MMSZ5259ET1G Equivalent & Substitute Parts

Part Overview

The MMSZ5259ET1G is a Zener diode manufactured by onsemi, rated at 39 V nominal Zener voltage with 500 mW power dissipation in a surface mount SOD-123 package. This part is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Equivalent parts maintain identical or superior electrical characteristics while substitute parts offer functional compatibility within specified parameter tolerances.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	39	V
Tolerance	±5%	%
Power - Max	500	mW
Impedance (Max)	80	Ohms
Current - Reverse Leakage @ Vr	100	nA @ 30 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount
Package / Case	SOD-123

Substitute Part Grouping Explanation

Substitution of the MMSZ5259ET1G is determined by the following critical parameters:

Primary Substitution Criteria:

Zener voltage: 39 V nominal
Tolerance: ±5%
Power rating: 500 mW (minimum acceptable)
Package: SOD-123 or SOD-123F (compatible footprints)
Operating temperature range: -55°C to 150°C (minimum)
Impedance: 80 Ohms (nominal specification)
Reverse leakage current: 100 nA @ 30 V (nominal specification)

Substitution Categories:

Direct Manufacturer Equivalents maintain all electrical parameters and series designation from onsemi, with active product status and RoHS3 compliance.

Parametric Equivalents from alternative manufacturers (Vishay, Diodes Incorporated) match all critical electrical specifications while offering different packaging options or certifications.

Automotive-Grade Equivalents include AEC-Q101 qualification and extended temperature ranges, suitable for automotive applications.

Similar Alternatives from Nexperia maintain 39 V Zener voltage and ±5% tolerance but with reduced power rating (375 mW) and alternative package variant (SOD-123F), requiring application-level verification.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Ir @ Vr (nA)	Vf @ If (mV)	Temp Range (°C)	Package	Status	RoHS
MMSZ5259ET1G	onsemi	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Obsolete	N/A
MMSZ39T1G	onsemi	39	±5%	500	130	50 @ 27.3V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
MMSZ5259BT1G	onsemi	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
SZMMSZ39T1G	onsemi	39	±5%	500	130	50 @ 27.3V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
SZMMSZ5259BT1G	onsemi	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
MMSZ5259B-7-F	Diodes Incorporated	39	±5%	500	80	100 @ 30V	900 @ 10mA	-65 to 150	SOD-123	Active	ROHS3
BZT52H-C39,115	Nexperia USA Inc.	39	±5%	375	75	50 @ 27.3V	900 @ 10mA	-65 to 150	SOD-123F	Active	ROHS3
MMSZ5259B-E3-08	Vishay General Semiconductor	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
MMSZ5259B-E3-18	Vishay General Semiconductor	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
MMSZ5259B-G3-08	Vishay General Semiconductor	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3
MMSZ5259B-G3-18	Vishay General Semiconductor	39	±5%	500	80	100 @ 30V	900 @ 10mA	-55 to 150	SOD-123	Active	ROHS3

Engineering Selection Recommendations

Primary Recommendation: MMSZ5259BT1G (onsemi)

MMSZ5259BT1G is the direct active equivalent from the original manufacturer onsemi. It maintains identical electrical specifications to MMSZ5259ET1G, including 39 V Zener voltage, 500 mW power rating, 80 Ohms impedance, and 100 nA reverse leakage current. Product status is active with RoHS3 compliance. Inventory availability is 6,908 units. This part is the preferred selection for direct replacement in existing designs.

Secondary Recommendation: SZMMSZ5259BT1G (onsemi, Automotive-Grade)

SZMMSZ5259BT1G provides identical electrical parameters to MMSZ5259ET1G with additional automotive qualification (AEC-Q101). This part is suitable for automotive applications requiring enhanced reliability standards. Product status is active with RoHS3 compliance. Inventory availability is 125,400 units, the highest among all equivalents.

