CLL4764A TR Equivalent & Substitute Parts

Part Overview

The CLL4764A TR is a 100 V, 1 W Zener diode manufactured by Central Semiconductor Corp in MELF surface mount packaging. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The part operates across a temperature range of -65°C to 200°C with ±5% voltage tolerance and is suitable for voltage regulation and protection applications in surface mount assemblies.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	100	V
Tolerance	±5%	—
Power - Max	1	W
Impedance (Max)	350	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 76 V
Voltage - Forward (Vf) (Max) @ If	1.2	V @ 200 mA
Operating Temperature	-65 to 200	°C
Mounting Type	Surface Mount	—
Package / Case	DO-213AB, MELF	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the CLL4764A TR is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 100 V nominal
Voltage tolerance: ±5% (exact match required for precision applications)
Power dissipation: 1 W minimum
Package type: DO-213AB or MELF surface mount
Mounting type: Surface mount
Forward voltage: 1.2 V @ 200 mA maximum

Secondary Compatibility Factors:

Impedance (Zzt): 350 Ohms maximum
Reverse leakage current: 5 µA @ 76 V or lower
Operating temperature range: Must support -65°C minimum
Moisture sensitivity: MSL 1 (Unlimited)

Substitute parts are grouped into three categories based on electrical performance:

Category 1 - Direct Equivalents (100 V, 1 W, ±5% tolerance): Parts with identical electrical specifications and packaging. These provide one-to-one replacement capability.

Category 2 - Enhanced Performance Substitutes (100 V, 1.25 W, ±5% tolerance): Parts with higher power rating and improved impedance characteristics. These are suitable for applications requiring additional thermal margin.

Category 3 - Tolerance Variants (100 V, 1 W, ±10% or ±20% tolerance): Parts with relaxed voltage tolerance specifications. These are applicable only when tolerance requirements permit.

Category 4 - Higher Power Alternatives (100 V, 3 W): Parts with significantly increased power dissipation in different packaging. These require mechanical and thermal design verification.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (W)	Zzt (Ohms)	Vf @ 200mA (V)	Temp Range (°C)	Package	Status
CLL4764A TR	Central Semiconductor	100	±5%	1	350	1.2	-65 to 200	DO-213AB, MELF	Obsolete
1N4764AUR	Microchip Technology	100	±5%	1	350	1.2	-65 to 175	DO-213AB, MELF	Active
1N3044BUR-1	Microchip Technology	100	±5%	1	350	1.2	-55 to 175	DO-213AB, MELF	Active
1N5949BUR-1	Microchip Technology	100	±5%	1.25	250	1.2	-65 to 175	DO-213AB, MELF	Active
1SMB5949BT3G	onsemi	100	±5%	3	250	1.5	-65 to 150	DO-214AA, SMB	Active
CDLL3044	Microchip Technology	100	±20%	1	350	1.2	-55 to 175	DO-213AB, MELF	Active
CDLL3044B	Microchip Technology	100	±5%	1	350	1.2	-55 to 175	DO-213AB, MELF	Active
CDLL4764	Microchip Technology	100	±10%	1	350	1.2	-65 to 175	DO-213AB, MELF	Active
CDLL4764A	Microchip Technology	100	±5%	1	350	1.2	-65 to 175	DO-213AB, MELF	Active
CDLL5949B	Microchip Technology	100	±5%	1.25	250	1.2	-65 to 175	DO-213AB, MELF	Active
CDLL5949C	Microchip Technology	100	±2%	1.25	250	1.2	-65 to 175	DO-213AB, MELF	Active

Engineering Selection Recommendations

Primary Substitute - CDLL4764A (Microchip Technology): This part provides the closest electrical and mechanical match to the CLL4764A TR. It maintains identical specifications for Zener voltage (100 V), tolerance (±5%), power rating (1 W), impedance (350 Ohms), and forward voltage. The operating temperature range extends to -65°C minimum, matching the original part. This substitute is active in production and available in bulk packaging. Selection of CDLL4764A is appropriate for direct replacement in existing designs without circuit modification.

Secondary Substitute - CDLL3044B (Microchip Technology): This part matches all critical electrical parameters: 100 V Zener voltage, ±5% tolerance, 1 W power rating, and 350 Ohms impedance. The operating temperature range is -55°C to 175°C, which represents a reduced low-temperature capability compared to the original part. This substitute is suitable for applications where the -55°C minimum temperature is acceptable. The part is active and available in bulk packaging.

