MM5Z43VT1 Equivalent & Substitute Parts

Part Overview

The MM5Z43VT1 is a 43 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 production, repair, and redesign applications.

Key Parameters

Parameter	Value
Voltage - Zener (Nom)	43 V
Tolerance	±7%
Power - Max	100 mW
Impedance (Max)	150 Ohms
Current - Reverse Leakage @ Vr	50 nA @ 30.1 V
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA
Operating Temperature	-65°C ~ 150°C
Mounting Type	Surface Mount
Package / Case	SC-79, SOD-523
RoHS Status	RoHS non-compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the MM5Z43VT1 is determined by the following critical parameters:

Electrical Parameters (Must Match):

Zener voltage: 43 V nominal
Reverse leakage current: 50 nA @ 30.1 V
Operating temperature range: -65°C ~ 150°C

Mechanical Parameters (Must Match or Exceed):

Power dissipation rating: minimum 100 mW
Impedance: maximum 150 Ohms
Mounting type: Surface Mount

Package Compatibility:

Primary package: SOD-523 (SC-79)
Alternative packages: SOD-323F, SOD-123F (with PCB layout modification)

Substitute parts are grouped into three categories based on package type and power rating:

SOD-523 Package (Direct Footprint Compatible): BZT585B43T-7, BZX585-B43,115, BZX585-C43,115
SOD-323F Package (Higher Power Rating): BZX84J-B43,115, BZX84J-C43,115
SOD-123F Package (Higher Power Rating): BZT52H-C43,115

All substitute parts maintain the 43 V zener voltage specification and 50 nA reverse leakage current at 30.1 V.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Package	Product Status	RoHS Status
MM5Z43VT1	onsemi	43 V	±7%	100 mW	150 Ω	SOD-523	Obsolete	Non-compliant
BZT585B43T-7	Diodes Incorporated	43 V	±2%	350 mW	150 Ω	SOD-523	Active	ROHS3 Compliant
BZX585-B43,115	NXP Semiconductors	43 V	±2%	300 mW	150 Ω	SOD-523	Active	Not specified
BZX585-C43,115	Nexperia USA Inc.	43 V	±5%	300 mW	150 Ω	SOD-523	Active	ROHS3 Compliant
BZX84J-B43,115	Nexperia USA Inc.	43 V	±2%	550 mW	80 Ω	SOD-323F	Active	ROHS3 Compliant
BZX84J-C43,115	Nexperia USA Inc.	43 V	±5%	550 mW	80 Ω	SOD-323F	Active	ROHS3 Compliant
BZT52H-C43,115	Nexperia USA Inc.	43 V	±5%	375 mW	80 Ω	SOD-123F	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Footprint Replacement (SOD-523 Package):

BZT585B43T-7 (Diodes Incorporated) is the primary substitute for the MM5Z43VT1. This part maintains identical package geometry (SOD-523), exceeds the minimum power rating (350 mW vs. 100 mW), and is actively manufactured with ROHS3 compliance. The ±2% tolerance provides improved voltage accuracy compared to the original ±7% specification.

BZX585-C43,115 (Nexperia USA Inc.) is an alternative SOD-523 substitute with 300 mW power rating, ROHS3 compliance, and AEC-Q100 automotive qualification. The ±5% tolerance falls between the original specification and the tighter BZT585B43T-7 tolerance.

BZX585-B43,115 (NXP Semiconductors) provides 300 mW power rating in SOD-523 package with ±2% tolerance. RoHS status is not specified in available documentation.

For Higher Power Applications (Alternative Packages):

BZX84J-B43,115 and BZX84J-C43,115 (Nexperia USA Inc.) offer 550 mW power dissipation in SOD-323F package with improved impedance characteristics (80 Ω vs. 150 Ω). Both parts carry AEC-Q101 automotive qualification and ROHS3 compliance. PCB layout modification is required for package transition.

BZT52H-C43,115 (Nexperia USA Inc.) provides 375 mW in SOD-123F package with 80 Ω impedance and ROHS3 compliance. This option requires PCB redesign for package accommodation.

Compliance Considerations:

The original MM5Z43VT1 is RoHS non-compliant. All recommended substitutes are ROHS3 compliant, supporting modern manufacturing and environmental standards. Nexperia parts include automotive-grade qualifications (AEC-Q100 or AEC-Q101), suitable for automotive and industrial applications.

Frequently Asked Questions (FAQ)

Q: Can BZT585B43T-7 directly replace MM5Z43VT1 without PCB modification?

A: Yes. Both parts use the SOD-523 package (SC-79), enabling direct footprint compatibility. No PCB layout changes are required. The BZT585B43T-7 exceeds the power rating requirement (350 mW vs. 100 mW) and maintains the same impedance specification (150 Ω).

Q: What is the difference between BZX585-C43,115 and BZX585-B43,115?

A: Both parts are SOD-523 packaged 43 V Zener diodes with 300 mW power rating and 150 Ω impedance. The primary difference is tolerance: BZX585-C43,115 has ±5% tolerance (matching the original specification closer), while BZX585-B43,115 has ±2% tolerance (tighter accuracy). BZX585-C43,115 carries AEC-Q100 automotive qualification; BZX585-B43,115 RoHS status is not specified.

Q: Why do BZX84J-B43,115 and BZX84J-C43,115 have lower impedance (80 Ω vs. 150 Ω)?

A: The lower impedance results from the larger SOD-323F package geometry, which accommodates higher power dissipation (550 mW) and improved thermal characteristics. Lower impedance indicates better voltage regulation performance under load variation. These parts are suitable for applications requiring enhanced power handling.

Q: Can I use BZT52H-C43,115 (SOD-123F) as a substitute?

A: BZT52H-C43,115 is electrically compatible (43 V, 50 nA leakage, -65°C to 150°C operating range) and offers higher power rating (375 mW). However, SOD-123F package dimensions differ from SOD-523, requiring PCB layout modification. Use this substitute only when PCB redesign is feasible and the larger package footprint can be accommodated.

Q: What is the significance of the ±2% vs. ±5% vs. ±7% tolerance specifications?

A: Tolerance indicates the acceptable deviation of the zener voltage from the nominal 43 V specification. The original MM5Z43VT1 (±7%) allows 40.0 V to 46.0 V variation. BZT585B43T-7 and BZX84J-B43,115 (±2%) allow 42.1 V to 43.9 V variation, providing tighter voltage regulation. BZX585-C43,115 and BZX84J-C43,115 (±5%) allow 40.85 V to 45.15 V variation. Select tolerance based on circuit voltage regulation requirements.

Q: Are all substitute parts RoHS compliant?

A: All recommended substitutes are ROHS3 compliant except BZX585-B43,115, for which RoHS status is not specified in available documentation. If RoHS compliance is a design requirement, use BZT585B43T-7, BZX585-C43,115, BZX84J-B43,115, BZX84J-C43,115, or BZT52H-C43,115.

Q: Which substitute offers the best balance of compatibility and performance?

A: BZT585B43T-7 provides optimal balance: direct SOD-523 footprint compatibility, 350 mW power rating (3.5× the original specification), ±2% tolerance (improved accuracy), ROHS3 compliance, and active manufacturing status. No PCB modification is required.

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