MMBZ5259C-G3-18 Equivalent & Substitute Parts

Part Overview

The MMBZ5259C-G3-18 is a Zener diode rated at 39 V nominal voltage with 225 mW maximum power dissipation in a surface mount SOT-23-3 package. Manufactured by Vishay General Semiconductor - Diodes Division, this component is classified as obsolete. Due to its obsolete status and limited ongoing availability, equivalent substitute parts with active product status are necessary for new designs and ongoing production requirements. Substitute parts maintain the core electrical specifications while offering improved availability and extended product lifecycles.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	39	V
Tolerance	±2%	—
Power - Max	225	mW
Impedance (Max)	80	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 30 V	—
Operating Temperature Range	-55°C to 150°C	—
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5259C-G3-18 is determined by the following critical parameters:

Electrical Compatibility Requirements:

Zener voltage: 39 V nominal (primary specification)
Voltage tolerance: ±2% to ±5% acceptable
Reverse leakage current: 100 nA @ 27.3 V to 30 V
Operating temperature range: -55°C minimum to 150°C maximum

Mechanical Compatibility Requirements:

Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting type: Surface Mount

Acceptable Variations:

Power dissipation: 225 mW or higher (substitute parts rated 350 mW are acceptable as they provide equal or greater capability)
Impedance: 80 Ohms to 130 Ohms (within acceptable range for this application class)
Voltage tolerance: ±5% is acceptable for applications originally designed for ±2% (represents a relaxation of specification)

All substitute parts listed maintain the 39 V zener voltage specification, SOT-23-3 package format, and surface mount configuration. Substitute parts with higher power ratings (350 mW) provide enhanced thermal margin and are electrically compatible with the original 225 mW specification.

Parameter Comparison

Parameter	MMBZ5259C-G3-18 (Main)	BZX84B39-TP	CMPZ5259B BK PBFREE	CMPZ5259B TR PBFREE	CZRT55C39-G	SZMMBZ5259BLT1G
Manufacturer	Vishay	Micro Commercial Co	Central Semiconductor	Central Semiconductor	Comchip Technology	onsemi
Voltage - Zener (Nom)	39 V	39 V	39 V	39 V	39 V	39 V
Tolerance	±2%	±2%	±5%	±5%	±5%	±5%
Power - Max	225 mW	350 mW	350 mW	350 mW	350 mW	225 mW
Impedance (Max)	80 Ohms	130 Ohms	80 Ohms	80 Ohms	130 Ohms	80 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 30 V	100 nA @ 27.3 V	100 nA @ 30 V	100 nA @ 30 V	100 nA @ 27.3 V	100 nA @ 30 V
Operating Temperature	-55°C to 150°C	-55°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C
Package / Case	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Compliance	ROHS3 Compliant	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	—	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitute Recommendation: SZMMBZ5259BLT1G (onsemi)

The SZMMBZ5259BLT1G is the optimal substitute for the MMBZ5259C-G3-18. This part maintains identical electrical specifications (39 V, 225 mW, 80 Ohms impedance) and package configuration. The part is active with extensive inventory availability (13,293 pcs). The component carries AEC-Q101 automotive qualification and is suitable for applications requiring automotive-grade reliability. Extended operating temperature range (-65°C to 150°C) provides additional margin beyond the original specification.

Secondary Substitute Recommendations:

CMPZ5259B TR PBFREE (Central Semiconductor Corp) offers the highest inventory availability (6,834 pcs) in tape and reel packaging. While rated for 350 mW power dissipation and ±5% tolerance, this part is electrically compatible and provides enhanced thermal performance. Extended temperature range (-65°C to 150°C) exceeds original specifications.

CMPZ5259B BK PBFREE (Central Semiconductor Corp) provides identical electrical characteristics to the tape and reel variant with 1,029 pcs available in bulk packaging. Selection between bulk and tape formats depends on production volume and assembly requirements.

BZX84B39-TP (Micro Commercial Co) maintains ±2% tolerance matching the original specification with 350 mW power rating. This part is suitable for applications requiring tighter voltage tolerance specifications.

CZRT55C39-G (Comchip Technology) offers 350 mW power rating with 1,010 pcs inventory availability. This part is suitable for applications requiring enhanced thermal margin.

All substitute parts are ROHS3 compliant, REACH unaffected, and classified under ECCN EAR99 with identical HTSUS coding (8541.10.0050) to the original part.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part rated for 350 mW instead of the original 225 mW specification?

A: Yes. A higher power rating (350 mW) is electrically compatible with applications designed for 225 mW. The substitute part provides equal or greater thermal capability and will function correctly in the original circuit. The zener voltage, impedance, and reverse leakage characteristics remain within acceptable parameters.

Q: What is the difference between ±2% and ±5% tolerance specifications?

A: The original MMBZ5259C-G3-18 specifies ±2% voltage tolerance, meaning the zener voltage will be between 38.22 V and 39.78 V. Substitute parts with ±5% tolerance will be between 37.05 V and 40.95 V. For applications requiring the tighter ±2% specification, select BZX84B39-TP. For applications with relaxed tolerance requirements, ±5% parts are acceptable.

Q: Are all substitute parts in the same SOT-23-3 package?

A: Yes. All listed substitute parts use the SOT-23-3 package (also designated TO-236-3 or SC-59). Pin configuration and footprint are identical, enabling direct board-level substitution without layout modifications.

Q: What is the difference between bulk and tape & reel packaging?

A: Bulk packaging is suitable for small-quantity orders and manual assembly. Tape & reel packaging is designed for automated pick-and-place assembly equipment and high-volume production. Electrical specifications are identical; packaging format selection depends on assembly process requirements.

Q: Does the SZMMBZ5259BLT1G automotive qualification affect its use in non-automotive applications?

A: No. AEC-Q101 automotive qualification indicates the part meets enhanced reliability and testing standards. Parts qualified to automotive standards are suitable for all applications, including non-automotive use. The qualification represents an additional quality assurance level.

Q: Can I substitute parts with different impedance values (80 Ohms vs. 130 Ohms)?

A: Yes. Both impedance values are within acceptable range for this zener diode category. Impedance affects transient response characteristics. For applications sensitive to impedance specifications, select parts with matching impedance values. For general applications, both values are compatible.

Q: What is the significance of the extended temperature range (-65°C to 150°C) in substitute parts?

A: The original part specifies -55°C to 150°C. Substitute parts with -65°C to 150°C range provide additional low-temperature margin. This extended range is beneficial for applications operating in cold environments or requiring enhanced thermal margin. The extended range does not negatively affect applications within the original -55°C to 150°C specification.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant, matching the original part's environmental compliance status. All parts are REACH unaffected and classified under ECCN EAR99.

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