MMBZ5249B Equivalent & Substitute Parts

Part Overview

The MMBZ5249B is a Zener diode rated at 19 V nominal voltage with 350 mW maximum power dissipation in a surface mount SOT-23-3 package. Manufactured by onsemi, this component is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary for new designs and ongoing production requirements. Substitute parts maintain the core electrical specifications while offering improved availability and active manufacturer support.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	19	V
Tolerance	±5	%
Power - Max	350	mW
Impedance (Max)	23	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 14 V	nA
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	mV
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOT-23-3	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5249B is determined by equivalence in the following critical parameters:

Zener Voltage (Vz): 19 V nominal with ±5% tolerance
Package Type: SOT-23-3 (TO-236-3, SC-59)
Mounting Configuration: Surface mount
Impedance (Zzt): 23 Ohms maximum
Reverse Leakage Current: 100 nA @ 14 V
Forward Voltage: 900 mV @ 10 mA

Substitute parts are grouped into two categories based on power rating:

Category A - Full Power Rating (350 mW): Parts maintaining the original 350 mW specification.

Category B - Reduced Power Rating (225 mW): Parts with lower maximum power dissipation but identical voltage and impedance characteristics.

All substitute parts maintain the same zener voltage, tolerance, impedance, leakage current, and forward voltage specifications. Differences in maximum power rating and operating temperature range are noted in the parameter comparison table.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power - Max	Zzt (Max)	Leakage @ Vr	Vf (Max) @ If	Temp Range	Status	Packaging
MMBZ5249B	onsemi	19 V	±5%	350 mW	23 Ω	100 nA @ 14 V	900 mV @ 10 mA	-55 to 150°C	Obsolete	SOT-23-3
MMBZ5249BLT1G	onsemi	19 V	±5%	225 mW	23 Ω	100 nA @ 14 V	900 mV @ 10 mA	-65 to 150°C	Active	Tape & Reel
SZMMBZ5249BLT1G	onsemi	19 V	±5%	225 mW	23 Ω	100 nA @ 14 V	900 mV @ 10 mA	-65 to 150°C	Active	Tape & Reel
CMPZ5249B TR PBFREE	Central Semiconductor Corp	19 V	±5%	350 mW	23 Ω	100 nA @ 14 V	900 mV @ 10 mA	-65 to 150°C	Active	Tape & Reel
MMBZ5249B_R1_00001	Panjit International Inc.	19 V	±5%	410 mW	23 Ω	100 nA @ 14 V	900 mV @ 10 mA	-55 to 150°C	Active	Tape & Reel

Engineering Selection Recommendations

Direct Replacement (Full Electrical Equivalence)

CMPZ5249B TR PBFREE from Central Semiconductor Corp provides direct electrical equivalence to the MMBZ5249B with identical 350 mW power rating and zener voltage specification. This part is active and RoHS3 compliant. Operating temperature range extends to -65°C, providing enhanced low-temperature performance.

MMBZ5249B_R1_00001 from Panjit International Inc. offers the highest power rating at 410 mW while maintaining all other electrical parameters. This part is active and RoHS3 compliant, with operating temperature range of -55 to 150°C.

Alternative Selection (Reduced Power Rating)

MMBZ5249BLT1G and SZMMBZ5249BLT1G from onsemi are active alternatives with reduced maximum power dissipation of 225 mW. Both parts maintain identical zener voltage, tolerance, impedance, and leakage specifications. SZMMBZ5249BLT1G includes AEC-Q101 automotive qualification. These parts feature extended low-temperature operation to -65°C and are RoHS3 compliant.

Selection between reduced-power and full-power alternatives depends on circuit power dissipation requirements. Applications requiring the full 350 mW rating should use CMPZ5249B TR PBFREE or MMBZ5249B_R1_00001. Applications with lower power dissipation budgets may use the 225 mW variants.

Frequently Asked Questions (FAQ)

Q: Can MMBZ5249BLT1G replace MMBZ5249B in all applications?

A: MMBZ5249BLT1G is electrically equivalent for zener voltage, tolerance, impedance, and leakage specifications. The primary difference is maximum power dissipation: 225 mW versus 350 mW. Substitution is valid only if circuit power dissipation does not exceed 225 mW. Extended operating temperature range (-65 to 150°C) provides additional capability.

Q: What is the difference between MMBZ5249BLT1G and SZMMBZ5249BLT1G?

A: Both parts are electrically identical with 19 V zener voltage and 225 mW power rating. SZMMBZ5249BLT1G includes AEC-Q101 automotive qualification and is designated for automotive applications. Selection depends on application requirements and qualification standards.

Q: Is CMPZ5249B TR PBFREE a suitable replacement for MMBZ5249B?

A: Yes. CMPZ5249B TR PBFREE maintains all electrical specifications including 350 mW power rating, 19 V zener voltage, and identical impedance and leakage characteristics. The part is manufactured by Central Semiconductor Corp and is RoHS3 compliant. Operating temperature range extends to -65°C.

Q: Why does MMBZ5249B_R1_00001 have a higher power rating?

A: MMBZ5249B_R1_00001 from Panjit International Inc. is rated at 410 mW maximum power dissipation, exceeding the original 350 mW specification. All other electrical parameters remain identical. This part provides additional thermal margin for applications with higher power dissipation requirements.

Q: Are all substitute parts available in Tape & Reel packaging?

A: Yes. All substitute parts listed are supplied in Tape & Reel (TR) packaging, suitable for automated assembly processes. The original MMBZ5249B packaging specification is not provided; however, all substitutes maintain SOT-23-3 package compatibility.

Q: What compliance certifications apply to these substitute parts?

A: MMBZ5249BLT1G, SZMMBZ5249BLT1G, CMPZ5249B TR PBFREE, and MMBZ5249B_R1_00001 are all RoHS3 compliant. SZMMBZ5249BLT1G includes AEC-Q101 automotive qualification. All parts are REACH unaffected and classified as EAR99 for export control purposes.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message