MSB709-RT1 Equivalent & Substitute Parts

Part Overview

The MSB709-RT1 is a PNP bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 100 mA maximum collector current in a surface mount SC-59 package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The MSB709-RT1 remains in stock with 16,593 units available, but alternative active components are available to ensure long-term supply chain reliability.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Maximum Collector Current (Ic)	100	mA
Collector-Emitter Breakdown Voltage (Max)	45	V
Maximum Power Dissipation	200	mW
Vce Saturation (Max)	500 mV @ 10 mA, 100 mA	—
DC Current Gain (hFE Min)	210 @ 2 mA, 10 V	—
Maximum Collector Cutoff Current	100	nA
Operating Temperature (Max)	150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—

Substitute Part Grouping Explanation

Substitution of the MSB709-RT1 is determined by strict electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Requirements:

Transistor type must be PNP
Maximum collector current must be ≥ 100 mA
Collector-emitter breakdown voltage must be ≥ 45 V
Maximum power dissipation must be ≥ 200 mW
Operating temperature range must support 150 °C maximum junction temperature
Package / case must be compatible with TO-236-3, SC-59, or SOT-23-3 footprints

Mechanical Compatibility Requirements:

Surface mount mounting type
Pin configuration compatible with SC-59 or SOT-23 packages

Substitute parts are classified into two categories:

Direct Substitutes: Parts meeting or exceeding all electrical parameters with active product status and modern compliance certifications (RoHS3, AEC-Q101 where applicable).

Similar Substitutes: Parts meeting core electrical parameters but with variations in secondary characteristics such as transition frequency, saturation voltage, or current gain specifications. These parts are suitable for applications where the MSB709-RT1 specifications are not exceeded.

Parameter Comparison

Parameter	MSB709-RT1	BC857A-TP	BC857B-TP	2PB709ART,215	2PB709ART,235	BC857BR TR PBFREE	BC857C TR PBFREE
Manufacturer	onsemi	Micro Commercial Co	Micro Commercial Co	NXP USA Inc.	Nexperia USA Inc.	Central Semiconductor Corp	Central Semiconductor Corp
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP	PNP
Ic (Max)	100 mA	100 mA	100 mA	100 mA	100 mA	100 mA	100 mA
Vce Breakdown (Max)	45 V	45 V	45 V	45 V	45 V	45 V	45 V
Power (Max)	200 mW	310 mW	310 mW	250 mW	250 mW	350 mW	350 mW
Vce Saturation (Max)	500 mV @ 10 mA, 100 mA	650 mV @ 5 mA, 100 mA	650 mV @ 5 mA, 100 mA	500 mV @ 10 mA, 100 mA	500 mV @ 10 mA, 100 mA	650 mV @ 5 mA, 100 mA	50 mV @ 5 mA, 100 mA
DC Current Gain (hFE Min)	210 @ 2 mA, 10 V	125 @ 2 mA, 5 V	220 @ 2 mA, 5 V	210 @ 2 mA, 10 V	120 @ 2 mA, 10 V	220 @ 2 mA, 5 V	420 @ 2 mA, 5 V
Icbo (Max)	100 nA	15 nA	15 nA	10 nA	10 nA	15 nA	15 nA
Frequency - Transition	—	200 MHz	200 MHz	70 MHz	70 MHz	100 MHz	100 MHz
Operating Temperature (Max)	150 °C	150 °C	150 °C	150 °C	150 °C	150 °C	150 °C
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Automotive Grade	—	—	—	AEC-Q101	AEC-Q101	—	—

Engineering Selection Recommendations

For Direct Substitution (Preferred):

BC857B-TP and BC857A-TP are the primary direct substitutes for the MSB709-RT1. Both parts are manufactured by Micro Commercial Co, carry active product status, and are RoHS3 compliant. BC857B-TP provides a DC current gain of 220 @ 2 mA, 5 V, matching the original specification more closely than BC857A-TP (125 @ 2 mA, 5 V). Both parts exceed the original 200 mW power rating at 310 mW and provide 200 MHz transition frequency, enabling use in higher-speed applications. These parts are available in high inventory quantities (49,269 and 12,972 units respectively) and are supplied in Tape & Reel packaging suitable for automated assembly.

For Automotive and Qualified Applications:

2PB709ART,215 and 2PB709ART,235 are manufactured by NXP USA Inc. / Nexperia USA Inc. and carry AEC-Q101 automotive qualification. These parts match the original Vce saturation specification (500 mV @ 10 mA, 100 mA) and DC current gain (210 @ 2 mA, 10 V), providing the closest electrical equivalence to the MSB709-RT1. Both are RoHS3 compliant and rated for 150 °C maximum junction temperature. 2PB709ART,215 is available in bulk packaging with 35,300 units in stock, while 2PB709ART,235 is supplied in Tape & Reel with limited inventory (731 units).