Alternative Recommendation: MMSZ5259B-E3-08 or MMSZ5259B-G3-08 (Vishay)

Vishay General Semiconductor parts MMSZ5259B-E3-08 and MMSZ5259B-G3-08 match all critical electrical specifications of MMSZ5259ET1G. Both are active products with RoHS3 compliance. These parts are suitable for applications where multi-source qualification is required. Inventory availability is 15,187 units (E3-08) and 1,012 units (G3-08).

Extended Temperature Range Option: MMSZ5259B-7-F (Diodes Incorporated)

MMSZ5259B-7-F from Diodes Incorporated maintains identical electrical specifications with extended operating temperature range (-65°C to 150°C versus -55°C to 150°C). This part is active with RoHS3 compliance and is suitable for applications requiring lower temperature operation limits.

Lower Power Alternative: BZT52H-C39,115 (Nexperia)

BZT52H-C39,115 maintains 39 V Zener voltage and ±5% tolerance but with reduced power rating (375 mW versus 500 mW) and alternative package variant (SOD-123F). This part includes automotive qualification (AEC-Q101) and extended temperature range (-65°C to 150°C). Selection of this part requires application-level verification that 375 mW power dissipation is sufficient for the intended circuit.

Frequently Asked Questions (FAQ)

Q: Can MMSZ39T1G be used as a direct replacement for MMSZ5259ET1G?

A: MMSZ39T1G is electrically compatible with identical Zener voltage (39 V), power rating (500 mW), and operating temperature range. However, impedance differs (130 Ohms versus 80 Ohms) and reverse leakage current is lower (50 nA @ 27.3V versus 100 nA @ 30V). For applications where impedance specification is critical, MMSZ5259BT1G is preferred. MMSZ39T1G is suitable for general-purpose 39 V Zener applications.

Q: What is the difference between MMSZ5259BT1G and SZMMSZ5259BT1G?

A: Both parts maintain identical electrical specifications (39 V, 500 mW, 80 Ohms impedance). SZMMSZ5259BT1G includes automotive-grade qualification (AEC-Q101) and is packaged in Tape & Reel format. MMSZ5259BT1G is available in Cut Tape and Digi-Reel packaging. Selection depends on application requirements and packaging preferences.

Q: Why does BZT52H-C39,115 have lower power rating (375 mW)?

A: BZT52H-C39,115 is manufactured by Nexperia and uses SOD-123F package variant. The 375 mW power rating reflects the thermal characteristics of this specific package design. This part is suitable only for applications where power dissipation does not exceed 375 mW. Verify circuit requirements before selection.

Q: Are all substitute parts RoHS3 compliant?

A: All active substitute parts listed are RoHS3 compliant. The original MMSZ5259ET1G is obsolete and RoHS status is not applicable. All recommended active equivalents meet current RoHS3 requirements.

Q: What is the significance of the impedance parameter (Zzt)?

A: Impedance (Zzt) affects the dynamic response of the Zener diode under transient conditions. MMSZ5259ET1G and MMSZ5259BT1G specify 80 Ohms, while MMSZ39T1G and SZMMSZ39T1G specify 130 Ohms. For applications sensitive to transient voltage regulation, the 80 Ohms specification is preferred. Verify impedance requirements in circuit design specifications.

Q: Can Vishay MMSZ5259B series parts be used interchangeably?

A: Vishay parts MMSZ5259B-E3-08, MMSZ5259B-E3-18, MMSZ5259B-G3-08, and MMSZ5259B-G3-18 maintain identical electrical specifications. Differences are in packaging format (tape reel specifications) and manufacturing date codes. These parts are electrically interchangeable for circuit design purposes.

Q: What is the operating temperature range difference between parts?

A: Most parts operate from -55°C to 150°C. MMSZ5259B-7-F (Diodes Incorporated) and BZT52H-C39,115 (Nexperia) extend the lower temperature limit to -65°C. Selection of extended range parts is necessary only for applications requiring operation below -55°C.

Q: Is automotive qualification (AEC-Q101) required for my application?

A: AEC-Q101 qualification is required for automotive applications and applications subject to automotive reliability standards. SZMMSZ39T1G, SZMMSZ5259BT1G, and BZT52H-C39,115 include AEC-Q101 qualification. Non-automotive applications do not require this qualification.

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