CLL4755A BK Zener Diode 43V 1W Equivalent & Substitute Parts

Part Overview

The CLL4755A BK is a 43 V, 1 W Zener diode manufactured by Central Semiconductor Corp in Surface Mount MELF package (DO-213AB). This component is classified as obsolete, which necessitates 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 CLL4755A BK requires engineers to select from active alternatives that maintain electrical compatibility within specified parameter tolerances.

Key Parameters

Parameter	CLL4755A BK	Unit
Voltage - Zener (Nom)	43	V
Tolerance	±5%	—
Power - Max	1	W
Impedance (Max)	70	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 32.7 V
Voltage - Forward (Vf) (Max) @ If	1.2	V @ 200 mA
Operating Temperature Range	-65°C ~ 200°C	—
Mounting Type	Surface Mount	—
Package / Case	DO-213AB, MELF	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the CLL4755A BK is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 43 V nominal
Package type: DO-213AB / MELF Surface Mount
Mounting type: Surface Mount
Moisture sensitivity: MSL 1 (Unlimited)

Secondary Compatibility Criteria:

Tolerance: ±5% (exact match to original)
Power rating: 1 W minimum
Impedance: 70 Ohms maximum
Operating temperature range: Must encompass application requirements
Forward voltage: 1.2 V maximum @ 200 mA

Substitute parts are grouped into three categories based on power rating and tolerance specifications:

Category 1 - Direct 1W Equivalents (±5% Tolerance): CDLL3035B matches the original specification exactly with 1 W power rating and ±5% tolerance.

Category 2 - Enhanced Performance 1.25W Alternatives: CDLL5940B, CDLL5940C, and CDLL5940D provide higher power dissipation (1.25 W) with improved impedance characteristics (53 Ohms), suitable for applications requiring thermal margin.

Category 3 - Microchip 1N Series Alternatives: 1N3035BUR-1 and 1N5940BUR-1 provide Microchip Technology equivalents with active product status.

Category 4 - Tolerance Variants: CDLL3035, CDLL3035A, CDLL4755, and CDLL4755A offer alternative tolerance grades (±20%, ±10%, ±5%) for applications with relaxed precision requirements.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (W)	Zzt (Ohms)	Ir @ Vr (µA)	Temp Range (°C)	Status
CLL4755A BK	Central Semiconductor	43	±5%	1	70	5 @ 32.7V	-65 ~ 200	Obsolete
CDLL3035B	Microchip Technology	43	±5%	1	70	0.5 @ 32.7V	-55 ~ 175	Active
CDLL5940B	Microchip Technology	43	±5%	1.25	53	1 @ 32.7V	-65 ~ 175	Active
CDLL5940C	Microchip Technology	43	±2%	1.25	53	1 @ 32.7V	-65 ~ 175	Active
CDLL5940D	Microchip Technology	43	±1%	1.25	53	1 @ 32.7V	-65 ~ 175	Active
1N3035BUR-1	Microchip Technology	43	±5%	1	70	10 @ 32.7V	-55 ~ 175	Active
1N5940BUR-1	Microchip Technology	43	±5%	1.25	53	1 @ 32.7V	-65 ~ 175	Active
CDLL3035	Microchip Technology	43	±20%	1	70	0.5 @ 32.7V	-55 ~ 175	Active
CDLL3035A	Microchip Technology	43	±10%	1	70	0.5 @ 32.7V	-55 ~ 175	Active
CDLL4755	Microchip Technology	43	±10%	—	70	0.1 @ 32.7V	-65 ~ 175	Active
CDLL4755A	Microchip Technology	43	±5%	—	70	0.1 @ 32.7V	-65 ~ 175	Active

Engineering Selection Recommendations

Primary Recommendation: CDLL3035B

CDLL3035B is the direct functional equivalent of CLL4755A BK. It maintains identical electrical specifications: 43 V nominal Zener voltage, ±5% tolerance, 1 W power rating, and 70 Ohms maximum impedance. The part is manufactured by Microchip Technology with active product status, ensuring long-term availability and supply chain stability. Operating temperature range (-55°C to 175°C) covers most industrial and commercial applications, though the original part's upper limit of 200°C is not matched. Reverse leakage current is superior (0.5 µA vs. 5 µA), providing better performance characteristics.

