CLL5251B BK PBFREE Zener Diode Equivalent & Substitute Parts

Part Overview

The CLL5251B BK PBFREE is a 22 V, 500 mW surface mount zener diode manufactured by Central Semiconductor Corp in SOD-80 (DO-213AC, MINI-MELF) package. This component is classified as Active product status with full RoHS3 compliance and unlimited moisture sensitivity level (MSL 1). Zener diodes of this specification are used in voltage regulation, overvoltage protection, and reference voltage circuits. Substitute parts are identified when equivalent electrical performance, mechanical compatibility, and regulatory compliance are maintained across alternative manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	22	V
Power - Max	500	mW
Tolerance	±5%	-
Impedance (Max)	29	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 17 V	-
Voltage - Forward (Vf) (Max) @ If	1.25 V @ 200 mA	-
Operating Temperature Range	-65°C to 200°C	-
Mounting Type	Surface Mount	-
Package / Case	DO-213AC, MINI-MELF, SOD-80	-
RoHS Status	ROHS3 Compliant	-
MSL	1 (Unlimited)	-

Substitute Part Grouping Explanation

Substitution eligibility for the CLL5251B BK PBFREE is determined by the following critical parameters:

Primary Electrical Criteria:

Zener voltage: 22 V nominal
Power dissipation: 500 mW maximum
Package type: SOD-80 (DO-213AC, MINI-MELF)
Mounting: Surface Mount

Secondary Compatibility Criteria:

Impedance (Zzt) within acceptable range for circuit function
Reverse leakage current characteristics
Forward voltage drop at specified current
Operating temperature range coverage

Regulatory & Environmental Criteria:

RoHS3 compliance
MSL rating of 1 (Unlimited)
REACH unaffected status
ECCN EAR99 classification

All four substitute parts (TLZ22B-GS08, TZM5251B-GS08, TZMB22-GS08, TZMC22-GS08) maintain the core electrical specifications of 22 V nominal zener voltage and 500 mW power rating in identical SOD-80 packaging. Variations in tolerance, impedance, and temperature range are documented in the parameter comparison table below.

Parameter Comparison

Parameter	CLL5251B BK PBFREE	TLZ22B-GS08	TZM5251B-GS08	TZMB22-GS08	TZMC22-GS08
Manufacturer	Central Semiconductor Corp	Vishay General Semiconductor	Vishay General Semiconductor	Vishay General Semiconductor	Vishay General Semiconductor
Voltage - Zener (Nom)	22 V	22 V	22 V	22 V	22 V
Tolerance	±5%	-	±5%	±2%	±5%
Power - Max	500 mW	500 mW	500 mW	500 mW	500 mW
Impedance (Max)	29 Ohms	30 Ohms	29 Ohms	55 Ohms	55 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 17 V	40 nA @ 19.6 V	100 nA @ 17 V	100 nA @ 16 V	100 nA @ 16 V
Voltage - Forward (Vf) (Max) @ If	1.25 V @ 200 mA	1.5 V @ 200 mA	1.1 V @ 200 mA	1.5 V @ 200 mA	1.5 V @ 200 mA
Operating Temperature Range	-65°C to 200°C	-65°C to 175°C	-65°C to 175°C	-65°C to 175°C	-65°C to 175°C
Package / Case	DO-213AC, MINI-MELF, SOD-80	DO-213AC, MINI-MELF, SOD-80	DO-213AC, MINI-MELF, SOD-80	DO-213AC, MINI-MELF, SOD-80	DO-213AC, MINI-MELF, SOD-80
Packaging Type	Bulk	Tape & Reel (TR)	Tape & Reel (TR)	Tape & Reel (TR)	Cut Tape (CT) & Digi-Reel®
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Product Status	Active	Active	Active	Active	Active

Engineering Selection Recommendations

TZM5251B-GS08 (Vishay): This substitute maintains identical electrical specifications to the CLL5251B BK PBFREE, including ±5% tolerance, 29 Ohms impedance, and 100 nA reverse leakage at 17 V. The forward voltage is lower at 1.1 V versus 1.25 V, which may reduce power dissipation in forward-biased applications. Operating temperature range is reduced to -65°C to 175°C. This part is suitable for direct replacement in applications not requiring the extended upper temperature limit of 200°C.

