MMBT5087 Equivalent & Substitute Parts

Part Overview

The MMBT5087 is a surface-mount PNP bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 package. This device is rated for 50 V collector-emitter breakdown voltage and 100 mA maximum collector current, with a maximum power dissipation of 350 mW. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Active alternatives with compatible electrical and mechanical characteristics are available from the onsemi product portfolio.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) (Max)	100	mA
Voltage - Collector Emitter Breakdown (Max)	50	V
Power - Max	350	mW
Frequency - Transition	40	MHz
Operating Temperature Range	-55 to 150	°C (TJ)
Package / Case	SOT-23-3 (TO-236)	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the MMBT5087 is determined by the following critical parameters:

Electrical Compatibility Requirements:

Transistor type must be PNP
Collector-emitter breakdown voltage must be greater than or equal to 50 V
Maximum collector current must be greater than or equal to 100 mA
Maximum power dissipation must be greater than or equal to 350 mW
Operating temperature range must encompass -55°C to 150°C

Mechanical Compatibility Requirements:

Package must be SOT-23-3 (TO-236-3, SC-59)
Mounting type must be surface mount

Substitute parts are grouped into two categories based on voltage rating:

50 V Rated Devices (Direct Electrical Equivalents): MMBT5087LT1G and MMBT5087LT3G maintain the exact 50 V breakdown voltage specification. These parts differ in collector current rating (50 mA vs. 100 mA) and power dissipation (300 mW vs. 350 mW), requiring application-level verification.
45 V Rated Devices (Reduced Voltage Alternatives): BC857ALT1G, BC857BLT1G, BC857BLT3G, BC857CLT1G, BC857CLT3G, and NSVBC857BLT3G operate at 45 V breakdown voltage, which is lower than the original 50 V specification. These parts are suitable only for applications where the actual operating voltage does not exceed 45 V.
Higher Voltage/Current Devices (Uprated Alternatives): MMBTA55LT1G is rated for 60 V and 500 mA, providing enhanced electrical headroom. This device is suitable for applications requiring higher current capacity or voltage margin.
Reduced Power Devices: BCW70LT1G operates at 45 V with 225 mW power dissipation, suitable for lower-power applications.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [mA]	Vce Breakdown (Max) [V]	Power (Max) [mW]	Frequency [MHz]	Package	Product Status	RoHS Status
MMBT5087	onsemi	100	50	350	40	SOT-23-3	Obsolete	—
MMBT5087LT1G	onsemi	50	50	300	40	SOT-23-3	Active	ROHS3 Compliant
MMBT5087LT3G	onsemi	50	50	300	40	SOT-23-3	Active	ROHS3 Compliant
BC857ALT1G	onsemi	100	45	300	100	SOT-23-3	Active	ROHS3 Compliant
BC857BLT1G	onsemi	100	45	300	100	SOT-23-3	Active	ROHS3 Compliant
BC857BLT3G	onsemi	100	45	300	100	SOT-23-3	Active	ROHS3 Compliant
BC857CLT1G	onsemi	100	45	300	100	SOT-23-3	Active	ROHS3 Compliant
BC857CLT3G	onsemi	100	45	300	100	SOT-23-3	Active	ROHS3 Compliant
BCW70LT1G	onsemi	100	45	225	—	SOT-23-3	Active	ROHS3 Compliant
MMBTA55LT1G	onsemi	500	60	225	50	SOT-23-3	Active	ROHS3 Compliant
NSVBC857BLT3G	onsemi	100	45	225	100	SOT-23-3	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes (Recommended for Direct Replacement):

MMBT5087LT1G and MMBT5087LT3G are the preferred substitutes, as they maintain the 50 V collector-emitter breakdown voltage rating of the original MMBT5087. Both parts are active products with ROHS3 compliance. The primary difference between these variants is packaging format: MMBT5087LT1G is supplied in Cut Tape & Digi-Reel format, while MMBT5087LT3G is supplied in Tape & Reel format. Selection between these two should be based on procurement and assembly requirements. Note that these parts are rated for 50 mA maximum collector current and 300 mW power dissipation, which are lower than the original 350 mW specification. Applications operating at or near the original 100 mA specification require verification that actual operating current does not exceed 50 mA.

