MMSZ5V1T1 Zener Diode 5.1V 500mW SOD-123 Equivalent & Substitute Parts

Part Overview

The MMSZ5V1T1 is a surface mount zener diode manufactured by onsemi, rated for 5.1 V nominal zener voltage with 500 mW maximum power dissipation in SOD-123 packaging. This part is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design support and procurement continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives with minor parameter variations within acceptable engineering tolerances.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	5.1	V
Tolerance	±5%	—
Power - Max	500	mW
Impedance (Max)	60	Ohms
Current - Reverse Leakage @ Vr	2	µA @ 2 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOD-123	—
RoHS Status	Non-compliant	—

Substitute Part Grouping Explanation

Substitution of the MMSZ5V1T1 is determined by the following critical parameters:

Electrical Compatibility Criteria:

Zener voltage: 5.1 V nominal (primary specification)
Operating temperature range: -55°C to 150°C (must be met or exceeded)
Package type: SOD-123 (mechanical and thermal compatibility)
Impedance maximum: 60 Ohms (electrical performance)

Substitution Categories:

Direct Equivalent (Parametric Match): Parts maintaining all electrical specifications with identical or superior performance characteristics. MMSZ5V1T1G and SZMMSZ5V1T1G fall into this category, offering active product status and RoHS3 compliance.

Similar Substitute (Functional Equivalent): Vishay BZT52 series parts (BZT52B5V1-E3-08, BZT52B5V1-E3-18, BZT52B5V1-G3-08, BZT52B5V1-G3-18, BZT52B5V1-HE3-08, BZT52C5V1-E3-18, BZT52C5V1-G3-08, BZT52C5V1-G3-18) provide functional substitution with reduced maximum power rating (410 mW versus 500 mW) and improved reverse leakage characteristics (100 nA @ 800 mV versus 2 µA @ 2 V). These parts maintain 5.1 V zener voltage, SOD-123 packaging, and operating temperature range. Tolerance variations exist: BZT52B series offers ±2% tolerance; BZT52C series offers ±5% tolerance matching the original specification.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power Max (mW)	Zzt Max (Ω)	Reverse Leakage	Vf Max (mV)	Temp Range (°C)	Package	Status	RoHS
MMSZ5V1T1	onsemi	5.1	±5%	500	60	2 µA @ 2 V	900 @ 10 mA	-55 to 150	SOD-123	Obsolete	Non-compliant
MMSZ5V1T1G	onsemi	5.1	±5%	500	60	2 µA @ 2 V	900 @ 10 mA	-55 to 150	SOD-123	Active	RoHS3 Compliant
SZMMSZ5V1T1G	onsemi	5.1	±5%	500	60	2 µA @ 2 V	900 @ 10 mA	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B5V1-E3-08	Vishay	5.1	±2%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B5V1-E3-18	Vishay	5.1	±2%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B5V1-G3-08	Vishay	5.1	±2%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B5V1-G3-18	Vishay	5.1	±2%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52B5V1-HE3-08	Vishay	5.1	±2%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Obsolete	RoHS3 Compliant
BZT52C5V1-E3-18	Vishay	5.1	±5%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52C5V1-G3-08	Vishay	5.1	±5%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant
BZT52C5V1-G3-18	Vishay	5.1	±5%	410	60	100 nA @ 800 mV	—	-55 to 150	SOD-123	Active	RoHS3 Compliant

Engineering Selection Recommendations

Primary Selection - Direct Equivalent:

MMSZ5V1T1G is the preferred direct replacement for MMSZ5V1T1. This part maintains identical electrical specifications (5.1 V, ±5% tolerance, 500 mW, 60 Ω impedance) and mechanical compatibility (SOD-123 surface mount package). The primary advantage is active product status with RoHS3 compliance, addressing regulatory requirements and ensuring long-term availability. Inventory availability is substantial (53,878 units).

SZMMSZ5V1T1G provides an alternative direct equivalent with automotive-grade qualification (AEC-Q101) and active status. This part is suitable for applications requiring automotive-level reliability and traceability. Inventory is lower (1,370 units) but adequate for most applications.

Secondary Selection - Functional Substitute:

Vishay BZT52 series parts provide functional substitution when direct equivalents are unavailable. Selection within this series depends on tolerance and packaging requirements:

BZT52B5V1 variants (±2% tolerance): BZT52B5V1-E3-08, BZT52B5V1-E3-18, BZT52B5V1-G3-08, BZT52B5V1-G3-18 offer tighter tolerance than the original specification. These parts are suitable for applications where improved voltage accuracy is beneficial. All variants are active status with RoHS3 compliance.
BZT52C5V1 variants (±5% tolerance): BZT52C5V1-E3-18, BZT52C5V1-G3-08, BZT52C5V1-G3-18 match the original ±5% tolerance specification. These parts provide direct tolerance compatibility while offering improved reverse leakage performance. All variants are active status with RoHS3 compliance.

