MMSZ22T3G Equivalent & Substitute Parts

Part Overview

The MMSZ22T3G is a Zener diode manufactured by onsemi, rated at 22 V nominal voltage with 500 mW power dissipation in a surface mount SOD-123 package. This component is classified as obsolete, indicating that direct procurement from original inventory may be limited. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for applications requiring 22 V Zener regulation in compact surface mount form factors.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	22	V
Tolerance	±5%	%
Power - Max	500	mW
Impedance (Max)	55	Ohms
Current - Reverse Leakage @ Vr	50 nA @ 15.4 V	nA
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	mV
Operating Temperature	-55 to 150	°C
Package / Case	SOD-123	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the MMSZ22T3G is determined by the following critical parameters:

Primary Substitution Criteria:

Voltage - Zener (Nom): 22 V
Power - Max: 500 mW
Package / Case: SOD-123
Mounting Type: Surface Mount
Operating Temperature Range: -55°C to 150°C

Secondary Compatibility Factors:

Tolerance: ±5% (primary specification)
Voltage - Forward (Vf) (Max) @ If: 900 mV @ 10 mA
Impedance (Max) (Zzt): 55 Ohms (standard specification)

Substitute parts are grouped into two categories:

Direct Equivalents (Identical Electrical and Mechanical Specifications): Parts that maintain all primary and secondary parameters within the specified tolerances, differing only in product status (active vs. obsolete) or packaging format (Tape & Reel vs. Cut Tape).

Parametric Equivalents (Modified Electrical Characteristics): Parts that maintain the 22 V nominal voltage, 500 mW power rating, and SOD-123 package but feature different impedance values (29 Ohms vs. 55 Ohms) or reverse leakage current specifications. These parts are functionally compatible in most applications but exhibit different dynamic impedance characteristics.

Similar Parts (Different Package or Power Rating): Parts that maintain the 22 V nominal voltage and surface mount technology but use alternative packages (SOD-323) or reduced power ratings (400 mW). These require circuit board layout modifications and are suitable only when space constraints or power requirements permit.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Vr Leakage	Package	Product Status	RoHS / AEC-Q101
MMSZ22T3G	onsemi	22 V	±5%	500 mW	55 Ω	50 nA @ 15.4 V	SOD-123	Obsolete	—
MMSZ22T1G	onsemi	22 V	±5%	500 mW	55 Ω	50 nA @ 15.4 V	SOD-123	Active	ROHS3
MMSZ4708T1G	onsemi	22 V	±5%	500 mW	—	10 nA @ 16.7 V	SOD-123	Active	ROHS3
MMSZ5251BT1G	onsemi	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	ROHS3
SZMMSZ5251BT1G	onsemi	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	ROHS3 / AEC-Q101
SZMMSZ5251ET1G	onsemi	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	ROHS3 / AEC-Q101
SZMMSZ22T1G	onsemi	22 V	±5%	500 mW	55 Ω	50 nA @ 15.4 V	SOD-123	Active	ROHS3 / AEC-Q101
MMSZ5251B-TP	Micro Commercial Co	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	ROHS3
PDZ22B,115	Nexperia USA Inc.	22 V	±2%	400 mW	25 Ω	50 nA @ 17 V	SOD-323	Active	ROHS3
PDZ22B,135	Nexperia USA Inc.	22 V	±2%	400 mW	25 Ω	50 nA @ 17 V	SOD-323	Active	ROHS3

Engineering Selection Recommendations

Recommended Primary Substitutes (Direct Equivalents):

MMSZ22T1G is the preferred direct replacement for MMSZ22T3G. This part maintains identical electrical specifications (22 V nominal, ±5% tolerance, 500 mW power, 55 Ω impedance) and SOD-123 package configuration. The part is active in production status and ROHS3 compliant, ensuring long-term availability and regulatory compliance.

SZMMSZ22T1G provides an alternative direct equivalent with identical electrical parameters and automotive-grade qualification (AEC-Q101). This part is suitable for applications requiring automotive-level reliability and traceability.

Recommended Secondary Substitutes (Parametric Equivalents):

MMSZ5251BT1G, SZMMSZ5251BT1G, SZMMSZ5251ET1G, and MMSZ5251B-TP are functionally compatible substitutes featuring reduced impedance (29 Ω vs. 55 Ω) and increased reverse leakage current (100 nA vs. 50 nA). These parts maintain the 22 V nominal voltage, ±5% tolerance, 500 mW power rating, and SOD-123 package. The SZMMSZ series parts include AEC-Q101 automotive qualification.