Secondary Substitutes (Conditional Replacement):

BC857ALT1G, BC857BLT1G, BC857BLT3G, BC857CLT1G, and BC857CLT3G are active alternatives rated for 45 V breakdown voltage. These parts support the full 100 mA collector current and 300 mW power dissipation. The 45 V rating is 5 V lower than the original specification. These parts are suitable only for applications where the maximum operating voltage does not exceed 45 V. All BC857 variants are ROHS3 compliant and available in multiple packaging formats (Cut Tape & Digi-Reel or Tape & Reel).

Uprated Alternative:

MMBTA55LT1G provides enhanced electrical specifications with 60 V breakdown voltage and 500 mA collector current capability. This part is suitable for applications requiring higher voltage margin or increased current capacity. Power dissipation is rated at 225 mW, which is lower than the original 350 mW. This device is ROHS3 compliant.

Lower Power Alternative:

BCW70LT1G and NSVBC857BLT3G are rated for 225 mW power dissipation at 45 V breakdown voltage. These parts are suitable for low-power applications where thermal constraints are critical.

All substitute parts listed maintain the SOT-23-3 surface-mount package format and operate across the -55°C to 150°C temperature range. All active substitutes carry ROHS3 compliance certification.

Frequently Asked Questions (FAQ)

Q: Can I use BC857BLT1G as a direct replacement for MMBT5087?

A: BC857BLT1G is mechanically and functionally compatible with MMBT5087 in the SOT-23-3 package. However, the BC857BLT1G is rated for 45 V breakdown voltage compared to the MMBT5087's 50 V rating. This part is suitable only if your application operates at voltages not exceeding 45 V. Both parts support 100 mA collector current.

Q: What is the difference between MMBT5087LT1G and MMBT5087LT3G?

A: Both parts are electrically identical with 50 V breakdown voltage, 50 mA maximum collector current, and 300 mW power dissipation. The difference is in packaging format: MMBT5087LT1G is supplied in Cut Tape & Digi-Reel format, while MMBT5087LT3G is supplied in Tape & Reel format. Selection depends on your assembly and procurement process requirements.

Q: Why is the MMBT5087 listed as obsolete?

A: The MMBT5087 is obsolete, but active alternatives are available. MMBT5087LT1G and MMBT5087LT3G are the direct successors maintaining the same 50 V voltage rating and SOT-23-3 package. These active parts should be used for new designs and ongoing production.

Q: Can I use MMBTA55LT1G instead of MMBT5087?

A: MMBTA55LT1G is mechanically compatible in the SOT-23-3 package and provides higher voltage (60 V) and current (500 mA) ratings. However, it is rated for only 225 mW power dissipation compared to the MMBT5087's 350 mW. This part is suitable for applications requiring higher electrical headroom but with lower power requirements.

Q: What does the voltage rating difference mean for my application?

A: The MMBT5087 is rated for 50 V collector-emitter breakdown voltage. Substitute parts rated at 45 V (such as BC857 variants) have a 5 V lower maximum voltage specification. These lower-rated parts are suitable only if your circuit's maximum operating voltage does not exceed 45 V. If your application requires the full 50 V rating, use MMBT5087LT1G, MMBT5087LT3G, or MMBTA55LT1G.

Q: Are all substitute parts ROHS3 compliant?

A: All active substitute parts listed (MMBT5087LT1G, MMBT5087LT3G, BC857 variants, BCW70LT1G, MMBTA55LT1G, and NSVBC857BLT3G) are ROHS3 compliant. The original MMBT5087 does not specify RoHS status.

Q: What is the difference between Cut Tape & Digi-Reel and Tape & Reel packaging?

A: Both are surface-mount delivery formats for the same SOT-23-3 component. Cut Tape & Digi-Reel format is typically used for smaller quantities and manual assembly processes. Tape & Reel format is standard for high-volume automated assembly. The electrical and mechanical specifications of the component are identical; only the delivery format differs.

Q: Can I use BC857CLT1G instead of BC857BLT1G?

A: Both parts are electrically compatible with identical 45 V breakdown voltage, 100 mA collector current, and 300 mW power dissipation ratings. The difference is in DC current gain (hFE): BC857CLT1G has a minimum hFE of 420 at specified conditions, while BC857BLT1G has a minimum hFE of 220. Selection depends on your circuit's bias requirements. Both are ROHS3 compliant and available in Cut Tape & Digi-Reel format.

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