BCX71K Equivalent & Substitute Parts

Part Overview

The BCX71K is a PNP bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This device is rated for 45 V collector-emitter breakdown voltage and 500 mA maximum collector current, with a maximum power dissipation of 350 mW. The BCX71K is classified as obsolete, necessitating identification of active substitute components that maintain electrical and mechanical compatibility for new designs and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	500	mA
Voltage - Collector Emitter Breakdown (Max)	45	V
Power - Max	350	mW
Vce Saturation (Max) @ Ib, Ic	550mV @ 1.25mA, 50mA	—
DC Current Gain (hFE) Min @ Ic, Vce	380 @ 2mA, 5V	—
Operating Temperature	-55 to 150	°C
Package / Case	SOT-23-3 (TO-236-3, SC-59)	—
Mounting Type	Surface Mount	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitute parts for the BCX71K are selected based on the following critical parameters that determine functional equivalence:

Primary Matching Criteria:

Transistor Type: PNP (required)
Package / Case: SOT-23-3 surface mount (required for mechanical compatibility)
Current - Collector (Ic) Max: 500 mA (required)
Voltage - Collector Emitter Breakdown: ≥45 V (minimum requirement)
Operating Temperature Range: -55°C to 150°C (required)

Secondary Considerations:

Power dissipation capability (≥350 mW preferred)
DC Current Gain (hFE) characteristics
Vce saturation performance
Product Status: Active (preferred for long-term availability)

Substitute parts are grouped into two categories:

Category A - Direct Electrical Equivalents (500 mA, 45 V Rating): BC807-16LT1G, BC807-16LT3G, BC807-25LT1G, BC807-25LT3G, BC807-40LT1G, BC807-40LT3G

These parts maintain the 500 mA collector current and 45 V breakdown voltage specifications. Variations in hFE (100, 160, or 250 @ 100mA, 1V) indicate different current gain grades within the BC807 family. All are active products with RoHS3 compliance.

Category B - Higher Voltage Alternative (500 mA, 50 V Rating): 50A02CH-TL-E

This part exceeds the voltage specification (50 V vs. 45 V) and offers higher power dissipation (700 mW vs. 350 mW), providing additional design margin. Transition frequency of 690 MHz supports higher-speed applications.

Category C - Lower Current Alternatives (100 mA, 45 V Rating): BC857ALT1G, BC857BLT1G, BC857BLT3G

These parts are suitable only for applications where collector current does not exceed 100 mA. They share the same 45 V voltage rating and SOT-23-3 package but are not direct substitutes for 500 mA designs.

Parameter Comparison

Part Number	Manufacturer	Ic Max (mA)	Vce Breakdown (V)	Power Max (mW)	hFE Min @ Ic, Vce	Frequency (MHz)	Product Status	Package
BCX71K	onsemi	500	45	350	380 @ 2mA, 5V	—	Obsolete	SOT-23-3
BC807-16LT1G	onsemi	500	45	300	100 @ 100mA, 1V	100	Active	SOT-23-3
BC807-16LT3G	onsemi	500	45	300	100 @ 100mA, 1V	100	Active	SOT-23-3
BC807-25LT1G	onsemi	500	45	300	160 @ 100mA, 1V	100	Active	SOT-23-3
BC807-25LT3G	onsemi	500	45	300	160 @ 100mA, 1V	100	Active	SOT-23-3
BC807-40LT1G	onsemi	500	45	300	250 @ 100mA, 1V	100	Active	SOT-23-3
BC807-40LT3G	onsemi	500	45	300	250 @ 100mA, 1V	100	Active	SOT-23-3
50A02CH-TL-E	onsemi	500	50	700	200 @ 10mA, 2V	690	Active	SOT-23-3
BC857ALT1G	onsemi	100	45	300	125 @ 2mA, 5V	100	Active	SOT-23-3
BC857BLT1G	onsemi	100	45	300	220 @ 2mA, 5V	100	Active	SOT-23-3
BC857BLT3G	onsemi	100	45	300	220 @ 2mA, 5V	100	Active	SOT-23-3

Engineering Selection Recommendations

For Direct Replacement (500 mA Applications):

The BC807 family (BC807-16LT1G, BC807-16LT3G, BC807-25LT1G, BC807-25LT3G, BC807-40LT1G, BC807-40LT3G) provides the most suitable substitutes for the BCX71K. All variants maintain the 500 mA collector current rating and 45 V breakdown voltage. These parts are active products with RoHS3 compliance and unlimited moisture sensitivity level (MSL 1), ensuring long-term availability and regulatory compliance.

