CLL4678 BK Equivalent & Substitute Parts

Part Overview

The CLL4678 BK is a Zener diode rated at 1.8 V with 500 mW power dissipation, manufactured by Central Semiconductor Corp in the SOD-80 (DO-213AC, MINI-MELF) surface mount package. This component is classified as obsolete, necessitating identification of active equivalent parts for new designs and ongoing production requirements. The obsolete status requires substitution planning to ensure supply chain continuity and design compatibility.

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	—

Substitute Part Grouping Explanation

Substitution of the CLL4678 BK is determined by electrical parameter equivalence and package compatibility. The primary substitute identified is the CMHZ4678 BK, which maintains identical electrical specifications across all critical parameters: 1.8 V nominal Zener voltage, ±5% tolerance, 500 mW maximum power rating, 7.5 µA reverse leakage current, and 1.5 V maximum forward voltage. Both components are surface mount Zener diodes manufactured by Central Semiconductor Corp.

The key differentiator between the main part and its substitute is the package format. The CLL4678 BK uses SOD-80 (MINI-MELF) packaging, while the CMHZ4678 BK uses SOD-123 packaging. This package difference requires PCB layout modification and is the primary consideration for substitution feasibility. The CMHZ4678 BK carries active product status, ensuring ongoing availability and supply chain support.

Parameter Comparison

Parameter	CLL4678 BK	CMHZ4678 BK	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
Mounting Type	Surface Mount	Surface Mount	Identical
Operating Temperature Range	-65°C ~ 200°C	-65°C ~ 150°C	Partial Match
Package / Case	SOD-80 (DO-213AC, MINI-MELF)	SOD-123	Different
Product Status	Obsolete	Active	Different

Engineering Selection Recommendations

The CMHZ4678 BK is the direct electrical equivalent to the CLL4678 BK, with all critical Zener diode parameters matching exactly. The substitute part carries active product status from Central Semiconductor Corp, ensuring long-term availability and supply chain reliability compared to the obsolete CLL4678 BK.

The primary design consideration for substitution is the package transition from SOD-80 to SOD-123. This change requires PCB footprint modification and layout adjustment. The operating temperature range of the CMHZ4678 BK extends to 150°C maximum junction temperature, compared to 200°C for the CLL4678 BK. Applications requiring operation above 150°C junction temperature require thermal analysis to confirm the substitute part remains within acceptable operating limits.

The CMHZ4678 BK is compliant with REACH regulations and carries EAR99 export classification, matching the regulatory profile of the original part.

Frequently Asked Questions (FAQ)

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

A: The CMHZ4678 BK provides electrical equivalence and can replace the CLL4678 BK functionally. However, the package change from SOD-80 to SOD-123 requires PCB footprint modification. Direct socket replacement is not possible without layout redesign.

Q: What is the impact of the operating temperature range difference?

A: The CLL4678 BK operates to 200°C junction temperature, while the CMHZ4678 BK operates to 150°C. For applications with maximum junction temperatures below 150°C, the substitute part operates within specification. Applications approaching or exceeding 150°C require thermal verification to confirm the substitute remains within acceptable limits.

Q: Are the electrical characteristics identical between the two parts?

A: Yes. The Zener voltage (1.8 V), tolerance (±5%), power rating (500 mW), reverse leakage current (7.5 µA @ 1 V), and forward voltage (1.5 V @ 100 mA) are identical between the CLL4678 BK and CMHZ4678 BK.

Q: What is the significance of the product status change from obsolete to active?

A: The CMHZ4678 BK carries active product status, indicating ongoing manufacturing and supply availability. The CLL4678 BK is obsolete, meaning production has ended and inventory is limited. Substitution to an active part ensures long-term design support and component availability.

Q: Are there package size differences between SOD-80 and SOD-123?

A: Yes. SOD-80 (MINI-MELF) and SOD-123 are different surface mount packages with different footprints, lead spacing, and board area requirements. PCB design modification is required for substitution.

Q: What compliance certifications apply to the substitute part?

A: The CMHZ4678 BK is REACH compliant and carries EAR99 export classification, matching the regulatory profile of the original CLL4678 BK.

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