Enhanced Performance Substitute - CDLL5949B or CDLL5949C (Microchip Technology): These parts provide 100 V Zener voltage with 1.25 W power rating and improved impedance characteristics (250 Ohms). CDLL5949B maintains ±5% tolerance, while CDLL5949C offers tighter ±2% tolerance. Both support the full -65°C to 175°C operating range. These substitutes are applicable when additional thermal margin or improved impedance performance is required. The higher power rating provides design flexibility for applications with variable load conditions.

Higher Power Alternative - 1SMB5949BT3G (onsemi): This part delivers 100 V Zener voltage with 3 W power dissipation in SMB packaging (DO-214AA). It is RoHS3 compliant and active in production. Selection of this part requires mechanical redesign due to different package geometry and thermal characteristics. The operating temperature range is -65°C to 150°C. This alternative is suitable only when circuit board layout permits SMB package integration and higher power dissipation is necessary.

Tolerance-Relaxed Substitutes - CDLL3044 or CDLL4764: CDLL3044 offers ±20% voltage tolerance, while CDLL4764 offers ±10% tolerance. Both maintain 100 V nominal voltage and 1 W power rating. These parts are applicable only in applications where voltage tolerance specifications permit relaxed accuracy. Selection requires verification that circuit performance remains acceptable across the wider tolerance band.

Frequently Asked Questions (FAQ)

Q: Can CDLL4764A directly replace CLL4764A TR without circuit modification?

A: Yes. CDLL4764A provides identical electrical specifications: 100 V Zener voltage, ±5% tolerance, 1 W power rating, 350 Ohms impedance, and 1.2 V forward voltage. Both use DO-213AB MELF surface mount packaging. Direct substitution is possible without circuit redesign.

Q: What is the difference between CDLL5949B and CDLL5949C?

A: Both parts share identical electrical performance except for voltage tolerance. CDLL5949B specifies ±5% tolerance, while CDLL5949C specifies ±2% tolerance. CDLL5949C is suitable for applications requiring tighter voltage regulation accuracy. Both provide 1.25 W power rating and 250 Ohms impedance, representing improved performance over the 1 W original specification.

Q: Why does 1N3044BUR-1 have a reduced operating temperature range?

A: 1N3044BUR-1 specifies -55°C to 175°C, compared to the original CLL4764A TR range of -65°C to 200°C. This part is suitable only for applications where the higher minimum temperature (-55°C instead of -65°C) and lower maximum temperature (175°C instead of 200°C) are acceptable. Verify application requirements before selection.

Q: Is 1SMB5949BT3G a suitable substitute?

A: 1SMB5949BT3G maintains 100 V Zener voltage and ±5% tolerance but differs in three critical aspects: (1) package type is SMB (DO-214AA) instead of MELF (DO-213AB), requiring board layout modification; (2) power rating is 3 W instead of 1 W; (3) forward voltage is 1.5 V instead of 1.2 V. This part is suitable only when mechanical redesign is feasible and higher power dissipation is required.

Q: What does the ±5% tolerance specification mean for substitution?

A: The ±5% tolerance indicates that the Zener voltage will fall within the range of 95 V to 105 V at the specified test current. Parts with identical ±5% tolerance are directly interchangeable. Parts with ±10% or ±20% tolerance have wider voltage ranges and are suitable only when circuit design permits this variation.

Q: Can CDLL3044 (±20% tolerance) be used instead of CLL4764A TR (±5% tolerance)?

A: CDLL3044 is suitable only if the application circuit can tolerate Zener voltage variation from 80 V to 120 V. This wide tolerance range may cause unacceptable performance variation in precision voltage regulation circuits. Verify circuit specifications before selecting this part.

Q: What is the significance of impedance (Zzt) in Zener diode substitution?

A: Impedance (Zzt) affects voltage regulation quality under varying load conditions. Lower impedance provides better voltage stability. The original CLL4764A TR specifies 350 Ohms. Substitutes with 250 Ohms impedance (CDLL5949B, CDLL5949C, 1SMB5949BT3G) provide improved regulation performance. Substitutes with 350 Ohms impedance maintain equivalent regulation characteristics.

Q: Are all substitute parts RoHS compliant?

A: No. The original CLL4764A TR and most Microchip Technology substitutes (1N4764AUR, 1N3044BUR-1, 1N5949BUR-1, CDLL3044, CDLL3044B, CDLL4764, CDLL4764A, CDLL5949B, CDLL5949C) are RoHS non-compliant. Only 1SMB5949BT3G from onsemi is RoHS3 compliant. Verify RoHS compliance requirements for your application before part selection.

Q: What is the difference between bulk and tape packaging?

A: Bulk packaging is suitable for manual assembly or small-volume production. Tape packaging (Cut Tape or Digi-Reel) is optimized for automated pick-and-place assembly. The electrical specifications remain identical. Select packaging based on assembly process requirements.

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