FMMT620TC Equivalent & Substitute Parts

Part Overview

The FMMT620TC is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for general-purpose switching and amplification applications. This device features an 80 V collector-emitter breakdown voltage, 1.5 A maximum collector current, and 625 mW power dissipation in a surface mount SOT-23-3 package. The FMMT620TC is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production support.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	80	V
Current - Collector (Ic) (Max)	1.5	A
Power - Max	625	mW
Frequency - Transition	160	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	300 @ 200mA, 2V	—
Vce Saturation (Max) @ Ib, Ic	200mV @ 50mA, 1.5A	—
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the FMMT620TC is determined by alignment of critical electrical parameters: collector-emitter breakdown voltage, maximum collector current, power dissipation capability, and transition frequency. The primary substitution criterion requires that the replacement part maintain or exceed the voltage and current ratings of the original device while operating within the same thermal and frequency envelope.

Substitute parts are grouped into two categories:

Parametric Equivalents (Direct Replacements): Parts that match all critical electrical specifications and package form factor. These include FMMT620QTA and FMMT620TA, both manufactured by Diodes Incorporated with identical voltage (80 V), current (1.5 A), power (625 mW), and frequency (160 MHz) ratings. These parts differ only in packaging format (Tape & Reel versus Cut Tape) and product status (Active versus Obsolete).

Manufacturer Recommended Alternatives: Parts that satisfy the core voltage and current requirements but may differ in secondary parameters such as transition frequency, power dissipation, saturation voltage, or package form. These include devices from Rohm Semiconductor (2SCR544RTL, 2SCR554RTL), Nexperia USA Inc. (BSS64,215, BSS64LT1G), and onsemi (MMBT2484LT1G, MMBT2484LT3G, MMBT6429LT1G, MMBT8099LT1G).

Key Parameters for Substitution Assessment:

Voltage - Collector Emitter Breakdown (Max): 80 V minimum
Current - Collector (Ic) (Max): 1.5 A minimum
Package / Case: SOT-23-3 or equivalent surface mount form factor
Mounting Type: Surface Mount
Operating Temperature Range: -55°C to 150°C minimum

Parameter Comparison

Part Number	Manufacturer	Product Status	Vce(BR) Max (V)	Ic Max (A)	Power Max (mW)	fT (MHz)	Package	Vce Sat @ Ib, Ic
FMMT620TC	Diodes Incorporated	Obsolete	80	1.5	625	160	SOT-23-3	200mV @ 50mA, 1.5A
FMMT620QTA	Diodes Incorporated	Active	80	1.5	625	160	SOT-23-3	200mV @ 20mA, 1.5A
FMMT620TA	Diodes Incorporated	Active	80	1.5	625	160	SOT-23-3	200mV @ 50mA, 1.5A
2SCR544RTL	Rohm Semiconductor	Active	80	2.5	1000	280	TSMT3	300mV @ 50mA, 1A
2SCR554RTL	Rohm Semiconductor	Active	80	1.5	1000	300	TSMT3	300mV @ 25mA, 500mA
BSS64,215	Nexperia USA Inc.	Not For New Designs	80	0.1	250	100	TO-236AB	200mV @ 15mA, 50mA
BSS64LT1G	onsemi	Active	80	0.1	225	60	SOT-23-3	200mV @ 15mA, 50mA
MMBT2484LT1G	onsemi	Active	60	0.1	225	—	SOT-23-3	350mV @ 100µA, 1mA
MMBT2484LT3G	onsemi	Active	60	0.1	225	—	SOT-23-3	350mV @ 100µA, 1mA
MMBT6429LT1G	onsemi	Active	45	0.2	225	700	SOT-23-3	600mV @ 5mA, 100mA
MMBT8099LT1G	onsemi	Active	80	0.5	225	150	SOT-23-3	400mV @ 5mA, 100mA

Engineering Selection Recommendations

Direct Replacement (Preferred): FMMT620TA and FMMT620QTA are the primary substitutes for the obsolete FMMT620TC. Both parts are manufactured by Diodes Incorporated and maintain identical electrical specifications (80 V, 1.5 A, 625 mW, 160 MHz). FMMT620TA is available in Cut Tape & Digi-Reel packaging with Active product status. FMMT620QTA is available in Tape & Reel packaging with Active product status and carries AEC-Q101 automotive qualification. Both parts are ROHS3 compliant and REACH unaffected.

