakage behavior, and SOT-23 package thermal performance in space-constrained 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 I_Z = 5 mA with V_Z = 18 V, dynamic impedance Z_Z = 15 Ω, and temperature coefficient of +0.07 %/°C.

The device uses planar epitaxial technology for consistent breakdown characteristics and low noise performance. Its SOT-23 package supports reflow soldering per JEDEC J-STD-020 and provides thermal resistance R_thj-amb = 375 K/W at 4.5 mm² copper pad.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	18 V ±2% at I_Z = 5 mA - defines regulated output voltage with tight tolerance for reference stability
Power Dissipation (P_tot)	250 mW at T_amb = 25 °C - limits continuous operating current to ~13.9 mA at 18 V
Dynamic Impedance (Z_Z)	15 Ω at I_Z = 5 mA - determines output voltage variation under load current changes
Reverse Leakage (I_R)	≤100 nA at V_R = 13.7 V - ensures minimal quiescent current in high-impedance bias networks
Temperature Coefficient	+0.07 %/°C - indicates positive drift of V_Z with rising junction temperature
Package	SOT-23 - enables automated placement and compact layout in portable and IoT edge devices

Pinout & Package

SOT-23 package with standard three-terminal configuration: anode (pin 1), cathode (pin 2), and unused pin 3 (internally unconnected). Cathode marked by band on top surface.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Anode	Connected to lower potential side; reverse-biased during regulation
Pin 2	Cathode	Connected to higher potential side; voltage reference node in shunt regulator
Pin 3	No Connect	Internally isolated; no electrical function or thermal path

Key Features

Feature	Design Value
Tight Zener voltage tolerance	±2% at 5 mA - reduces calibration overhead in precision analog front-ends
Low dynamic impedance	15 Ω - minimizes output voltage deviation under ±1 mA load step
Guaranteed reverse leakage	≤100 nA at 13.7 V - preserves battery life in always-on sensor nodes
SOT-23 reflow compatibility	JEDEC J-STD-020 compliant - supports high-yield automated assembly without lead damage

Applications

Industrial Sensor Biasing

Portable Device Reference

Use Scenario: Providing stable 18 V bias to MEMS pressure sensor bridge in factory-floor transmitters.

IC Role / Device Role / Timing Role: Shunt voltage reference maintaining excitation voltage within ±0.36 V over temperature and supply drift.

Use Value: Enables <1% full-scale error in 4–20 mA loop-powered sensors without trimming resistors.

Use Scenario: Generating precise 18 V reference for ADC input scaling in handheld multimeters.

IC Role / Device Role / Timing Role: Passive voltage clamp defining upper rail for ratiometric measurement circuitry.

Use Value: Delivers 12-bit effective resolution with <±1 LSB integral nonlinearity over 0–55 °C.

IoT Node Power Management

Automotive Cabin Control

Use Scenario: Regulating auxiliary 18 V rail for BLE SoC LDO input in battery-operated asset trackers.

IC Role / Device Role / Timing Role: Pre-regulator limiting input to downstream LDO under 24 V vehicle supply transients.

Use Value: Reduces LDO thermal stress and extends coin-cell runtime by limiting peak dissipation to 1.2 mW.

Use Scenario: Stabilizing microcontroller reset threshold voltage in HVAC control modules.

IC Role / Device Role / Timing Role: Voltage supervisor reference element triggering POR at 17.64 V during cold-crank events.

Use Value: Prevents brown-out resets during 6–10 V battery dips while rejecting 100 ms spikes up to 32 V.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84-C18,215	±5% tolerance, 20 Ω Z_Z, same SOT-23 package	Higher voltage drift and looser regulation; suitable only for non-critical biasing	Select when cost sensitivity outweighs reference accuracy requirements
MMSZ5245B-TP	18 V ±5%, 200 mW, SOD-123 package, R_thj-amb = 500 K/W	Larger footprint and higher thermal resistance; less suitable for dense PCBs	Prefer for legacy designs using SOD-123 or where board-level rework tolerance is prioritized

Compared with BZX84-C18,215 and MMSZ5245B-TP, the BZX84-B18/DG/B3,21 delivers tighter voltage control and lower thermal resistance in the same SOT-23 footprint-critical for high-density, battery-sensitive, or temperature-stable reference designs.

