MMBT123S-7-F Equivalent & Substitute Parts

Part Overview

The MMBT123S-7-F is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for general-purpose switching and amplification applications. This device features an 18 V collector-emitter breakdown voltage, 1 A maximum collector current, and 300 mW power dissipation in a surface-mount SOT-23-3 package. The part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain functional compatibility within specified electrical and mechanical parameters.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	18	V
Current - Collector (Ic) (Max)	1	A
Power - Max	300	mW
Frequency - Transition	100	MHz
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the MMBT123S-7-F is determined by electrical parameter compatibility within the following criteria:

Primary Substitution Parameters:

Transistor Type: NPN (required match)
Package / Case: SOT-23-3 or equivalent surface-mount form factor (required match)
Voltage - Collector Emitter Breakdown (Max): Must equal or exceed 18 V
Current - Collector (Ic) (Max): Must equal or exceed 1 A
Power - Max: Must equal or exceed 300 mW
Operating Temperature Range: Must encompass -55°C to 150°C
Mounting Type: Surface Mount (required match)

Secondary Compatibility Factors:

Frequency - Transition: 100 MHz or higher preferred for equivalent performance
RoHS Compliance: ROHS3 Compliant (environmental standard alignment)
Product Status: Active status preferred for long-term availability

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

Category A - Direct Electrical Equivalents: Parts meeting or exceeding all primary electrical parameters while maintaining identical or superior performance characteristics.

Category B - Functional Alternatives: Parts with modified electrical specifications that serve specific application requirements while maintaining NPN type, SOT-23-3 packaging, and surface-mount configuration.

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Vce Breakdown (Max) [V]	Ic (Max) [A]	Power (Max) [mW]	Frequency [MHz]	Operating Temp [°C]	Package	Product Status
MMBT123S-7-F	Diodes Incorporated	NPN	18	1	300	100	-55 to 150	SOT-23-3	Obsolete
FMMTL618TA	Diodes Incorporated	NPN	20	1.25	500	195	-55 to 150	SOT-23-3	Active
MMBT489LT1G	onsemi	NPN	30	1	710	100	-55 to 150	SOT-23-3	Active
NSS20201LT1G	onsemi	NPN	20	2	460	150	-55 to 150	SOT-23-3	Active
MMBT6429LT1G	onsemi	NPN	45	0.2	225	700	-55 to 150	SOT-23-3	Active
PBSS4120T,215	Nexperia USA Inc.	NPN	20	1	480	100	-55 to 150	SOT-23-3	Active
BFS19,215	Nexperia USA Inc.	NPN	20	0.03	250	260	-55 to 150	SOT-23-3	Active
BFS19,235	NXP USA Inc.	NPN	20	0.03	250	260	-55 to 150	SOT-23-3	Active
MMBT2484LT1G	onsemi	NPN	60	0.1	225	—	-55 to 150	SOT-23-3	Active
MMBT2484LT3G	onsemi	NPN	60	0.1	225	—	-55 to 150	SOT-23-3	Active

Engineering Selection Recommendations

Category A - Direct Electrical Equivalents (Recommended for Drop-In Replacement):

FMMTL618TA (Diodes Incorporated) provides the closest electrical performance match. This part exceeds the MMBT123S-7-F in collector current (1.25 A vs. 1 A), power dissipation (500 mW vs. 300 mW), and transition frequency (195 MHz vs. 100 MHz), while maintaining the 18 V minimum breakdown voltage requirement through its 20 V specification. Active product status ensures long-term availability. ROHS3 compliance and identical operating temperature range (-55°C to 150°C) confirm environmental and thermal compatibility.

MMBT489LT1G (onsemi) offers superior electrical performance with 30 V breakdown voltage, 1 A collector current matching, and significantly higher power dissipation (710 mW). Transition frequency remains at 100 MHz. Active status and ROHS3 compliance support production continuity. This part is suitable for applications requiring enhanced voltage margin.

NSS20201LT1G (onsemi) provides 2 A collector current capability with 20 V breakdown voltage, exceeding the original 1 A specification. Power dissipation of 460 mW and 150 MHz transition frequency support higher-performance applications. Active status and full temperature range compatibility confirm substitution viability.

