MMBZ5229B Zener Diode Equivalent & Substitute Parts

Part Overview

The MMBZ5229B is a 4.3 V Zener diode manufactured by onsemi, rated for 350 mW maximum power dissipation in a surface mount SOT-23-3 package. This component is classified as obsolete, indicating discontinuation from the original manufacturer. Identification of equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this Zener diode specification.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	4.3	V
Tolerance	±5%	—
Power - Maximum	350	mW
Impedance (Maximum)	22	Ohms
Current - Reverse Leakage @ 1 V	5	µA
Voltage - Forward (Maximum) @ 10 mA	900	mV
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5229B is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Zener voltage: 4.3 V nominal
Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting configuration: Surface mount
Moisture sensitivity level: 1 (Unlimited)

Secondary Compatibility Factors:

Power rating: 350 mW (primary specification) or 225 mW (reduced rating acceptable for lower power applications)
Voltage tolerance: ±5% (primary) or ±7% (acceptable with design margin verification)
Impedance: 22 Ohms (primary) or 90 Ohms (acceptable with circuit analysis)
Operating temperature range: -55°C to 150°C (primary) or -65°C to 150°C (extended lower limit acceptable)
Reverse leakage current: 5 µA @ 1 V (primary) or 3 µA @ 1 V (improved specification)

Substitute parts are grouped into three categories: direct equivalents (matching 350 mW power rating), functional equivalents (225 mW power rating with compatible electrical characteristics), and manufacturer alternatives (different manufacturers with identical specifications).

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Temp Range (°C)	Status	RoHS
MMBZ5229B	onsemi	4.3	±5%	350	22	-55 to 150	Obsolete	—
BZX84C4V3LT1G	onsemi	4.3	±7%	225	90	-65 to 150	Active	ROHS3
BZX84C4V3LT3G	onsemi	4.3	±7%	225	90	-65 to 150	Active	ROHS3
MMBZ5229BLT1G	onsemi	4.3	±5%	225	22	-65 to 150	Active	ROHS3
SZBZX84C4V3ET1G	onsemi	4.3	±7%	225	90	-65 to 150	Active	ROHS3
SZBZX84C4V3LT1G	onsemi	4.3	±7%	225	90	-65 to 150	Active	ROHS3
SZMMBZ5229BLT1G	onsemi	4.3	±5%	225	22	-65 to 150	Active	ROHS3
CMPZ5229B BK PBFREE	Central Semiconductor Corp	4.3	±5%	350	22	-65 to 150	Active	ROHS3
CMPZ5229B TR PBFREE	Central Semiconductor Corp	4.3	±5%	350	22	-65 to 150	Active	ROHS3
MMBZ5229B-7	Diodes Incorporated	4.3	±5%	350	22	-65 to 150	Discontinued	Non-compliant
MMBZ5229B-7-F	Diodes Incorporated	4.3	±5%	350	22	-65 to 150	Active	ROHS3

Engineering Selection Recommendations

Direct Equivalents (350 mW, ±5% Tolerance):

The CMPZ5229B BK PBFREE and CMPZ5229B TR PBFREE (Central Semiconductor Corp) provide direct electrical and mechanical equivalence to the MMBZ5229B. Both parts maintain the 350 mW power rating, ±5% voltage tolerance, and 22 Ohm impedance specification. These components are active products with ROHS3 compliance, offering superior supply chain availability compared to the obsolete original part. The CMPZ5229B TR PBFREE in cut tape packaging is recommended for production environments requiring standard tape and reel formats.

The MMBZ5229B-7-F (Diodes Incorporated) is an active alternative with identical electrical specifications and ROHS3 compliance. This part is suitable for applications where Diodes Incorporated qualification is required.

Functional Equivalents (225 mW, ±5% Tolerance, 22 Ohm Impedance):

The MMBZ5229BLT1G and SZMMBZ5229BLT1G (onsemi) maintain the ±5% voltage tolerance and 22 Ohm impedance of the original part while reducing maximum power dissipation to 225 mW. Both are active products with ROHS3 compliance and extended operating temperature range (-65°C to 150°C). The SZMMBZ5229BLT1G includes automotive-grade qualification (AEC-Q101), suitable for automotive applications. These parts are appropriate for applications where the 225 mW power rating is sufficient.

Alternative Equivalents (225 mW, ±7% Tolerance, 90 Ohm Impedance):

The BZX84C4V3LT1G, BZX84C4V3LT3G, SZBZX84C4V3ET1G, and SZBZX84C4V3LT1G (onsemi) provide functional substitution with relaxed voltage tolerance (±7%) and increased impedance (90 Ohms). These parts are active with ROHS3 compliance. The SZBZX84C4V3ET1G and SZBZX84C4V3LT1G include automotive-grade qualification (AEC-Q101). Selection of these alternatives requires circuit analysis to confirm tolerance and impedance compatibility.

Product Status Considerations:

The original MMBZ5229B is obsolete. Active substitute parts ensure long-term supply availability and compliance with current manufacturing standards. ROHS3-compliant alternatives are recommended for new designs and ongoing production to meet regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can the MMBZ5229B be directly replaced with a 225 mW rated substitute?

A: Yes, provided the application circuit operates within the reduced power dissipation limit. The MMBZ5229BLT1G and SZMMBZ5229BLT1G maintain the ±5% voltage tolerance and 22 Ohm impedance of the original part. Circuit analysis is required to confirm thermal and electrical performance at the lower power rating.

Q: What is the difference between ±5% and ±7% voltage tolerance substitutes?

A: The MMBZ5229B specifies ±5% tolerance, while alternatives such as BZX84C4V3LT1G specify ±7%. The wider tolerance may affect voltage regulation precision in sensitive applications. Design margin verification is necessary when selecting ±7% tolerance parts.

Q: Are automotive-grade substitutes (AEC-Q101) compatible with non-automotive applications?

A: Yes. Automotive-grade parts meet or exceed standard industrial specifications. SZMMBZ5229BLT1G and SZBZX84C4V3LT1G are automotive-qualified alternatives suitable for any application requiring the specified electrical characteristics.

Q: What is the significance of impedance differences (22 Ohms vs. 90 Ohms)?

A: Impedance affects dynamic response and voltage regulation characteristics. The original MMBZ5229B specifies 22 Ohms maximum impedance. Substitutes with 90 Ohms impedance (BZX84C4V3LT1G series) exhibit different transient response. Circuit analysis is required to confirm compatibility in applications sensitive to impedance variation.

Q: Which substitute offers the best supply chain availability?

A: The CMPZ5229B BK PBFREE and CMPZ5229B TR PBFREE (Central Semiconductor Corp) and MMBZ5229B-7-F (Diodes Incorporated) are active products with high inventory levels and direct electrical equivalence to the original part.

Q: Are all substitutes RoHS compliant?

A: All recommended active substitutes are ROHS3 compliant except MMBZ5229B-7 (Diodes Incorporated), which is RoHS non-compliant. ROHS3-compliant alternatives are required for applications subject to RoHS regulations.

Q: What is the difference between cut tape (CT) and tape & reel (TR) packaging?

A: Cut tape packaging is supplied in individual strips suitable for manual assembly or small-volume production. Tape & reel packaging is supplied on continuous reels for automated pick-and-place assembly. Both formats contain identical components; packaging selection depends on assembly process requirements.

Q: Can the operating temperature range difference (-55°C to 150°C vs. -65°C to 150°C) affect part selection?

A: The original MMBZ5229B operates from -55°C to 150°C. Most active substitutes extend the lower limit to -65°C, providing enhanced cold-temperature performance. This difference does not restrict substitution; the extended range is a specification improvement.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message