Availability

BZX84-B18/DG/B3,21 is available at Aetrix Electronics and suitable for industrial sensor biasing, portable device reference generation, and IoT node power management requiring stable component supply and long-term production continuity.

Supply support for BZX84-B18/DG/B3,21 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, serving automotive, industrial, and consumer markets with ISO/TS 16949-certified manufacturing.

The BZX84 series belongs to Nexperia's precision Zener diode product line, engineered for stable voltage reference and regulation in space-constrained, low-power analog signal chains.

FAQ

What is the maximum reverse current before breakdown onset for BZX84-B18/DG/B3,21?

The device exhibits ≤100 nA reverse leakage at 13.7 V, well below the 5 mA test current where nominal Zener voltage is specified. Breakdown onset occurs gradually starting near 16.2 V, with 90% of final V_Z reached at approximately 17.1 V per Nexperia's characterization curves.

Can BZX84-B18/DG/B3,21 be used in series with another Zener for higher voltage reference?

Yes, but thermal coupling must be controlled: series connection increases total power dissipation and alters individual junction temperatures. The device's +0.07 %/°C tempco means mismatched heating can cause >0.5% combined voltage drift over 50 °C ambient swing-use matched pairs on shared thermal pads if implemented.

Is the SOT-23 pin 3 internally connected in this variant?

No. Pin 3 is electrically isolated and thermally disconnected per Nexperia's package drawing 9337 739 02021. It serves only as a mechanical alignment aid during pick-and-place and must not be soldered to ground or any net to avoid mechanical stress on the die bond wire.

How does derating work above 25 °C ambient for continuous operation?

Derating follows linear reduction: P_tot = 250 mW − (T_amb − 25) × 0.67 mW/°C, down to zero at 262 °C junction temperature. At 70 °C ambient, max continuous power drops to 218 mW, limiting safe DC current to ~12.1 mA at 18 V with standard PCB copper area.

BZX84-B18/DG/B3,21 Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 18 V

Tolerance:: ±2%

Power - Max:: 250 mW

Impedance (Max) (Zzt):: 45 Ohms

Current - Reverse Leakage @ Vr:: 50 nA @ 12.6 V

Voltage - Forward (Vf) (Max) @ If:: 900 mV @ 10 mA

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: TO-236AB

BZX84-B18/DG/B3,21 FAQ

1.How can I place an order for BZX84-B18/DG/B3,21 through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX84-B18/DG/B3,21 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BZX84-B18/DG/B3,21 reliable?

The price and inventory of BZX84-B18/DG/B3,21 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84-B18/DG/B3,21 is usually 5 days.

3.What payment methods are accepted for BZX84-B18/DG/B3,21?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84-B18/DG/B3,21 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX84-B18/DG/B3,21?

BZX84-B18/DG/B3,21 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX84-B18/DG/B3,21 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BZX84-B18/DG/B3,21?

For technical support, including BZX84-B18/DG/B3,21 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84-B18/DG/B3,21 requirements.

6.How does Aetrix verify that BZX84-B18/DG/B3,21 is sourced from the original manufacturer or authorized distributors?

All BZX84-B18/DG/B3,21 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BZX84-B18/DG/B3,21 meets industry standards.

7.What is the process for return or replacement of BZX84-B18/DG/B3,21?

All BZX84-B18/DG/B3,21 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84-B18/DG/B3,21, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BZX84-B18/DG/B3,21 part is unused and in its original packaging.

Return procedure for BZX84-B18/DG/B3,21:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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