PBSS4120T,215 (Nexperia USA Inc.) matches the original 1 A collector current and 100 MHz transition frequency with 20 V breakdown voltage. Power dissipation of 480 mW exceeds the 300 mW requirement. AEC-Q100 automotive qualification and active product status provide additional reliability assurance for automotive-grade applications.

Category B - Functional Alternatives (Application-Specific Selection):

MMBT6429LT1G (onsemi) is suitable for high-frequency applications requiring 700 MHz transition frequency, though collector current is limited to 200 mA. The 45 V breakdown voltage provides enhanced voltage margin. Selection is appropriate only when frequency performance is prioritized over current capacity.

BFS19,215 and BFS19,235 (Nexperia/NXP) are small-signal transistors with 30 mA maximum collector current, suitable only for low-current signal applications. These parts are not recommended for applications requiring the original 1 A current capability.

MMBT2484LT1G and MMBT2484LT3G (onsemi) are limited to 100 mA collector current and are suitable only for reduced-current applications. Selection is appropriate when current requirements do not exceed 100 mA.

Frequently Asked Questions (FAQ)

Q: Can FMMTL618TA directly replace MMBT123S-7-F in all applications?

A: FMMTL618TA is electrically compatible for direct replacement in applications operating at or below the original 18 V specification. The higher breakdown voltage (20 V), increased current capacity (1.25 A), and enhanced power dissipation (500 mW) provide performance margin. Verify circuit design does not depend on specific saturation voltage or gain characteristics before substitution.

Q: What is the primary difference between MMBT489LT1G and FMMTL618TA?

A: MMBT489LT1G provides higher voltage margin (30 V vs. 20 V breakdown) and significantly greater power dissipation capability (710 mW vs. 500 mW). Both maintain 1 A collector current and 100 MHz transition frequency. Selection depends on circuit voltage stress requirements and thermal design constraints.

Q: Why are BFS19,215 and BFS19,235 listed as substitutes if they have only 30 mA current capacity?

A: These parts are listed as manufacturer-identified substitutes for specific low-signal applications where collector current does not exceed 30 mA. They are not suitable for applications requiring the original 1 A capability. Verify application current requirements before selection.

Q: Are MMBT2484LT1G and MMBT2484LT3G interchangeable?

A: Both parts are electrically identical with 100 mA collector current, 60 V breakdown voltage, and 225 mW power dissipation. The difference is packaging: MMBT2484LT1G is supplied in Cut Tape & Digi-Reel format, while MMBT2484LT3G is supplied in Tape & Reel format. Selection depends on procurement and assembly requirements.

Q: Does NSS20201LT1G provide backward compatibility with MMBT123S-7-F?

A: NSS20201LT1G is electrically compatible with enhanced current capacity (2 A vs. 1 A) and improved saturation voltage characteristics (100 mV @ 200 mA, 2 A). The 20 V breakdown voltage meets the 18 V minimum requirement. Verify circuit design does not depend on specific gain or frequency characteristics at the original operating point.

Q: What is the significance of AEC-Q101 and AEC-Q100 qualifications?

A: AEC-Q101 qualification (MMBT123S-7-F) and AEC-Q100 qualification (PBSS4120T,215) indicate automotive-grade reliability testing. PBSS4120T,215 meets AEC-Q100 standard, suitable for automotive applications. Verify qualification requirements for your specific application before substitution.

Q: Can MMBT6429LT1G replace MMBT123S-7-F in high-frequency circuits?

A: MMBT6429LT1G is suitable only for applications where collector current does not exceed 200 mA and high transition frequency (700 MHz) is required. The 45 V breakdown voltage provides voltage margin. This part is not recommended for applications requiring the original 1 A current capability.

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts are ROHS3 compliant, matching the environmental compliance status of the original MMBT123S-7-F. Verify compliance documentation for specific procurement batches if required by your quality system.

Q: What packaging formats are available for substitute parts?

A: Substitute parts are available in multiple packaging formats: Tape & Reel (TR), Cut Tape (CT) & Digi-Reel, and Bulk. All maintain SOT-23-3 or equivalent surface-mount form factor. Verify packaging format compatibility with your assembly equipment and procurement requirements.

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