CMPZ5256B BK PBFREE Zener Diode 30V 350mW Equivalent & Substitute Parts

Part Overview

The CMPZ5256B BK PBFREE is a surface mount zener diode manufactured by Central Semiconductor Corp, rated for 30 V nominal zener voltage with 350 mW maximum power dissipation in SOT-23 packaging. This component is classified as Active product status with ROHS3 compliance and unlimited moisture sensitivity level (MSL 1). Equivalent and substitute parts are identified based on matching electrical specifications and mechanical compatibility within the zener diode category. Substitutes are necessary when the primary part experiences supply constraints, lead time extensions, or when design requirements permit tolerance or power rating variations within acceptable operational parameters.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	30	V
Tolerance	±5%	-
Power - Max	350	mW
Impedance (Max)	49	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 23 V	-
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	-
Operating Temperature Range	-65°C to 150°C	-
Mounting Type	Surface Mount	-
Package / Case	TO-236-3, SC-59, SOT-23-3	-
RoHS Status	ROHS3 Compliant	-
MSL	1 (Unlimited)	-

Substitute Part Grouping Explanation

Substitution logic for the CMPZ5256B BK PBFREE is based on the following critical parameters that must be maintained or exceeded:

Primary Matching Criteria:

Zener voltage: 30 V nominal (determines circuit regulation point)
Package type: SOT-23-3 / TO-236-3 (mechanical and thermal compatibility)
Mounting type: Surface Mount (PCB assembly compatibility)
Operating temperature range: Minimum -65°C to 150°C (thermal envelope)
RoHS compliance: ROHS3 Compliant (regulatory requirement)

Secondary Compatibility Parameters:

Power rating: 350 mW or higher (thermal capability)
Tolerance: ±5% or tighter (voltage accuracy)
Forward voltage: 900 mV @ 10 mA or lower (switching characteristics)
Reverse leakage: 100 nA @ 23 V or lower (static performance)
Impedance: 49 Ohms or lower (dynamic response)

Substitute parts are grouped into two categories: Direct Equivalents (matching all primary parameters) and Compatible Alternatives (matching primary parameters with acceptable variations in secondary parameters such as power rating, tolerance, or impedance).

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power Max	Impedance Max	Reverse Leakage @ Vr	Vf Max @ If	Temp Range	Package	Status
CMPZ5256B BK PBFREE	Central Semiconductor Corp	30 V	±5%	350 mW	49 Ω	100 nA @ 23 V	900 mV @ 10 mA	-65°C to 150°C	SOT-23	Active
BZX84-B30,215	NXP Semiconductors	30 V	±2%	250 mW	80 Ω	50 nA @ 21 V	900 mV @ 10 mA	-65°C to 150°C	TO-236AB	Active
BZX84-C30,215	NXP Semiconductors	30 V	±5%	250 mW	80 Ω	50 nA @ 21 V	900 mV @ 10 mA	-65°C to 150°C	TO-236AB	Active
BZX84-C30,235	NXP USA Inc.	30 V	±5%	250 mW	80 Ω	50 nA @ 21 V	900 mV @ 10 mA	-65°C to 150°C	SOT-23	Active
BZX84B30-7-F	Diodes Incorporated	30 V	±2%	300 mW	80 Ω	100 nA @ 21 V	900 mV @ 10 mA	-65°C to 150°C	SOT-23-3	Active
BZX84B30-G3-08	Vishay General Semiconductor	30 V	±2%	300 mW	80 Ω	50 nA @ 21 V	-	-55°C to 150°C	SOT-23-3	Active
BZX84C30-7-F	Diodes Incorporated	30 V	±7%	300 mW	80 Ω	100 nA @ 21 V	900 mV @ 10 mA	-65°C to 150°C	SOT-23-3	Active
BZX84C30-E3-08	Vishay General Semiconductor	30 V	±5%	300 mW	80 Ω	50 nA @ 21 V	-	-55°C to 150°C	SOT-23-3	Active
BZX84C30-HE3-18	Vishay General Semiconductor	30 V	±5%	300 mW	80 Ω	50 nA @ 21 V	-	-55°C to 150°C	SOT-23-3	Obsolete
BZX84C30-TP	Micro Commercial Co	30 V	±5%	350 mW	80 Ω	100 nA @ 21 V	900 mV @ 10 mA	-55°C to 150°C	SOT-23	Active
MMBZ5256B-7-F	Diodes Incorporated	30 V	±5%	350 mW	49 Ω	100 nA @ 23 V	900 mV @ 10 mA	-65°C to 150°C	SOT-23-3	Active

Engineering Selection Recommendations

Direct Equivalent (Highest Compatibility):

MMBZ5256B-7-F (Diodes Incorporated) is the closest functional equivalent to CMPZ5256B BK PBFREE. This part matches all critical electrical parameters: 30 V nominal zener voltage, ±5% tolerance, 350 mW power rating, 49 Ohms impedance, and 100 nA reverse leakage at 23 V. Operating temperature range (-65°C to 150°C) and SOT-23-3 package are identical. Both parts are Active status with ROHS3 compliance. This substitute requires no circuit redesign and provides equivalent thermal and electrical performance.

