MMBZ5243B Zener Diode Equivalent & Substitute Parts

Part Overview

The MMBZ5243B is a 13 V, 350 mW surface mount zener diode manufactured by onsemi in SOT-23-3 package configuration. This component is classified as obsolete, necessitating identification of equivalent and substitute parts for ongoing design requirements and procurement needs. The part operates across a temperature range of -55°C to 150°C with ±5% voltage tolerance and is suitable for voltage regulation and protection applications in electronic circuits.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	13	V
Power - Maximum	350	mW
Tolerance	±5%	—
Impedance (Maximum)	13	Ohms
Current - Reverse Leakage @ Vr	500 nA @ 9.9 V	—
Voltage - Forward (Maximum) @ If	900 mV @ 10 mA	—
Operating Temperature Range	-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 MMBZ5243B is determined by the following critical parameters:

Primary Substitution Criteria:

Zener voltage: 13 V nominal
Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting configuration: Surface mount
Tolerance specification: ±5% or tighter
Maximum power dissipation: 350 mW or greater
Operating temperature range: Must encompass or exceed -55°C to 150°C

Substitution Categories:

Direct Equivalents maintain all electrical specifications including 350 mW power rating and ±5% tolerance. These parts are functionally interchangeable with the MMBZ5243B.

Similar Substitutes share the 13 V zener voltage and SOT-23-3 package but may differ in power rating (225 mW or 300 mW), impedance characteristics, or tolerance specifications (±2% or ±6%). These parts are suitable when circuit design permits reduced power dissipation or when tighter tolerance is beneficial.

Upgrade Options provide enhanced specifications such as extended temperature ranges (-65°C to 150°C), improved compliance certifications (RoHS3, AEC-Q101), or active product status, while maintaining core electrical compatibility.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Power (mW)	Tolerance	Zzt (Ohms)	Temp Range (°C)	Package	Status	Compliance
MMBZ5243B	onsemi	13	350	±5%	13	-55 to 150	SOT-23-3	Obsolete	—
MMBZ5243BLT1G	onsemi	13	225	±5%	13	-65 to 150	SOT-23-3	Active	RoHS3
SZMMBZ5243BLT1G	onsemi	13	225	±5%	13	-65 to 150	SOT-23-3	Active	RoHS3, AEC-Q101
CMPZ5243B BK PBFREE	Central Semiconductor Corp	13	350	±5%	13	-65 to 150	SOT-23-3	Active	RoHS3
CMPZ5243B TR PBFREE	Central Semiconductor Corp	13	350	±5%	13	-65 to 150	SOT-23-3	Active	RoHS3
MMBZ5243B-TP	Micro Commercial Co	13	350	±5%	13	-55 to 150	SOT-23-3	Active	RoHS3
MMBZ5243B-7-F	Diodes Incorporated	13	350	±5%	13	-65 to 150	SOT-23-3	Active	RoHS3
BZX84B13-7-F	Diodes Incorporated	13	300	±2%	30	-65 to 150	SOT-23-3	Active	RoHS3
BZX84B13-TP	Micro Commercial Co	13	350	±2%	30	-55 to 150	SOT-23-3	Active	—
BZX84B13Q-7-F	Diodes Incorporated	13	300	±2%	30	-65 to 150	SOT-23-3	Active	RoHS3, AEC-Q101
BZX84C13-7-F	Diodes Incorporated	13	300	±6%	30	-65 to 150	SOT-23-3	Active	RoHS3, AEC-Q101

Engineering Selection Recommendations

For Direct Replacement (Obsolete Part Mitigation):

CMPZ5243B TR PBFREE and CMPZ5243B BK PBFREE from Central Semiconductor Corp provide direct electrical equivalence to the MMBZ5243B with identical 13 V, 350 mW specifications and ±5% tolerance. Both parts are active products with RoHS3 compliance and extended operating temperature range (-65°C to 150°C). These parts are recommended as primary substitutes for existing MMBZ5243B applications.

MMBZ5243B-7-F from Diodes Incorporated offers equivalent specifications with active product status, RoHS3 compliance, and extended temperature range (-65°C to 150°C). This part is suitable for direct substitution in new designs and legacy system updates.

