GDZ18B-G3-08 Equivalent & Substitute Parts

Part Overview

The GDZ18B-G3-08 is a Zener diode manufactured by Vishay General Semiconductor - Diodes Division, rated at 18 V nominal with 200 mW power dissipation in a surface mount SOD-323 package. The device is Active status and ROHS3 compliant. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are maintained across the specified parameter range, enabling component procurement flexibility and supply chain continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	18	V
Tolerance	±4%	-
Power - Max	200	mW
Impedance (Max)	65	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 13 V	-
Operating Temperature	-55°C ~ 150°C	-
Mounting Type	Surface Mount	-
Package / Case	SC-76, SOD-323	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution logic is based on the following critical parameters that must remain constant or within acceptable operating margins:

Mandatory Equivalence Criteria:

Voltage - Zener (Nom): 18 V (exact match required)
Package / Case: SOD-323 (mechanical and thermal compatibility)
Mounting Type: Surface Mount (assembly process compatibility)
RoHS Status: ROHS3 Compliant (regulatory requirement)

Allowable Parameter Variance:

Tolerance: ±4% or tighter (±2% or ±6% acceptable)
Power - Max: 200 mW or greater (higher ratings provide design margin)
Impedance (Max): 65 Ohms or lower (lower impedance acceptable)
Current - Reverse Leakage: 100 nA @ 13 V or lower (lower leakage acceptable)
Operating Temperature: -55°C ~ 150°C or wider range (extended range acceptable)

Substitute parts are grouped into two categories: Parametric Equivalents (identical electrical specifications from Vishay) and Manufacturer Recommended (alternative manufacturers with enhanced or equivalent performance characteristics).

Parameter Comparison

Part Number	Manufacturer	Voltage - Zener (Nom)	Tolerance	Power - Max	Impedance (Max)	Current - Reverse Leakage @ Vr	Operating Temperature	Package	RoHS Status
GDZ18B-G3-08	Vishay	18 V	±4%	200 mW	65 Ohms	100 nA @ 13 V	-55°C ~ 150°C	SOD-323	ROHS3
GDZ18B-E3-08	Vishay	18 V	±4%	200 mW	65 Ohms	100 nA @ 13 V	-55°C ~ 150°C	SOD-323	ROHS3
GDZ18B-HE3-08	Vishay	18 V	±4%	200 mW	65 Ohms	100 nA @ 13 V	-55°C ~ 150°C	SOD-323	ROHS3
GDZ18B-HE3-18	Vishay	18 V	±4%	200 mW	65 Ohms	100 nA @ 13 V	-55°C ~ 150°C	SOD-323	ROHS3
MM3Z18VST1G	onsemi	18 V	±2%	300 mW	45 Ohms	50 nA @ 12.6 V	-65°C ~ 150°C	SOD-323	ROHS3
MM3Z18VT1G	onsemi	18 V	±6%	300 mW	45 Ohms	50 nA @ 12.6 V	-65°C ~ 150°C	SOD-323	ROHS3
SZMM3Z18VST1G	onsemi	18 V	±2%	300 mW	45 Ohms	50 nA @ 12.6 V	-65°C ~ 150°C	SOD-323	ROHS3
SZMM3Z18VT1G	onsemi	18 V	±6%	300 mW	45 Ohms	50 nA @ 12.6 V	-65°C ~ 150°C	SOD-323	ROHS3

Engineering Selection Recommendations

Parametric Equivalents (Vishay GDZ Series):

GDZ18B-E3-08, GDZ18B-HE3-08, and GDZ18B-HE3-18 are direct parametric equivalents to GDZ18B-G3-08. All devices share identical electrical specifications and operating characteristics. GDZ18B-HE3-08 and GDZ18B-HE3-18 carry AEC-Q101 automotive qualification, suitable for applications requiring automotive-grade reliability.

