BZX284-B51,115 Equivalent & Substitute Parts

Part Overview

The BZX284-B51,115 is a Zener diode rated at 51 V nominal voltage with 400 mW maximum power dissipation, manufactured by NXP USA Inc. in SOD-110 surface mount package. This component is classified as obsolete, necessitating identification of active equivalent parts for new designs and ongoing production requirements. The part maintains ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1), making it suitable for industrial and commercial applications within the specified temperature range of -65°C to 150°C.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	51	V
Tolerance	±2%	-
Power - Max	400	mW
Impedance (Max)	110	Ohms
Current - Reverse Leakage @ Vr	50	nA @ 35.7 V
Voltage - Forward (Vf) (Max) @ If	1.1	V @ 100 mA
Operating Temperature Range	-65 to 150	°C
Mounting Type	Surface Mount	-
Package / Case	SOD-110	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution of the BZX284-B51,115 is determined by the following critical electrical and mechanical parameters:

Electrical Equivalence Criteria:

Zener voltage (Nom): 51 V ±2% tolerance
Reverse leakage current: 50 nA @ 35.7 V
Forward voltage: 1.1 V @ 100 mA
Operating temperature range: -65°C to 150°C

Mechanical Compatibility Criteria:

Surface mount technology
RoHS3 compliance
MSL 1 (Unlimited) moisture sensitivity

The BZX384-B51,115 qualifies as a manufacturer-recommended substitute. While the power rating differs (300 mW versus 400 mW), the electrical characteristics remain equivalent within the specified tolerance band. The package transition from SOD-110 to SOD-323 represents a standard industry evolution in component miniaturization, with both packages supporting surface mount assembly processes.

Parameter Comparison

Parameter	BZX284-B51,115	BZX384-B51,115	Match Status
Voltage - Zener (Nom)	51 V	51 V	Equivalent
Tolerance	±2%	±2%	Equivalent
Power - Max	400 mW	300 mW	Reduced
Impedance (Max)	110 Ohms	180 Ohms	Increased
Current - Reverse Leakage @ Vr	50 nA @ 35.7 V	50 nA @ 35.7 V	Equivalent
Voltage - Forward (Vf) (Max) @ If	1.1 V @ 100 mA	1.1 V @ 100 mA	Equivalent
Operating Temperature Range	-65 to 150°C	-65 to 150°C	Equivalent
Mounting Type	Surface Mount	Surface Mount	Equivalent
Package / Case	SOD-110	SOD-323	Different
Product Status	Obsolete	Active	Upgrade
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent

Engineering Selection Recommendations

The BZX384-B51,115 is the designated manufacturer-recommended substitute for the obsolete BZX284-B51,115. Selection of this substitute is supported by the following factors:

Compliance and Status: The BZX384-B51,115 maintains active product status with full ROHS3 compliance, ensuring long-term availability and regulatory alignment. The obsolete status of the original part necessitates transition to an active equivalent for production continuity.

Electrical Compatibility: Core electrical parameters—zener voltage, tolerance, reverse leakage, and forward voltage—are identical between the two parts. Operating temperature range remains unchanged at -65°C to 150°C, preserving thermal performance specifications.

Power Dissipation Consideration: The substitute part exhibits reduced maximum power dissipation (300 mW versus 400 mW). Circuit designs operating at or near the 400 mW limit of the original part require thermal analysis to confirm the 300 mW rating is adequate for the application.

Package Transition: The shift from SOD-110 to SOD-323 represents standard industry miniaturization. Both packages are surface mount compatible. PCB layout modifications are required to accommodate the smaller SOD-323 footprint.

Frequently Asked Questions (FAQ)

Q: Can the BZX384-B51,115 directly replace the BZX284-B51,115 without circuit modification?

A: Electrical substitution is valid. The zener voltage, tolerance, leakage current, and forward voltage specifications are identical. However, the reduced power rating (300 mW versus 400 mW) requires thermal verification for applications operating near maximum power dissipation. PCB layout changes are mandatory due to package size differences (SOD-110 to SOD-323).

Q: What is the significance of the impedance difference (110 Ohms versus 180 Ohms)?

A: Impedance variation reflects the different package geometries and internal construction. The 180 Ohms impedance of the SOD-323 package is within acceptable range for 51 V zener applications. Circuit performance impact is negligible for typical voltage regulation and transient suppression applications.

Q: Is the BZX384-B51,115 available in the same packaging format as the original part?

A: No. The BZX284-B51,115 is supplied in bulk form, while the BZX384-B51,115 is available in Tape & Reel (TR) packaging. This represents standard industry practice for active components. Reel quantities typically accommodate high-volume production requirements.

Q: Are there any compliance or certification differences between these parts?

A: Both parts maintain ROHS3 compliance, MSL 1 (Unlimited) moisture sensitivity rating, and REACH unaffected status. Regulatory and environmental certifications are equivalent.

Q: What design considerations apply when transitioning from SOD-110 to SOD-323 package?

A: PCB footprint redesign is required. SOD-323 is significantly smaller than SOD-110, enabling higher component density. Thermal management may improve due to reduced package size, though the lower power rating must be verified for the specific application. Assembly process parameters (reflow profile, solder paste) may require adjustment based on manufacturing equipment specifications.

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