BCX71J Equivalent & Substitute Parts

Part Overview

The BCX71J is a PNP bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This component is rated for 45 V collector-emitter breakdown voltage and 100 mA maximum collector current, with a maximum power dissipation of 350 mW. The BCX71J is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering active product status and current manufacturing availability.

Key Parameters

Parameter	BCX71J Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	45	V
Current - Collector (Ic) (Max)	100	mA
Power - Max	350	mW
Vce Saturation (Max) @ Ib, Ic	550mV @ 1.25mA, 50mA	—
Current - Collector Cutoff (Max)	20	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	250 @ 2mA, 5V	—
Package / Case	SOT-23-3 (TO-236)	—
Mounting Type	Surface Mount	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the BCX71J is determined by strict adherence to the following electrical and mechanical parameters:

Critical Compatibility Parameters:

Transistor Type: PNP (mandatory match)
Voltage - Collector Emitter Breakdown (Max): 45 V or greater
Current - Collector (Ic) (Max): 100 mA or greater
Package / Case: SOT-23-3 (TO-236) (mandatory match)
Mounting Type: Surface Mount (mandatory match)

Substitute parts are grouped into two categories:

Category 1: Direct Current Rating Match (100 mA) Parts with maximum collector current of 100 mA, matching the BCX71J specification exactly. These components include BC857ALT1G, BC857BLT1G, BC857BLT3G, and BC857CLT1G. All maintain the 45 V breakdown voltage, SOT-23-3 package, and surface mount configuration. These parts are preferred for direct replacement in applications where the 100 mA current rating is the design requirement.

Category 2: Higher Current Rating (500 mA) Parts with maximum collector current of 500 mA, exceeding the BCX71J specification. These components include BC807-16LT1G, BC807-16LT3G, BC807-25LT1G, BC807-25LT3G, BC807-40LT1G, and BC807-40LT3G. All maintain the 45 V breakdown voltage, SOT-23-3 package, and surface mount configuration. These parts provide additional current capacity and are suitable for applications where higher current capability is beneficial or required.

All substitute parts listed are active products with current manufacturing status, RoHS3 compliance, and REACH unaffected designation.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce Breakdown (Max) V	Power (Max) mW	Package	hFE (Min) @ Ic, Vce	Frequency - Transition
BCX71J	onsemi	Obsolete	100	45	350	SOT-23-3	250 @ 2mA, 5V	—
BC857ALT1G	onsemi	Active	100	45	300	SOT-23-3	125 @ 2mA, 5V	100MHz
BC857BLT1G	onsemi	Active	100	45	300	SOT-23-3	220 @ 2mA, 5V	100MHz
BC857BLT3G	onsemi	Active	100	45	300	SOT-23-3	220 @ 2mA, 5V	100MHz
BC857CLT1G	onsemi	Active	100	45	300	SOT-23-3	420 @ 2mA, 5V	100MHz
BC807-16LT1G	onsemi	Active	500	45	300	SOT-23-3	100 @ 100mA, 1V	100MHz
BC807-16LT3G	onsemi	Active	500	45	300	SOT-23-3	100 @ 100mA, 1V	100MHz
BC807-25LT1G	onsemi	Active	500	45	300	SOT-23-3	160 @ 100mA, 1V	100MHz
BC807-25LT3G	onsemi	Active	500	45	300	SOT-23-3	160 @ 100mA, 1V	100MHz
BC807-40LT1G	onsemi	Active	500	45	300	SOT-23-3	250 @ 100mA, 1V	100MHz
BC807-40LT3G	onsemi	Active	500	45	300	SOT-23-3	250 @ 100mA, 1V	100MHz

Engineering Selection Recommendations

For Direct Current Rating Replacement (100 mA Applications):

BC857BLT1G and BC857BLT3G are the primary selections for applications requiring exact current rating matching. Both parts are active products with RoHS3 compliance and REACH unaffected status. BC857BLT1G is available in Cut Tape (CT) & Digi-Reel packaging with 125,100 pieces in stock, while BC857BLT3G is available in Tape & Reel (TR) packaging with 41,676 pieces in stock. Both maintain the 45 V breakdown voltage and SOT-23-3 package configuration. The DC current gain of 220 @ 2mA, 5V provides adequate performance for general-purpose switching applications.

