MMBZ5243C-E3-08 Equivalent & Substitute Parts

Part Overview

The MMBZ5243C-E3-08 is a 13 V Zener diode manufactured by Vishay General Semiconductor - Diodes Division, rated for 225 mW power dissipation in a surface mount SOT-23-3 package. This component is classified as obsolete product status. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications requiring 13 V Zener regulation in compact surface mount form factors.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	13	V
Tolerance	±2%	—
Power - Maximum	225	mW
Impedance (Maximum)	13	Ohms
Current - Reverse Leakage @ Vr	500 nA @ 9.9 V	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5243C-E3-08 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: Surface mount
Regulatory compliance: RoHS3 compliant

Secondary Compatibility Factors:

Power rating: 225 mW or higher
Impedance: 13 Ohms or lower
Reverse leakage current: 500 nA @ 9.9 V or lower
Operating temperature range: Must encompass -55°C to 150°C or equivalent
Tolerance: ±2% to ±6% acceptable

Substitute parts are grouped into two categories based on electrical performance alignment:

Category A - Direct Electrical Equivalents (Matching or Exceeding Original Specifications): Parts with 13 V nominal Zener voltage, SOT-23-3 package, and specifications meeting or exceeding the original MMBZ5243C-E3-08 parameters.

Category B - Functional Alternatives (Acceptable Performance Variance): Parts with 13 V nominal Zener voltage, SOT-23-3 package, with minor tolerance or impedance variations that remain within acceptable operating margins for typical 13 V Zener regulation applications.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Ir @ Vr	Temp Range	Package	Status
MMBZ5243C-E3-08	Vishay	13 V	±2%	225 mW	13 Ω	500 nA @ 9.9 V	-55 to 150°C	SOT-23-3	Obsolete
BZX84B13-7-F	Diodes Inc.	13 V	±2%	300 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	SOT-23-3	Active
BZX84B13Q-7-F	Diodes Inc.	13 V	±2%	300 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	SOT-23-3	Active
BZX84C13LT1G	onsemi	13 V	±6%	225 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	SOT-23-3	Active
BZX84C13Q-7-F	Diodes Inc.	13 V	±6%	300 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	SOT-23-3	Active
CMPZ5243B BK PBFREE	Central Semiconductor	13 V	±5%	350 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	SOT-23-3	Active
CZRT5243B-G	Comchip Technology	13 V	±5%	300 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	SOT-23-3	Active
CZRT55C13-G	Comchip Technology	13 V	±6%	350 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	SOT-23-3	Active
MMBZ5243B-TP	Micro Commercial Co	13 V	±5%	350 mW	13 Ω	500 nA @ 9.9 V	-55 to 150°C	SOT-23-3	Active
MMBZ5243BLT1G	onsemi	13 V	±5%	225 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	SOT-23-3	Active
MMBZ5243BW-7-F	Diodes Inc.	13 V	±5%	200 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	SOT-323	Active

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

BZX84B13-7-F and BZX84B13Q-7-F (Diodes Incorporated) are the preferred substitutes. Both maintain the 13 V nominal Zener voltage and ±2% tolerance matching the original specification. These parts offer increased power rating (300 mW versus 225 mW), extended lower temperature limit (-65°C versus -55°C), and active product status ensuring long-term availability. The BZX84B13Q-7-F includes AEC-Q101 automotive qualification.

MMBZ5243BLT1G (onsemi) provides an alternative with matching 225 mW power rating and identical impedance characteristics. This part maintains the same base product family designation and offers extended temperature range (-65°C) with active status and high inventory availability.

Secondary Substitutes (Acceptable Alternatives):

BZX84C13LT1G (onsemi) and BZX84C13Q-7-F (Diodes Incorporated) are suitable where tolerance relaxation to ±6% is acceptable. Both provide active status and extended temperature ranges.

CMPZ5243B BK PBFREE (Central Semiconductor) and CZRT5243B-G (Comchip Technology) offer higher power ratings (300-350 mW) with matching impedance characteristics (13 Ohms) and reverse leakage specifications identical to the original part.

CZRT55C13-G (Comchip Technology) provides the highest power rating (350 mW) with extended temperature range and active status.

Package Consideration:

MMBZ5243BW-7-F (Diodes Incorporated) uses SOT-323 package instead of SOT-23-3. This part is suitable only for applications where PCB layout accommodates the smaller SOT-323 form factor.

All recommended substitutes maintain RoHS3 compliance and are classified as active products with established supply chains.

Frequently Asked Questions (FAQ)

Q: Can BZX84B13-7-F directly replace MMBZ5243C-E3-08 without circuit modification?

A: Yes. Both parts share identical 13 V nominal Zener voltage, ±2% tolerance, and SOT-23-3 package. The BZX84B13-7-F offers higher power rating (300 mW versus 225 mW) and extended temperature range, making it a direct functional upgrade. No circuit changes are required.

Q: What is the difference between BZX84B13-7-F and BZX84B13Q-7-F?

A: Both parts are electrically identical with 13 V nominal voltage, ±2% tolerance, and 300 mW power rating. The BZX84B13Q-7-F includes AEC-Q101 automotive qualification and is specified for automotive-grade applications. Select BZX84B13Q-7-F for automotive or high-reliability applications.

Q: Why do some substitutes have ±6% tolerance instead of ±2%?

A: Parts such as BZX84C13LT1G and BZX84C13Q-7-F are from the BZX84C series with relaxed tolerance specifications. These remain functionally compatible for most 13 V Zener regulation applications where ±6% voltage variation is acceptable. Verify tolerance requirements against circuit design specifications before selection.

Q: Is MMBZ5243BW-7-F compatible with existing PCB layouts?

A: MMBZ5243BW-7-F uses SOT-323 package, which is physically smaller than the SOT-23-3 package of the original part. This part is compatible only if PCB footprints are redesigned to accommodate SOT-323 dimensions. Verify PCB layout compatibility before substitution.

Q: What is the significance of impedance (Zzt) differences between parts?

A: Impedance affects dynamic Zener voltage regulation characteristics. The original MMBZ5243C-E3-08 specifies 13 Ohms maximum impedance. Substitutes with higher impedance (30 Ohms) exhibit slightly higher dynamic resistance but remain suitable for typical voltage regulation applications. Applications requiring precise dynamic regulation should prioritize parts with matching or lower impedance values.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts are RoHS3 compliant and REACH unaffected, matching the regulatory status of the original MMBZ5243C-E3-08.

Q: Which substitute offers the best long-term availability?

A: MMBZ5243BLT1G (onsemi) and BZX84C13LT1G (onsemi) demonstrate the highest inventory levels (125,100 and 167,300 units respectively) and active product status, indicating strong long-term supply chain support.

Q: Can I use a higher power-rated Zener diode as a substitute?

A: Yes. Substituting with higher power-rated parts (300 mW or 350 mW) is acceptable and provides design margin. The circuit will function identically; the higher power rating simply provides additional thermal headroom. Verify that PCB thermal management remains adequate for the selected part.

Q: What is the operating temperature range difference between substitutes?

A: The original MMBZ5243C-E3-08 operates from -55°C to 150°C. Most active substitutes extend the lower limit to -65°C, providing wider temperature coverage. MMBZ5243B-TP maintains the -55°C lower limit. Select based on application temperature requirements.

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