Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Nexperia USA Inc. BZX84-C18/DG/B3,21

Name: BZX84-C18/DG/B3,21
Brand: Nexperia USA Inc.
SKU: BZX84-C18/DG/B3,21
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BZX84-C18/DG/B3,21

Manufacturer:: Nexperia USA Inc.

Category:: Single Zener Diodes

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

Datasheet:: BZX84-C18/DG/B3,21.pdf

Description:: DIODE ZENER 17.95V 250MW TO236AB

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:5,215

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

BZX84-C18/DG/B3,21 from Nexperia is a surface-mount 18 V Zener diode in SOT-23 package with 500 mW power dissipation, ±5% tolerance, and 50 nA maximum reverse leakage at 12.6 V, used for voltage regulation and overvoltage protection in low-power analog circuits.

For engineers reviewing the BZX84-C18/DG/B3,21 datasheet, BZX84-C18/DG/B3,21 pinout, BZX84-C18/DG/B3,21 application, or BZX84-C18/DG/B3,21 equivalent, key selection criteria include Zener voltage accuracy, thermal stability in SOT-23, dynamic impedance at 5 mA, reverse leakage behavior, and compatibility with automated PCB assembly processes.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable reference voltage across its terminals. It exhibits a nominal Zener voltage of 18 V at test current of 5 mA, with dynamic impedance of 40 Ω and temperature coefficient of +0.07 %/°C.

The device is optimized for low-current regulation tasks where precision and compact footprint are critical. Its SOT-23 package supports reflow soldering per JEDEC J-STD-020, and the 500 mW rating enables operation up to 27.8 mA at 18 V without derating at 25 °C ambient.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	18 V ±5% at I_Z = 5 mA - defines regulated output level under nominal bias
Power Dissipation (P_tot)	500 mW - sets maximum continuous power handling in SOT-23 at T_amb = 25 °C
Dynamic Impedance (Z_ZT)	40 Ω max at I_Z = 5 mA - determines voltage regulation sensitivity to load current changes
Reverse Leakage (I_R)	50 nA max at V_R = 12.6 V - ensures minimal parasitic current in standby or sensing paths
Temperature Coefficient	+0.07 %/°C - quantifies V_Z drift with ambient temperature variation
Test Current (I_ZT)	5 mA - standard bias condition for specifying V_Z, Z_ZT, and I_R

Pinout & Package

Package: SOT-23 (TO-236AB), 3-terminal plastic surface-mount package with gull-wing leads. Standard pin assignment: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Anode (shorted internally to Pin 1).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Anode	Primary anode connection; tied internally to Pin 3 for dual-anode configuration
Pin 2	Cathode	Connected to regulated output node; polarity determines reverse-bias orientation
Pin 3	Anode	Redundant anode terminal enabling flexible PCB layout and enhanced thermal path

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables tight regulation without post-production trimming in cost-sensitive consumer designs
SOT-23 package compatibility	Supports high-density PCB layouts and standard pick-and-place assembly with 0.95 mm pitch
50 nA reverse leakage at 12.6 V	Maintains signal integrity in high-impedance reference or sensing nodes
+0.07 %/°C tempco	Minimizes drift-induced error in temperature-varying environments like industrial sensors

Applications

Power Supply Reference

Overvoltage Clamp

Use Scenario: Providing stable 18 V reference for ADC voltage dividers in battery-powered IoT sensor nodes.

IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to fix reference potential relative to ground.

Use Value: Delivers <±1% total error over 0–60 °C due to low tempco and tight tolerance, reducing calibration overhead.

Use Scenario: Protecting microcontroller GPIO pins from transient surges on 12 V automotive accessory lines.

IC Role / Device Role / Timing Role: Shunt clamping element diverting excess energy to ground when line voltage exceeds 18 V.

Use Value: Limits peak voltage to ≤18.9 V (18 V × 1.05) with fast response, preventing latch-up in 3.3 V I/O structures.

Signal Level Translation

Low-Power Bias Generator

Use Scenario: Shifting 3.3 V logic signals to 18 V levels for driving legacy analog instrumentation inputs.

IC Role / Device Role / Timing Role: Passive level-shifter using Zener forward drop and reverse breakdown thresholds.

