CLL4764A BK Zener Diode 100V 1W MELF Equivalent & Substitute Parts

Part Overview

The CLL4764A BK is a surface mount Zener diode manufactured by Central Semiconductor Corp, rated for 100 V nominal Zener voltage with 1 W maximum power dissipation in MELF (DO-213AB) package. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design support and procurement.

Zener diodes in this voltage and power class are used for voltage regulation, overvoltage protection, and reference applications in electronic circuits. The obsolete status of the CLL4764A BK requires engineers to select from active alternatives that maintain electrical and mechanical compatibility.

Key Parameters

Parameter	CLL4764A BK Value	Unit
Voltage - Zener (Nom)	100	V
Tolerance	±5%	—
Power - Max	1	W
Impedance (Max) (Zzt)	350	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 76 V
Voltage - Forward (Vf) (Max) @ If	1.2	V @ 200 mA
Operating Temperature Range	-65 to 200	°C
Mounting Type	Surface Mount	—
Package / Case	DO-213AB, MELF	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—
REACH Status	REACH Unaffected	—

Substitute Part Grouping Explanation

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

Primary Matching Criteria:

Zener voltage: 100 V nominal
Tolerance: ±5% (exact match required for precision applications)
Power rating: 1 W minimum
Package: DO-213AB / MELF surface mount
Mounting type: Surface mount
Impedance: 350 Ohms maximum

Secondary Compatibility Factors:

Reverse leakage current at 76 V
Forward voltage at 200 mA
Operating temperature range
Product status (active preferred over obsolete)

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

Category 1: Direct Electrical Equivalents (100 V, 1 W, ±5% tolerance) Parts with identical voltage, power, and tolerance specifications. These provide the closest functional replacement.

Category 2: Enhanced Performance Substitutes (100 V, 1.25 W or higher power) Parts with higher power ratings and improved impedance characteristics. These are suitable when thermal margin or reliability enhancement is required.

Category 3: Tolerance Variants (100 V, 1 W, different tolerance) Parts with the same voltage and power but different tolerance specifications. Selection depends on circuit tolerance requirements.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (W)	Zzt (Ohms)	Ir @ 76V	Vf @ 200mA	Temp Range (°C)	Package	Status
CLL4764A BK	Central Semiconductor	100	±5%	1	350	5 µA	1.2 V	-65 to 200	DO-213AB	Obsolete
1N4764AUR	Microchip Technology	100	±5%	1	350	5 µA	1.2 V	-65 to 175	DO-213AB	Active
1N3044BUR-1	Microchip Technology	100	±5%	1	350	10 µA	1.2 V	-55 to 175	DO-213AB	Active
1N5949BUR-1	Microchip Technology	100	±5%	1.25	250	1 µA	1.2 V	-65 to 175	DO-213AB	Active
1SMB5949BT3G	onsemi	100	±5%	3	250	1 µA	1.5 V	-65 to 150	DO-214AA (SMB)	Active
CDLL3044	Microchip Technology	100	±20%	1	350	500 nA	1.2 V	-55 to 175	DO-213AB	Active
CDLL3044B	Microchip Technology	100	±5%	1	350	500 nA	1.2 V	-55 to 175	DO-213AB	Active
CDLL4764	Microchip Technology	100	±10%	1	350	100 nA	1.2 V	-65 to 175	DO-213AB	Active
CDLL4764A	Microchip Technology	100	±5%	1	350	100 nA	1.2 V	-65 to 175	DO-213AB	Active
CDLL5949B	Microchip Technology	100	±5%	1.25	250	1 µA	1.2 V	-65 to 175	DO-213AB	Active
CDLL5949C	Microchip Technology	100	±2%	1.25	250	1 µA	1.2 V	-65 to 175	DO-213AB	Active

Engineering Selection Recommendations

Primary Recommendation: CDLL4764A

CDLL4764A from Microchip Technology is the preferred direct substitute. It matches all critical electrical parameters of the CLL4764A BK: 100 V Zener voltage, ±5% tolerance, 1 W power rating, 350 Ohms impedance, and DO-213AB package. The part is active with 1103 units in stock. Operating temperature range extends to -65°C to 175°C, covering the lower bound of the original specification. Reverse leakage current is 100 nA at 76 V, which is superior to the original 5 µA specification.

Secondary Recommendation: 1N4764AUR

1N4764AUR from Microchip Technology provides identical electrical specifications to the CLL4764A BK with 1024 units available. This part is active and maintains the same voltage, tolerance, power, and impedance ratings. Operating temperature range is -65°C to 175°C. This part is suitable for direct replacement in applications where the upper temperature limit of 175°C is acceptable.

