MM3Z18VT1 Equivalent & Substitute Parts

Part Overview

The MM3Z18VT1 is a Zener diode rated at 18 V nominal voltage with 200 mW maximum power dissipation in a surface mount SOD-323 package. Manufactured by onsemi, this component is classified as obsolete product status. Due to its obsolete designation, direct replacement with active production alternatives is necessary for new designs and ongoing procurement requirements. Substitute parts must maintain electrical equivalence across voltage regulation, power handling, and thermal operating characteristics while accommodating modern supply chain availability.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	18	V
Tolerance	±6%	—
Power - Max	200	mW
Impedance (Max)	45	Ohms
Current - Reverse Leakage @ Vr	50	nA @ 12.6 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature Range	-65 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SC-76, SOD-323	—

Substitute Part Grouping Explanation

Substitution of the MM3Z18VT1 is determined by the following critical parameters:

Electrical Equivalence Requirements:

Zener voltage (Nom): 18 V
Voltage tolerance: ±6% or tighter
Power dissipation capability: minimum 200 mW
Impedance (Max): 45 Ohms or lower
Reverse leakage current: 50 nA @ 12.6 V or lower
Forward voltage: 900 mV @ 10 mA or lower
Operating temperature range: -65°C to 150°C minimum

Mechanical Compatibility:

Mounting type: Surface Mount
Package / Case: SOD-323 or equivalent footprint

Substitute parts are grouped into three categories based on their relationship to the main part:

Direct Manufacturer Equivalent – Same manufacturer (onsemi) with identical electrical specifications but higher power rating and active product status
Similar Manufacturer Parts – Alternative manufacturers with matching or superior electrical parameters and active production status
Parametric Equivalents – Parts meeting all critical electrical specifications with minor variations in secondary parameters

Parameter Comparison

Parameter	MM3Z18VT1	MM3Z18VT1G	BZX384-C18,115	CZRF52C18	BZT52C18S-7-F	BZT52C18S-TP
Manufacturer	onsemi	onsemi	Nexperia USA Inc.	Comchip Technology	Diodes Incorporated	Micro Commercial Co
Voltage - Zener (Nom)	18 V	18 V	18 V	18 V	18 V	18 V
Tolerance	±6%	±6%	±5%	±5%	±6%	±6%
Power - Max	200 mW	300 mW	300 mW	200 mW	200 mW	200 mW
Impedance (Max)	45 Ω	45 Ω	45 Ω	50 Ω	45 Ω	45 Ω
Current - Reverse Leakage @ Vr	50 nA @ 12.6 V	50 nA @ 12.6 V	50 nA @ 12.6 V	100 nA @ 14 V	100 nA @ 12.6 V	100 nA @ 12.6 V
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	900 mV @ 10 mA	1.1 V @ 100 mA	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA
Operating Temperature	-65 to 150°C	-65 to 150°C	-65 to 150°C	-55 to 125°C	-65 to 150°C	-65 to 150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	SC-76, SOD-323	SC-76, SOD-323	SC-76, SOD-323	1005 (2512 Metric)	SC-76, SOD-323	SC-76, SOD-323
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: MM3Z18VT1G

The MM3Z18VT1G is the direct manufacturer equivalent from onsemi with active product status. This part maintains identical electrical specifications to the MM3Z18VT1 while offering increased power dissipation capability (300 mW versus 200 mW). The part is ROHS3 compliant and available in high inventory quantities (15,737 pcs). Selection of this part eliminates obsolescence risk while preserving design compatibility.

Secondary Recommendation: BZX384-C18,115

The BZX384-C18,115 from Nexperia USA Inc. provides an alternative from an established manufacturer with active production status. This part meets all electrical requirements with tighter voltage tolerance (±5% versus ±6%) and higher power rating (300 mW). The part is ROHS3 compliant with substantial inventory availability (107,960 pcs). Package compatibility is maintained in SOD-323 format.