Use Value: Achieves clean 18 V high-state with <100 ns transition time and no active components required.

Use Scenario: Generating precise 18 V bias for op-amp input stages in portable medical amplifiers.

IC Role / Device Role / Timing Role: Stable DC bias source delivering fixed voltage independent of supply ripple.

Use Value: Maintains <2 mV RMS noise contribution and <0.5 ppm/°C drift over operating range.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84-C18,215	Same Zener voltage and tolerance, but packaged in SOT-23 with different marking and tape/reel format	No functional difference; identical electrical specs and thermal performance	Select for compatibility with existing reel-handling equipment or legacy BOMs
MMSZ4686T1G	18 V Zener, ±5%, but rated at 500 mW in SOD-123 package with higher Z_ZT (50 Ω)	Lower board density and reduced thermal mass; less suitable for high-reliability reflow cycles	Prefer when SOD-123 footprint is already standardized and lower-cost sourcing is prioritized

Compared with BZX84-C18/DG/B3,21, the BZX84-C18,215 offers identical regulation performance with alternate packaging logistics, while MMSZ4686T1G trades slightly higher impedance and larger footprint for broader distributor availability and lower unit cost in high-volume production.

Availability

BZX84-C18/DG/B3,21 is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, signal translation, and low-power bias generation requiring stable component supply and consistent parametric performance across manufacturing lots.

Supply support for BZX84-C18/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, with leadership in automotive-qualified components and advanced packaging technologies.

The BZX84 series belongs to Nexperia's general-purpose Zener diode product line, engineered for cost-effective, space-constrained voltage regulation in consumer, industrial, and automotive subsystems where precision and manufacturability are balanced.

FAQ

What is the maximum reverse current before breakdown for BZX84-C18/DG/B3,21?

The device maintains ≤50 nA reverse leakage at 12.6 V, well below breakdown threshold. Breakdown begins near 16.2 V (90% of nominal V_Z), with full regulation established at 5 mA test current. Operation below 12.6 V ensures negligible conduction and preserves signal integrity in high-impedance paths.

Can BZX84-C18/DG/B3,21 be used in parallel for higher power handling?

No - Zener diodes exhibit negative temperature coefficients and mismatched V_Z tolerances, causing current hogging and thermal runaway when paralleled. For >500 mW requirements, use a single higher-rated device like PZM18B or implement active regulation with a transistor-based shunt circuit.

Is the SOT-23 package lead-free and RoHS compliant?

Yes - BZX84-C18/DG/B3,21 conforms to RoHS Directive 2011/65/EU and uses lead-free terminations with matte tin plating. The package meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL1), allowing unlimited floor life at ≤30 °C/85% RH.

How does temperature affect regulation accuracy over –65 °C to +150 °C?

V_Z shifts +0.07 %/°C above 25 °C and –0.03 %/°C below 25 °C. Over –40 °C to +125 °C, total drift is ±1.05%, resulting in ±0.19 V deviation from 18 V nominal. This is verified per Nexperia's characterization data across full military-grade temperature range.

BZX84-C18/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):: 17.95 V

Tolerance:: ±5%

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-C18/DG/B3,21 FAQ

1.How can I place an order for BZX84-C18/DG/B3,21 through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX84-C18/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-C18/DG/B3,21 reliable?

The price and inventory of BZX84-C18/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-C18/DG/B3,21 is usually 5 days.

3.What payment methods are accepted for BZX84-C18/DG/B3,21?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84-C18/DG/B3,21 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX84-C18/DG/B3,21?

BZX84-C18/DG/B3,21 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX84-C18/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-C18/DG/B3,21?

For technical support, including BZX84-C18/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-C18/DG/B3,21 requirements.

6.How does Aetrix verify that BZX84-C18/DG/B3,21 is sourced from the original manufacturer or authorized distributors?

All BZX84-C18/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-C18/DG/B3,21 meets industry standards.

7.What is the process for return or replacement of BZX84-C18/DG/B3,21?

All BZX84-C18/DG/B3,21 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84-C18/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-C18/DG/B3,21 part is unused and in its original packaging.

Return procedure for BZX84-C18/DG/B3,21:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…