MMBZ5259B-HE3-08 Equivalent & Substitute Parts

Part Overview

The MMBZ5259B-HE3-08 is a 39 V Zener diode rated at 225 mW, manufactured by Vishay General Semiconductor - Diodes Division in a surface mount SOT-23-3 package. This component is classified as obsolete, which necessitates identification of active equivalent parts for ongoing design support and procurement. The part carries automotive-grade qualification (AEC-Q101) and is RoHS3 compliant, making it suitable for regulated applications requiring long-term component availability and traceability.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	39	V
Tolerance	±5	%
Power - Maximum	225	mW
Impedance (Maximum)	80	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 30 V	nA
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3 (TO-236-3, SC-59)	—
Mounting Type	Surface Mount	—
Grade	Automotive	—
Qualification	AEC-Q101	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5259B-HE3-08 is determined by the following critical parameters:

Electrical Compatibility Requirements:

Zener voltage: 39 V nominal with ±5% tolerance
Reverse leakage current: 100 nA @ 30 V
Impedance (maximum): 80 Ohms or equivalent performance

Mechanical & Package Compatibility:

Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting type: Surface Mount
Moisture Sensitivity Level: 1 (Unlimited)

Regulatory & Compliance Requirements:

RoHS3 compliance
Automotive grade qualification (AEC-Q101)
REACH unaffected status

Substitute parts are grouped into two categories based on power rating:

Category A - Direct Electrical Equivalents (225 mW): Parts maintaining the original 225 mW power specification with identical electrical characteristics.

Category B - Higher Power Alternatives (350 mW): Parts with increased power dissipation capability (350 mW) while maintaining all other electrical and mechanical specifications. These parts provide enhanced thermal margin and are suitable for applications where the original 225 mW rating may approach design limits.

Parameter Comparison

Parameter	MMBZ5259B-HE3-08 (Main)	SZMMBZ5259BLT1G	CMPZ5259B BK PBFREE	CMPZ5259B TR PBFREE	CZRT55C39-G	MMBZ5259B-7-F
Manufacturer	Vishay	onsemi	Central Semiconductor	Central Semiconductor	Comchip Technology	Diodes Incorporated
Voltage - Zener (Nom)	39 V	39 V	39 V	39 V	39 V	39 V
Tolerance	±5%	±5%	±5%	±5%	±5%	±5%
Power - Max	225 mW	225 mW	350 mW	350 mW	350 mW	350 mW
Impedance (Max)	80 Ω	80 Ω	80 Ω	80 Ω	130 Ω	80 Ω
Current - Reverse Leakage @ Vr	100 nA @ 30 V	100 nA @ 30 V	100 nA @ 30 V	100 nA @ 30 V	100 nA @ 27.3 V	100 nA @ 30 V
Voltage - Forward (Vf) Max @ If	—	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA
Operating Temperature	-55 to 150°C	-65 to 150°C	-65 to 150°C	-65 to 150°C	-65 to 150°C	-65 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
Grade	Automotive	Automotive	—	—	—	—
Qualification	AEC-Q101	AEC-Q101	—	—	—	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Packaging	—	Tape & Reel	Bulk	Tape & Reel	Tape & Reel	Tape & Reel

Engineering Selection Recommendations

For Direct Replacement (Electrical & Thermal Equivalence):

SZMMBZ5259BLT1G (onsemi) is the primary direct substitute. This part maintains the 225 mW power rating, identical impedance specification (80 Ω), and carries automotive-grade AEC-Q101 qualification. The extended operating temperature range (-65 to 150°C versus -55 to 150°C) provides additional margin for extreme environment applications. Active product status ensures long-term availability and supply chain continuity.

For Enhanced Thermal Performance:

MMBZ5259B-7-F (Diodes Incorporated), CMPZ5259B TR PBFREE (Central Semiconductor), and CZRT55C39-G (Comchip Technology) offer 350 mW power dissipation capability. These parts are suitable for applications where thermal margin is critical or where the original 225 mW specification approaches design limits. All three maintain the SOT-23-3 package and core electrical specifications.

Impedance Consideration:

CZRT55C39-G exhibits a maximum impedance of 130 Ω compared to the 80 Ω specification of the main part and other substitutes. This parameter difference may affect circuit performance in applications with tight impedance requirements. Verification against circuit design specifications is necessary before selection.

Compliance & Qualification:

SZMMBZ5259BLT1G is the only substitute carrying explicit automotive-grade AEC-Q101 qualification matching the original part. Applications requiring automotive qualification should prioritize this part. Other substitutes are suitable for general industrial and commercial applications where automotive qualification is not mandated.

Frequently Asked Questions (FAQ)

Q: Can MMBZ5259B-7-F replace MMBZ5259B-HE3-08 in automotive applications?

A: MMBZ5259B-7-F is electrically compatible and maintains the SOT-23-3 package specification. However, it does not carry explicit automotive-grade qualification or AEC-Q101 certification in the provided specifications. For applications requiring automotive qualification, SZMMBZ5259BLT1G is the recommended choice.

Q: What is the difference between the 225 mW and 350 mW variants?

A: The 225 mW rating represents the original part's maximum power dissipation capability. The 350 mW variants (CMPZ5259B series, CZRT55C39-G, and MMBZ5259B-7-F) provide increased thermal headroom. Both ratings are suitable for the same circuit applications; the 350 mW parts offer enhanced reliability margin in high-power dissipation scenarios.

Q: Are all substitutes available in the same package?

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

Q: What is the significance of the impedance difference in CZRT55C39-G?

A: CZRT55C39-G specifies a maximum impedance of 130 Ω, compared to 80 Ω for other parts. Impedance affects circuit transient response and voltage regulation characteristics. Applications with impedance-sensitive circuits should verify compatibility before substitution.

Q: Why is SZMMBZ5259BLT1G recommended for automotive applications?

A: SZMMBZ5259BLT1G carries explicit automotive-grade qualification and AEC-Q101 certification, matching the original part's compliance profile. This qualification ensures the part meets automotive industry reliability and testing standards required for regulated applications.

Q: Can I use a 350 mW part in place of a 225 mW part without circuit modification?

A: Yes. The 350 mW parts are electrically and mechanically compatible with the 225 mW specification. Higher power rating provides additional thermal margin and does not degrade circuit performance. No circuit modifications are required.

Q: What is the difference between Tape & Reel and Bulk packaging?

A: Tape & Reel packaging is suitable for automated assembly processes and high-volume production. Bulk packaging is used for manual assembly or lower-volume applications. Both packaging formats contain identical components; the difference is in delivery and handling format only.

Q: Is the extended temperature range of substitute parts a concern?

A: The extended operating range (-65 to 150°C for substitutes versus -55 to 150°C for the original) provides additional margin and does not introduce compatibility issues. Applications operating within the original temperature range are unaffected.

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