MM5Z68VT1 Equivalent & Substitute Parts

Part Overview

The MM5Z68VT1 is a 68 V Zener diode manufactured by onsemi, rated for 100 mW maximum power dissipation in a surface mount SOD-523 package. This component is classified as obsolete, indicating that direct procurement from the original manufacturer is no longer available. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs, repairs, and system upgrades.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	68	V
Tolerance	±6%	—
Power - Max	100	mW
Impedance (Max)	240	Ohms
Current - Reverse Leakage @ Vr	50	nA @ 47.6 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature	-65 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOD-523	—

Substitute Part Grouping Explanation

Substitution of the MM5Z68VT1 is determined by the following critical parameters:

Electrical Compatibility Requirements:

Zener voltage (Vz) must be 68 V nominal
Operating temperature range must encompass -65°C to 150°C
Reverse leakage current must not exceed 50 nA @ 47.6 V
Forward voltage characteristics must be compatible with circuit design

Mechanical Compatibility Requirements:

Surface mount mounting type
Package footprint compatibility (SOD-523 or equivalent land pattern)

Substitution Categories:

Category 1: Direct Package Substitutes (SOD-523) Parts maintaining the original SOD-523 package with enhanced electrical performance characteristics.

Category 2: Higher Power Density Substitutes (SOD-323F, SOD-123F) Parts with increased power dissipation ratings in alternative surface mount packages, suitable for applications requiring thermal margin or higher current handling.

All substitute parts listed maintain the 68 V nominal zener voltage, -65°C to 150°C operating temperature range, and 50 nA reverse leakage specification, ensuring functional equivalence within the specified electrical envelope.

Parameter Comparison

Parameter	MM5Z68VT1	BZX585-B68,115	BZX585-C68,115	BZX84J-B68,115	BZX84J-C68,115	BZT52H-C68,115
Manufacturer	onsemi	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.	NXP Semiconductors	NXP Semiconductors
Product Status	Obsolete	Active	Active	Active	Active	Active
Voltage - Zener (Nom)	68 V	68 V	68 V	68 V	68 V	68 V
Tolerance	±6%	±2%	±5%	±2%	±5%	±5%
Power - Max	100 mW	300 mW	300 mW	550 mW	550 mW	375 mW
Impedance (Max)	240 Ohms	240 Ohms	240 Ohms	160 Ohms	160 Ohms	160 Ohms
Current - Reverse Leakage @ Vr	50 nA @ 47.6 V	50 nA @ 47.6 V	50 nA @ 47.6 V	50 nA @ 47.6 V	50 nA @ 47.6 V	50 nA @ 47.6 V
Operating Temperature	-65 to 150°C	-65 to 150°C	-65 to 150°C	-65 to 150°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	SOD-523	SOD-523	SOD-523	SOD-323F	SOD-323F	SOD-123F
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not specified	Not specified
Automotive Grade	Not specified	Yes (AEC-Q100)	Yes (AEC-Q100)	Yes (AEC-Q101)	Yes (AEC-Q101)	Yes (AEC-Q101)

Engineering Selection Recommendations

For Direct Package Replacement (SOD-523):

BZX585-B68,115 and BZX585-C68,115 maintain the original SOD-523 package footprint. Both parts are active products from Nexperia USA Inc. with ROHS3 compliance and AEC-Q100 automotive qualification. BZX585-B68,115 offers ±2% tolerance with 300 mW power rating, while BZX585-C68,115 provides ±5% tolerance with identical power and impedance specifications. Both are suitable for direct PCB layout compatibility without redesign.

For Enhanced Thermal Performance (SOD-323F):

BZX84J-B68,115 and BZX84J-C68,115 provide 550 mW power dissipation in SOD-323F packages, offering superior thermal characteristics compared to the original 100 mW rating. Both parts carry AEC-Q101 automotive qualification. BZX84J-B68,115 specifies ±2% tolerance, while BZX84J-C68,115 specifies ±5% tolerance. These parts require PCB layout modification to accommodate the different package footprint.