Selection among BC807 variants depends on required DC current gain:

BC807-16 series: hFE minimum of 100 @ 100mA, 1V
BC807-25 series: hFE minimum of 160 @ 100mA, 1V
BC807-40 series: hFE minimum of 250 @ 100mA, 1V

Packaging variants (LT1G with Cut Tape & Digi-Reel or LT3G with Tape & Reel) are functionally identical; selection depends on procurement and assembly requirements.

For Higher Voltage Margin Applications:

The 50A02CH-TL-E offers 50 V breakdown voltage (5 V higher than BCX71K specification) and 700 mW power dissipation (2× the BCX71K rating). This part is suitable for designs requiring additional voltage headroom or thermal margin. The 690 MHz transition frequency supports higher-frequency switching applications compared to the 100 MHz BC807 family.

For Current-Limited Applications (≤100 mA):

BC857ALT1G, BC857BLT1G, and BC857BLT3G are appropriate only for circuits where maximum collector current does not exceed 100 mA. These parts are not suitable as direct replacements for 500 mA designs.

Frequently Asked Questions (FAQ)

Q: Can BC807-16LT1G directly replace BCX71K in all applications?

A: BC807-16LT1G is mechanically and electrically compatible with BCX71K for applications requiring up to 500 mA collector current and 45 V breakdown voltage. Both parts use SOT-23-3 packaging and operate across -55°C to 150°C. The primary difference is DC current gain (hFE 100 vs. 380 @ specified test conditions). Circuit designs relying on specific hFE values must account for this variation.

Q: What is the difference between BC807-25LT1G and BC807-25LT3G?

A: BC807-25LT1G and BC807-25LT3G are electrically identical. The difference is packaging format: LT1G is supplied in Cut Tape & Digi-Reel format, while LT3G is supplied in Tape & Reel format. Both have identical electrical specifications and are suitable for the same applications.

Q: Why is the BC857 series not recommended as a direct BCX71K substitute?

A: BC857 series transistors are rated for maximum 100 mA collector current, compared to BCX71K's 500 mA rating. While both share the same 45 V breakdown voltage and SOT-23-3 package, BC857 parts are unsuitable for circuits designed to operate at 500 mA. Using BC857 in a 500 mA application would exceed the device's absolute maximum ratings.

Q: Is 50A02CH-TL-E a suitable substitute for BCX71K?

A: 50A02CH-TL-E is functionally compatible with BCX71K for 500 mA applications and offers superior specifications: 50 V breakdown voltage (vs. 45 V) and 700 mW power dissipation (vs. 350 mW). The higher voltage rating and power capability provide additional design margin. The 690 MHz transition frequency supports faster switching than BCX71K. This part is suitable for direct substitution in most applications.

Q: Are all recommended substitutes RoHS3 compliant?

A: All active substitute parts listed (BC807 series and 50A02CH-TL-E) are RoHS3 compliant. The obsolete BCX71K does not carry RoHS3 certification. For new designs and production, RoHS3-compliant substitutes are required to meet current regulatory requirements.

Q: What is the significance of the hFE variations in the BC807 family?

A: The BC807 family offers three hFE grades (16, 25, 40) representing minimum DC current gain at specified test conditions. Higher hFE grades (40 series at 250 minimum) require less base current to achieve saturation, reducing base drive power requirements. Lower hFE grades (16 series at 100 minimum) provide more conservative gain specifications. Circuit designs should specify the appropriate hFE grade based on base drive availability and switching speed requirements.

Q: Can BCX71K be used interchangeably with BC807 in existing designs?

A: BCX71K and BC807 parts share identical mechanical compatibility (SOT-23-3 package) and similar electrical ratings (500 mA, 45 V). However, the BCX71K is obsolete and no longer manufactured. For production continuity, designs using BCX71K should transition to active BC807 variants. Existing designs may continue using remaining BCX71K inventory, but new designs must use active substitutes.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message