CLL4733A BK Zener Diode 5.1V 1W MELF Equivalent & Substitute Parts

Part Overview

The CLL4733A BK is a surface mount Zener diode manufactured by Central Semiconductor Corp, rated at 5.1 V nominal 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 continuity. Substitute parts must maintain electrical compatibility across voltage regulation, power handling, and thermal operating ranges while accommodating packaging and tolerance variations.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	5.1	V
Tolerance	±5%	—
Power - Max	1	W
Impedance (Max)	7	Ohms
Current - Reverse Leakage @ Vr	10	µA @ 1 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 eligibility is determined by the following critical parameters:

Primary Matching Criteria:

Voltage - Zener (Nom): 5.1 V (exact match required)
Mounting Type: Surface Mount
Package / Case: DO-213AB or MELF (equivalent mechanical form factor)
Moisture Sensitivity Level: 1 (Unlimited)

Secondary Compatibility Parameters:

Tolerance: ±5% or tighter (±5%, ±2%, ±1% acceptable; ±10% acceptable with design verification)
Power - Max: 1 W or greater (1 W, 1.25 W acceptable)
Impedance (Max): 7 Ohms or lower (7 Ohms, 4 Ohms acceptable)
Current - Reverse Leakage @ Vr: 10 µA @ 1 V or lower (acceptable range: 3–10 µA)
Voltage - Forward (Vf) (Max) @ If: 1.2 V @ 200 mA (exact match across all substitutes)
Operating Temperature: -65°C minimum and 175°C or higher maximum

All substitute parts are manufactured by Microchip Technology and carry active product status, ensuring long-term availability and supply chain stability.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Ir @ Vr	Vf (Max)	Temp Range	Status
CLL4733A BK	Central Semiconductor	5.1 V	±5%	1 W	7 Ω	10 µA @ 1 V	1.2 V @ 200 mA	-65 to 200°C	Obsolete
1N4733AUR	Microchip Technology	5.1 V	±5%	1 W	7 Ω	10 µA @ 1 V	1.2 V @ 200 mA	-65 to 175°C	Active
1N5918BUR-1	Microchip Technology	5.1 V	±5%	1.25 W	4 Ω	5 µA @ 2 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL3826	Microchip Technology	5.1 V	±10%	1 W	7 Ω	3 µA @ 1 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL3826A	Microchip Technology	5.1 V	±5%	1 W	7 Ω	3 µA @ 1 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL4733	Microchip Technology	5.1 V	±10%	Not specified	7 Ω	5 µA @ 1 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL4733A	Microchip Technology	5.1 V	±5%	Not specified	7 Ω	5 µA @ 1 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL5918B	Microchip Technology	5.1 V	±5%	1.25 W	4 Ω	5 µA @ 2 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL5918C	Microchip Technology	5.1 V	±2%	1.25 W	4 Ω	5 µA @ 2 V	1.2 V @ 200 mA	-65 to 175°C	Active
CDLL5918D	Microchip Technology	5.1 V	±1%	1.25 W	4 Ω	5 µA @ 2 V	1.2 V @ 200 mA	-65 to 175°C	Active

Engineering Selection Recommendations

Direct Replacement (Highest Compatibility):

1N4733AUR is the primary direct substitute for CLL4733A BK. Both parts share identical electrical specifications: 5.1 V nominal voltage, ±5% tolerance, 1 W power rating, 7 Ohms maximum impedance, and 1.2 V forward voltage. The only difference is the maximum operating temperature (175°C versus 200°C for the original). This part is manufactured by Microchip Technology with active product status, ensuring supply continuity.

Enhanced Performance Substitutes (Higher Power Rating):

1N5918BUR-1, CDLL5918B, CDLL5918C, and CDLL5918D offer 1.25 W power dissipation with improved impedance characteristics (4 Ohms maximum). These parts are suitable for applications requiring higher thermal margin or increased power handling. CDLL5918D provides the tightest tolerance specification (±1%), while CDLL5918C offers ±2% tolerance. All maintain the 5.1 V nominal voltage and 1.2 V forward voltage specification.

Tolerance-Variant Substitutes:

CDLL3826 and CDLL4733 provide ±10% tolerance alternatives with 1 W power rating. These parts are acceptable where tolerance specifications permit wider voltage deviation. CDLL3826A and CDLL4733A offer ±5% tolerance matching the original specification.

Temperature Operating Range Consideration:

All substitute parts operate to a maximum of 175°C, compared to the original 200°C specification. Applications requiring operation above 175°C require design review and thermal analysis.

Compliance and Availability:

All substitute parts carry RoHS non-compliant status and REACH Unaffected designation, matching the original part's regulatory profile. All are currently in active production with confirmed inventory availability.

Frequently Asked Questions (FAQ)

Q: Can 1N4733AUR directly replace CLL4733A BK without circuit modification?

A: Yes. 1N4733AUR is electrically and mechanically equivalent to CLL4733A BK across all critical parameters: 5.1 V nominal voltage, ±5% tolerance, 1 W power rating, DO-213AB MELF package, and identical forward voltage characteristics. The maximum operating temperature difference (175°C versus 200°C) does not affect standard applications operating below 175°C.

Q: What is the advantage of using 1N5918BUR-1 or CDLL5918 series parts?

A: These parts provide 1.25 W power dissipation versus 1 W for the original, with lower impedance (4 Ohms versus 7 Ohms). This configuration offers improved thermal margin and faster transient response in voltage regulation circuits. Selection depends on circuit power budget and dynamic performance requirements.

Q: Are CDLL3826 and CDLL4733 acceptable substitutes despite ±10% tolerance?

A: CDLL3826 and CDLL4733 are electrically compatible but carry ±10% tolerance versus ±5% for the original. These parts are acceptable only in applications where the wider voltage tolerance does not compromise circuit performance. Design verification is required to confirm tolerance compatibility with downstream circuit requirements.

Q: Does the DO-213AB MELF package differ between manufacturers?

A: No. DO-213AB and MELF designations are equivalent industry-standard surface mount packages. All substitute parts use identical mechanical form factors, enabling direct PCB footprint compatibility without layout modification.

Q: What is the significance of tolerance grades in CDLL5918 series (±1%, ±2%, ±5%)?

A: Tolerance grades indicate voltage regulation accuracy. CDLL5918D (±1%) provides the tightest voltage specification, suitable for precision voltage reference applications. CDLL5918C (±2%) and CDLL5918B (±5%) offer progressively wider tolerance bands. Selection depends on downstream circuit voltage tolerance requirements.

Q: Are all substitute parts suitable for high-reliability applications?

A: All substitute parts are manufactured by Microchip Technology with active product status and unlimited moisture sensitivity level (MSL 1). Regulatory compliance (RoHS non-compliant, REACH Unaffected) matches the original part. Suitability for high-reliability applications depends on specific qualification requirements and design standards.

Q: What is the impact of lower reverse leakage current in substitute parts?

A: Substitute parts exhibit reverse leakage current ranging from 3 µA to 10 µA, compared to 10 µA for the original. Lower leakage current improves circuit efficiency and reduces standby power consumption. This characteristic is beneficial across all application types and does not require circuit modification.

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