FSB619 Equivalent & Substitute Parts

Part Overview

The FSB619 is an NPN bipolar junction transistor manufactured by onsemi, rated for 50V collector-emitter breakdown voltage and 2A maximum collector current in a surface mount SOT-23-3 package. This device is classified as obsolete product status. Due to its obsolete classification, equivalent and substitute parts from active manufacturers are necessary for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility within the specified parameter ranges while accommodating modern supply chain availability.

Key Parameters

Parameter	FSB619 Specification
Transistor Type	NPN
Voltage - Collector Emitter Breakdown (Max)	50 V
Current - Collector (Ic) (Max)	2 A
Power - Max	500 mW
Frequency - Transition	100 MHz
Vce Saturation (Max) @ Ib, Ic	320 mV @ 50 mA, 2 A
DC Current Gain (hFE) (Min) @ Ic, Vce	200 @ 1 A, 2 V
Operating Temperature Range	-55°C 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

Substitution of the FSB619 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor type must be NPN
Collector-emitter breakdown voltage must be ≥50V
Maximum collector current must be ≥2A
Package must be SOT-23-3 (TO-236-3 or SC-59 equivalent)
Surface mount mounting type
Operating temperature range must encompass -55°C to 150°C

Direct Equivalent Classification: Parts meeting all primary criteria with identical or superior electrical ratings qualify as direct equivalents. The FMMT619TA from Diodes Incorporated satisfies all parameters with matching 50V/2A ratings and active product status.

Functional Substitute Classification: Parts with reduced current ratings (below 2A) or reduced power dissipation (below 500mW) are classified as functional substitutes suitable only for applications where the FSB619 operates below its maximum rated current. These include the MMBT6428LT1G (200mA), MMBT6429LT1G (200mA), 2PD601 series (100-200mA), and MSD601-RT1G (100mA).

Limited Substitute Classification: The BC817-40LT1G presents reduced voltage rating (45V vs. 50V) and reduced current rating (500mA vs. 2A), limiting its application scope.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max)	Vce(BR)max	Power (Max)	Vce Sat @ Ib, Ic	hFE (Min)	Frequency	Package
FSB619	onsemi	Obsolete	2 A	50 V	500 mW	320 mV @ 50 mA, 2 A	200 @ 1 A, 2 V	100 MHz	SOT-23-3
FMMT619TA	Diodes Incorporated	Active	2 A	50 V	625 mW	220 mV @ 50 mA, 2 A	200 @ 1 A, 2 V	165 MHz	SOT-23-3
MMBT6428LT1G	onsemi	Active	200 mA	50 V	225 mW	600 mV @ 5 mA, 100 mA	250 @ 100 µA, 5 V	700 MHz	SOT-23-3
MMBT6429LT1G	onsemi	Active	200 mA	45 V	225 mW	600 mV @ 5 mA, 100 mA	500 @ 100 µA, 5 V	700 MHz	SOT-23-3
BC817-40LT1G	onsemi	Active	500 mA	45 V	300 mW	700 mV @ 50 mA, 500 mA	250 @ 100 mA, 1 V	100 MHz	SOT-23-3
2PD601ARL,215	Nexperia USA Inc.	Active	100 mA	50 V	250 mW	250 mV @ 10 mA, 100 mA	210 @ 2 mA, 10 V	100 MHz	TO-236AB
2PD601ASL,215	Nexperia USA Inc.	Active	100 mA	50 V	250 mW	250 mV @ 10 mA, 100 mA	290 @ 2 mA, 10 V	100 MHz	TO-236AB
2PD601BRL,215	Nexperia USA Inc.	Active	200 mA	50 V	250 mW	250 mV @ 10 mA, 100 mA	210 @ 2 mA, 10 V	250 MHz	TO-236AB
2PD601BSL,215	NXP Semiconductors	Active	200 mA	50 V	250 mW	250 mV @ 10 mA, 100 mA	290 @ 2 mA, 10 V	250 MHz	TO-236AB
MSD601-RT1G	onsemi	Active	100 mA	50 V	200 mW	500 mV @ 10 mA, 100 mA	210 @ 2 mA, 10 V	Not specified	SC-59

