FMMT455TC Equivalent & Substitute Parts

Part Overview

The FMMT455TC is a Surface Mount NPN Bipolar Junction Transistor manufactured by Diodes Incorporated, rated for 140V collector-emitter breakdown voltage and 1A maximum collector current. This device is classified as Obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. The FMMT455TC operates across a temperature range of -55°C to 150°C and is housed in a SOT-23-3 package, making it suitable for compact surface mount applications requiring moderate power dissipation (500 mW maximum).

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector Current (Max)	1	A
Collector-Emitter Breakdown Voltage (Max)	140	V
Power Dissipation (Max)	500	mW
Transition Frequency	100	MHz
DC Current Gain (hFE Min)	100	@ 150mA, 10V
Operating Temperature Range	-55 to 150	°C
Package Type	SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the FMMT455TC is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN configuration required
Package Type: SOT-23-3 (TO-236-3, SC-59) surface mount package
Collector-Emitter Breakdown Voltage: Minimum 140V
Maximum Collector Current: Minimum 1A
Operating Temperature Range: Minimum -55°C to 150°C coverage
Mounting Type: Surface Mount

Parametric Equivalence Classification:

The FMMT455TA from Diodes Incorporated is a parametric equivalent with identical electrical specifications and is classified as Active product status, making it the direct replacement for the obsolete FMMT455TC.

Substitute parts are grouped into two categories based on electrical performance trade-offs:

Category A - High Current Capability (≥600 mA): Parts meeting or exceeding the 1A collector current specification or providing equivalent performance within reduced current ratings include MMBT5550LT1G, MMBT5550LT3G, MMBT5551-TP, MMBT5551LT1G, and MMBT5551LT3G. These devices maintain the 140V-160V breakdown voltage range and SOT-23-3 packaging.

Category B - Reduced Voltage or Current Rating: Parts with reduced electrical specifications (BSR19A,215 at 300mA, MMBT2484LT1G and MMBT2484LT3G at 100mA, MMBT6429LT1G at 200mA) are suitable only for applications where the reduced ratings do not exceed circuit requirements.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) [A]	Vce(br) (Max) [V]	Power (Max) [mW]	fT [MHz]	Temp Range [°C]	Package
FMMT455TC	Diodes Incorporated	Obsolete	1.0	140	500	100	-55 to 150	SOT-23-3
FMMT455TA	Diodes Incorporated	Active	1.0	140	500	100	-55 to 150	SOT-23-3
BSR19A,215	Nexperia USA Inc.	Active	0.3	160	250	300	-55 to 150	SOT-23-3
MMBT2484LT1G	onsemi	Active	0.1	60	225	—	-55 to 150	SOT-23-3
MMBT2484LT3G	onsemi	Active	0.1	60	225	—	-55 to 150	SOT-23-3
MMBT5550LT1G	onsemi	Active	0.6	140	225	—	-55 to 150	SOT-23-3
MMBT5550LT3G	onsemi	Active	0.6	140	225	—	-55 to 150	SOT-23-3
MMBT5551-TP	Micro Commercial Co	Active	0.6	160	300	100	-55 to 150	SOT-23-3
MMBT5551LT1G	onsemi	Active	0.6	160	225	—	-55 to 150	SOT-23-3
MMBT5551LT3G	onsemi	Active	0.6	160	225	—	-55 to 150	SOT-23-3
MMBT6429LT1G	onsemi	Active	0.2	45	225	700	-55 to 150	SOT-23-3

Engineering Selection Recommendations

Primary Recommendation:

FMMT455TA (Diodes Incorporated) is the direct parametric equivalent for FMMT455TC replacement. This part maintains identical electrical specifications (1A collector current, 140V breakdown voltage, 500mW power dissipation, 100MHz transition frequency) and identical SOT-23-3 packaging. FMMT455TA carries Active product status and is ROHS3 compliant with unlimited moisture sensitivity level (MSL 1), ensuring long-term availability and compliance with current manufacturing standards.

Secondary Recommendations for Reduced Current Applications:

For applications where collector current requirements do not exceed 600mA, the MMBT5551LT1G or MMBT5551LT3G (onsemi) provide equivalent 160V breakdown voltage rating with SOT-23-3 packaging and Active product status. These parts are suitable for circuits operating below 600mA maximum collector current.

For applications where collector current requirements do not exceed 300mA, the BSR19A,215 (Nexperia USA Inc.) offers 160V breakdown voltage with Active product status and AEC-Q101 automotive qualification.

Not Recommended for Direct Substitution:

MMBT2484LT1G and MMBT2484LT3G are not suitable for applications requiring the full 1A collector current specification, as these parts are rated for maximum 100mA collector current and 60V breakdown voltage.

MMBT6429LT1G is not suitable for applications requiring 140V breakdown voltage, as this part is rated for maximum 45V collector-emitter breakdown voltage.

All substitute parts maintain the required SOT-23-3 surface mount package, -55°C to 150°C operating temperature range, ROHS3 compliance, and MSL 1 moisture sensitivity level.

Frequently Asked Questions (FAQ)

Q: Can FMMT455TA directly replace FMMT455TC in existing designs?

A: Yes. FMMT455TA is a parametric equivalent with identical electrical specifications and packaging. The only difference is product status (Active versus Obsolete). No circuit modifications are required.

Q: What is the primary difference between FMMT455TC and FMMT455TA?

A: Both parts are electrically identical. FMMT455TA is the active production version of the same device. FMMT455TC is classified as Obsolete and is no longer in active production.

Q: Can MMBT5551LT1G replace FMMT455TC in all applications?

A: MMBT5551LT1G can replace FMMT455TC only in applications where the maximum collector current does not exceed 600mA. The FMMT455TC is rated for 1A maximum collector current, while MMBT5551LT1G is rated for 600mA. If your circuit requires the full 1A capability, MMBT5551LT1G is not suitable. Both parts share the same 160V breakdown voltage rating and SOT-23-3 package.

Q: Are all substitute parts available in the same SOT-23-3 package?

A: Yes. All substitute parts listed are available in SOT-23-3 (TO-236-3, SC-59) surface mount package, ensuring mechanical and thermal compatibility with existing PCB layouts.

Q: What is the difference between MMBT5551LT1G and MMBT5551LT3G?

A: Both parts are electrically identical with 600mA collector current rating and 160V breakdown voltage. The difference is in packaging format: LT1G is supplied in Cut Tape (CT) & Digi-Reel format, while LT3G is supplied in Tape & Reel (TR) format. Selection depends on procurement and assembly requirements.

Q: Do all substitute parts meet the same temperature operating range as FMMT455TC?

A: Yes. All listed substitute parts operate across the -55°C to 150°C temperature range, matching the FMMT455TC specification.

Q: Is ROHS3 compliance maintained across all substitute parts?

A: Yes. All substitute parts listed are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity level, matching the compliance profile of FMMT455TC.

Q: Why is MMBT2484LT1G listed as a substitute if it has lower current rating?

A: MMBT2484LT1G is listed for applications where circuit requirements do not exceed 100mA collector current. It is not suitable for applications requiring the full 1A capability of FMMT455TC. Selection must be based on actual circuit current requirements.

Q: Can I use BSR19A,215 in high-current applications?

A: No. BSR19A,215 is rated for maximum 300mA collector current. It is suitable only for applications where collector current does not exceed 300mA. For applications requiring 1A capability, use FMMT455TA or equivalent 1A-rated devices.

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