Manufacturer Recommended Alternatives (onsemi MM3Z18 and SZMM3Z18 Series):

onsemi MM3Z18VST1G, MM3Z18VT1G, SZMM3Z18VST1G, and SZMM3Z18VT1G provide enhanced performance characteristics while maintaining 18 V nominal zener voltage and SOD-323 package compatibility. These devices offer:

Increased power dissipation (300 mW vs. 200 mW)
Lower impedance (45 Ohms vs. 65 Ohms)
Reduced reverse leakage current (50 nA vs. 100 nA)
Extended lower operating temperature limit (-65°C vs. -55°C)

MM3Z18VST1G and SZMM3Z18VST1G feature ±2% tolerance. SZMM3Z18VST1G and SZMM3Z18VT1G carry AEC-Q101 automotive qualification. Selection between onsemi variants depends on tolerance and automotive qualification requirements.

Frequently Asked Questions (FAQ)

Q: Can GDZ18B-E3-08 be used as a direct replacement for GDZ18B-G3-08?

A: Yes. GDZ18B-E3-08 is a parametric equivalent with identical voltage rating (18 V), tolerance (±4%), power rating (200 mW), impedance (65 Ohms), reverse leakage current (100 nA @ 13 V), operating temperature range (-55°C ~ 150°C), and SOD-323 package. No circuit modifications are required.

Q: What is the difference between GDZ18B-HE3-08 and GDZ18B-HE3-18?

A: Both devices are electrically identical with respect to zener voltage, tolerance, power rating, impedance, and reverse leakage specifications. The difference lies in packaging configuration or tape reel specifications. Both carry AEC-Q101 automotive qualification.

Q: Can onsemi MM3Z18 series devices replace the Vishay GDZ18B-G3-08?

A: Yes, with design considerations. onsemi MM3Z18 devices maintain the 18 V nominal zener voltage and SOD-323 package. However, they offer enhanced specifications: 300 mW power rating (vs. 200 mW), lower impedance (45 Ohms vs. 65 Ohms), and reduced reverse leakage (50 nA vs. 100 nA). These improvements provide additional design margin and are electrically compatible. Tolerance options range from ±2% to ±6%.

Q: What is the significance of AEC-Q101 qualification on GDZ18B-HE3 and SZMM3Z18 variants?

A: AEC-Q101 qualification indicates the device meets automotive industry reliability and quality standards. These variants are suitable for automotive applications requiring formal qualification documentation. Non-qualified variants (GDZ18B-G3-08, GDZ18B-E3-08, MM3Z18 series without SZMM prefix) are suitable for general industrial and consumer applications.

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

A: All substitute parts use SOD-323 package (SC-76). Packaging format differs: GDZ18B-G3-08, GDZ18B-E3-08, GDZ18B-HE3-08, and GDZ18B-HE3-18 are supplied in Tape & Reel (TR). MM3Z18VST1G and MM3Z18VT1G are supplied in Cut Tape (CT) & Digi-Reel®. SZMM3Z18VST1G and SZMM3Z18VT1G are supplied in Tape & Reel (TR). Verify packaging format compatibility with assembly equipment before procurement.

Q: Which substitute part offers the best performance improvement?

A: SZMM3Z18VST1G and SZMM3Z18VT1G provide the most comprehensive performance enhancement: 300 mW power rating, 45 Ohms impedance, 50 nA reverse leakage, and -65°C lower temperature limit. SZMM3Z18VST1G additionally offers ±2% tolerance and AEC-Q101 qualification, making it suitable for precision and automotive applications.

Q: Is tolerance selection critical for circuit operation?

A: Tolerance selection depends on circuit design requirements. GDZ18B-G3-08 and all Vishay equivalents provide ±4% tolerance. onsemi MM3Z18VST1G and SZMM3Z18VST1G offer tighter ±2% tolerance for applications requiring precise voltage regulation. MM3Z18VT1G and SZMM3Z18VT1G provide ±6% tolerance for less stringent applications. Verify tolerance requirements against circuit specifications before selection.

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