FMMT5179TC Equivalent & Substitute Parts

Part Overview

The FMMT5179TC is an RF transistor NPN manufactured by Diodes Incorporated, designed for 12V applications with a 2GHz transition frequency and 330mW maximum power dissipation in a surface mount SOT-23-3 package. This device is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement needs.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	12	V
Frequency - Transition	2	GHz
Power - Max	330	mW
Current - Collector (Ic) (Max)	50	mA
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 3mA, 1V	—
Noise Figure (dB Typ @ f)	4.5 @ 200MHz	dB
Gain	15	dB
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOT-23-3	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the FMMT5179TC is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (polarity requirement)
Voltage - Collector Emitter Breakdown (Max): 12V minimum
Frequency - Transition: 2GHz or higher
Power - Max: 330mW or higher
Current - Collector (Ic) (Max): 50mA or higher
Mounting Type: Surface Mount
Package / Case: SOT-23-3 compatible footprint

Substitution Logic: Substitute parts are grouped based on adherence to these electrical and mechanical parameters. Parts meeting all primary criteria are classified as direct substitutes. Parts with enhanced specifications (higher voltage, frequency, or power ratings) are classified as functional equivalents suitable for drop-in replacement. Parts with reduced specifications or different mounting technologies are classified as alternative solutions requiring circuit evaluation.

Parameter Comparison

Parameter	FMMT5179TC	2SC4915-O,LF	2SD2653KT146	BFP720FESDH6327XTSA1	BSV52,215	BSV52LT1G
Manufacturer	Diodes Inc.	Toshiba	Rohm	Infineon	Nexperia	onsemi
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	12V	30V	12V	4.7V	12V	12V
Frequency - Transition	2GHz	550MHz	360MHz	45GHz	500MHz	400MHz
Power - Max	330mW	100mW	200mW	100mW	250mW	225mW
Current - Collector (Ic) (Max)	50mA	20mA	2A	30mA	100mA	100mA
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 3mA, 1V	70 @ 1mA, 6V	270 @ 200mA, 2V	160 @ 15mA, 3V	40 @ 10mA, 1V	40 @ 10mA, 1V
Operating Temperature	-55 to 150°C	125°C (TJ)	150°C (TJ)	150°C (TJ)	150°C (TJ)	-55 to 150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	SOT-23-3	SOT-416	SOT-23-3	4-TSFP	SOT-23-3	SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Substitutes (SOT-23-3 Package, 12V Rating):

The BSV52LT1G and BSV52,215 are active NPN transistors rated for 12V operation in SOT-23-3 packages. Both devices maintain the same voltage rating and package footprint as the FMMT5179TC. The BSV52LT1G offers extended operating temperature range (-55 to 150°C) matching the original part specification. Both are ROHS3 compliant with MSL 1 rating.

Functional Equivalents (Enhanced Specifications):

The 2SD2653KT146 is an active NPN transistor in SOT-23-3 package rated for 12V with 2A maximum collector current and 360MHz transition frequency. This device provides higher current handling capability and maintains package compatibility. ROHS3 compliant with MSL 1 rating.

Alternative Solutions (Different Package or Reduced Specifications):

The 2SC4915-O,LF is an active NPN RF transistor rated for 30V with 550MHz transition frequency in SOT-416 package. This device requires PCB layout modification due to different package footprint but offers enhanced voltage rating and RF performance.

The BFP720FESDH6327XTSA1 is an active NPN RF transistor with 45GHz transition frequency in 4-TSFP package. This device is suitable for ultra-high-frequency applications but operates at reduced voltage (4.7V) and requires different PCB layout.

Compliance Status:

All recommended active substitutes maintain ROHS3 compliance and MSL 1 moisture sensitivity rating. All devices are classified as EAR99 for export control purposes.

Frequently Asked Questions (FAQ)

Q: Can BSV52LT1G directly replace FMMT5179TC in existing PCB layouts?

A: Yes. Both devices are packaged in SOT-23-3 and share identical pin configurations. The BSV52LT1G maintains the same 12V voltage rating and surface mount footprint. No PCB modification is required.

Q: What is the primary difference between BSV52,215 and BSV52LT1G?

A: Both are BSV52 base devices with identical electrical specifications and SOT-23-3 packaging. The primary difference is packaging format: BSV52,215 is supplied in Cut Tape (CT) & Digi-Reel format, while BSV52LT1G is supplied in Tape & Reel (TR) format. The BSV52LT1G specifies extended operating temperature range (-55 to 150°C) versus BSV52,215 at 150°C maximum.

Q: Is 2SD2653KT146 suitable for RF applications requiring 2GHz operation?

A: The 2SD2653KT146 has a transition frequency of 360MHz, which is below the 2GHz requirement of the FMMT5179TC. This device is suitable for general-purpose switching applications at 12V but not for RF applications requiring 2GHz performance.

Q: Why does BFP720FESDH6327XTSA1 have a lower voltage rating than FMMT5179TC?

A: The BFP720FESDH6327XTSA1 is optimized for ultra-high-frequency operation (45GHz) with reduced voltage rating (4.7V). This is a design trade-off in RF transistor architecture. This device is not suitable for 12V applications.

Q: What packaging considerations apply when substituting 2SC4915-O,LF?

A: The 2SC4915-O,LF uses SOT-416 (SSM) package instead of SOT-23-3. PCB layout modification is required, including different pad spacing and trace routing. Verify footprint compatibility with design tools before implementation.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All recommended active substitute parts are ROHS3 compliant with MSL 1 moisture sensitivity rating, matching the compliance profile of the FMMT5179TC.

Q: Can MMBT2484LT1G or MMBT2484LT3G replace FMMT5179TC?

A: No. The MMBT2484 series is rated for 60V operation with unspecified transition frequency. These devices are not suitable for 2GHz RF applications and represent a different device class (general-purpose switching transistor).

Q: What is the significance of the JANTX2N5109 and KSP10BU in the substitute list?

A: These devices are through-hole components (TO-39 and TO-92-3 packages respectively) and are not direct substitutes for the surface mount SOT-23-3 FMMT5179TC. They require different PCB assembly processes and are listed as alternative solutions only for applications where through-hole technology is acceptable.

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