MMSZ5251B-TP Zener Diode 22V 500mW SOD-123 Equivalent & Substitute Parts

Part Overview

The MMSZ5251B-TP is a surface mount Zener diode manufactured by Micro Commercial Co, rated for 22 V nominal Zener voltage with 500 mW maximum power dissipation in SOD-123 package. This component is Active status and ROHS3 compliant. Equivalent and substitute parts are identified to support design flexibility, supply chain continuity, and component availability across multiple manufacturers including onsemi, Vishay, Diodes Incorporated, and Central Semiconductor Corp.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	22	V
Tolerance	±5%	—
Power - Max	500	mW
Impedance (Max)	29	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 17 V	—
Voltage - Forward (Max) @ If	900 mV @ 10 mA	—
Operating Temperature	-55°C to 150°C	—
Package / Case	SOD-123	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the MMSZ5251B-TP are classified based on electrical and mechanical compatibility. The primary substitution criteria are:

Critical Parameters for Substitution:

Zener voltage: 22 V nominal
Tolerance: ±5% or tighter
Power rating: 500 mW or greater
Package: SOD-123 (direct substitutes) or SOD-323 (similar with reduced power)
Mounting type: Surface Mount
Operating temperature range: -55°C to 150°C minimum
RoHS3 compliance and MSL 1 rating

Direct Substitutes (SOD-123, 500 mW): Parts meeting all critical parameters with identical or superior electrical characteristics.

Similar Substitutes (SOD-123, 500 mW, different impedance): Parts with matching voltage, power, and package but variations in impedance or leakage current within acceptable ranges.

Similar Substitutes (SOD-323, 200 mW): Parts with matching voltage and package family but reduced power rating, suitable for lower power applications.

Automotive Grade Substitutes: Parts qualified to AEC-Q101 standard for automotive applications.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Reverse Leakage @ Vr	Package	Status	Classification
MMSZ5251B-TP	Micro Commercial Co	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	Main Part
MMSZ22T1G	onsemi	22 V	±5%	500 mW	55 Ω	50 nA @ 15.4 V	SOD-123	Active	Direct Substitute
MMSZ4708T1G	onsemi	22 V	±5%	500 mW	—	10 nA @ 16.7 V	SOD-123	Active	Direct Substitute
SZMMSZ22T1G	onsemi	22 V	±5%	500 mW	55 Ω	50 nA @ 15.4 V	SOD-123	Active	Direct Substitute (Automotive)
BZT52B22-E3-08	Vishay General Semiconductor	22 V	±2%	410 mW	55 Ω	100 nA @ 17 V	SOD-123	Active	Similar Substitute
BZT52C22S-7-F	Diodes Incorporated	22 V	±6%	200 mW	55 Ω	100 nA @ 15.4 V	SOD-323	Active	Similar Substitute (Reduced Power)
CMHZ5251B TR PBFREE	Central Semiconductor Corp	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	Direct Substitute
DDZ22D-7	Diodes Incorporated	22 V	±3%	500 mW	30 Ω	50 nA @ 17 V	SOD-123	Active	Direct Substitute
DDZ9708-7	Diodes Incorporated	22 V	±5%	500 mW	—	50 nA @ 16.7 V	SOD-123	Active	Direct Substitute
MMSZ5251B-7-F	Diodes Incorporated	22 V	±5%	500 mW	29 Ω	100 nA @ 17 V	SOD-123	Active	Direct Substitute
MMSZ5251BS-7-F	Diodes Incorporated	22 V	±5%	200 mW	29 Ω	100 nA @ 17 V	SOD-323	Active	Similar Substitute (Reduced Power)

Engineering Selection Recommendations

Direct Substitutes (Recommended for 1:1 Replacement):

The following parts are functionally equivalent to MMSZ5251B-TP and support direct substitution in designs requiring 22 V, 500 mW Zener diodes in SOD-123 package:

MMSZ22T1G (onsemi): Identical electrical specifications with lower reverse leakage current (50 nA vs. 100 nA). Higher impedance (55 Ω vs. 29 Ω) has minimal impact on typical applications.
MMSZ4708T1G (onsemi): Superior reverse leakage performance (10 nA). Recommended for low-leakage applications.
CMHZ5251B TR PBFREE (Central Semiconductor Corp): Identical impedance and leakage characteristics to main part. Direct pin-compatible replacement.
DDZ22D-7 (Diodes Incorporated): Tighter tolerance (±3%) and lower impedance (30 Ω). Suitable for precision voltage regulation applications.
DDZ9708-7 (Diodes Incorporated): Matches main part specifications with extended temperature range to -65°C.
MMSZ5251B-7-F (Diodes Incorporated): Identical electrical characteristics. Available in Cut Tape and Digi-Reel packaging.

