VLZ43-GS08 Equivalent & Substitute Parts

Part Overview

The VLZ43-GS08 is a Zener diode rated at 42.5 V, 500 mW, manufactured by Vishay General Semiconductor - Diodes Division in SOD-80 QuadroMELF surface mount package. This part is classified as obsolete, necessitating identification of active equivalent components for new designs and ongoing production requirements. Substitute parts must maintain electrical performance within the specified voltage, power dissipation, and thermal operating ranges while meeting applicable compliance standards.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	42.5	V
Power - Maximum	500	mW
Impedance (Maximum)	90	Ohms
Current - Reverse Leakage @ Vr	40	µA @ 38 V
Voltage - Forward (Maximum) @ If	1.5	V @ 200 mA
Operating Temperature Range	-65 to 175	°C
Mounting Type	Surface Mount	—
Package / Case	SOD-80 QuadroMELF	—
Grade	Automotive	—
Qualification	AEC-Q101	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the VLZ43-GS08 is determined by the following critical parameters:

Electrical Equivalence Criteria:

Zener voltage nominal rating within acceptable tolerance of 42.5 V
Power dissipation capacity of 500 mW minimum
Operating temperature range spanning -65°C to 175°C minimum
Surface mount configuration

Mechanical Compatibility Criteria:

SOD-80 package family (includes SOD-80 QuadroMELF, SOD-80 MiniMELF, DO-213AC variants)
Surface mount technology

Compliance Criteria:

RoHS3 compliance preferred for new designs
AEC-Q101 automotive qualification where applicable

Three substitute parts meet these criteria with varying degrees of parameter alignment:

TLZ43-GS08 (Vishay) — Direct manufacturer alternative with active product status
BZV55-B43,115 (Nexperia) — Active equivalent with enhanced temperature range
1N4124UR-1 (Microchip) — Active alternative with different package variant

Parameter Comparison

Parameter	VLZ43-GS08	TLZ43-GS08	BZV55-B43,115	1N4124UR-1
Manufacturer	Vishay	Vishay	Nexperia	Microchip
Voltage - Zener (Nom)	42.5 V	43 V	43 V	43 V
Tolerance	—	—	±2%	±5%
Power - Max	500 mW	500 mW	500 mW	500 mW
Impedance (Max)	90 Ohms	90 Ohms	150 Ohms	250 Ohms
Current - Reverse Leakage @ Vr	40 µA @ 38 V	40 nA @ 38 V	50 nA @ 30.1 V	10 nA @ 32.7 V
Voltage - Forward (Max) @ If	1.5 V @ 200 mA	1.5 V @ 200 mA	900 mV @ 10 mA	1.1 V @ 200 mA
Operating Temperature	-65 to 175°C	-65 to 175°C	-65 to 200°C	-65 to 175°C
Product Status	Obsolete	Active	Active	Active
Package / Case	SOD-80 QuadroMELF	SOD-80 MiniMELF	DO-213AC, MINI-MELF, SOD-80	DO-213AA
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	RoHS Non-compliant
AEC-Q101	Yes	—	—	—

Engineering Selection Recommendations

Primary Substitute: TLZ43-GS08

The TLZ43-GS08 is the recommended direct substitute. Both parts are manufactured by Vishay General Semiconductor - Diodes Division, share identical electrical specifications (500 mW power rating, 90 Ohm impedance), and operate across the same temperature range (-65°C to 175°C). The TLZ43-GS08 is active in production with 22,700 units in stock. The zener voltage is 43 V versus 42.5 V on the original part, representing a 1.2% variance within acceptable engineering tolerance. Both parts are ROHS3 compliant. Package variant changes from SOD-80 QuadroMELF to SOD-80 MiniMELF; both are surface mount SOD-80 family components suitable for equivalent PCB footprints.