TLZ22B-GS08 (Vishay): This substitute provides 22 V nominal zener voltage and 500 mW power rating with SOD-80 packaging. Impedance is 30 Ohms (within 1 Ohm of the original). Reverse leakage is lower at 40 nA, indicating superior leakage characteristics. Forward voltage is higher at 1.5 V. Tolerance specification is not provided. Operating temperature range is -65°C to 175°C. This part is suitable for applications where lower reverse leakage is beneficial and the extended temperature range is not required.

TZMB22-GS08 (Vishay): This substitute features ±2% tolerance (tighter than the original ±5%), providing superior voltage accuracy. Impedance is 55 Ohms, which is significantly higher than the original 29 Ohms and may affect circuit performance in applications sensitive to dynamic impedance. This part carries AEC-Q101 automotive qualification and Automotive grade designation. Operating temperature range is -65°C to 175°C. This part is suitable for automotive applications requiring tighter voltage tolerance and automotive-grade qualification.

TZMC22-GS08 (Vishay): This substitute maintains ±5% tolerance matching the original specification. Impedance is 55 Ohms, identical to TZMB22-GS08. This part also carries AEC-Q101 automotive qualification and Automotive grade designation. Packaging is Cut Tape (CT) & Digi-Reel® rather than standard Tape & Reel. Operating temperature range is -65°C to 175°C. This part is suitable for automotive applications where ±5% tolerance is acceptable and alternative packaging formats are compatible with assembly processes.

All substitute parts maintain RoHS3 compliance, MSL 1 (Unlimited), REACH unaffected status, and ECCN EAR99 classification, ensuring regulatory equivalence with the original part.

Frequently Asked Questions (FAQ)

Q: Can TZM5251B-GS08 be used as a direct replacement for CLL5251B BK PBFREE?

A: Yes. Both parts share identical nominal zener voltage (22 V), power rating (500 mW), tolerance (±5%), impedance (29 Ohms), and reverse leakage characteristics (100 nA @ 17 V). The primary difference is the reduced operating temperature range (175°C maximum versus 200°C). Direct substitution is valid for applications operating within -65°C to 175°C.

Q: What is the significance of impedance differences between substitute parts?

A: Impedance (Zzt) affects the dynamic voltage regulation characteristics of the zener diode. The original CLL5251B and TZM5251B-GS08 specify 29 Ohms impedance, while TZMB22-GS08 and TZMC22-GS08 specify 55 Ohms. Higher impedance results in greater voltage variation with load current changes. Substitution with higher impedance parts may require circuit re-evaluation in precision voltage regulation applications.

Q: Are the automotive-qualified parts (TZMB22-GS08, TZMC22-GS08) suitable for non-automotive applications?

A: Yes. Automotive-qualified parts exceed standard reliability requirements and are fully compatible with non-automotive applications. AEC-Q101 qualification indicates enhanced testing and quality assurance. These parts are suitable for any application where the electrical specifications match the circuit requirements.

Q: What is the difference between Tape & Reel (TR) and Cut Tape (CT) & Digi-Reel® packaging?

A: Tape & Reel (TR) is standard continuous reel packaging for automated assembly. Cut Tape (CT) & Digi-Reel® provides flexibility for lower-volume orders or mixed component picking. Both formats contain identical components; the difference is in supply format and handling for assembly processes.

Q: Does the lower forward voltage of TZM5251B-GS08 (1.1 V vs. 1.25 V) affect substitution suitability?

A: Forward voltage characteristics are relevant only in forward-biased applications. In typical zener diode voltage regulation circuits, the diode operates in reverse bias (zener mode), where forward voltage is not a functional parameter. For applications utilizing forward-biased operation, the lower forward voltage of TZM5251B-GS08 reduces power dissipation and may improve efficiency.

Q: Can parts with different tolerances (±2%, ±5%) be intermixed in production?

A: Tolerance differences affect voltage accuracy. The original CLL5251B specifies ±5%, while TZMB22-GS08 specifies ±2%. If circuit design requires ±5% tolerance, both parts are acceptable. If tighter ±2% tolerance is required, only TZMB22-GS08 qualifies. Intermixing parts with different tolerances in the same circuit is valid only if the circuit design accommodates the wider tolerance band.

Q: What is the impact of reduced operating temperature range (175°C vs. 200°C) on substitute part selection?

A: All substitute parts specify maximum operating temperature of 175°C, while the original CLL5251B specifies 200°C. Substitution is valid for applications with maximum operating temperature of 175°C or lower. Applications requiring sustained operation above 175°C require the original CLL5251B or alternative parts with extended temperature specifications.

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