MMSZ5256B Equivalent & Substitute Parts

Part Overview

The MMSZ5256B is a 30 V Zener diode rated for 500 mW power dissipation in a surface mount SOD-123 package. Manufactured by onsemi, this component is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary for new designs and ongoing production requirements. Substitute parts maintain the same electrical specifications and package form factor while offering improved availability and compliance with current manufacturing standards.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	30	V
Tolerance	±5	%
Power - Max	500	mW
Impedance (Max)	49	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 23 V	nA
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	mV
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOD-123	—

Substitute Part Grouping Explanation

Substitution of the MMSZ5256B is determined by the following critical parameters:

Zener Voltage (Vz): 30 V nominal with ±5% tolerance
Power Rating: 500 mW maximum
Package Type: SOD-123 surface mount
Operating Temperature Range: -55°C to 150°C
Voltage - Forward (Vf): 900 mV maximum at 10 mA
Tolerance: ±5%

Substitute parts are grouped into three categories:

Direct Manufacturer Substitutes (onsemi): Parts with identical electrical specifications and active product status, including MMSZ30T1G, MMSZ4713T1G, and MMSZ5256BT1G. These parts maintain the same base performance characteristics as the obsolete MMSZ5256B.

Automotive-Grade Equivalents (onsemi): Parts qualified to AEC-Q101 automotive standards with the SZ prefix designation, including SZMMSZ30T1G, SZMMSZ4713T1G, SZMMSZ5256BT1G, and SZMMSZ5256ET1G. These parts meet automotive reliability requirements while maintaining electrical equivalence.

Cross-Manufacturer Equivalent (Diodes Incorporated): The DDZ9713Q-7 from Diodes Incorporated provides electrical equivalence with AEC-Q101 qualification and extended operating temperature range (-65°C to 150°C).

Parameter Comparison

Part Number	Manufacturer	Product Status	Vz (V)	Tolerance (%)	Power (mW)	Zzt (Ohms)	Ir @ Vr (nA)	Vf @ If (mV)	Temp Range (°C)	Grade	RoHS
MMSZ5256B	onsemi	Obsolete	30	±5	500	49	100 @ 23 V	900 @ 10 mA	-55 to 150	Standard	—
MMSZ30T1G	onsemi	Active	30	±5	500	80	50 @ 21 V	900 @ 10 mA	-55 to 150	Standard	ROHS3
MMSZ4713T1G	onsemi	Active	30	±5	500	—	10 @ 22.8 V	900 @ 10 mA	-55 to 150	Standard	ROHS3
MMSZ5256BT1G	onsemi	Active	30	±5	500	49	100 @ 23 V	900 @ 10 mA	-55 to 150	Standard	ROHS3
SZMMSZ30T1G	onsemi	Active	30	±5	500	80	50 @ 21 V	900 @ 10 mA	-55 to 150	Automotive	ROHS3
SZMMSZ4713T1G	onsemi	Active	30	±5	500	—	10 @ 22.8 V	900 @ 10 mA	-55 to 150	Automotive	ROHS3
MMSZ5256ET1G	onsemi	Active	30	±5	500	49	100 @ 23 V	900 @ 10 mA	-55 to 150	Standard	ROHS3
SMMSZ5256BT1G	onsemi	Obsolete	30	±5	500	49	100 @ 23 V	900 @ 10 mA	-55 to 150	Automotive	ROHS3
SZMMSZ5256BT1G	onsemi	Active	30	±5	500	49	100 @ 23 V	900 @ 10 mA	-55 to 150	Automotive	ROHS3
SZMMSZ5256ET1G	onsemi	Active	30	±5	500	49	100 @ 23 V	900 @ 10 mA	-55 to 150	Automotive	ROHS3
DDZ9713Q-7	Diodes Incorporated	Active	30	±5	500	—	50 @ 22.8 V	900 @ 10 mA	-65 to 150	Automotive	ROHS3

Engineering Selection Recommendations

For Standard Industrial Applications: MMSZ5256BT1G, MMSZ5256ET1G, or MMSZ30T1G are direct active-status replacements for the obsolete MMSZ5256B. All three maintain identical electrical specifications and are ROHS3 compliant. MMSZ5256BT1G and MMSZ5256ET1G provide the closest impedance match (49 Ohms) to the original part.

For Automotive Applications: SZMMSZ5256BT1G or SZMMSZ5256ET1G are the preferred selections. Both are AEC-Q101 qualified, automotive-grade components with active product status and ROHS3 compliance. These parts maintain the same impedance (49 Ohms) and reverse leakage characteristics as the original MMSZ5256B.

For Extended Temperature Range Requirements: DDZ9713Q-7 from Diodes Incorporated extends the operating range to -65°C minimum and includes AEC-Q101 automotive qualification. This part is suitable for applications requiring enhanced low-temperature performance.

For General-Purpose Substitution: MMSZ4713T1G or SZMMSZ4713T1G (automotive variant) are functionally equivalent with lower reverse leakage current (10 nA @ 22.8 V) compared to the original specification. These parts are suitable when lower leakage is beneficial to circuit performance.

Frequently Asked Questions (FAQ)

Q: Can MMSZ5256BT1G directly replace MMSZ5256B without circuit modification?

A: Yes. MMSZ5256BT1G maintains identical electrical specifications including 30 V zener voltage, 500 mW power rating, 49 Ohms impedance, and 100 nA reverse leakage at 23 V. The SOD-123 package is mechanically identical. No circuit modifications are required.

Q: What is the difference between standard-grade and automotive-grade (SZ prefix) parts?

A: Automotive-grade parts with the SZ prefix are qualified to AEC-Q101 standards and undergo additional reliability testing for automotive applications. Electrical specifications remain identical to standard-grade equivalents. Selection depends on application requirements and qualification mandates.

Q: Why do some substitute parts have different impedance values?

A: Impedance variation (49 Ohms vs. 80 Ohms) reflects different manufacturing processes within the same voltage and power rating. Both values fall within acceptable zener diode performance parameters. For impedance-critical applications, select parts with matching impedance specifications.

Q: Is MMSZ4713T1G a suitable replacement despite lower reverse leakage?

A: Yes. Lower reverse leakage (10 nA @ 22.8 V vs. 100 nA @ 23 V) is a performance improvement that does not compromise compatibility. This part is suitable for all applications where the original MMSZ5256B was used.

Q: What is the significance of the T1G suffix in part numbers?

A: The T1G suffix indicates Tape & Reel packaging format suitable for automated assembly. This is the standard packaging for surface mount components in production environments.

Q: Can DDZ9713Q-7 from Diodes Incorporated be used in place of onsemi parts?

A: Yes. DDZ9713Q-7 meets all electrical specifications for 30 V, 500 mW zener operation in SOD-123 package. It includes AEC-Q101 automotive qualification and extends the operating temperature range to -65°C. Cross-manufacturer substitution is valid when electrical and package specifications align.

Q: Are all substitute parts ROHS3 compliant?

A: All active-status substitute parts listed are ROHS3 compliant. The original MMSZ5256B does not specify RoHS status due to its obsolete classification. Current production parts meet ROHS3 requirements.

Q: What inventory considerations apply when selecting substitutes?

A: Inventory levels vary across substitute parts. MMSZ5256BT1G has the highest inventory (74,100 pcs), while SZMMSZ5256ET1G has lower availability (3,200 pcs). Selection should account for supply chain requirements and lead time considerations.

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