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Nexperia USA Inc. BZX84W-B51X
- Part No.:
- BZX84W-B51X
- Manufacturer:
- Nexperia USA Inc.
- Category:
- Single Zener Diodes
- Package:
- SC-70, SOT-323
- Datasheet:
-
BZX84W-B51X.pdf
- Description:
- DIODE ZENER 51V 275MW SOT323
- Quantity:
- Payment:
- Shipping:
Inventory:7,277
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Product details
Overview
BZX84W-B51X from Nexperia is a ±2% tolerance Zener voltage regulator diode in SOT323 (SC-70) package, rated for 51 V nominal Zener voltage at 5 mA, 275 mW total power dissipation, and 455 K/W junction-to-ambient thermal resistance. It serves as a precision reference or overvoltage clamp in low-power analog circuits, power supply feedback paths, and ESD-protected signal conditioning stages.
For engineers reviewing the BZX84W-B51X datasheet, BZX84W-B51X pinout, BZX84W-B51X application, or BZX84W-B51X equivalent, key selection criteria include Zener voltage tolerance (±2%), differential resistance (400 Ω at 5 mA), temperature coefficient (+51.0 mV/K), reverse leakage (50 nA at 35.7 V), and SOT323 thermal performance under FR4 PCB mounting conditions.
Technical Context
This Zener diode operates in reverse breakdown to maintain stable voltage regulation across its specified current range (1–20 mA). Its ±2% tolerance and +51.0 mV/K temperature coefficient indicate tight initial accuracy but positive drift with junction temperature rise - requiring thermal derating above 25 °C ambient.
The SOT323 package enables high-density placement while limiting power handling to 275 mW on standard FR4; non-repetitive surge capability reaches 40 W for 100 µs pulses. The unconnected terminal (Pin 2) isolates internal structure from circuit routing, confirming true two-terminal Zener functionality despite three-pin package form.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 50.0 V to 52.0 V at IZ = 5 mA - defines regulation setpoint with ±2% initial accuracy |
| Differential Resistance (rdif) | 400 Ω max at IZ = 5 mA - determines output impedance and load regulation error |
| Temperature Coefficient (SZ) | +51.0 mV/K at IZ = 5 mA - quantifies voltage drift per degree Celsius rise in junction temperature |
| Reverse Leakage (IR) | 50 nA max at VR = 35.7 V - sets minimum bias current required to avoid regulation dropout |
| Total Power Dissipation (Ptot) | 275 mW at Tamb = 25 °C on FR4 PCB - establishes maximum continuous DC power before thermal shutdown |
| Junction-to-Ambient Thermal Resistance (Rth(j-a)) | 455 K/W - confirms thermal bottleneck on standard single-sided copper layout |
| Forward Voltage (VF) | 0.9 V max at IF = 10 mA - defines conduction loss when used in forward-biased protection roles |
Pinout & Package
SOT323 (SC-70) leadless surface-mount package with 3 terminals; Pin 2 is internally not connected and must remain unbonded in PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Anode (A) | Connected to lower-potential node in reverse-bias regulation configuration |
| 2 | Not Connected (n.c.) | No internal bond; must be left floating - not tied to ground or any net |
| 3 | Cathode (K) | Connected to higher-potential node; Zener breakdown occurs between K and A |
Key Features
| Feature | Design Value |
|---|---|
| ±2% Zener voltage tolerance | Enables tighter regulation than ±5% variants without trimming circuitry |
| Low differential resistance (400 Ω) | Reduces output voltage variation under load current changes up to ±2 mA |
| Positive temperature coefficient (+51.0 mV/K) | Allows predictable compensation when paired with negative-coefficient components |
| 275 mW power rating on FR4 | Supports regulation in space-constrained consumer and industrial PCBs without heatsinking |
| SOT323 footprint compatibility | Enables drop-in replacement for other SC-70 Zeners while maintaining board-level reflow profile |
Applications
| Power Supply Feedback Reference | Overvoltage Clamp in Signal Lines |
|---|---|
|
Use Scenario: Stabilizing output voltage in adjustable buck converter feedback loop using TL431-like topology. IC Role / Device Role / Timing Role: Provides precise 51 V reference point for error amplifier comparison. Use Value: ±2% tolerance ensures output accuracy within ±0.5% of target, reducing need for post-production calibration. |
Use Scenario: Protecting ADC input pins from transient overvoltage in industrial sensor interface. IC Role / Device Role / Timing Role: Clamps fast-rising spikes above 51 V to prevent damage to downstream CMOS inputs. Use Value: 400 Ω dynamic impedance limits clamping voltage overshoot to <53 V during 100 ns transients. |
| Low-Power Voltage Reference | ESD-Suppressed Bias Network |
|
Use Scenario: Generating stable bias for op-amp input stage in battery-powered instrumentation. IC Role / Device Role / Timing Role: Supplies regulated 51 V to high-impedance divider network feeding precision amplifier. Use Value: 50 nA leakage at 35.7 V ensures minimal current draw (<1 µA) in standby mode. |
Use Scenario: Combining ESD protection and DC biasing in RS-485 receiver termination. IC Role / Device Role / Timing Role: Acts as bidirectional clamp between data line and 51 V rail while sourcing bias current. Use Value: Forward voltage of 0.9 V at 10 mA allows safe forward conduction during negative ESD events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84W-C51 | ±5% tolerance (48–54 V range), 400 Ω rdif, +51.0 mV/K SZ | Acceptable where system-level calibration compensates for wider voltage spread | Select for cost-sensitive designs where ±5% regulation accuracy suffices |
| MMSZ5256B | ±5% tolerance, 500 Ω rdif, +52 mV/K SZ, same SOT323 package | Higher differential resistance increases load regulation error by ~25% | Choose only if BZX84W-B51X is unavailable; verify stability under worst-case current step loads |
Compared with BZX84W-C51 and MMSZ5256B, the BZX84W-B51X delivers tighter initial voltage accuracy and lower dynamic impedance - critical for closed-loop feedback stability and low-drift bias networks where post-calibration is impractical.