For Intermediate Power Density (SOD-123F):

BZT52H-C68,115 from NXP Semiconductors provides 375 mW power dissipation in SOD-123F package with ±5% tolerance and AEC-Q101 automotive qualification. This option offers a middle ground between the original 100 mW specification and the higher-power SOD-323F alternatives.

All substitute parts maintain the 68 V nominal zener voltage, -65°C to 150°C operating temperature range, and 50 nA reverse leakage current specification, ensuring functional equivalence within the specified electrical envelope.

Frequently Asked Questions (FAQ)

Q: Can BZX585-B68,115 or BZX585-C68,115 be used as direct replacements for MM5Z68VT1?

A: Yes. Both parts maintain the SOD-523 package, 68 V nominal zener voltage, -65°C to 150°C operating temperature range, and 50 nA reverse leakage current specification. No PCB layout modification is required. BZX585-B68,115 offers tighter ±2% tolerance, while BZX585-C68,115 matches the original ±6% tolerance specification more closely with ±5%.

Q: What is the difference between the SOD-523 and SOD-323F package options?

A: SOD-523 is a smaller surface mount package used in the original MM5Z68VT1 and maintained in BZX585 series parts. SOD-323F is a larger package used in BZX84J series parts, offering increased power dissipation capability (550 mW versus 100-300 mW). SOD-323F requires different PCB land patterns and cannot be used as a direct footprint replacement without circuit board redesign.

Q: Are all substitute parts automotive qualified?

A: Yes. All listed substitute parts carry automotive-grade qualifications: BZX585 series parts hold AEC-Q100 certification, while BZX84J and BZT52H series parts hold AEC-Q101 certification. The original MM5Z68VT1 does not specify automotive qualification.

Q: What does the tolerance specification mean for zener diode selection?

A: Tolerance specifies the allowable deviation of the nominal 68 V zener voltage. The original MM5Z68VT1 specifies ±6%, meaning the actual zener voltage can range from 63.92 V to 72.08 V. BZX585-B68,115 and BZX84J-B68,115 offer tighter ±2% tolerance (66.64 V to 69.36 V), while BZX585-C68,115, BZX84J-C68,115, and BZT52H-C68,115 specify ±5% tolerance (64.6 V to 71.4 V). Tighter tolerance may improve circuit performance in precision applications.

Q: Can I use a higher power-rated substitute in a circuit designed for 100 mW?

A: Yes. Higher power-rated parts (300 mW, 375 mW, or 550 mW) are electrically compatible with circuits designed for 100 mW operation. The higher power rating provides additional thermal margin and does not degrade circuit performance. However, package footprint compatibility must be verified before substitution.

Q: What is the difference between RoHS compliance status?

A: The original MM5Z68VT1 is RoHS non-compliant. All substitute parts are ROHS3 compliant, indicating compliance with the Restriction of Hazardous Substances Directive. ROHS3 compliance is required for many commercial and industrial applications, particularly in European markets.

Q: How do impedance specifications affect substitution?

A: Impedance (Zzt) affects the dynamic response of the zener diode under transient conditions. The original MM5Z68VT1 specifies 240 Ohms maximum impedance. BZX585 series parts maintain 240 Ohms, while BZX84J and BZT52H series parts specify 160 Ohms maximum impedance. Lower impedance provides faster transient response and may improve circuit stability in high-frequency applications.

Q: Is forward voltage specification important for substitution?

A: Forward voltage (Vf) becomes relevant only when the diode conducts in forward bias mode, which is not the primary operating condition for zener regulators. The original MM5Z68VT1 specifies 900 mV @ 10 mA, while substitute parts specify 1.1 V @ 100 mA. This difference is not critical for standard zener regulation applications but should be considered in circuits where forward conduction occurs.

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