Alternative Substitutes for Reduced Current Applications: When collector current requirements are below 1.5 A, BSS64LT1G (onsemi) provides an 80 V, 100 mA rated device in SOT-23-3 packaging with Active product status. This part is suitable for low-current switching applications and maintains the same package footprint as the original device.

Alternative Substitutes for Enhanced Performance: 2SCR554RTL (Rohm Semiconductor) matches the 80 V, 1.5 A ratings with enhanced power dissipation (1 W) and transition frequency (300 MHz). This part is packaged in TSMT3 (SC-96) form factor and is Active. 2SCR544RTL provides 80 V, 2.5 A capability with 1 W power dissipation and 280 MHz transition frequency, also in TSMT3 packaging.

Not Recommended for New Designs: BSS64,215 (Nexperia USA Inc.) carries a "Not For New Designs" status and is therefore unsuitable for new product development. MMBT2484LT1G and MMBT2484LT3G feature reduced voltage ratings (60 V) and are not suitable as direct replacements for 80 V applications.

Frequently Asked Questions (FAQ)

Q: Can FMMT620QTA be used as a direct replacement for FMMT620TC?

A: Yes. FMMT620QTA is a parametric equivalent with identical voltage (80 V), current (1.5 A), power (625 mW), and frequency (160 MHz) specifications. The primary difference is packaging format (Tape & Reel) and product status (Active). FMMT620QTA includes AEC-Q101 automotive qualification.

Q: What is the difference between FMMT620TA and FMMT620QTA?

A: Both parts are parametric equivalents with identical electrical ratings. FMMT620TA is supplied in Cut Tape & Digi-Reel packaging, while FMMT620QTA is supplied in Tape & Reel packaging. FMMT620QTA carries AEC-Q101 automotive qualification. Selection depends on packaging and supply chain requirements.

Q: Can MMBT8099LT1G replace FMMT620TC?

A: MMBT8099LT1G is not a direct replacement. While it maintains the 80 V voltage rating and SOT-23-3 package, the maximum collector current is 500 mA, which is below the 1.5 A requirement of the original device. MMBT8099LT1G is suitable only for applications requiring less than 500 mA collector current.

Q: Why are 2SCR554RTL and 2SCR544RTL listed as alternatives if they use different packages?

A: These Rohm Semiconductor devices are listed as manufacturer-recommended alternatives because they satisfy the core voltage (80 V) and current (1.5 A minimum) requirements. However, they use TSMT3 (SC-96) packaging instead of SOT-23-3. PCB layout modifications are required for package substitution. These parts offer enhanced power dissipation and transition frequency.

Q: Can MMBT2484LT1G or MMBT2484LT3G be used in place of FMMT620TC?

A: No. Both MMBT2484 variants feature a reduced voltage rating of 60 V, which is below the 80 V requirement of the original device. These parts are not suitable for applications requiring 80 V collector-emitter breakdown voltage.

Q: What does "Not For New Designs" mean for BSS64,215?

A: "Not For New Designs" indicates that the manufacturer (Nexperia USA Inc.) has discontinued active support for this part and recommends against its use in new product development. While BSS64,215 may be available in inventory, it should not be selected for new designs. BSS64LT1G (onsemi) is the recommended active alternative.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed in this reference are RoHS3 compliant and REACH unaffected, matching the compliance status of the original FMMT620TC.

Q: What is the significance of the TSMT3 package used by Rohm Semiconductor alternatives?

A: TSMT3 (SC-96) is a surface mount package with different footprint and pin configuration compared to SOT-23-3. While electrically compatible, TSMT3 devices require PCB redesign and cannot be used as direct drop-in replacements without layout modifications.

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