For Active Product Status with Enhanced Specifications:

MMBZ5243BLT1G from onsemi provides active product status with RoHS3 compliance and extended temperature range (-65°C to 150°C). The reduced power rating (225 mW) is suitable for applications where circuit design permits lower power dissipation while maintaining the same zener voltage and tolerance.

SZMMBZ5243BLT1G from onsemi combines active status with AEC-Q101 automotive qualification and RoHS3 compliance. This part is appropriate for automotive and mission-critical applications requiring formal qualification standards.

For Tighter Tolerance Requirements:

BZX84B13-7-F and BZX84B13Q-7-F from Diodes Incorporated provide ±2% tolerance compared to the ±5% specification of the MMBZ5243B. The BZX84B13Q-7-F includes AEC-Q101 automotive qualification. These parts are suitable when circuit design requires improved voltage regulation accuracy. Power rating is 300 mW, which is acceptable for applications not requiring the full 350 mW capability.

BZX84C13-7-F from Diodes Incorporated offers ±6% tolerance with 300 mW power rating and AEC-Q101 automotive qualification. This part is suitable for cost-optimized designs where the wider tolerance is acceptable.

For Packaging Considerations:

All substitute parts maintain SOT-23-3 package compatibility with the MMBZ5243B. Tape & Reel (TR) packaging is available for high-volume production environments, while bulk packaging options support lower-volume requirements.

Frequently Asked Questions (FAQ)

Q: Can MMBZ5243BLT1G replace MMBZ5243B in all applications?

A: MMBZ5243BLT1G shares the same 13 V zener voltage, ±5% tolerance, and SOT-23-3 package as the MMBZ5243B. The primary difference is reduced power rating (225 mW versus 350 mW). Substitution is valid when circuit design permits operation within the 225 mW power envelope. Extended temperature range (-65°C to 150°C) provides enhanced performance compared to the original part.

Q: What is the difference between BZX84B13 and MMBZ5243B series?

A: Both series provide 13 V zener diodes in SOT-23-3 packages. The BZX84B13 series features ±2% tolerance and 30 Ohm impedance compared to ±5% tolerance and 13 Ohm impedance in the MMBZ5243B series. BZX84B13 parts are suitable when tighter voltage regulation is required. Power ratings vary between 300 mW and 350 mW depending on specific part number.

Q: Are all substitute parts RoHS3 compliant?

A: Most active substitute parts listed are RoHS3 compliant. BZX84B13-TP from Micro Commercial Co does not specify RoHS3 compliance in the provided data. Verify compliance requirements for your specific application before selection.

Q: Which substitute part is recommended for automotive applications?

A: SZMMBZ5243BLT1G from onsemi and BZX84B13Q-7-F from Diodes Incorporated both carry AEC-Q101 automotive qualification. SZMMBZ5243BLT1G maintains the original 13 V, ±5% specification with 225 mW power rating. BZX84B13Q-7-F provides tighter ±2% tolerance with 300 mW power rating. Selection depends on specific power and tolerance requirements.

Q: Can I use a 225 mW rated part instead of 350 mW?

A: Substitution with lower power-rated parts (225 mW or 300 mW) is valid when circuit design analysis confirms that actual power dissipation remains below the substitute part's rating. Thermal analysis and worst-case operating conditions must be evaluated to ensure reliable operation.

Q: What packaging options are available for production?

A: Substitute parts are available in multiple packaging formats: Tape & Reel (TR) for automated assembly and high-volume production, Cut Tape (CT) for moderate volumes, and Bulk for lower-volume applications. All parts maintain SOT-23-3 physical compatibility.

Q: How do impedance differences affect circuit performance?

A: The MMBZ5243B series specifies 13 Ohm maximum impedance, while BZX84 series parts specify 30 Ohm maximum impedance. Lower impedance provides better voltage regulation characteristics. For applications requiring precise voltage regulation, the lower impedance of MMBZ5243B-series substitutes is preferred. BZX84 series parts are suitable for general-purpose voltage clamping applications where impedance variation is less critical.

Q: Are there temperature range considerations for substitution?

A: The original MMBZ5243B operates from -55°C to 150°C. Most active substitutes extend the lower temperature limit to -65°C, providing enhanced cold-temperature performance. Applications operating at temperatures below -55°C require substitutes with extended range. For standard applications within -55°C to 150°C, both original and extended-range parts are functionally equivalent.

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