CLL4678 TR Equivalent & Substitute Parts

Part Overview

The CLL4678 TR is a Zener diode rated at 1.8 V with 500 mW power dissipation, manufactured by Central Semiconductor Corp in a surface mount SOD-80 package. This component is classified as obsolete, indicating discontinued production and limited availability. Identification of equivalent and substitute parts is necessary to support ongoing design requirements, maintenance operations, and production continuity where original components are no longer readily procurable.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	1.8	V
Tolerance	±5	%
Power - Max	500	mW
Current - Reverse Leakage @ Vr	7.5	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.5	V @ 100 mA
Operating Temperature Range	-65 to 200	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	SOD-80, DO-213AC, MINI-MELF	—

Substitute Part Grouping Explanation

Substitution of the CLL4678 TR is determined by electrical and mechanical parameter alignment within the Zener diode category. The following parameters establish substitution validity:

Electrical Parameters (Critical):

Zener voltage (Vz): 1.8 V nominal
Tolerance: ±5%
Maximum power dissipation: 500 mW
Reverse leakage current: 7.5 µA @ 1 V
Forward voltage: 1.5 V @ 100 mA

Mechanical Parameters (Critical):

Mounting type: Surface Mount
Package compatibility: SOD-80 or equivalent surface mount packages

Operational Parameters:

Operating temperature range must support the application requirements

The CMHZ4678 TR meets all electrical specifications and maintains surface mount compatibility. Package differences between SOD-80 and SOD-123 represent the primary mechanical distinction and must be evaluated against PCB layout constraints.

Parameter Comparison

Parameter	CLL4678 TR (Main)	CMHZ4678 TR (Substitute)	Match Status
Manufacturer	Central Semiconductor Corp	Central Semiconductor Corp	Identical
Category	Diodes, Zener	Diodes, Zener	Identical
Voltage - Zener (Nom)	1.8 V	1.8 V	Identical
Tolerance	±5%	±5%	Identical
Power - Max	500 mW	500 mW	Identical
Current - Reverse Leakage @ Vr	7.5 µA @ 1 V	7.5 µA @ 1 V	Identical
Voltage - Forward (Vf) (Max) @ If	1.5 V @ 100 mA	1.5 V @ 100 mA	Identical
Operating Temperature Range	-65°C ~ 200°C (TJ)	-65°C ~ 150°C (TJ)	Substitute Range Narrower
Mounting Type	Surface Mount	Surface Mount	Identical
Package / Case	SOD-80, DO-213AC, MINI-MELF	SOD-123	Different Package
Product Status	Obsolete	Active	Substitute is Current

Engineering Selection Recommendations

The CMHZ4678 TR is a valid electrical substitute for the CLL4678 TR based on identical Zener voltage, tolerance, power rating, reverse leakage current, and forward voltage specifications. Both components are manufactured by Central Semiconductor Corp and share identical electrical performance characteristics.

Product Status Consideration: The CLL4678 TR is obsolete, while the CMHZ4678 TR maintains active production status. This distinction provides supply chain continuity and long-term component availability for new designs and production runs.

Temperature Range Consideration: The CMHZ4678 TR operates across -65°C to 150°C, compared to the CLL4678 TR range of -65°C to 200°C. Applications requiring operation above 150°C junction temperature require evaluation of the reduced upper temperature limit.

Package Consideration: The CLL4678 TR uses SOD-80 packaging, while the CMHZ4678 TR uses SOD-123 packaging. Both are surface mount packages with different footprints. PCB layout modifications are required to accommodate the SOD-123 package geometry.

Compliance: Both components carry identical ECCN (EAR99) and HTSUS (8541.10.0050) classifications. The CMHZ4678 TR includes REACH Unaffected status, confirming regulatory compliance for European applications.

Frequently Asked Questions (FAQ)

Q: Can the CMHZ4678 TR directly replace the CLL4678 TR without circuit modification?

A: Electrical substitution is valid. The CMHZ4678 TR provides identical Zener voltage, tolerance, power dissipation, and leakage characteristics. However, package differences (SOD-80 versus SOD-123) require PCB footprint modification. Applications operating above 150°C junction temperature require thermal analysis of the reduced temperature range.

Q: What is the primary difference between these two parts?

A: The main differences are product status (obsolete versus active), operating temperature range (200°C versus 150°C maximum), and package type (SOD-80 versus SOD-123). All electrical specifications are identical.

Q: Is the SOD-123 package smaller or larger than SOD-80?

A: SOD-123 and SOD-80 are both surface mount packages with different physical dimensions. Specific footprint dimensions must be referenced in the respective component datasheets to determine PCB layout compatibility.

Q: Does the CMHZ4678 TR meet the same regulatory requirements as the CLL4678 TR?

A: Both components share identical ECCN and HTSUS classifications. The CMHZ4678 TR includes REACH Unaffected status, confirming compliance with European chemical regulations.

Q: What applications are affected by the 150°C maximum junction temperature of the CMHZ4678 TR?

A: Applications with sustained junction temperatures above 150°C require thermal analysis. The CLL4678 TR supports operation to 200°C. Thermal management and derating calculations determine whether the CMHZ4678 TR is suitable for high-temperature environments.

Q: Is the CMHZ4678 TR available in inventory?

A: The CMHZ4678 TR is listed as active production status with 862 pieces in stock, compared to the obsolete CLL4678 TR with 958 pieces in stock. Availability should be confirmed with the component supplier for current procurement.

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