MMBZ5243B-E3-08 Equivalent & Substitute Parts

Part Overview

The MMBZ5243B-E3-08 is a Zener diode rated at 13 V nominal with 225 mW maximum power dissipation in a surface mount SOT-23-3 package. Manufactured by Vishay General Semiconductor - Diodes Division, this component is classified as obsolete. Due to its obsolete status and limited availability relative to active alternatives, equivalent substitute parts with matching or superior electrical characteristics are necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	13	V
Tolerance	±5%	—
Power - Max	225	mW
Impedance (Max)	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	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5243B-E3-08 is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 13 V nominal
Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting: Surface mount
Tolerance: ±5% or tighter
Reverse leakage current: 500 nA @ 9.9 V or lower
Operating temperature range: Minimum -55°C to 150°C

Secondary Compatibility Factors:

Power dissipation: 225 mW or higher
Impedance: 13 Ohms or lower
RoHS3 compliance
MSL rating: 1 (Unlimited)

Substitute parts are grouped into three categories based on availability and product status:

Direct Substitutes (Active Status): Parts with identical electrical specifications and active manufacturing status
Upgraded Alternatives (Active Status): Parts with equal or superior power ratings and extended temperature ranges
Manufacturer Recommended Alternatives: Parts with comparable performance from established manufacturers, including automotive-qualified variants

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power Max	Zzt (Max)	Ir @ Vr	Temp Range	Status	Packaging
MMBZ5243B-E3-08	Vishay	13 V	±5%	225 mW	13 Ω	500 nA @ 9.9 V	-55 to 150°C	Obsolete	SOT-23-3
CZRT5243B-G	Comchip Technology	13 V	±5%	300 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	Active	SOT-23-3 (TR)
MMBZ5243B-7-F	Diodes Incorporated	13 V	±5%	350 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	Active	SOT-23-3 (TR)
MMBZ5243BLT1G	onsemi	13 V	±5%	225 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	Active	SOT-23-3 (TR)
SZMMBZ5243BLT1G	onsemi	13 V	±5%	225 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	Active	SOT-23-3 (TR)
BZX84B13-7-F	Diodes Incorporated	13 V	±2%	300 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	Active	SOT-23-3 (TR)
BZX84B13-TP	Micro Commercial Co	13 V	±2%	350 mW	30 Ω	100 nA @ 8 V	-55 to 150°C	Active	SOT-23-3
BZX84B13Q-7-F	Diodes Incorporated	13 V	±2%	300 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	Active	SOT-23-3 (TR)
BZX84C13-TP	Micro Commercial Co	13 V	±5%	350 mW	30 Ω	100 nA @ 8 V	-55 to 150°C	Active	SOT-23-3
BZX84C13LT1G	onsemi	13 V	±6%	225 mW	30 Ω	100 nA @ 8 V	-65 to 150°C	Active	SOT-23-3 (TR)
CMPZ5243B TR PBFREE	Central Semiconductor Corp	13 V	±5%	350 mW	13 Ω	500 nA @ 9.9 V	-65 to 150°C	Active	SOT-23-3 (TR)

Engineering Selection Recommendations

Direct Replacement (Identical Specifications):

MMBZ5243BLT1G (onsemi) and SZMMBZ5243BLT1G (onsemi) are direct functional equivalents with identical electrical parameters to the MMBZ5243B-E3-08. Both are active products with extended temperature range (-65°C to 150°C versus -55°C to 150°C). SZMMBZ5243BLT1G carries AEC-Q101 automotive qualification, suitable for applications requiring automotive-grade components.

Higher Power Capability Alternatives:

CZRT5243B-G (Comchip Technology), MMBZ5243B-7-F (Diodes Incorporated), and CMPZ5243B TR PBFREE (Central Semiconductor Corp) provide 300 mW to 350 mW power ratings while maintaining the 13 Ω impedance specification. These parts are suitable for applications requiring increased thermal margin or higher power dissipation tolerance.

Tighter Tolerance Variants:

BZX84B13-7-F, BZX84B13Q-7-F (both Diodes Incorporated), and BZX84B13-TP (Micro Commercial Co) offer ±2% voltage tolerance compared to the ±5% specification of the original part. These variants feature 30 Ω maximum impedance and lower reverse leakage current (100 nA @ 8 V). BZX84B13Q-7-F includes AEC-Q101 automotive qualification.

Selection Basis:

All recommended substitutes maintain SOT-23-3 package compatibility, RoHS3 compliance, and MSL 1 rating. Selection should prioritize active product status and compliance certifications matching application requirements. Automotive applications should specify AEC-Q101 qualified variants (SZMMBZ5243BLT1G or BZX84B13Q-7-F).

Frequently Asked Questions (FAQ)

Q: Can MMBZ5243BLT1G directly replace MMBZ5243B-E3-08 without circuit modification?

A: Yes. MMBZ5243BLT1G is electrically identical with matching 13 V nominal voltage, ±5% tolerance, 225 mW power rating, and 13 Ω impedance. Both use SOT-23-3 packaging. The extended temperature range (-65°C to 150°C) provides additional operational margin.

Q: What is the difference between MMBZ5243BLT1G and SZMMBZ5243BLT1G?

A: Both parts are electrically identical. SZMMBZ5243BLT1G carries AEC-Q101 automotive qualification and is designated for automotive applications. Select SZMMBZ5243BLT1G for automotive or safety-critical applications; use MMBZ5243BLT1G for general industrial applications.

Q: Why do BZX84B13 variants have different impedance (30 Ω vs. 13 Ω)?

A: BZX84B13 series parts feature different internal design characteristics resulting in higher impedance. This affects dynamic impedance behavior but maintains the 13 V nominal zener voltage. Circuits designed for 13 Ω impedance may experience different transient response with 30 Ω variants. Verify circuit performance if impedance is critical.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts are RoHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity rating, matching the original part's environmental compliance profile.

Q: What is the advantage of higher power-rated substitutes (300 mW or 350 mW)?

A: Higher power ratings provide increased thermal margin and allow operation at higher current levels without exceeding maximum junction temperature. CZRT5243B-G (300 mW), MMBZ5243B-7-F (350 mW), and CMPZ5243B TR PBFREE (350 mW) are suitable for applications with elevated power dissipation requirements or thermal constraints.

Q: Can I use BZX84C13LT1G as a substitute despite ±6% tolerance?

A: BZX84C13LT1G meets the core substitution criteria (13 V nominal, SOT-23-3 package, 225 mW power, active status). The ±6% tolerance is slightly wider than the original ±5% specification. Use only if circuit design tolerates ±6% voltage variation. Verify performance in applications with tight voltage regulation requirements.

Q: What packaging options are available for substitutes?

A: Most active substitutes are supplied in Tape & Reel (TR) format for automated assembly. BZX84B13-TP and BZX84C13-TP are available in bulk packaging. Confirm packaging format with supplier to match production requirements.

Q: Is the operating temperature range difference significant?

A: The original part operates -55°C to 150°C. Most substitutes extend the lower limit to -65°C, providing 10°C additional margin at low temperature. This is beneficial for applications in cold environments but not critical for standard industrial temperature ranges.

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