MMSZ33T1 Equivalent & Substitute Parts

Part Overview

The MMSZ33T1 is a Zener diode rated at 33 V nominal voltage with 500 mW power dissipation in a surface mount SOD-123 package. This component is classified as obsolete, which necessitates identification of equivalent and substitute parts for ongoing design requirements and procurement needs. Active alternatives with identical or comparable electrical characteristics are available from multiple manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	33	V
Tolerance	±5%	—
Power - Max	500	mW
Impedance (Max)	80	Ohms
Current - Reverse Leakage @ Vr	50	nA @ 23.1 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature	-55°C ~ 150°C	—
Mounting Type	Surface Mount	—
Package / Case	SOD-123	—

Substitute Part Grouping Explanation

Substitution of the MMSZ33T1 is determined by the following critical parameters: nominal Zener voltage (33 V), power dissipation capability, package type, and operating temperature range. Parts are grouped into three categories based on electrical equivalence and application suitability.

Direct Equivalents maintain all key electrical parameters (33 V nominal, 500 mW power, ±5% tolerance, 80 Ohm impedance) and SOD-123 packaging. These parts are interchangeable without circuit modification.

Parametric Equivalents retain the 33 V nominal voltage and core electrical characteristics but may differ in packaging designation (Tape & Reel versus bulk) or include automotive-grade qualification. These parts satisfy the same electrical function with identical performance specifications.

Similar Parts maintain the 33 V nominal voltage and SOD-123 or compatible package family but differ in one or more of the following: power dissipation rating, impedance, tolerance, or operating temperature range. Selection of similar parts requires circuit-level analysis to confirm adequacy for the intended application.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Package	Product Status	RoHS Status
MMSZ33T1	onsemi	33 V	±5%	500 mW	80 Ω	SOD-123	Obsolete	Non-compliant
MMSZ33T1G	onsemi	33 V	±5%	500 mW	80 Ω	SOD-123	Active	ROHS3 Compliant
SZMMSZ33ET1G	onsemi	33 V	±5%	500 mW	80 Ω	SOD-123	Active	ROHS3 Compliant
SZMMSZ33ET3G	onsemi	33 V	±5%	500 mW	80 Ω	SOD-123	Active	ROHS3 Compliant
SZMMSZ33T1G	onsemi	33 V	±5%	500 mW	80 Ω	SOD-123	Active	ROHS3 Compliant
BZT52C33-TP	Micro Commercial Co	33 V	±6%	200 mW	80 Ω	SOD-123	Active	ROHS3 Compliant
BZT52H-C33,115	Nexperia USA Inc.	33 V	±5%	375 mW	40 Ω	SOD-123F	Active	ROHS3 Compliant
DDZ33-7	Diodes Incorporated	33 V	±2.5%	310 mW	75 Ω	SOD-123	Active	ROHS3 Compliant
PDZ33B,115	Nexperia USA Inc.	33 V	±2%	400 mW	40 Ω	SOD-323	Active	ROHS3 Compliant
PZU33BA,115	Nexperia USA Inc.	33 V	±5%	320 mW	40 Ω	SOD-323	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (Preferred): MMSZ33T1G is the primary direct equivalent. This part is manufactured by onsemi, maintains identical electrical specifications (33 V, 500 mW, ±5%, 80 Ω), and is available in active product status with ROHS3 compliance. The transition from MMSZ33T1 (obsolete, non-compliant) to MMSZ33T1G requires no circuit modification.

Automotive-Grade Alternatives: SZMMSZ33ET1G, SZMMSZ33ET3G, and SZMMSZ33T1G are automotive-qualified variants (AEC-Q101) with identical electrical parameters. These parts are suitable for applications requiring automotive-grade components and are available in active status with ROHS3 compliance.

Lower Power Alternatives: BZT52C33-TP (200 mW) and DDZ33-7 (310 mW) are suitable only when circuit design permits reduced power dissipation. BZT52C33-TP introduces ±6% tolerance versus the original ±5%. DDZ33-7 offers improved tolerance (±2.5%) but reduced power rating.

Alternative Package Options: PDZ33B,115 and PZU33BA,115 use SOD-323 packaging instead of SOD-123. These parts are suitable only when PCB layout accommodates the different package footprint. PDZ33B,115 offers ±2% tolerance and 400 mW power; PZU33BA,115 provides ±5% tolerance and 320 mW power.

Nexperia BZT52H-C33,115: This part uses SOD-123F packaging (distinct from SOD-123) with 375 mW power rating and lower impedance (40 Ω). Selection requires confirmation that SOD-123F footprint compatibility exists in the target application.

Frequently Asked Questions (FAQ)

Q: Can MMSZ33T1G be used as a direct replacement for MMSZ33T1?

A: Yes. MMSZ33T1G is a direct equivalent with identical electrical specifications (33 V nominal, 500 mW, ±5% tolerance, 80 Ω impedance) and SOD-123 packaging. The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 compliant versus non-compliant). No circuit modification is required.

Q: What is the difference between MMSZ33T1G and the automotive-qualified variants (SZMMSZ33ET1G, SZMMSZ33ET3G, SZMMSZ33T1G)?

A: The automotive variants carry AEC-Q101 qualification and are designated for automotive applications. Electrical specifications remain identical to MMSZ33T1G. Selection depends on application requirements; automotive-grade parts are necessary only for automotive or safety-critical applications.

Q: Can BZT52C33-TP be used as a substitute?

A: BZT52C33-TP is a similar part with 33 V nominal voltage and SOD-123 packaging but differs in power rating (200 mW versus 500 mW) and tolerance (±6% versus ±5%). This part is suitable only if circuit design analysis confirms that 200 mW power dissipation is adequate for the application. The reduced power rating and increased tolerance may affect circuit performance.

Q: Why do PDZ33B,115 and PZU33BA,115 use different packaging (SOD-323)?

A: PDZ33B,115 and PZU33BA,115 are manufactured in SOD-323 (SC-76) package, which is physically distinct from SOD-123. These parts are suitable only when the PCB layout and component placement accommodate SOD-323 footprint. Package compatibility must be confirmed before selection.

Q: What is the significance of the impedance (Zzt) parameter in selecting a substitute?

A: Impedance affects the dynamic response of the Zener diode under transient conditions. The original MMSZ33T1 specifies 80 Ω maximum impedance. Substitutes with lower impedance (such as BZT52H-C33,115 and PDZ33B,115 at 40 Ω) provide improved transient response but may alter circuit behavior. Substitutes with similar impedance (DDZ33-7 at 75 Ω) are more directly compatible.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All active substitute parts listed are ROHS3 compliant. The original MMSZ33T1 is RoHS non-compliant. Transition to any active substitute ensures compliance with current environmental regulations.

Q: Can DDZ33-7 be used despite its lower power rating (310 mW)?

A: DDZ33-7 is suitable only if circuit analysis confirms that maximum power dissipation does not exceed 310 mW under all operating conditions. DDZ33-7 offers superior tolerance (±2.5% versus ±5%), which may be beneficial in precision applications. However, the reduced power margin requires careful thermal and electrical analysis.

Q: What is the difference between tape and reel (TR) packaging and bulk packaging?

A: Tape and reel packaging is suitable for automated assembly processes and high-volume production. Bulk packaging is used for manual assembly or lower-volume applications. Electrical performance is identical; the difference is in handling and assembly methodology. MMSZ33T1G, SZMMSZ33ET1G, SZMMSZ33T1G, and all similar parts listed are available in tape and reel format.

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