BC857CLT1G offers the highest DC current gain specification (420 @ 2mA, 5V) among the 100 mA rated options, suitable for applications requiring enhanced amplification characteristics. This part is active with RoHS3 compliance and available in Cut Tape packaging with 3,575 pieces in stock.

BC857ALT1G provides the lowest DC current gain specification (125 @ 2mA, 5V) among the 100 mA rated options and is available in Tape & Reel packaging with 747,693 pieces in stock, offering the highest inventory availability.

For Higher Current Capacity Applications (500 mA):

BC807-40LT1G and BC807-40LT3G are recommended for applications where higher current capacity is required or beneficial. Both parts feature a DC current gain of 250 @ 100mA, 1V, matching the BCX71J hFE specification at different measurement conditions. BC807-40LT1G is available in Cut Tape packaging with 119,400 pieces in stock, while BC807-40LT3G is available in Cut Tape packaging with 95,300 pieces in stock. Both are active products with RoHS3 compliance and REACH unaffected status.

BC807-25LT1G and BC807-25LT3G provide intermediate current gain specifications (160 @ 100mA, 1V) and are available with substantial inventory: 293,400 and 305,300 pieces respectively.

All substitute parts are manufactured by onsemi, maintaining design continuity and supply chain consistency with the original BCX71J component.

Frequently Asked Questions (FAQ)

Q: Can BC807 series parts directly replace BCX71J in all applications?

A: BC807 series parts (500 mA rated) are electrically compatible with BCX71J in applications designed for 100 mA operation. The higher current rating does not prevent operation at lower currents. However, circuit design verification is necessary to confirm that the different hFE measurement conditions (100 mA, 1V for BC807 versus 2 mA, 5V for BCX71J) do not impact circuit performance.

Q: What is the difference between BC857 and BC807 series substitutes?

A: BC857 series parts are rated for 100 mA maximum collector current, matching the BCX71J specification exactly. BC807 series parts are rated for 500 mA maximum collector current, providing higher current capacity. Both series maintain the 45 V breakdown voltage and SOT-23-3 package. Selection depends on application current requirements.

Q: Are packaging variants (LT1G versus LT3G) electrically equivalent?

A: Yes. The suffix designations indicate packaging format only: LT1G denotes Cut Tape (CT) & Digi-Reel packaging, while LT3G denotes Tape & Reel (TR) packaging. Electrical specifications are identical between these variants. Selection is based on procurement and assembly process requirements.

Q: What is the significance of the hFE suffix numbers in BC807 and BC857 part numbers?

A: The numeric suffix (16, 25, 40) indicates the minimum DC current gain specification. BC807-16 specifies hFE minimum of 100, BC807-25 specifies hFE minimum of 160, and BC807-40 specifies hFE minimum of 250. BC857A specifies hFE minimum of 125, BC857B specifies hFE minimum of 220, and BC857C specifies hFE minimum of 420. Selection is based on circuit gain requirements.

Q: Is the BCX71J truly obsolete, and are all substitute parts actively manufactured?

A: Yes. BCX71J is classified as obsolete product status. All listed substitute parts are classified as active products with current manufacturing status. BC857ALT1G, BC857BLT1G, BC857BLT3G, BC857CLT1G, BC807-16LT1G, BC807-16LT3G, BC807-25LT1G, BC807-25LT3G, BC807-40LT1G, and BC807-40LT3G are all actively manufactured by onsemi.

Q: Do all substitute parts meet RoHS and REACH compliance requirements?

A: Yes. All substitute parts listed are RoHS3 compliant and REACH unaffected. The BCX71J does not specify RoHS status, but all active substitute components meet current environmental compliance standards.

Q: What is the maximum power dissipation difference between BCX71J and substitute parts?

A: BCX71J is rated for 350 mW maximum power dissipation. All substitute parts are rated for 300 mW maximum power dissipation. This represents a 50 mW reduction. Circuit thermal design must account for this difference if the original design operated near the 350 mW limit.

Q: Can BC857 and BC807 parts be used interchangeably in the same circuit?

A: Interchangeability depends on circuit design. Both series maintain the 45 V breakdown voltage and SOT-23-3 package. The primary differences are maximum collector current (100 mA versus 500 mA) and DC current gain specifications. Circuits designed for 100 mA operation will function with 500 mA rated parts. However, circuits dependent on specific hFE values must be verified against the measurement conditions specified for each part.

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