PDZ18B/ZLX Equivalent & Substitute Parts

Part Overview

The PDZ18B/ZLX is a Zener diode manufactured by Nexperia USA Inc., rated at 17.96 V nominal with 400 mW power dissipation in a surface mount SOD-323 package. This component is classified as obsolete, necessitating identification of equivalent substitute parts for ongoing design requirements and procurement needs. The obsolete status requires engineers to evaluate active alternative components that maintain functional compatibility within circuit specifications.

Substiute Parts

PDZ18B/ZLX

Nexperia USA Inc.In Stock: 1207PDZ18B/ZLX Datasheet

Current PartRFQ

MM3Z18VST1G

onsemiIn Stock: 35144MM3Z18VST1G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the PDZ18B/ZLX is determined by the following critical parameters:

Primary Substitution Criteria:

• Zener voltage nominal rating within tolerance band
• Power dissipation capacity equal to or greater than original specification
• Identical package type (SOD-323) for mechanical and thermal compatibility
• Surface mount configuration matching PCB layout requirements
• Reverse leakage current specifications compatible with circuit operation
• Forward voltage characteristics suitable for application requirements

Secondary Compatibility Factors:

• RoHS3 compliance for regulatory alignment
• Moisture sensitivity level (MSL) rating
• Operating temperature range coverage

The MM3Z18VST1G from onsemi qualifies as a substitute based on matching package geometry, surface mount configuration, and nominal voltage rating within the tolerance specification. The substitute maintains functional equivalence for zener regulation applications while offering active product status and improved availability.

Parameter Comparison

Engineering Selection Recommendations

PDZ18B/ZLX (Original Component): The PDZ18B/ZLX is obsolete and no longer in active production. While 1160 pieces remain in current inventory, this component should not be selected for new designs or long-term procurement strategies. The obsolete status limits future availability and supplier support.

MM3Z18VST1G (Substitute Component): The MM3Z18VST1G is the recommended substitute for the PDZ18B/ZLX. This component is in active production status with 35100 pieces in inventory, ensuring reliable long-term procurement. Both components share identical package geometry (SOD-323), surface mount configuration, and RoHS3 compliance. The nominal zener voltage differs by 0.04 V (17.96 V vs. 18 V), which falls within the ±2% tolerance specification of both devices and is functionally equivalent for regulation applications.

The MM3Z18VST1G exhibits lower maximum power dissipation (300 mW vs. 400 mW) and higher impedance (45 Ohms vs. 20 Ohms). Circuit designs must confirm that the reduced power rating and increased impedance are acceptable for the intended application. The substitute provides an extended operating temperature range (-65°C to 150°C) compared to the original specification (150°C maximum), offering improved thermal performance margin.

Both components maintain identical reverse leakage current specifications (50 nA) and RoHS3 compliance, ensuring regulatory and environmental compatibility.

Frequently Asked Questions (FAQ)

Q: Can the MM3Z18VST1G directly replace the PDZ18B/ZLX without circuit modification?

A: The MM3Z18VST1G is mechanically and electrically compatible for most applications. Both components use the SOD-323 package and share ±2% tolerance zener voltage ratings. However, the reduced power dissipation (300 mW vs. 400 mW) and increased impedance (45 Ohms vs. 20 Ohms) require circuit verification to confirm the application does not exceed these limits.

Q: What is the voltage difference between these two zener diodes?

A: The PDZ18B/ZLX is rated at 17.96 V nominal, while the MM3Z18VST1G is rated at 18 V nominal. The 0.04 V difference represents 0.22% variation, which is well within the ±2% tolerance specification of both devices. This difference is functionally negligible for zener regulation applications.

Q: Are both components RoHS compliant?

A: Yes, both the PDZ18B/ZLX and MM3Z18VST1G are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements.

Q: What is the significance of the product status difference?

A: The PDZ18B/ZLX is classified as obsolete, indicating discontinued production and limited future availability. The MM3Z18VST1G is in active production status, ensuring reliable procurement for current and future designs. New designs should utilize the active component.

Q: How do the impedance specifications affect circuit performance?

A: The MM3Z18VST1G exhibits higher impedance (45 Ohms maximum vs. 20 Ohms maximum). Higher impedance results in increased output impedance of the zener regulator, which may affect voltage regulation quality under varying load conditions. Circuit designs with tight regulation requirements should evaluate this parameter against application specifications.

Q: Are the packaging and mounting configurations identical?

A: Yes, both components use the SOD-323 surface mount package (SC-76 case designation). PCB layouts, footprints, and reflow soldering profiles are directly compatible between these two components.

Q: What is the operating temperature range for each component?

A: The PDZ18B/ZLX specifies a maximum junction temperature of 150°C without a minimum specification. The MM3Z18VST1G specifies an operating range of -65°C to 150°C junction temperature, providing a defined lower temperature limit and extended thermal operating margin.