Compatible Alternatives (Acceptable Variations):

BZX84C30-TP (Micro Commercial Co) provides 350 mW power rating matching the primary part, with ±5% tolerance and identical forward voltage characteristics. Operating temperature minimum is -55°C (versus -65°C), which is acceptable for most industrial and commercial applications. Impedance is 80 Ohms versus 49 Ohms, representing a 63% increase in dynamic impedance; this may affect transient response in high-frequency applications but is acceptable for standard voltage regulation circuits.

BZX84B30-7-F and BZX84C30-E3-08 (Diodes Incorporated and Vishay) offer 300 mW power rating, which is 14% below the primary part specification. These parts are suitable for applications where the 350 mW rating provides design margin and 300 mW is sufficient for the actual circuit load. Both maintain 30 V nominal voltage, SOT-23-3 package compatibility, and -65°C to -55°C minimum operating temperature.

BZX84-C30,235 (NXP USA Inc.) provides SOT-23 package compatibility with 30 V nominal voltage and ±5% tolerance. Power rating is 250 mW, representing 29% reduction from the primary part. This substitute is applicable only when circuit power dissipation is confirmed below 250 mW.

Not Recommended:

BZX84-C30,215 and BZX84-B30,215 (NXP Semiconductors) use TO-236AB package designation, which differs from SOT-23-3. While mechanically compatible in many PCB layouts, package designation variation introduces assembly risk. Power rating of 250 mW is below primary specification.

BZX84C30-HE3-18 (Vishay) is marked Obsolete status and should not be selected for new designs or long-term supply requirements.

Frequently Asked Questions (FAQ)

Q: Can BZX84-C30,235 replace CMPZ5256B BK PBFREE in all applications?

A: BZX84-C30,235 matches the 30 V nominal zener voltage, ±5% tolerance, and SOT-23 package. However, power rating is 250 mW versus 350 mW. Substitution is valid only if circuit analysis confirms power dissipation remains below 250 mW under all operating conditions including worst-case temperature and load variations.

Q: What is the significance of impedance differences between 49 Ohms and 80 Ohms?

A: Impedance (Zzt) determines the zener diode's dynamic response to load current changes. Lower impedance (49 Ohms) provides better voltage regulation stability under transient conditions. Higher impedance (80 Ohms) results in slightly larger voltage variations during rapid load changes. For standard DC regulation applications, 80 Ohms is acceptable. For noise-sensitive analog circuits or high-frequency switching applications, the 49 Ohms specification is preferred.

Q: Are NXP BZX84 series parts interchangeable with Central Semiconductor CMPZ5256B?

A: NXP BZX84 series parts share identical 30 V nominal voltage and SOT-23 package compatibility. However, power ratings differ: BZX84-C30,215 and BZX84-B30,215 are rated 250 mW, while CMPZ5256B is 350 mW. Electrical performance is equivalent for applications within the 250 mW power envelope. Tolerance specifications vary: BZX84-B30,215 offers ±2% versus ±5% for CMPZ5256B, providing tighter voltage regulation if required.

Q: Why do some substitute parts specify -55°C minimum temperature while the primary part specifies -65°C?

A: Operating temperature range defines the component's guaranteed performance envelope. CMPZ5256B BK PBFREE is rated -65°C to 150°C, while some Vishay parts (BZX84B30-G3-08, BZX84C30-E3-08) are rated -55°C to 150°C. Substitution is acceptable for applications operating above -55°C. For equipment requiring -65°C operation, select parts with matching or lower minimum temperature specification.

Q: Is MMBZ5256B-7-F the recommended substitute?

A: MMBZ5256B-7-F is the closest equivalent based on electrical and mechanical parameters. It matches all critical specifications: 30 V nominal voltage, ±5% tolerance, 350 mW power rating, 49 Ohms impedance, 100 nA reverse leakage, and -65°C to 150°C operating range. SOT-23-3 package and Active product status confirm suitability for direct substitution without circuit modification.

Q: Can I use a 300 mW rated part instead of 350 mW?

A: Power rating substitution depends on actual circuit power dissipation. If circuit analysis confirms maximum power dissipation is below 300 mW under all operating conditions (including temperature extremes and worst-case load), a 300 mW part is acceptable. If design margin requires the full 350 mW capability, use parts rated 350 mW or higher. Exceeding a component's power rating causes thermal stress and reduces reliability.

Q: What packaging differences exist between SOT-23 and SOT-23-3?

A: SOT-23 and SOT-23-3 refer to the same physical package outline (TO-236-3, SC-59). The "-3" designation explicitly indicates three leads. Both are surface mount packages with identical pin spacing and PCB footprint. Parts specified as SOT-23 or SOT-23-3 are mechanically interchangeable on standard PCB layouts.

Q: Are all substitute parts ROHS3 compliant?

A: All substitute parts listed are ROHS3 compliant, matching the primary part's regulatory status. ROHS3 compliance confirms lead-free construction and compliance with European Union Restriction of Hazardous Substances Directive. All parts carry MSL 1 (Unlimited) moisture sensitivity level, indicating no special moisture control requirements during storage or assembly.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message