Alternative for Enhanced Thermal Performance: CDLL5949B or 1N5949BUR-1

Both CDLL5949B and 1N5949BUR-1 provide 1.25 W power rating with improved impedance of 250 Ohms and significantly lower reverse leakage of 1 µA. These parts are suitable for applications requiring enhanced thermal margin or lower leakage characteristics. Both maintain 100 V voltage and ±5% tolerance in DO-213AB package.

Higher Power Alternative: 1SMB5949BT3G

1SMB5949BT3G from onsemi offers 3 W power rating with 100 V voltage and ±5% tolerance. This part uses DO-214AA (SMB) package, which is physically larger than MELF. Selection requires PCB layout modification. This part is suitable only when higher power dissipation is required and package change is acceptable. RoHS3 compliance status differs from other alternatives.

Tolerance-Variant Options:

CDLL3044B provides ±5% tolerance match with lower reverse leakage (500 nA). CDLL4764 offers ±10% tolerance with 100 nA leakage. CDLL3044 provides ±20% tolerance. These variants are suitable only when circuit design permits the specified tolerance deviation.

Frequently Asked Questions (FAQ)

Q1: Can I use 1N4764AUR as a direct replacement for CLL4764A BK?

Yes. 1N4764AUR matches all critical electrical parameters: 100 V Zener voltage, ±5% tolerance, 1 W power rating, 350 Ohms impedance, and DO-213AB MELF package. The operating temperature range is -65°C to 175°C, which covers the lower specification of the original part. This is a direct electrical equivalent.

Q2: What is the difference between CDLL4764A and 1N4764AUR?

Both parts have identical electrical specifications for voltage, tolerance, power, and impedance. The primary difference is manufacturer: CDLL4764A is from Microchip Technology's CDLL series, while 1N4764AUR is from Microchip's 1N series. Both are active products with equivalent performance. Selection can be based on availability and procurement preference.

Q3: Why would I choose CDLL5949B over CDLL4764A?

CDLL5949B provides higher power rating (1.25 W vs. 1 W) and lower impedance (250 Ohms vs. 350 Ohms), resulting in improved thermal performance and lower dynamic impedance. Reverse leakage is also lower (1 µA vs. 100 nA). Selection depends on whether the application requires enhanced thermal margin or lower leakage characteristics. Both maintain 100 V voltage and ±5% tolerance.

Q4: Can I use 1SMB5949BT3G in place of CLL4764A BK?

1SMB5949BT3G is electrically compatible (100 V, ±5% tolerance) but uses DO-214AA (SMB) package instead of DO-213AB (MELF). This requires PCB layout modification due to different package dimensions and pin spacing. Use this part only when higher power dissipation (3 W) is required and package change is acceptable.

Q5: What does the tolerance specification mean for substitution?

Tolerance specifies the accuracy of the Zener voltage. CLL4764A BK has ±5% tolerance, meaning the actual Zener voltage will be between 95 V and 105 V. Direct substitutes must have ±5% tolerance for equivalent performance. Parts with ±10% or ±20% tolerance (such as CDLL4764 or CDLL3044) have wider voltage variation and are suitable only when circuit design permits this deviation.

Q6: Is reverse leakage current important for my application?

Reverse leakage current affects standby power consumption and circuit performance in high-impedance applications. CLL4764A BK specifies 5 µA at 76 V. Alternatives like CDLL4764A (100 nA) or CDLL5949B (1 µA) have significantly lower leakage. If your circuit is sensitive to leakage current, select a part with lower specified leakage.

Q7: Does operating temperature range affect substitution?

CLL4764A BK operates from -65°C to 200°C. Most active substitutes operate to -65°C to 175°C, which covers the lower bound but not the upper 200°C limit. If your application requires operation above 175°C, verify that the selected substitute meets this requirement. For most commercial and industrial applications, -65°C to 175°C is sufficient.

Q8: Are all substitute parts in the same MELF package?

Most substitutes (1N4764AUR, 1N3044BUR-1, 1N5949BUR-1, CDLL3044, CDLL3044B, CDLL4764, CDLL4764A, CDLL5949B, CDLL5949C) use DO-213AB MELF package. The exception is 1SMB5949BT3G, which uses DO-214AA (SMB) package. Verify package compatibility with your PCB layout before selection.

Q9: What is the difference between CDLL5949B and CDLL5949C?

Both parts have identical electrical specifications except for tolerance: CDLL5949B has ±5% tolerance, while CDLL5949C has ±2% tolerance. CDLL5949C provides tighter voltage accuracy. Selection depends on circuit tolerance requirements. Both have 1.25 W power rating and 250 Ohms impedance.

Q10: Why is CLL4764A BK obsolete?

Product obsolescence is determined by manufacturer discontinuation. Central Semiconductor Corp has discontinued the CLL4764A BK line. Active alternatives from Microchip Technology and onsemi provide equivalent or superior performance and are recommended for new designs and ongoing procurement.

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