MMBZ5255B-TP Zener Diode Equivalent & Substitute Parts

Part Overview

The MMBZ5255B-TP is a 28 V, 350 mW surface mount zener diode manufactured by Micro Commercial Co, supplied in Tape & Reel packaging with SOT-23 package configuration. This component is classified as Active product status and is ROHS3 compliant. Equivalent and substitute parts are identified when circuit designs require alternative sourcing due to inventory constraints, supply chain disruptions, or specific packaging and thermal performance requirements while maintaining electrical compatibility within defined parameter tolerances.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	28	V
Tolerance	±5%	%
Power - Maximum	350	mW
Impedance (Maximum)	44	Ohms
Current - Reverse Leakage @ Vr	100	nA @ 21 V
Voltage - Forward (Maximum) @ If	900	mV @ 10 mA
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Surface Mount
Package / Case	TO-236-3, SC-59, SOT-23-3
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the MMBZ5255B-TP is determined by the following critical parameters: Zener voltage (28 V nominal), voltage tolerance (±5%), impedance (44 Ohms maximum), reverse leakage current (100 nA @ 21 V), forward voltage (900 mV @ 10 mA maximum), and surface mount configuration. Parts are grouped as direct substitutes when all electrical parameters match the main part specifications. Power dissipation ratings may vary; lower power ratings indicate reduced thermal capability and require circuit-level verification of current limiting conditions. Package variants (SOT-23 versus SOT-323) represent mechanical substitutes with identical electrical performance but different footprint geometries. Operating temperature range extensions provide enhanced thermal performance but do not affect substitution eligibility when the main part's temperature range is within the substitute's range.

Parameter Comparison

Parameter	MMBZ5255B-TP (Main)	CMPZ5255B TR PBFREE	MMBZ5255BLT1G	MMBZ5255BW-7-F
Manufacturer	Micro Commercial Co	Central Semiconductor Corp	onsemi	Diodes Incorporated
Voltage - Zener (Nom)	28 V	28 V	28 V	28 V
Tolerance	±5%	±5%	±5%	±5%
Power - Max	350 mW	350 mW	225 mW	200 mW
Impedance (Max)	44 Ohms	44 Ohms	44 Ohms	44 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 21 V	100 nA @ 21 V	100 nA @ 21 V	100 nA @ 21 V
Voltage - Forward (Max) @ If	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA
Operating Temperature	-55°C ~ 150°C	-65°C ~ 150°C	-65°C ~ 150°C	-65°C ~ 150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	SC-70, SOT-323
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active	Active

Engineering Selection Recommendations

CMPZ5255B TR PBFREE (Central Semiconductor Corp): This substitute maintains identical electrical specifications to the main part, including 28 V zener voltage, 350 mW power rating, 44 Ohms impedance, and all leakage and forward voltage parameters. Package configuration (SOT-23-3) and Tape & Reel delivery match the main part. Operating temperature range extends to -65°C, providing enhanced low-temperature performance. ROHS3 compliance and REACH Unaffected status align with regulatory requirements. This part is suitable for direct replacement in applications where the main part is unavailable.

MMBZ5255BLT1G (onsemi): This substitute provides identical zener voltage (28 V), tolerance (±5%), impedance (44 Ohms), and leakage specifications. Power dissipation is reduced to 225 mW, representing a 35.7% decrease from the main part's 350 mW rating. Package configuration (SOT-23-3) is mechanically compatible with the main part. Operating temperature range extends to -65°C. ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited) are provided. Selection of this part requires verification that circuit current-limiting conditions do not exceed 225 mW thermal dissipation.

MMBZ5255BW-7-F (Diodes Incorporated): This substitute maintains 28 V zener voltage, ±5% tolerance, 44 Ohms impedance, and identical leakage and forward voltage parameters. Power dissipation is reduced to 200 mW, representing a 42.9% decrease from the main part. Package configuration differs: SOT-323 (SC-70) versus SOT-23-3, requiring PCB layout modification and different land pattern geometry. Operating temperature range extends to -65°C. ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited) are provided. This part is suitable only when PCB footprint redesign is acceptable and thermal dissipation does not exceed 200 mW.

Frequently Asked Questions (FAQ)

Q: Can CMPZ5255B TR PBFREE be used as a direct replacement for MMBZ5255B-TP?

A: Yes. Both parts share identical electrical specifications: 28 V zener voltage, ±5% tolerance, 350 mW power rating, 44 Ohms impedance, 100 nA reverse leakage, and 900 mV forward voltage. Package configuration (SOT-23-3) and Tape & Reel delivery are identical. PCB layout and assembly processes require no modification.

Q: What is the primary limitation of MMBZ5255BLT1G as a substitute?

A: Power dissipation is reduced from 350 mW to 225 mW. Applications requiring thermal dissipation exceeding 225 mW will experience junction temperature rise beyond design specifications. Circuit current-limiting conditions must be verified to ensure dissipation remains within the 225 mW limit.

Q: Why does MMBZ5255BW-7-F require PCB redesign?

A: MMBZ5255BW-7-F uses SOT-323 (SC-70) package geometry, which differs from the main part's SOT-23-3 (TO-236-3) package. Land pattern dimensions, lead spacing, and component footprint are incompatible. PCB layout modification is required for mechanical fit and electrical connection.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed (CMPZ5255B TR PBFREE, MMBZ5255BLT1G, MMBZ5255BW-7-F) are ROHS3 compliant and REACH Unaffected, matching the main part's regulatory status.

Q: Can lower power-rated substitutes be used in high-current applications?

A: No. Power dissipation is determined by zener current and voltage. Applications with high reverse current will generate thermal dissipation proportional to current magnitude. Lower power-rated parts (225 mW or 200 mW) will exceed thermal limits in high-current circuits. Circuit design must limit current to ensure dissipation remains within the selected part's power rating.

Q: What is the operating temperature advantage of substitute parts?

A: Substitute parts extend the lower operating temperature limit from -55°C to -65°C, providing 10°C additional low-temperature performance margin. Upper temperature limit remains 150°C across all parts. This extension does not affect substitution eligibility when the main part's temperature range is within the substitute's range.

Q: Are moisture sensitivity levels different between parts?

A: The main part (MMBZ5255B-TP) does not specify Moisture Sensitivity Level (MSL). Substitute parts CMPZ5255B TR PBFREE, MMBZ5255BLT1G, and MMBZ5255BW-7-F specify MSL 1 (Unlimited), indicating no moisture sensitivity restrictions during storage and handling.

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