Availability
BZX84W-B51X is available at Aetrix Electronics and suitable for power supply feedback references, overvoltage clamps, low-power voltage references, and ESD-suppressed bias networks requiring stable component supply across production lifecycles.
Supply support for BZX84W-B51X 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 manufacturer specializing in high-volume logic, discrete, and MOSFET devices, with emphasis on reliability, efficiency, and miniaturization for industrial and consumer markets.
The BZX84W series belongs to Nexperia's general-purpose Zener diode product line, designed specifically for compact, thermally constrained regulation tasks in SMT-based power management and signal conditioning circuits.
FAQ
What is the maximum continuous reverse current for stable regulation?
The BZX84W-B51X maintains regulation across 1 mA to 20 mA reverse current. At 20 mA, power dissipation reaches 1.02 W - exceeding its 275 mW rating. For continuous operation, limit IZ to ≤5.4 mA to stay within Ptot at 25 °C ambient. Derate linearly above 25 °C using Rth(j-a) = 455 K/W.
Can Pin 2 be grounded or left floating in PCB layout?
Pin 2 is internally not connected and must remain electrically floating - neither grounded nor tied to any net. Connecting it risks mechanical stress on die bonding or unintended parasitic coupling. The SOT323 outline explicitly defines Pin 2 as n.c., and solder mask should fully cover this pad to prevent accidental bridging.
How does temperature affect regulation accuracy above 25 °C?
At IZ = 5 mA, the +51.0 mV/K temperature coefficient causes VZ to increase by 51 mV per °C rise in junction temperature. With Rth(j-a) = 455 K/W and Ptot = 275 mW, Tj rises ~125 °C above ambient at full power - shifting VZ by +6.4 V. Use derated current or heatsinking to constrain ΔTj.
Is this device suitable for automotive applications?
No. The BZX84W-B51X is non-automotive qualified per Nexperia's revision history (v.2, Jan 2023). It lacks AEC-Q200 qualification, automotive-grade screening, and extended temperature validation. For automotive use, select the -Q qualified variant (e.g., BZX84W-B51-Q) or consult Nexperia's automotive Zener portfolio directly.
BZX84W-B51X Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Nexperia USA Inc.
- Series:
- BZX84W
- Package/Case:
- SC-70, SOT-323
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 51 V
- Tolerance:
- ±2%
- Power - Max:
- 275 mW
- Impedance (Max) (Zzt):
- 180 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 35.7 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-323
BZX84W-B51X FAQ
1.How can I place an order for BZX84W-B51X through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84W-B51X 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 BZX84W-B51X reliable?
The price and inventory of BZX84W-B51X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84W-B51X is usually 5 days.
3.What payment methods are accepted for BZX84W-B51X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84W-B51X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84W-B51X?
BZX84W-B51X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84W-B51X 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 BZX84W-B51X?
For technical support, including BZX84W-B51X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84W-B51X requirements.
6.How does Aetrix verify that BZX84W-B51X is sourced from the original manufacturer or authorized distributors?
All BZX84W-B51X 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 BZX84W-B51X meets industry standards.
7.What is the process for return or replacement of BZX84W-B51X?
All BZX84W-B51X units undergo pre-shipment inspection (PSI). If there is an issue with BZX84W-B51X, 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 BZX84W-B51X part is unused and in its original packaging.
Return procedure for BZX84W-B51X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX84W-B51X Tags
-
MMBZ5240B-7-F
Diodes Incorporated
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BZT52C5V6T-7
Diodes Incorporated
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MMSZ5231B-7-F
Diodes Incorporated
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BZT52C15-7-F
Diodes Incorporated
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BZX84C3V3LT1G
onsemi
-
MMSZ5245BS-7-F
Diodes Incorporated
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
Diodes Incorporated
-
MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
Micro Commercial Co
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BZT52C3V6LP-7
Diodes Incorporated
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SMAZ12-13-F
Diodes Incorporated
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