FSB660 Equivalent & Substitute Parts

Part Overview

The FSB660 is a PNP bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 2 A maximum collector current in a surface mount SOT-23-3 package. This device is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and production continuity. The FSB660 operates across a temperature range of -55°C to 150°C and delivers 500 mW maximum power dissipation with a transition frequency of 75 MHz.

Key Parameters

Parameter	FSB660 Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	60	V
Current - Collector (Ic) (Max)	2	A
Vce Saturation (Max)	350 mV @ 200 mA, 2 A	mV
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) (Min)	100 @ 500 mA, 2 V	—
Power - Max	500	mW
Frequency - Transition	75	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOT-23-3	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the FSB660 is determined by strict adherence to the following electrical and mechanical parameters:

Critical Substitution Criteria:

Transistor polarity must remain PNP
Collector-emitter breakdown voltage must equal or exceed 60 V
Maximum collector current must equal or exceed 2 A
Package type must be SOT-23-3 (TO-236-3, SC-59)
Operating temperature range must encompass -55°C to 150°C
Moisture sensitivity level must be 1 (Unlimited)

Secondary Compatibility Parameters:

Vce saturation characteristics
DC current gain (hFE)
Power dissipation capability
Transition frequency
Collector cutoff current

Substitute parts are grouped into two categories based on their electrical performance relative to the FSB660:

Group A - Direct Functional Equivalents: Parts meeting or exceeding all critical substitution criteria with comparable or superior electrical performance.

Group B - Reduced Performance Substitutes: Parts meeting critical substitution criteria but with reduced maximum collector current or power dissipation, suitable only for applications with lower current demands.

Parameter Comparison

Parameter	FSB660	BC856B-7-F	DSS5160T-7	FMMT722TA	MMBT2907A-7-F	PBSS4041PT,215	SMBT2907AE6327HTSA1
Manufacturer	onsemi	Diodes Inc.	Diodes Inc.	Diodes Inc.	Diodes Inc.	Nexperia USA Inc.	Infineon Tech.
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	60 V	65 V	60 V	70 V	60 V	60 V	60 V
Current - Collector (Ic) (Max)	2 A	100 mA	1 A	1.5 A	600 mA	2.7 A	600 mA
Vce Saturation (Max)	350 mV @ 200 mA, 2 A	650 mV @ 5 mA, 100 mA	340 mV @ 100 mA, 1 A	260 mV @ 200 mA, 1.5 A	1.6 V @ 50 mA, 500 mA	360 mV @ 300 mA, 3 A	1.6 V @ 50 mA, 500 mA
Current - Collector Cutoff (Max)	100 nA	15 nA	100 nA	100 nA	10 nA	100 nA	10 nA
DC Current Gain (hFE) (Min)	100 @ 500 mA, 2 V	220 @ 2 mA, 5 V	150 @ 500 mA, 5 V	300 @ 100 mA, 5 V	100 @ 150 mA, 10 V	150 @ 1 A, 2 V	100 @ 150 mA, 10 V
Power - Max	500 mW	300 mW	725 mW	625 mW	300 mW	1.1 W	330 mW
Frequency - Transition	75 MHz	200 MHz	150 MHz	200 MHz	200 MHz	150 MHz	200 MHz
Operating Temperature	-55 to 150 °C	-65 to 150 °C	-55 to 150 °C	-55 to 150 °C	-55 to 150 °C	150 °C	150 °C
Package / Case	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active	Active	Last Time Buy
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

PBSS4041PT,215 (Nexperia USA Inc.)

The PBSS4041PT,215 is the primary substitute for the FSB660. This part exceeds the FSB660 in maximum collector current (2.7 A versus 2 A) and power dissipation (1.1 W versus 500 mW), providing superior performance headroom. The device maintains identical collector-emitter breakdown voltage (60 V) and operates within the required temperature range. The PBSS4041PT,215 carries AEC-Q100 automotive qualification and ROHS3 compliance, with active product status ensuring long-term availability. Vce saturation characteristics (360 mV @ 300 mA, 3 A) are comparable to the FSB660 (350 mV @ 200 mA, 2 A).

DSS5160T-7 (Diodes Incorporated)

The DSS5160T-7 serves as a secondary substitute with reduced maximum collector current (1 A versus 2 A) and lower power dissipation (725 mW versus 500 mW). This part is suitable for applications requiring currents up to 1 A. The device maintains 60 V collector-emitter breakdown voltage and operates across the full temperature range. ROHS3 compliance and active product status support design continuity. Vce saturation (340 mV @ 100 mA, 1 A) is superior to the FSB660 at comparable current levels.

