MMSZ5256B-7 Equivalent & Substitute Parts

Part Overview

The MMSZ5256B-7 is a Zener diode rated at 30 V nominal voltage with 500 mW maximum power dissipation in a surface mount SOD-123 package. Manufactured by Diodes Incorporated, this component is designed for voltage regulation and protection applications in electronic circuits. The part is currently discontinued at DiGi Electronics, necessitating identification of equivalent and substitute components that maintain functional compatibility while meeting current procurement requirements.

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	—
Voltage - Forward (Max) @ If	900 mV @ 10 mA	—
Operating Temperature	-65°C to 150°C	—
Mounting Type	Surface Mount	—
Package / Case	SOD-123	—

Substitute Part Grouping Explanation

Substitution of the MMSZ5256B-7 is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 30 V nominal
Package type: SOD-123 (surface mount)
Mounting type: Surface mount
Operating temperature range: Minimum -55°C to 150°C (acceptable if equal to or exceeding the original -65°C to 150°C range)

Secondary Compatibility Factors:

Power dissipation: 500 mW or greater
Tolerance: ±5% or tighter
Impedance: 49 Ohms or lower (lower impedance provides better regulation)
Reverse leakage current: 100 nA or lower @ specified voltage

Substitute parts are grouped into two categories:

Category A - Direct Parametric Equivalents: Parts matching all primary criteria with identical or superior secondary parameters. These include MMSZ5256B-7-F (Diodes Incorporated) and MMSZ30T1G (onsemi).

Category B - Functional Equivalents: Parts meeting primary criteria with acceptable variations in secondary parameters. These include Vishay BZT52 series components, Comchip CZRW5256B-G, and NXP BZT52H-C30,115. These parts maintain 30 V zener voltage and SOD-123 packaging but may have reduced power ratings (200–410 mW) or different impedance characteristics.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vz (V)	Tolerance	Power Max (mW)	Impedance Max (Ohms)	Reverse Leakage @ Vr	Operating Temp (°C)	Package	Product Status	RoHS Status
MMSZ5256B-7	Diodes Incorporated	30	±5%	500	49	100 nA @ 23 V	-65 to 150	SOD-123	Discontinued	Non-compliant
MMSZ5256B-7-F	Diodes Incorporated	30	±5%	500	49	100 nA @ 23 V	-65 to 150	SOD-123	Active	RoHS3 Compliant
MMSZ30T1G	onsemi	30	±5%	500	80	50 nA @ 21 V	-55 to 150	SOD-123	Active	RoHS3 Compliant
MMSZ4713-E3-08	Vishay General Semiconductor	30	±5%	500	—	10 nA @ 22.8 V	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B30-G3-08	Vishay General Semiconductor	30	±2%	410	80	100 nA @ 22.5 V	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B30-G3-18	Vishay General Semiconductor	30	±2%	410	80	100 nA @ 22.5 V	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52C30-G3-08	Vishay General Semiconductor	30	±5%	410	80	100 nA @ 22.5 V	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52C30-G3-18	Vishay General Semiconductor	30	±5%	410	80	100 nA @ 22.5 V	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52C30-TP	Micro Commercial Co	30	±7%	200	80	100 nA @ 21 V	-65 to 150	SOD-123	Active	RoHS3 Compliant
BZT52H-C30,115	NXP Semiconductors	30	±5%	375	40	50 nA @ 21 V	-65 to 150	SOD-123F	Active	—
CZRW5256B-G	Comchip Technology	30	±5%	350	49	100 nA @ 23 V	-65 to 150	SOD-123	Active	RoHS3 Compliant

Engineering Selection Recommendations

Tier 1 - Recommended Direct Replacements:

MMSZ5256B-7-F (Diodes Incorporated) is the primary recommended substitute. This part is electrically and mechanically identical to the original MMSZ5256B-7, with identical zener voltage (30 V), power rating (500 mW), impedance (49 Ohms), and operating temperature range (-65°C to 150°C). The part is currently in active production status with RoHS3 compliance, addressing the discontinuation of the original component.

MMSZ30T1G (onsemi) is a secondary direct replacement option. It maintains the 30 V zener voltage and 500 mW power rating with RoHS3 compliance and active product status. The operating temperature range is -55°C to 150°C, which is acceptable for most applications. Impedance is specified at 80 Ohms, which is higher than the original 49 Ohms but remains within acceptable regulation performance for typical circuit applications.

Tier 2 - Functional Equivalents with Reduced Power Rating:

BZT52C30-G3-08 and BZT52C30-G3-18 (Vishay General Semiconductor) are suitable for applications where the 410 mW power rating is sufficient. These parts maintain 30 V zener voltage with ±5% tolerance and RoHS3 compliance. The reduced power dissipation capability requires circuit-level verification that thermal stress remains within acceptable limits.

