VLZ18C-GS08 Equivalent & Substitute Parts

Part Overview

The VLZ18C-GS08 is a Zener diode rated at 17.88 V nominal with 500 mW power dissipation in a SOD-80 QuadroMELF surface mount package, manufactured by Vishay General Semiconductor - Diodes Division. This component is classified as Obsolete, requiring identification of equivalent alternatives for new designs and ongoing production support. The part carries AEC-Q101 automotive qualification and ROHS3 compliance. Substitute parts must maintain electrical performance within the specified voltage, power, and thermal operating ranges while accommodating available packaging options.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	17.88	V
Power - Maximum	500	mW
Impedance (Maximum)	23	Ohms
Current - Reverse Leakage @ Vr	40	µA @ 16.5 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	-
Grade	Automotive	-
Qualification	AEC-Q101	-

Substitute Part Grouping Explanation

Substitution of the VLZ18C-GS08 is determined by the following critical parameters: nominal Zener voltage, maximum power dissipation, maximum impedance, reverse leakage current, forward voltage characteristics, and operating temperature range. All substitute parts must operate within the specified thermal envelope (-65°C to 175°C) and maintain surface mount compatibility. The nominal Zener voltage of 17.88 V establishes the primary selection criterion, with acceptable substitutes operating at 18 V nominal, representing a 0.67% deviation within typical circuit tolerance margins. Maximum power rating of 500 mW must be maintained or exceeded. Impedance and leakage characteristics must remain within specified limits to preserve circuit performance. Package form factors may vary between SOD-80 QuadroMELF, SOD-80 MiniMELF, and DO-213AA configurations, provided surface mount capability is retained.

Parameter Comparison

Parameter	VLZ18C-GS08	TLZ18C-GS08	1N4112UR-1
Manufacturer	Vishay General Semiconductor	Vishay General Semiconductor	Microchip Technology
Voltage - Zener (Nominal)	17.88 V	18 V	18 V
Tolerance	-	-	±5%
Power - Maximum	500 mW	500 mW	500 mW
Impedance (Maximum)	23 Ohms	23 Ohms	100 Ohms
Current - Reverse Leakage @ Vr	40 µA @ 16.5 V	40 nA @ 16.5 V	50 nA @ 13.7 V
Voltage - Forward (Maximum) @ If	1.5 V @ 200 mA	1.5 V @ 200 mA	1.1 V @ 200 mA
Operating Temperature Range	-65 to 175°C	-65 to 175°C	-65 to 175°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Package / Case	SOD-80 QuadroMELF	SOD-80 MiniMELF	DO-213AA
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS Non-compliant
Grade	Automotive	-	-
Qualification	AEC-Q101	-	-

Engineering Selection Recommendations

TLZ18C-GS08 is the primary substitute for VLZ18C-GS08. Both components are manufactured by Vishay General Semiconductor and share identical electrical specifications: 18 V nominal Zener voltage, 500 mW power rating, 23 Ohms maximum impedance, and -65°C to 175°C operating temperature range. The TLZ18C-GS08 features improved reverse leakage characteristics (40 nA versus 40 µA) and maintains ROHS3 compliance. The primary distinction is packaging: TLZ18C-GS08 uses SOD-80 MiniMELF versus the original QuadroMELF variant. Both are surface mount configurations with equivalent thermal and electrical performance. The TLZ18C-GS08 carries Active product status with 2967 units in stock, ensuring supply continuity.

1N4112UR-1 is a secondary substitute manufactured by Microchip Technology. This component maintains the 18 V nominal Zener voltage, 500 mW power rating, and -65°C to 175°C operating temperature range. The 1N4112UR-1 exhibits higher impedance (100 Ohms maximum) and lower forward voltage (1.1 V at 200 mA) compared to the original specification. The component uses DO-213AA packaging, a standard surface mount configuration. Critical limitation: 1N4112UR-1 is RoHS non-compliant, restricting use in applications requiring ROHS3 certification. This substitute is suitable only for legacy systems or applications without RoHS compliance requirements.

For automotive applications requiring AEC-Q101 qualification, TLZ18C-GS08 is the recommended substitute. For general-purpose applications where RoHS compliance is not mandatory, 1N4112UR-1 provides an alternative with acceptable electrical performance within specified operating parameters.

Frequently Asked Questions (FAQ)

Q: Can TLZ18C-GS08 directly replace VLZ18C-GS08 in existing PCB layouts?

A: TLZ18C-GS08 uses SOD-80 MiniMELF packaging while VLZ18C-GS08 uses SOD-80 QuadroMELF. Both are SOD-80 variants with surface mount capability, but physical dimensions differ. PCB footprint verification is required before substitution. Consult component datasheets for precise dimensional specifications.

Q: What is the significance of the 17.88 V versus 18 V Zener voltage difference?

A: The 0.67% deviation between 17.88 V and 18 V nominal ratings falls within typical circuit tolerance margins for Zener diode applications. Both substitute parts operate at 18 V nominal, which is functionally equivalent for voltage regulation and protection circuits designed around the original 17.88 V specification.

Q: Why is reverse leakage current significantly lower in TLZ18C-GS08?

A: TLZ18C-GS08 exhibits 40 nanoamperes reverse leakage versus 40 microamperes in the original VLZ18C-GS08. This represents improved device quality and manufacturing process evolution. Lower leakage current reduces standby power consumption and improves circuit performance in precision applications.

Q: Is 1N4112UR-1 suitable for automotive applications?

A: 1N4112UR-1 is not qualified for automotive use. The component lacks AEC-Q101 certification and is RoHS non-compliant. For automotive applications, TLZ18C-GS08 is the appropriate substitute, maintaining Vishay manufacturing standards and automotive-grade specifications.

Q: What is the impact of 100 Ohms impedance in 1N4112UR-1 versus 23 Ohms in the original?

A: Higher impedance affects transient response and voltage regulation characteristics. The 1N4112UR-1 impedance of 100 Ohms is approximately 4.3 times higher than the original 23 Ohms specification. This difference may impact circuit performance in applications requiring tight voltage regulation or fast transient response. Circuit simulation or testing is necessary to confirm compatibility in specific applications.

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

A: No. VLZ18C-GS08 is SOD-80 QuadroMELF, TLZ18C-GS08 is SOD-80 MiniMELF, and 1N4112UR-1 is DO-213AA. While all are surface mount configurations, physical dimensions and PCB footprints differ. Component selection must account for available PCB real estate and manufacturing capabilities.

Q: What is the RoHS compliance status for each part?

A: VLZ18C-GS08 and TLZ18C-GS08 are both ROHS3 compliant. 1N4112UR-1 is RoHS non-compliant. For applications subject to RoHS regulations or customer requirements, only VLZ18C-GS08 and TLZ18C-GS08 are acceptable substitutes.

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