Secondary Recommendation: CDLL5940B or 1N5940BUR-1

For applications requiring enhanced thermal performance or higher power dissipation margins, CDLL5940B and 1N5940BUR-1 provide 1.25 W power rating with improved impedance (53 Ohms). Both maintain 43 V nominal voltage and ±5% tolerance. CDLL5940B extends the lower temperature limit to -65°C, matching the original part. These alternatives are suitable when circuit design permits the higher power rating without thermal management concerns.

Precision Applications: CDLL5940C or CDLL5940D

Applications requiring tighter voltage tolerance specifications should use CDLL5940C (±2%) or CDLL5940D (±1%). Both provide 1.25 W power rating and superior impedance characteristics. These parts are recommended for precision voltage reference and regulation circuits where tolerance stack-up is critical.

Cost-Optimized Alternatives: CDLL3035 or CDLL3035A

For applications with relaxed tolerance requirements, CDLL3035 (±20%) or CDLL3035A (±10%) provide cost-effective alternatives while maintaining 1 W power rating and 70 Ohms impedance. These parts are suitable for general-purpose overvoltage protection and non-critical regulation applications.

Compliance Considerations:

All recommended substitutes are RoHS non-compliant and REACH unaffected, matching the compliance profile of the original part. MSL rating of 1 (Unlimited) is maintained across all alternatives, eliminating moisture sensitivity concerns in storage and handling.

Frequently Asked Questions (FAQ)

Q1: Can CDLL3035B directly replace CLL4755A BK without circuit modification?

A: Yes. CDLL3035B is a direct electrical equivalent with identical Zener voltage (43 V), tolerance (±5%), power rating (1 W), impedance (70 Ohms), and forward voltage characteristics. Both use DO-213AB MELF surface mount packaging. The only consideration is the operating temperature range: CDLL3035B operates to 175°C versus the original's 200°C upper limit. Verify that your application does not require operation above 175°C.

Q2: What is the difference between CDLL5940B, CDLL5940C, and CDLL5940D?

A: All three parts share identical electrical characteristics except for tolerance specification. CDLL5940B has ±5% tolerance, CDLL5940C has ±2% tolerance, and CDLL5940D has ±1% tolerance. All provide 1.25 W power rating and 53 Ohms impedance. Select based on your circuit's voltage tolerance requirements. Tighter tolerance parts (C and D) are necessary only for precision regulation or reference applications.

Q3: Why does CDLL5940B have lower impedance (53 Ohms) than the original (70 Ohms)?

A: Lower impedance is a performance advantage, not a limitation. Impedance (Zzt) represents the dynamic resistance of the Zener diode in the reverse bias region. Lower impedance provides better voltage regulation and faster transient response. CDLL5940B can be used as a direct substitute in any application designed for the original part.

Q4: Is the higher reverse leakage current of 1N3035BUR-1 (10 µA) a concern?

A: For most applications, the difference between 5 µA and 10 µA reverse leakage is negligible. However, in precision analog circuits or high-impedance applications, this difference may be significant. If your circuit design is sensitive to leakage current, select CDLL3035B (0.5 µA) or CDLL5940 series parts (1 µA) instead.

Q5: Can I use a 1.25 W part (CDLL5940 series) in a circuit designed for 1 W?

A: Yes. Higher power rating provides additional thermal margin and is always acceptable as a substitute. The 1.25 W rating means the part can safely dissipate more power without exceeding junction temperature limits. This is beneficial for reliability and circuit longevity.

Q6: What is the significance of the DO-213AB / MELF package designation?

A: DO-213AB and MELF are equivalent designations for the same surface mount package. Both terms refer to a cylindrical component with axial leads, commonly used for diodes. All substitute parts listed use this identical package, ensuring mechanical and electrical compatibility with existing PCB layouts and solder reflow processes.

Q7: Are there any RoHS or REACH compliance differences between the original and substitutes?

A: No. The original CLL4755A BK and all recommended substitutes share identical compliance status: RoHS non-compliant and REACH unaffected. If your application requires RoHS-compliant components, none of these parts meet that requirement. Consult with your supplier for RoHS-compliant 43 V Zener diode alternatives.

Q8: Which substitute should I choose for a new design?

A: For new designs, use CDLL3035B as the baseline equivalent. If your circuit requires higher power dissipation margin or operates at the lower temperature extreme (-65°C), use CDLL5940B or 1N5940BUR-1. For precision applications, use CDLL5940C or CDLL5940D. All are active products with stable long-term availability from Microchip Technology.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message