MMSZ4708T1G offers an alternative with superior reverse leakage characteristics (10 nA @ 16.7 V) while maintaining all other primary specifications.

Alternative Substitutes (Different Package):

PDZ22B,115 and PDZ22B,135 are functionally similar parts manufactured by Nexperia USA Inc. These components feature the same 22 V nominal voltage but use the SOD-323 package (smaller form factor) and reduced power rating (400 mW). These parts are suitable only when circuit board space constraints permit package substitution and application power requirements do not exceed 400 mW. The ±2% tolerance provides improved voltage accuracy compared to the ±5% specification of the primary part.

Compliance and Availability:

All recommended active substitutes are ROHS3 compliant and REACH unaffected. Automotive-grade variants (SZMMSZ series) carry AEC-Q101 qualification for applications requiring automotive reliability standards. Current inventory levels support immediate procurement for all active parts listed.

Frequently Asked Questions (FAQ)

Q: Can MMSZ22T1G be used as a direct replacement for MMSZ22T3G?

A: Yes. MMSZ22T1G is a direct electrical and mechanical equivalent. Both parts specify 22 V nominal voltage, ±5% tolerance, 500 mW power dissipation, 55 Ω maximum impedance, and SOD-123 surface mount package. The primary difference is product status: MMSZ22T1G is active in production, while MMSZ22T3G is obsolete.

Q: What is the difference between MMSZ22T1G and MMSZ5251BT1G?

A: Both parts maintain the 22 V nominal voltage, ±5% tolerance, 500 mW power rating, and SOD-123 package. The key differences are impedance (55 Ω vs. 29 Ω) and reverse leakage current (50 nA @ 15.4 V vs. 100 nA @ 17 V). The MMSZ5251BT1G exhibits lower impedance and higher leakage, making it suitable for applications where these characteristics are acceptable or beneficial.

Q: Are the SZMMSZ series parts suitable for automotive applications?

A: Yes. SZMMSZ5251BT1G, SZMMSZ5251ET1G, and SZMMSZ22T1G carry AEC-Q101 automotive qualification. These parts are suitable for automotive-grade applications requiring documented reliability and traceability standards.

Q: Can PDZ22B,115 or PDZ22B,135 replace MMSZ22T3G in all applications?

A: PDZ22B,115 and PDZ22B,135 maintain the 22 V nominal voltage but differ in three aspects: package (SOD-323 vs. SOD-123), power rating (400 mW vs. 500 mW), and tolerance (±2% vs. ±5%). These parts are suitable only when circuit board layout accommodates the smaller SOD-323 package and application power requirements do not exceed 400 mW. The improved ±2% tolerance may provide design benefits in voltage-critical applications.

Q: What is the significance of impedance differences between substitute parts?

A: Impedance (Zzt) affects the dynamic response of the Zener diode to transient voltage changes. Lower impedance (29 Ω) provides faster transient response and lower output impedance, beneficial in high-frequency noise filtering applications. Higher impedance (55 Ω) is suitable for standard voltage regulation applications. Selection depends on specific circuit requirements.

Q: Are all substitute parts ROHS3 compliant?

A: All active substitute parts listed are ROHS3 compliant. The original MMSZ22T3G does not specify RoHS status due to its obsolete classification. All recommended substitutes meet current environmental and regulatory requirements.

Q: What is the difference between Tape & Reel (TR) and Cut Tape (CT) packaging?

A: Tape & Reel packaging is supplied on continuous tape suitable for automated pick-and-place assembly equipment. Cut Tape & Digi-Reel packaging provides smaller quantities on tape segments. Both formats contain identical components; packaging format selection depends on production volume and assembly equipment compatibility.

Q: Can MMSZ4708T1G be used where MMSZ22T1G is specified?

A: Yes. MMSZ4708T1G maintains the 22 V nominal voltage, ±5% tolerance, 500 mW power rating, and SOD-123 package. The primary advantage is superior reverse leakage performance (10 nA @ 16.7 V vs. 50 nA @ 15.4 V), making it suitable for applications requiring minimal leakage current.

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