Secondary Substitute: BZV55-B43,115

The BZV55-B43,115 manufactured by Nexperia USA Inc. is an active alternative meeting all electrical requirements. It provides 500 mW power dissipation, 43 V zener voltage, and operates from -65°C to 200°C, exceeding the original temperature range. The impedance specification is 150 Ohms (versus 90 Ohms on VLZ43-GS08), representing a 67% increase. Reverse leakage current is 50 nA @ 30.1 V, significantly lower than the original 40 µA @ 38 V. The part is ROHS3 compliant with 3,928 units in stock. Package is DO-213AC MINI-MELF SOD-80 variant, compatible with SOD-80 family footprints.

Tertiary Substitute: 1N4124UR-1

The 1N4124UR-1 manufactured by Microchip Technology meets core electrical specifications: 43 V zener voltage, 500 mW power rating, and -65°C to 175°C operating range. However, this part is RoHS non-compliant, limiting suitability for new designs subject to RoHS3 requirements. Impedance is 250 Ohms (2.8× higher than original). Package is DO-213AA, a different SOD-80 variant. Selection of this part requires explicit compliance exemption documentation. Inventory is 741 units.

Compliance Considerations:

For applications requiring AEC-Q101 automotive qualification, the VLZ43-GS08 original specification includes this certification. Substitute parts TLZ43-GS08, BZV55-B43,115, and 1N4124UR-1 do not list AEC-Q101 qualification in provided specifications. Automotive applications must verify qualification status with manufacturers before substitution.

Frequently Asked Questions (FAQ)

Q: Can TLZ43-GS08 directly replace VLZ43-GS08 on existing PCBs?

A: The TLZ43-GS08 uses SOD-80 MiniMELF packaging versus the original SOD-80 QuadroMELF. Both are SOD-80 family surface mount components. PCB footprint compatibility depends on specific land pattern design. Verify footprint dimensions with manufacturer datasheets before board-level substitution.

Q: What is the significance of the 42.5 V to 43 V zener voltage difference?

A: The 0.5 V difference represents 1.2% variance from the original 42.5 V specification. This falls within typical engineering tolerance for zener diode applications. Circuit design must confirm that 43 V operation is acceptable for the intended voltage regulation or protection function.

Q: Why does BZV55-B43,115 have higher impedance (150 Ohms) than VLZ43-GS08 (90 Ohms)?

A: Impedance variation reflects different semiconductor manufacturing processes and die designs between manufacturers. Higher impedance affects voltage regulation characteristics under load changes. Circuit analysis is required to confirm acceptable performance with the 150 Ohm impedance specification.

Q: Is 1N4124UR-1 suitable for new automotive designs?

A: The 1N4124UR-1 is RoHS non-compliant and lacks AEC-Q101 qualification in provided specifications. New automotive designs typically require both certifications. This part is suitable only for legacy production or non-automotive applications with explicit compliance approval.

Q: What is the impact of reverse leakage current differences?

A: VLZ43-GS08 specifies 40 µA reverse leakage at 38 V. Substitute parts show significantly lower leakage: TLZ43-GS08 (40 nA), BZV55-B43,115 (50 nA), and 1N4124UR-1 (10 nA). Lower leakage improves circuit efficiency and reduces standby power consumption. This is a beneficial characteristic change.

Q: Are all substitute parts available in the same packaging format?

A: No. VLZ43-GS08 is SOD-80 QuadroMELF. TLZ43-GS08 is SOD-80 MiniMELF. BZV55-B43,115 is LLDS MiniMELF (DO-213AC variant). 1N4124UR-1 is DO-213AA. All are surface mount SOD-80 family variants, but specific land patterns differ. Consult PCB layout requirements and manufacturer footprint specifications.

Q: Which substitute offers the best long-term availability?

A: TLZ43-GS08 has the highest inventory (22,700 units) and active product status from the same manufacturer as the original part. BZV55-B43,115 has 3,928 units in stock and active status. Both provide superior long-term availability compared to the obsolete VLZ43-GS08.

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