MMBZ5231B Equivalent & Substitute Parts

Part Overview

The MMBZ5231B is a Zener diode manufactured by onsemi, rated at 5.1 V nominal with 350 mW maximum power dissipation in a surface mount SOT-23-3 package. This component is classified as obsolete, necessitating identification of equivalent and substitute parts for ongoing design requirements and procurement needs. Substitute parts maintain the core electrical specifications while offering active product status and improved availability.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	5.1	V
Tolerance	±5%	—
Power - Max	350	mW
Impedance (Max)	17	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 2 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5231B is determined by the following critical parameters:

Electrical Equivalence Requirements:

Voltage - Zener (Nom): 5.1 V
Tolerance: ±5%
Impedance (Max): 17 Ohms
Current - Reverse Leakage @ Vr: 5 µA @ 2 V
Voltage - Forward (Vf) (Max) @ If: 900 mV @ 10 mA

Mechanical Compatibility Requirements:

Mounting Type: Surface Mount
Package / Case: TO-236-3, SC-59, SOT-23-3

Power Rating Consideration: Substitute parts are grouped into two categories based on maximum power dissipation:

Direct Equivalents (350 mW): CMPZ5231B BK PBFREE, CMPZ5231B TR PBFREE, MMBZ5231B-7-F, MMBZ5231BQ-7-F
Reduced Power Equivalents (225 mW): MMBZ5231BLT1G, MMBZ5231BLT3G, MMBZ5231ELT1G, SZMMBZ5231BLT1G, SZMMBZ5231BLT3G

All substitute parts maintain identical zener voltage, tolerance, impedance, reverse leakage current, and forward voltage specifications. Reduced power variants are suitable for applications where the 350 mW rating is not required.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Ir @ Vr (µA)	Vf (mV)	Temp Range (°C)	Package	Status
MMBZ5231B	onsemi	5.1	±5%	350	17	5 @ 2V	900 @ 10mA	-55 to 150	SOT-23-3	Obsolete
MMBZ5231BLT1G	onsemi	5.1	±5%	225	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
MMBZ5231BLT3G	onsemi	5.1	±5%	225	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
MMBZ5231ELT1G	onsemi	5.1	±5%	225	17	5 @ 2V	900 @ 10mA	-55 to 150	SOT-23-3	Active
SZMMBZ5231BLT1G	onsemi	5.1	±5%	225	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
SZMMBZ5231BLT3G	onsemi	5.1	±5%	225	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
CMPZ5231B BK PBFREE	Central Semiconductor Corp	5.1	±5%	350	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
CMPZ5231B TR PBFREE	Central Semiconductor Corp	5.1	±5%	350	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
MMBZ5231B-7-F	Diodes Incorporated	5.1	±5%	350	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
MMBZ5231BQ-7-F	Diodes Incorporated	5.1	±5%	350	17	5 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active
BZX84-A5V1,215	Nexperia USA Inc.	5.1	±1%	250	60	2 @ 2V	900 @ 10mA	-65 to 150	SOT-23-3	Active

Engineering Selection Recommendations

Direct Replacement (350 mW Power Rating):

For applications requiring the full 350 mW power dissipation specification of the original MMBZ5231B, the following active alternatives are available:

MMBZ5231B-7-F (Diodes Incorporated): Active status with 47,100 units in stock. Maintains all electrical parameters and operating temperature range of -65°C to 150°C. RoHS3 compliant.
MMBZ5231BQ-7-F (Diodes Incorporated): Active status with automotive qualification (AEC-Q101). Operating temperature range -65°C to 150°C. RoHS3 compliant. Limited inventory (757 units).
CMPZ5231B BK PBFREE (Central Semiconductor Corp): Active status, bulk packaging. 788 units in stock. RoHS3 compliant.
CMPZ5231B TR PBFREE (Central Semiconductor Corp): Active status, tape and reel packaging. 18,472 units in stock. RoHS3 compliant.

Reduced Power Alternatives (225 mW Power Rating):

For applications where 225 mW power dissipation is sufficient, the following onsemi variants provide active product status:

MMBZ5231BLT1G: Cut tape and Digi-Reel packaging. 125,200 units in stock. Extended temperature range -65°C to 150°C. RoHS3 compliant.
MMBZ5231BLT3G: Tape and reel packaging. 21,475 units in stock. Extended temperature range -65°C to 150°C. RoHS3 compliant.
MMBZ5231ELT1G: Tape and reel packaging. 1,951 units in stock. Operating temperature range -55°C to 150°C. RoHS3 compliant.

Automotive-Grade Alternatives:

For automotive applications requiring AEC-Q101 qualification:

SZMMBZ5231BLT1G: Cut tape and Digi-Reel packaging. 41,100 units in stock. 225 mW power rating. Operating temperature -65°C to 150°C. RoHS3 compliant.
SZMMBZ5231BLT3G: Tape and reel packaging. 37,151 units in stock. 225 mW power rating. Operating temperature -65°C to 150°C. RoHS3 compliant.
MMBZ5231BQ-7-F: Automotive-grade with AEC-Q101 qualification. 350 mW power rating. 757 units in stock.
BZX84-A5V1,215 (Nexperia): Automotive-grade with AEC-Q101 qualification. 250 mW power rating. 88,027 units in stock. Note: ±1% tolerance and 60 Ohms impedance differ from original specification.

Frequently Asked Questions (FAQ)

Q: Can MMBZ5231BLT1G replace MMBZ5231B in all applications?

A: MMBZ5231BLT1G is electrically equivalent for zener voltage, tolerance, impedance, and leakage current. The primary difference is reduced power rating (225 mW vs. 350 mW). Substitution is valid only if the application does not require the full 350 mW dissipation capability. The extended operating temperature range (-65°C to 150°C vs. -55°C to 150°C) provides additional margin.

Q: What is the difference between MMBZ5231BLT1G and MMBZ5231BLT3G?

A: Both parts are electrically identical with 5.1 V zener voltage, ±5% tolerance, 225 mW power rating, and SOT-23-3 package. The difference is packaging format: MMBZ5231BLT1G is supplied in cut tape and Digi-Reel format, while MMBZ5231BLT3G is supplied in tape and reel format. Selection depends on assembly process requirements.

Q: Are automotive-grade variants (SZMMBZ5231BLT1G, SZMMBZ5231BLT3G) suitable for non-automotive applications?

A: Yes. Automotive-grade parts with AEC-Q101 qualification meet or exceed commercial-grade specifications. These parts are suitable for any application requiring the specified electrical parameters and reliability level.

Q: How does BZX84-A5V1,215 differ from MMBZ5231B?

A: BZX84-A5V1,215 maintains the 5.1 V zener voltage and SOT-23-3 package. However, it differs in three parameters: tolerance (±1% vs. ±5%), impedance (60 Ohms vs. 17 Ohms), and reverse leakage current (2 µA vs. 5 µA at 2 V). Power rating is 250 mW. These differences may affect circuit performance in applications sensitive to impedance or tolerance specifications.

Q: What packaging options are available for substitute parts?

A: Substitute parts are available in the following packaging formats: cut tape and Digi-Reel (CT), tape and reel (TR), and bulk. Selection depends on assembly equipment compatibility and procurement volume requirements. All variants use the SOT-23-3 package footprint.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts carry RoHS3 compliance status. The original MMBZ5231B does not specify RoHS status due to its obsolete classification.

Q: Which substitute offers the highest inventory availability?

A: MMBZ5231BLT1G offers the highest inventory with 125,200 units in stock, followed by BZX84-A5V1,215 with 88,027 units.

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