Automotive Grade Substitute:

SZMMSZ22T1G (onsemi): AEC-Q101 qualified automotive-grade equivalent. Identical to MMSZ22T1G with automotive qualification. Required for automotive applications.

Similar Substitutes (Power Reduction):

The following parts have reduced power ratings (200 mW vs. 500 mW) and different package (SOD-323 vs. SOD-123). These are suitable only for applications with lower power dissipation requirements:

BZT52C22S-7-F (Diodes Incorporated): 200 mW rating, SOD-323 package. Tighter tolerance (±6%). Extended temperature range to -65°C.
MMSZ5251BS-7-F (Diodes Incorporated): 200 mW rating, SOD-323 package. Identical impedance to main part.

Similar Substitute (Power Reduction, Tighter Tolerance):

BZT52B22-E3-08 (Vishay): 410 mW rating (reduced from 500 mW), SOD-123 package. Tighter tolerance (±2%). Suitable for applications where power dissipation is not critical and tolerance precision is required.

All listed parts are Active status, ROHS3 compliant, and carry MSL 1 (Unlimited) moisture sensitivity rating, matching the main part's compliance profile.

Frequently Asked Questions (FAQ)

Q: Can MMSZ22T1G directly replace MMSZ5251B-TP?

A: Yes. MMSZ22T1G is a direct substitute with identical Zener voltage (22 V), tolerance (±5%), power rating (500 mW), and SOD-123 package. The higher impedance (55 Ω vs. 29 Ω) does not affect functionality in standard voltage regulation circuits.

Q: What is the difference between SOD-123 and SOD-323 packages?

A: SOD-123 and SOD-323 are both surface mount packages for diodes but differ in physical dimensions and power handling. SOD-323 is smaller and typically rated for lower power dissipation. Parts listed with SOD-323 package (BZT52C22S-7-F, MMSZ5251BS-7-F) have 200 mW ratings versus 500 mW for SOD-123 variants. Package selection depends on PCB space constraints and power dissipation requirements.

Q: Is SZMMSZ22T1G suitable for automotive applications?

A: Yes. SZMMSZ22T1G carries AEC-Q101 automotive qualification and is designated for automotive-grade applications. It is electrically equivalent to MMSZ22T1G with added automotive certification.

Q: Can I use BZT52B22-E3-08 as a substitute if my circuit dissipates 450 mW?

A: BZT52B22-E3-08 has a maximum power rating of 410 mW. At 450 mW dissipation, this part would exceed its rated power and is not suitable. Use a 500 mW rated part such as MMSZ22T1G, CMHZ5251B TR PBFREE, or DDZ22D-7.

Q: What is the advantage of DDZ22D-7 over MMSZ5251B-TP?

A: DDZ22D-7 offers tighter Zener voltage tolerance (±3% vs. ±5%), lower impedance (30 Ω vs. 29 Ω), and lower reverse leakage current (50 nA vs. 100 nA). These characteristics provide improved voltage regulation precision and are beneficial in precision analog circuits.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity rating, matching the compliance profile of MMSZ5251B-TP.

Q: What is the operating temperature range for substitute parts?

A: Most substitute parts operate from -55°C to 150°C, matching the main part. DDZ22D-7, DDZ9708-7, BZT52C22S-7-F, MMSZ5251B-7-F, and MMSZ5251BS-7-F extend the lower temperature limit to -65°C, providing wider operating range for extreme environment applications.

Q: Can I use MMSZ4708T1G in a high-reliability application?

A: Yes. MMSZ4708T1G demonstrates superior reverse leakage performance (10 nA vs. 100 nA at rated voltage), making it suitable for high-reliability and low-leakage applications. It is Active status and ROHS3 compliant.

Q: What packaging options are available for 22 V, 500 mW Zener diodes?

A: Direct substitutes are available in SOD-123 package (MMSZ22T1G, MMSZ4708T1G, SZMMSZ22T1G, CMHZ5251B TR PBFREE, DDZ22D-7, DDZ9708-7, MMSZ5251B-7-F). MMSZ5251B-7-F is also available in Cut Tape and Digi-Reel packaging. Reduced-power variants (200 mW) are available in SOD-323 package.

Q: Is impedance (Zzt) a critical parameter for substitution?

A: Impedance affects voltage regulation stability and transient response. The main part specifies 29 Ω maximum impedance. Substitute parts with higher impedance (55 Ω) are acceptable for most applications but may show slightly different transient behavior. For precision voltage regulation, select parts with impedance ≤30 Ω (DDZ22D-7, CMHZ5251B TR PBFREE, MMSZ5251B-7-F).

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