For High-Performance Applications:

BC857BR TR PBFREE and BC857C TR PBFREE, manufactured by Central Semiconductor Corp, provide enhanced power dissipation (350 mW) and transition frequency (100 MHz). BC857C TR PBFREE offers exceptional DC current gain (420 @ 2 mA, 5 V) and extremely low saturation voltage (50 mV @ 5 mA, 100 mA), making it suitable for low-loss switching applications. Both parts are RoHS3 compliant and support extended operating temperature range (-65 °C to 150 °C).

Compliance Considerations:

All substitute parts listed are RoHS3 compliant, addressing environmental and regulatory requirements that the obsolete MSB709-RT1 does not meet. For applications requiring automotive qualification, 2PB709ART,215 and 2PB709ART,235 are the only options carrying AEC-Q101 certification.

Frequently Asked Questions (FAQ)

Q: Can BC857A-TP and BC857B-TP be used interchangeably with the MSB709-RT1?

A: Both BC857A-TP and BC857B-TP meet the core electrical requirements of the MSB709-RT1 (100 mA collector current, 45 V breakdown voltage, 150 °C maximum temperature, and compatible TO-236-3/SOT-23-3 packages). BC857B-TP provides closer DC current gain matching (220 vs. 210). Both parts exceed the original power rating and provide higher transition frequency (200 MHz), making them suitable for direct substitution in most applications.

Q: What is the difference between the BC857 variants (A, B, C)?

A: The BC857 variants differ in DC current gain specifications. BC857A-TP has a minimum hFE of 125 @ 2 mA, 5 V; BC857B-TP has 220 @ 2 mA, 5 V; BC857C TR PBFREE has 420 @ 2 mA, 5 V. All three variants share identical maximum ratings (100 mA, 45 V, 150 °C) and package compatibility. Selection depends on the required current gain for the specific circuit application.

Q: Are the 2PB709ART parts better substitutes than the BC857 series?

A: The 2PB709ART parts (both ,215 and ,235 variants) provide closer electrical equivalence to the MSB709-RT1 in terms of Vce saturation voltage (500 mV matching) and DC current gain (210 matching). Additionally, these parts carry AEC-Q101 automotive qualification, making them mandatory for automotive applications. However, BC857 variants offer higher power dissipation (310-350 mW vs. 250 mW) and faster transition frequency (100-200 MHz vs. 70 MHz), which may be advantageous for high-speed or high-power applications.

Q: What is the significance of RoHS3 compliance for substitution?

A: RoHS3 compliance indicates that the substitute part meets current environmental and hazardous substance restrictions. The original MSB709-RT1 is RoHS non-compliant, meaning it may contain restricted materials. All listed substitute parts are RoHS3 compliant, ensuring compatibility with modern supply chain requirements and regulatory standards in most markets.

Q: Can I use BC857BR TR PBFREE or BC857C TR PBFREE in place of the MSB709-RT1?

A: Yes. Both parts meet all core electrical requirements and package compatibility. BC857BR TR PBFREE and BC857C TR PBFREE provide enhanced performance characteristics: higher power dissipation (350 mW vs. 200 mW), faster transition frequency (100 MHz), and extended operating temperature range (-65 °C to 150 °C vs. 150 °C maximum). BC857C TR PBFREE additionally offers very low saturation voltage (50 mV), making it ideal for low-loss switching applications.

Q: What packaging options are available for substitute parts?

A: Substitute parts are available in multiple packaging formats: Tape & Reel (TR) for automated assembly, Cut Tape (CT) for manual assembly, and Bulk for high-volume applications. BC857A-TP and BC857B-TP are supplied in Tape & Reel. BC857BR TR PBFREE is supplied in Cut Tape. 2PB709ART,215 is available in Bulk, while 2PB709ART,235 is supplied in Tape & Reel. Selection depends on assembly process requirements and order quantities.

Q: Are there any performance trade-offs when substituting the MSB709-RT1?

A: Substitute parts generally offer performance improvements over the obsolete MSB709-RT1. The primary trade-off is saturation voltage: BC857A-TP and BC857B-TP have higher saturation voltage (650 mV @ 5 mA, 100 mA) compared to the original (500 mV @ 10 mA, 100 mA). This may affect switching speed in saturation-mode applications. For applications requiring matched saturation voltage, 2PB709ART parts or BC857C TR PBFREE are recommended.

Q: Which substitute part has the highest inventory availability?

A: BC857A-TP has the highest inventory with 49,269 units in stock, followed by 2PB709ART,215 with 35,300 units. BC857BR TR PBFREE has 28,905 units available. BC857B-TP has 12,972 units, and 2PB709ART,235 has the lowest availability at 731 units. Inventory levels should be confirmed with suppliers for current availability.

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