Engineering Selection Recommendations

Direct Equivalent Selection:

The FMMT619TA from Diodes Incorporated is the primary direct equivalent for the FSB619. This part maintains identical electrical specifications (50V/2A rating) with active product status and ROHS3 compliance. The FMMT619TA demonstrates superior performance characteristics including higher power dissipation capability (625mW vs. 500mW) and increased transition frequency (165MHz vs. 100MHz). Pin-for-pin compatibility in SOT-23-3 packaging enables direct substitution without circuit modification.

Functional Substitute Selection for Current-Limited Applications:

For applications operating at collector currents below 200mA, the MMBT6428LT1G and 2PD601 series (both A and B variants) provide active alternatives with 50V voltage rating. The 2PD601 series offers automotive-grade qualification (AEC-Q101) suitable for automotive applications. The MMBT6428LT1G provides superior transition frequency (700MHz) for high-speed switching applications.

Voltage-Constrained Applications:

The MMBT6429LT1G and BC817-40LT1G are suitable only for applications with maximum operating voltage of 45V or lower. These parts are not recommended for circuits requiring the full 50V rating of the FSB619.

Compliance and Availability:

All substitute parts listed maintain ROHS3 compliance and unlimited moisture sensitivity level (MSL-1). The 2PD601 series variants include automotive-grade qualification where specified. Current inventory availability favors the FMMT619TA (155,100 pcs), MMBT6429LT1G (155,200 pcs), and 2PD601BSL,215 (15,300 pcs).

Frequently Asked Questions (FAQ)

Q: Can the FMMT619TA directly replace the FSB619 in all applications?

A: Yes. The FMMT619TA maintains identical collector current (2A) and collector-emitter breakdown voltage (50V) ratings with superior power dissipation capability. Pin configuration and SOT-23-3 packaging are identical, enabling direct substitution without circuit modification.

Q: What is the primary limitation of the MMBT6428LT1G as a substitute?

A: The MMBT6428LT1G is rated for maximum collector current of 200mA, compared to the FSB619's 2A rating. This part is suitable only for applications where the transistor operates at or below 200mA collector current. Applications requiring the full 2A capability must use the FMMT619TA.

Q: Are the 2PD601 series parts suitable for automotive applications?

A: The 2PD601ARL,215, 2PD601ASL,215, 2PD601BRL,215, and 2PD601BSL,215 variants carry automotive-grade qualification (AEC-Q101). These parts are suitable for automotive applications within their specified current ratings (100-200mA).

Q: Why is the BC817-40LT1G not recommended as a primary substitute?

A: The BC817-40LT1G has reduced voltage rating (45V vs. 50V) and reduced current rating (500mA vs. 2A). This part is suitable only for applications operating below 45V and 500mA, making it unsuitable for circuits designed to the full FSB619 specifications.

Q: What is the difference between the 2PD601A and 2PD601B variants?

A: The 2PD601A series is rated for maximum collector current of 100mA, while the 2PD601B series is rated for 200mA. Both maintain 50V voltage rating and 250mW power dissipation. The 2PD601B series provides higher transition frequency (250MHz vs. 100MHz).

Q: Can I use the MSD601-RT1G as a substitute?

A: The MSD601-RT1G is limited to 100mA collector current and 200mW power dissipation. It is suitable only for low-current applications. Additionally, this part uses SC-59 packaging rather than SOT-23-3, requiring PCB layout modification.

Q: What packaging differences exist among the substitute parts?

A: Most substitute parts use SOT-23-3 (TO-236-3) packaging identical to the FSB619. The 2PD601 series uses TO-236AB packaging, which is mechanically compatible with SOT-23-3. The MSD601-RT1G uses SC-59 packaging, which differs from SOT-23-3 and requires layout verification.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance status, consistent with the FSB619 specification.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message