CZRW5256B-G (Comchip Technology) provides 350 mW power dissipation with 30 V zener voltage, ±5% tolerance, and impedance matching the original at 49 Ohms. Operating temperature range extends to -65°C to 150°C, matching the original specification. RoHS3 compliance is confirmed.

Tier 3 - Specialized Applications:

BZT52H-C30,115 (NXP Semiconductors) is qualified to AEC-Q101 automotive standards and is suitable for automotive and high-reliability applications. The 375 mW power rating and 40 Ohms impedance provide superior regulation characteristics. Package variant SOD-123F differs from the standard SOD-123, requiring physical footprint verification.

BZT52C30-TP (Micro Commercial Co) is suitable only for applications with reduced power dissipation requirements (200 mW maximum). The ±7% tolerance is wider than the original ±5%, which may impact circuit performance in precision voltage regulation applications.

Compliance Considerations:

All recommended substitutes maintain RoHS3 compliance status, addressing environmental regulatory requirements. The original MMSZ5256B-7 is RoHS non-compliant; substitution with compliant alternatives is necessary for new designs and procurement cycles subject to RoHS regulations.

Frequently Asked Questions (FAQ)

Q: Can MMSZ5256B-7-F be used as a direct replacement for MMSZ5256B-7?

A: Yes. MMSZ5256B-7-F is electrically and mechanically identical to MMSZ5256B-7. Both components have 30 V zener voltage, 500 mW power rating, 49 Ohms impedance, and -65°C to 150°C operating temperature range. The primary difference is product status (active vs. discontinued) and RoHS compliance (RoHS3 vs. non-compliant). MMSZ5256B-7-F is the recommended direct replacement.

Q: What is the difference between BZT52B30 and BZT52C30 series?

A: The primary difference is tolerance specification. BZT52B30 series components have ±2% tolerance, while BZT52C30 series components have ±5% tolerance. Both series maintain 30 V zener voltage and are available in SOD-123 packaging. Selection depends on circuit tolerance requirements. For applications originally designed with ±5% tolerance (MMSZ5256B-7), BZT52C30 series is appropriate.

Q: Why do some substitutes have lower power ratings (200–410 mW vs. 500 mW)?

A: Power rating reflects the maximum continuous power dissipation the component can handle without exceeding thermal limits. Lower-rated components are suitable for circuits with reduced power dissipation requirements. Circuit-level analysis is necessary to confirm that actual power dissipation does not exceed the substitute component's rating. Substitutes with reduced power ratings are not appropriate for applications requiring the full 500 mW capability.

Q: Is the SOD-123F package compatible with SOD-123 footprints?

A: SOD-123F is a variant of SOD-123 with different physical dimensions. While both are surface mount packages, they have different footprints. BZT52H-C30,115 in SOD-123F package requires PCB footprint verification before substitution. Standard SOD-123 packages (MMSZ5256B-7-F, MMSZ30T1G, BZT52C30 series, CZRW5256B-G) are directly compatible with existing SOD-123 footprints.

Q: What does RoHS3 compliance mean for component selection?

A: RoHS3 compliance indicates the component meets Restriction of Hazardous Substances Directive requirements, restricting use of lead, cadmium, mercury, and other hazardous materials. For new designs and procurement in regulated markets, RoHS3 compliant components are required. All recommended substitutes except BZT52H-C30,115 explicitly confirm RoHS3 compliance.

Q: Can MMSZ4713-E3-08 be used as a substitute?

A: Yes, MMSZ4713-E3-08 is a functional equivalent with 30 V zener voltage and 500 mW power rating. The component is RoHS3 compliant and in active production. Reverse leakage current is specified at 10 nA @ 22.8 V, which is superior to the original 100 nA @ 23 V. Operating temperature range is -55°C to 150°C. This part is suitable for direct substitution in most applications.

Q: What is impedance and why does it matter for zener diode selection?

A: Impedance (Zzt) is the dynamic resistance of the zener diode in its regulation region. Lower impedance provides better voltage regulation and lower output impedance. The original MMSZ5256B-7 has 49 Ohms impedance. Substitutes with higher impedance (80 Ohms) have slightly reduced regulation performance but remain acceptable for typical applications. Substitutes with lower impedance (40 Ohms) provide superior regulation characteristics.

Q: Are there inventory considerations for substitute selection?

A: Yes. MMSZ30T1G (onsemi) has the highest inventory availability at 43,978 pieces. MMSZ5256B-7-F (Diodes Incorporated) has 32,100 pieces available. Other substitutes have lower inventory levels (648–9,685 pieces). For high-volume procurement, MMSZ30T1G or MMSZ5256B-7-F are preferred based on availability.

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

A: Tape and Reel (TR) packaging is standard for automated assembly processes, with components wound on continuous tape for pick-and-place equipment. Bulk packaging is loose components suitable for manual assembly or small-quantity applications. Most substitutes are available in TR packaging. BZT52H-C30,115 is specified in bulk packaging, which may require reeling or manual handling for automated assembly.

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