FMMT722TA (Diodes Incorporated)

The FMMT722TA provides an alternative with 1.5 A maximum collector current and 625 mW power dissipation. This part exceeds the FSB660 in collector-emitter breakdown voltage (70 V versus 60 V) and transition frequency (200 MHz versus 75 MHz). The device is suitable for applications with current demands between 1 A and 1.5 A. ROHS3 compliance and active product status are confirmed.

MMBT2907A-7-F (Diodes Incorporated)

The MMBT2907A-7-F is limited to 600 mA maximum collector current and 300 mW power dissipation, making it unsuitable for applications requiring the full 2 A capability of the FSB660. This part is applicable only to low-current designs. The device carries AEC-Q101 automotive qualification and ROHS3 compliance with active product status.

BC856B-7-F (Diodes Incorporated)

The BC856B-7-F is restricted to 100 mA maximum collector current and 300 mW power dissipation. This part is not suitable for applications requiring currents above 100 mA and does not meet the FSB660 substitution criteria for higher-current applications.

SMBT2907AE6327HTSA1 (Infineon Technologies)

The SMBT2907AE6327HTSA1 is limited to 600 mA maximum collector current and 330 mW power dissipation. This part carries Last Time Buy product status, indicating discontinued manufacturing. While ROHS3 compliant, the limited availability and reduced current rating restrict its use to low-current applications only.

Frequently Asked Questions (FAQ)

Q: Can the BC856B-7-F replace the FSB660 in all applications?

A: No. The BC856B-7-F is rated for maximum 100 mA collector current, while the FSB660 is rated for 2 A. The BC856B-7-F is suitable only for applications with collector currents below 100 mA. Applications requiring the full 2 A capability of the FSB660 require the PBSS4041PT,215 or equivalent higher-current devices.

Q: What is the primary reason for substituting the FSB660?

A: The FSB660 is classified as obsolete. Substitution is necessary to ensure design continuity and production support. Active alternatives such as the PBSS4041PT,215, DSS5160T-7, and FMMT722TA provide equivalent or superior electrical performance with confirmed long-term availability.

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 package (also designated TO-236-3 or SC-59), ensuring mechanical and electrical compatibility with existing PCB layouts and sockets.

Q: Which substitute part provides the best performance match to the FSB660?

A: The PBSS4041PT,215 provides the closest performance match, exceeding the FSB660 in maximum collector current (2.7 A versus 2 A) and power dissipation (1.1 W versus 500 mW) while maintaining identical collector-emitter breakdown voltage (60 V). This part is recommended for direct replacement in applications requiring full 2 A capability.

Q: Do all substitute parts meet RoHS compliance requirements?

A: All active substitute parts (PBSS4041PT,215, DSS5160T-7, FMMT722TA, MMBT2907A-7-F, BC856B-7-F) are ROHS3 compliant. The SMBT2907AE6327HTSA1 is also ROHS3 compliant but carries Last Time Buy status.

Q: What is the operating temperature range for substitute parts?

A: Most substitute parts operate across -55°C to 150°C, matching the FSB660. The BC856B-7-F extends the lower temperature limit to -65°C. The PBSS4041PT,215 and SMBT2907AE6327HTSA1 specify 150°C maximum without a lower limit in the provided data.

Q: Can the MMBT2907A-7-F be used in high-current applications?

A: No. The MMBT2907A-7-F is rated for maximum 600 mA collector current, which is insufficient for applications requiring the full 2 A capability of the FSB660. This part is suitable only for low-current designs below 600 mA.

Q: What is the significance of the PBSS4041PT,215 carrying AEC-Q100 qualification?

A: AEC-Q100 qualification indicates that the PBSS4041PT,215 meets automotive-grade reliability and quality standards. This certification supports use in automotive and mission-critical applications where component reliability is essential.

Q: Why is the SMBT2907AE6327HTSA1 marked as Last Time Buy?

A: Last Time Buy status indicates that the manufacturer has discontinued production of this part. While existing inventory may be available, long-term supply cannot be guaranteed. For new designs, active alternatives such as the PBSS4041PT,215 or DSS5160T-7 are recommended.

Q: Are there differences in Vce saturation between the FSB660 and substitute parts?

A: Yes. Vce saturation varies across substitute parts. The FMMT722TA exhibits the lowest saturation voltage (260 mV @ 200 mA, 1.5 A), while the MMBT2907A-7-F and SMBT2907AE6327HTSA1 exhibit higher saturation (1.6 V @ 50 mA, 500 mA). Applications sensitive to saturation voltage must verify compatibility with the selected substitute.

Q: What is the transition frequency significance for substitution?

A: Transition frequency (fT) indicates the maximum frequency at which the transistor maintains useful gain. The FSB660 operates at 75 MHz, while most substitutes operate at 150 MHz or higher. Higher transition frequency provides improved high-frequency performance but does not prevent substitution in lower-frequency applications.

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