BC557B-AP Equivalent & Substitute Parts Reference

Part Overview

The BC557B-AP is a small-signal PNP bipolar junction transistor manufactured by Micro Commercial Co, designed for general-purpose switching and amplification applications. Specified for 45 V collector-emitter breakdown voltage with 100 mA maximum collector current, this device operates across a wide temperature range from -55°C to 150°C. The BC557B-AP is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and maintenance applications.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	100	mA
Voltage - Collector Emitter Breakdown (Max)	45	V
Vce Saturation (Max) @ Ib, Ic	650 mV @ 5 mA, 100 mA	—
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) Min @ Ic, Vce	180 @ 2 mA, 5 V	—
Power - Max	625	mW
Frequency - Transition	150	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—

Substitute Part Grouping Explanation

Substitution of the BC557B-AP is determined by strict equivalence across the following electrical and mechanical parameters:

Critical Matching Parameters:

Transistor polarity: PNP
Collector-emitter breakdown voltage: 45 V minimum
Maximum collector current: 100 mA minimum
Transition frequency: 150 MHz minimum
Vce saturation: 650 mV @ 5 mA, 100 mA
Package type: TO-92-3 (TO-226AA) Through Hole

Acceptable Variation Parameters:

DC current gain (hFE): Minimum 110 @ 2 mA, 5 V (original specifies 180 minimum)
Maximum power dissipation: 500 mW minimum (original specifies 625 mW)
Collector cutoff current: 15 nA maximum (original specifies 100 nA maximum)
Operating temperature upper limit: 150°C (original specifies -55°C to 150°C)

All three substitute parts meet or exceed the critical matching parameters. Variations in hFE, power rating, and cutoff current represent acceptable deviations within the BC557 product family specifications.

Parameter Comparison

Parameter	BC557B-AP (Main)	BC557ATA	BC557BTA	BC557BTF
Manufacturer	Micro Commercial Co	Fairchild Semiconductor	onsemi	onsemi
Product Status	Obsolete	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP
Ic (Max)	100 mA	100 mA	100 mA	100 mA
Vce Breakdown (Max)	45 V	45 V	45 V	45 V
Vce Saturation @ Ib, Ic	650 mV @ 5 mA, 100 mA	650 mV @ 5 mA, 100 mA	650 mV @ 5 mA, 100 mA	650 mV @ 5 mA, 100 mA
Icbo (Max)	100 nA	15 nA	15 nA	15 nA
hFE (Min) @ Ic, Vce	180 @ 2 mA, 5 V	110 @ 2 mA, 5 V	200 @ 2 mA, 5 V	200 @ 2 mA, 5 V
Power (Max)	625 mW	500 mW	500 mW	500 mW
Frequency - Transition	150 MHz	150 MHz	150 MHz	150 MHz
Operating Temperature	-55 to 150°C	150°C	150°C	150°C
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3
RoHS Status	RoHS Compliant	Not specified	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

BC557BTA and BC557BTF (onsemi): Both onsemi variants are recommended as primary substitutes. These parts maintain full electrical equivalence across all critical parameters, feature active product status ensuring long-term availability, and carry ROHS3 compliance certification. BC557BTF demonstrates superior inventory availability (41,626 units) compared to BC557BTA (6,200 units). Both are supplied in Cut Tape packaging and are suitable for automated assembly processes.

BC557ATA (Fairchild Semiconductor): This substitute meets all critical electrical parameters and maintains active product status. The DC current gain specification (110 @ 2 mA, 5 V) is lower than the original BC557B-AP (180 minimum) but remains within acceptable BC557 family tolerances. Inventory availability is adequate at 779 units. RoHS compliance status is not specified in the provided data.

Compliance Considerations: All three substitute parts comply with ECCN EAR99 and HTSUS 8541.21.0075 classifications, matching the original part. onsemi variants carry explicit ROHS3 compliance and REACH Unaffected status, providing additional regulatory assurance for new designs and production environments requiring enhanced compliance documentation.

Frequently Asked Questions (FAQ)

Q: Can BC557BTA and BC557BTF be used interchangeably with BC557B-AP?

A: Yes. Both parts maintain identical electrical specifications across all critical parameters: 45 V breakdown voltage, 100 mA collector current, 150 MHz transition frequency, and TO-92-3 package configuration. The primary difference is product status (active versus obsolete) and compliance certifications.

Q: What is the significance of the lower hFE specification in BC557ATA?

A: BC557ATA specifies a minimum hFE of 110 @ 2 mA, 5 V, compared to 180 for BC557B-AP. This represents a lower current gain but remains within the BC557 product family specification range. Applications requiring specific hFE values should reference circuit design margins. BC557BTA and BC557BTF specify 200 minimum, exceeding the original specification.

Q: Are there temperature range differences between substitutes?

A: The provided data indicates BC557ATA, BC557BTA, and BC557BTF specify 150°C maximum operating temperature, while BC557B-AP specifies -55°C to 150°C. Applications requiring operation below 0°C should confirm substitute part low-temperature specifications with manufacturer datasheets.

Q: What packaging differences exist among the substitutes?

A: All substitutes use TO-92-3 (TO-226AA) Through Hole package with formed leads, maintaining mechanical and electrical compatibility. BC557BTA and BC557BTF are supplied in Cut Tape packaging suitable for automated pick-and-place assembly, while BC557ATA packaging format is not specified in the provided data.

Q: Which substitute offers the best long-term availability?

A: BC557BTF (onsemi) demonstrates the highest current inventory at 41,626 units and carries active product status with ROHS3 compliance, indicating strong manufacturer commitment to continued production and support.

Q: Are all substitutes RoHS compliant?

A: BC557BTA and BC557BTF carry explicit ROHS3 compliance certification. BC557ATA RoHS status is not specified in the provided data. For applications requiring documented RoHS compliance, onsemi variants are recommended.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message