FMMTL618TC Equivalent & Substitute Parts

Part Overview

The FMMTL618TC is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for surface mount applications in the SOT-23-3 package. This device operates at a maximum collector current of 1.25 A with a 20 V collector-emitter breakdown voltage and 500 mW power dissipation capability. The FMMTL618TC is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design support and production requirements. Substitute parts are selected based on matching or exceeding electrical performance parameters while maintaining compatible packaging and thermal characteristics.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) Max	1.25	A
Voltage - Collector Emitter Breakdown (Max)	20	V
Power - Max	500	mW
Frequency - Transition	195	MHz
Operating Temperature Range	-55 to 150	°C (TJ)
Package / Case	SOT-23-3 (TO-236-3, SC-59)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the FMMTL618TC are categorized based on electrical parameter compatibility and product status. The primary substitution criterion is the ability to handle the specified collector current (1.25 A maximum), collector-emitter breakdown voltage (20 V), and power dissipation (500 mW) within the same SOT-23-3 surface mount package.

Parametric Equivalent Category: Parts that match all critical electrical specifications and package requirements.

Manufacturer Recommended Category: Parts that provide equivalent or enhanced electrical performance with active product status and full compliance certifications.

The following key parameters determine substitution validity:

Transistor Type: NPN
Collector Current Rating: ≥ 1.25 A
Collector-Emitter Breakdown Voltage: ≥ 20 V
Power Dissipation: ≥ 500 mW
Package: SOT-23-3 surface mount
Operating Temperature Range: -55°C to 150°C (TJ)
RoHS3 Compliance

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce Breakdown (Max) [V]	Power (Max) [mW]	Frequency [MHz]	Product Status	Package
FMMTL618TC	Diodes Incorporated	1.25	20	500	195	Obsolete	SOT-23-3
FMMTL618TA	Diodes Incorporated	1.25	20	500	195	Active	SOT-23-3
MMBT3904LT1G	onsemi	0.2	40	300	300	Active	SOT-23-3
MMBT3904LT3G	onsemi	0.2	40	300	300	Active	SOT-23-3
MMBT2484LT1G	onsemi	0.1	60	225	—	Active	SOT-23-3
MMBT2484LT3G	onsemi	0.1	60	225	—	Active	SOT-23-3
MMBT6429LT1G	onsemi	0.2	45	225	700	Active	SOT-23-3
PBSS4320T,215	Nexperia USA Inc.	2	20	540	100	Active	SOT-23-3
PBSS4021NT,215	Nexperia USA Inc.	4.3	20	1100	165	Active	SOT-23-3
SMMBT3904LT1G	onsemi	0.2	40	300	300	Active	SOT-23-3

Engineering Selection Recommendations

Direct Parametric Equivalent:

FMMTL618TA is the primary substitute for FMMTL618TC. Both parts are manufactured by Diodes Incorporated and share identical electrical specifications: 1.25 A collector current, 20 V breakdown voltage, 500 mW power dissipation, and 195 MHz transition frequency. FMMTL618TA maintains active product status and ROHS3 compliance. The only difference is packaging format (Tape & Reel versus individual packaging), which does not affect electrical performance or functional compatibility.

Higher Current Capacity Alternatives:

PBSS4320T,215 (Nexperia USA Inc.) and PBSS4021NT,215 (Nexperia USA Inc.) provide enhanced current handling at the same 20 V breakdown voltage. PBSS4320T,215 supports 2 A collector current with 540 mW power dissipation and carries AEC-Q100 automotive qualification. PBSS4021NT,215 supports 4.3 A collector current with 1.1 W power dissipation and also carries AEC-Q100 qualification. Both maintain SOT-23-3 packaging and -55°C to 150°C operating temperature range. These parts are suitable for applications requiring higher current capacity within the same voltage class.

Lower Current Alternatives:

MMBT3904LT1G, MMBT3904LT3G, and SMMBT3904LT1G (onsemi) provide 200 mA collector current with 40 V breakdown voltage and 300 mW power dissipation. SMMBT3904LT1G carries AEC-Q101 automotive qualification. These parts are suitable only for applications where collector current requirements do not exceed 200 mA.

MMBT2484LT1G and MMBT2484LT3G (onsemi) provide 100 mA collector current with 60 V breakdown voltage and 225 mW power dissipation. These parts are suitable only for applications where collector current requirements do not exceed 100 mA.

MMBT6429LT1G (onsemi) provides 200 mA collector current with 45 V breakdown voltage, 225 mW power dissipation, and 700 MHz transition frequency. This part is suitable for high-frequency applications with collector current requirements not exceeding 200 mA.

All substitute parts maintain ROHS3 compliance, MSL Level 1 moisture sensitivity, and SOT-23-3 surface mount packaging.

Frequently Asked Questions (FAQ)

Q: Can FMMTL618TA directly replace FMMTL618TC in production?

A: Yes. FMMTL618TA is a parametric equivalent with identical electrical specifications and active product status. The parts are functionally interchangeable. The primary difference is packaging format (Tape & Reel), which does not affect circuit performance.

Q: What is the minimum collector current rating required for a direct substitute?

A: A direct substitute must support a minimum collector current of 1.25 A. Parts with lower current ratings (such as MMBT3904 series at 200 mA or MMBT2484 series at 100 mA) are not direct substitutes and are suitable only for applications with reduced current requirements.

Q: Can I use PBSS4320T,215 or PBSS4021NT,215 as substitutes?

A: Yes, with design verification. Both parts maintain the 20 V breakdown voltage and SOT-23-3 package. PBSS4320T,215 supports 2 A (exceeding the 1.25 A requirement) and PBSS4021NT,215 supports 4.3 A. Both carry AEC-Q100 automotive qualification. These parts are suitable for applications where higher current capacity is beneficial or required. Verify that the lower transition frequency (100 MHz for PBSS4320T,215 and 165 MHz for PBSS4021NT,215) does not conflict with circuit timing requirements.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance and MSL Level 1 moisture sensitivity rating, matching the original FMMTL618TC specifications.

Q: What is the difference between Cut Tape and Tape & Reel packaging?

A: Cut Tape (CT) and Tape & Reel (TR) are packaging and delivery formats that do not affect electrical performance or functional compatibility. Cut Tape is supplied in smaller quantities on individual tape strips, while Tape & Reel is supplied in continuous reel format for automated assembly. Selection depends on production volume and assembly equipment requirements.

Q: Can I use MMBT3904 series parts as substitutes?

A: MMBT3904 series parts (MMBT3904LT1G, MMBT3904LT3G, SMMBT3904LT1G) are not direct substitutes due to reduced collector current rating (200 mA versus 1.25 A). These parts are suitable only for applications where the circuit design can operate with 200 mA or less collector current. Verify circuit requirements before substitution.

Q: What certifications do the Nexperia parts carry?

A: PBSS4320T,215 and PBSS4021NT,215 carry AEC-Q100 automotive qualification, indicating compliance with automotive-grade reliability and performance standards. These parts are suitable for automotive and industrial applications requiring enhanced qualification levels.

Q: Does SMMBT3904LT1G have automotive qualification?

A: Yes. SMMBT3904LT1G carries AEC-Q101 automotive qualification, indicating compliance with automotive-grade reliability standards. This part is suitable for automotive applications requiring qualified components.

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