Tertiary Recommendation: BZT52C18S-7-F or BZT52C18S-TP

Both BZT52C18S-7-F (Diodes Incorporated) and BZT52C18S-TP (Micro Commercial Co) provide parametric equivalence with identical power ratings (200 mW) and electrical specifications matching the original part. Both are ROHS3 compliant with active product status. These selections are appropriate for applications where the 200 mW power specification is a design constraint.

Alternative Consideration: CZRF52C18

The CZRF52C18 from Comchip Technology meets electrical specifications but operates within a reduced temperature range (-55°C to 125°C versus -65°C to 150°C) and uses a different package format (1005/SOD-323F). This part is suitable only for applications where the narrower operating temperature range is acceptable and where package footprint compatibility can be verified.

Frequently Asked Questions (FAQ)

Q: Can MM3Z18VT1G be used as a direct replacement for MM3Z18VT1?

A: Yes. The MM3Z18VT1G maintains identical electrical specifications for zener voltage (18 V), tolerance (±6%), impedance (45 Ω), reverse leakage (50 nA @ 12.6 V), and forward voltage (900 mV @ 10 mA). The higher power rating (300 mW versus 200 mW) provides additional design margin. Both parts use SOD-323 packaging with identical footprints.

Q: What is the primary reason to substitute the MM3Z18VT1?

A: The MM3Z18VT1 is classified as obsolete product status. Substitute parts with active production status ensure long-term supply chain availability and compliance with current manufacturing standards including ROHS3 certification.

Q: Are there package compatibility concerns with any substitute parts?

A: The CZRF52C18 uses a 1005 (2512 Metric) package format, which differs from the SOD-323 package of the original part. PCB layout verification is required if this part is selected. All other substitute parts maintain SOD-323 packaging with identical footprints.

Q: How do voltage tolerance differences affect substitution?

A: The MM3Z18VT1 specifies ±6% tolerance. Substitute parts with ±5% tolerance (BZX384-C18,115 and CZRF52C18) provide tighter voltage regulation. Parts with ±6% tolerance (MM3Z18VT1G, BZT52C18S-7-F, BZT52C18S-TP) maintain identical tolerance specifications. Tighter tolerance does not create incompatibility; it represents improved performance.

Q: What is the significance of power rating differences?

A: The MM3Z18VT1 is rated at 200 mW maximum power dissipation. Substitute parts rated at 300 mW (MM3Z18VT1G and BZX384-C18,115) provide increased thermal headroom without affecting electrical operation. Parts rated at 200 mW (CZRF52C18, BZT52C18S-7-F, BZT52C18S-TP) maintain identical power specifications. Higher power ratings do not create incompatibility; they provide additional design margin.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed are ROHS3 compliant. The original MM3Z18VT1 is RoHS non-compliant. Selection of any substitute part ensures compliance with current environmental and regulatory standards.

Q: What operating temperature range should be considered for substitution?

A: The MM3Z18VT1 operates from -65°C to 150°C. Most substitute parts (MM3Z18VT1G, BZX384-C18,115, BZT52C18S-7-F, BZT52C18S-TP) maintain this full range. The CZRF52C18 operates from -55°C to 125°C, which is narrower. Selection of CZRF52C18 is appropriate only for applications where the reduced temperature range is acceptable.

Q: How does reverse leakage current affect part selection?

A: The MM3Z18VT1 specifies 50 nA @ 12.6 V reverse leakage. Substitute parts with identical or lower leakage specifications (50 nA @ 12.6 V for MM3Z18VT1G and BZX384-C18,115) maintain equivalent performance. Parts with higher leakage (100 nA @ 12.6 V for BZT52C18S-7-F and BZT52C18S-TP, or 100 nA @ 14 V for CZRF52C18) remain within acceptable parameters for zener diode applications.

Q: Can impedance differences between substitute parts affect circuit performance?

A: The MM3Z18VT1 specifies 45 Ω maximum impedance. Substitute parts with 45 Ω impedance (MM3Z18VT1G, BZX384-C18,115, BZT52C18S-7-F, BZT52C18S-TP) maintain identical impedance characteristics. The CZRF52C18 specifies 50 Ω maximum impedance, which represents a minor increase. This difference is negligible for typical zener diode voltage regulation applications.

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