Power Dissipation Consideration:

BZT52 series parts are rated for 410 mW maximum power dissipation compared to 500 mW for MMSZ5V1T1. Substitution is appropriate for applications where actual power dissipation does not exceed 410 mW. Thermal analysis of the specific application is required to confirm compatibility when power margins are limited.

Compliance Status:

All recommended substitutes are RoHS3 compliant, addressing modern regulatory requirements. The original MMSZ5V1T1 is non-compliant; migration to compliant alternatives is recommended for new designs and long-term product support.

Frequently Asked Questions (FAQ)

Q: Can MMSZ5V1T1G be used as a direct replacement for MMSZ5V1T1?

A: Yes. MMSZ5V1T1G is a direct parametric equivalent with identical zener voltage (5.1 V), tolerance (±5%), power rating (500 mW), impedance (60 Ω), and operating temperature range (-55°C to 150°C). The primary differences are active product status and RoHS3 compliance. No circuit modifications are required.

Q: What is the difference between MMSZ5V1T1G and SZMMSZ5V1T1G?

A: Both parts are direct parametric equivalents of MMSZ5V1T1. SZMMSZ5V1T1G includes automotive-grade qualification (AEC-Q101) and is designated for automotive applications. Selection depends on application requirements. For non-automotive applications, MMSZ5V1T1G is appropriate. For automotive applications, SZMMSZ5V1T1G provides required qualification.

Q: Can BZT52B5V1-E3-08 replace MMSZ5V1T1?

A: BZT52B5V1-E3-08 provides functional substitution with the following considerations: zener voltage is identical (5.1 V), operating temperature range is identical (-55°C to 150°C), and SOD-123 packaging is identical. However, maximum power dissipation is reduced from 500 mW to 410 mW, and tolerance is improved from ±5% to ±2%. Substitution is appropriate if actual circuit power dissipation does not exceed 410 mW. Thermal analysis is required to confirm compatibility.

Q: What is the difference between BZT52B5V1 and BZT52C5V1 variants?

A: The primary difference is tolerance specification. BZT52B5V1 variants offer ±2% tolerance, while BZT52C5V1 variants offer ±5% tolerance. Both series maintain identical zener voltage (5.1 V), power rating (410 mW), impedance (60 Ω), and operating temperature range (-55°C to 150°C). Selection depends on tolerance requirements of the specific application. For applications matching the original ±5% specification, BZT52C5V1 variants are appropriate.

Q: What do the suffixes -E3-08, -E3-18, -G3-08, and -G3-18 indicate in BZT52 part numbers?

A: These suffixes indicate packaging and tape configuration. The -E3 and -G3 designations refer to different manufacturing processes or tape specifications. The -08 and -18 suffixes indicate different tape reel configurations. All variants maintain identical electrical specifications. Selection is based on procurement and assembly equipment compatibility.

Q: Is the reduced power rating of BZT52 series (410 mW vs. 500 mW) a concern?

A: The reduced power rating requires thermal analysis of the specific application. If actual power dissipation in the circuit is below 410 mW, substitution is appropriate. If power dissipation approaches or exceeds 410 mW, the BZT52 series is not suitable. Thermal design margins must be verified before substitution.

Q: Are all recommended substitutes RoHS compliant?

A: Yes. MMSZ5V1T1G, SZMMSZ5V1T1G, and all BZT52 series variants listed are RoHS3 compliant. The original MMSZ5V1T1 is non-compliant. For applications subject to RoHS requirements, compliant alternatives must be selected.

Q: Can I mix different BZT52 variants in the same design?

A: Yes, provided all variants meet the electrical requirements of the specific circuit. All BZT52 variants listed maintain 5.1 V zener voltage, 60 Ω impedance, and -55°C to 150°C operating temperature range. Tolerance differences (±2% for B-series, ±5% for C-series) and packaging configurations do not affect electrical interchangeability within a single circuit.

Q: What is the inventory status of recommended parts?

A: MMSZ5V1T1G has the highest inventory (53,878 units), making it the most readily available direct equivalent. SZMMSZ5V1T1G has lower inventory (1,370 units). BZT52 series variants have varying inventory levels, with BZT52B5V1-E3-08 and BZT52B5V1-HE3-08 having the highest availability (118,690 and 31,444 units respectively). Procurement planning should account for these availability differences.

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