BC557C-AP Equivalent & Substitute Parts

Part Overview

The BC557C-AP is a PNP bipolar junction transistor manufactured by Micro Commercial Co, rated for 45 V collector-emitter breakdown voltage and 100 mA maximum collector current. This device is packaged in a TO-92 through-hole configuration and is classified as obsolete. Due to its obsolete product status, equivalent substitute parts from active manufacturers are necessary to maintain design continuity and ensure long-term component availability for new production and field replacements.

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	—
Power - Max	625	mW
Frequency - Transition	150	MHz
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—
Operating Temperature Range	-55 to 150	°C

Substitute Part Grouping Explanation

Substitution of the BC557C-AP is determined by electrical and mechanical parameter equivalence. All substitute parts must satisfy the following criteria:

Critical Matching Parameters:

Transistor Type: PNP
Maximum Collector Current (Ic): 100 mA
Maximum Collector-Emitter Breakdown Voltage: 45 V
Vce Saturation: 650 mV @ 5 mA, 100 mA
Transition Frequency: 150 MHz
Mounting Type: Through Hole
Package: TO-92-3 (TO-226AA)

The substitute parts BC557ATA, BC557BTA, and BC557BTF meet all critical electrical specifications and mechanical packaging requirements. These parts are sourced from active manufacturers (Fairchild Semiconductor and onsemi) with current product status, ensuring ongoing availability and supply chain reliability.

Parameter Comparison

Parameter	BC557C-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
Current - Collector (Ic) Max	100 mA	100 mA	100 mA	100 mA
Voltage - Collector Emitter Breakdown (Max)	45 V	45 V	45 V	45 V
Vce Saturation (Max) @ 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
Current - Collector Cutoff (Max)	100 nA	15 nA	15 nA	15 nA
Power - Max	625 mW	500 mW	500 mW	500 mW
Frequency - Transition	150 MHz	150 MHz	150 MHz	150 MHz
Operating Temperature (Max)	150°C	150°C	150°C	150°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
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

BC557ATA (Fairchild Semiconductor): This substitute is sourced from an active manufacturer with current product status. It meets all critical electrical and mechanical parameters. The part is available in standard inventory quantities (779 Pcs). Selection of this part is appropriate for applications requiring Fairchild Semiconductor supply chain integration.

BC557BTA (onsemi): This substitute is manufactured by onsemi with active product status and ROHS3 compliance certification. It provides the highest inventory availability (6200 Pcs) among substitute options. The part is supplied in Cut Tape packaging and meets all electrical specifications. This part is suitable for high-volume production requirements.

BC557BTF (onsemi): This substitute is also manufactured by onsemi with active product status and ROHS3 compliance certification. It offers the largest inventory position (41,626 Pcs) and is supplied in Cut Tape packaging. This part is recommended for applications requiring maximum supply chain security and availability.

All three substitute parts are RoHS compliant and carry identical electrical ratings for the critical parameters that determine functional equivalence. Selection between these options should be based on supply chain preference, packaging format requirements, and inventory availability.

Frequently Asked Questions (FAQ)

Q: Can BC557ATA, BC557BTA, and BC557BTF be used interchangeably with BC557C-AP?

A: Yes. All three substitute parts meet the critical electrical specifications (45 V breakdown voltage, 100 mA collector current, 150 MHz transition frequency, 650 mV saturation voltage) and are packaged in identical TO-92-3 through-hole configuration. They are direct functional equivalents for circuit applications.

Q: What is the difference between BC557BTA and BC557BTF?

A: Both parts are manufactured by onsemi and share identical electrical specifications and TO-92-3 packaging. The primary difference is packaging format: BC557BTA is supplied in Cut Tape, while BC557BTF is also supplied in Cut Tape. Both parts have active product status and ROHS3 compliance. Selection between these parts depends on supplier availability and procurement requirements.

Q: Why does the BC557C-AP have a higher maximum power rating (625 mW) than the substitute parts (500 mW)?

A: The substitute parts are rated at 500 mW maximum power dissipation, which is lower than the original BC557C-AP specification of 625 mW. However, all parts share identical voltage and current ratings (45 V, 100 mA). Circuit designs operating within the 100 mA collector current and 45 V breakdown voltage limits will function correctly with substitute parts. Applications requiring power dissipation above 500 mW should be evaluated against actual circuit operating conditions.

Q: Are the substitute parts RoHS compliant?

A: BC557BTA and BC557BTF are ROHS3 compliant. BC557ATA compliance status is not specified in available documentation. For applications requiring RoHS certification, BC557BTA or BC557BTF are recommended.

Q: What is the difference in DC Current Gain (hFE) between the main part and substitutes?

A: The BC557C-AP specifies minimum hFE of 420 @ 2 mA, 5V. BC557ATA specifies minimum hFE of 110 @ 2 mA, 5V, while BC557BTA and BC557BTF specify minimum hFE of 200 @ 2 mA, 5V. These variations fall within the BC557 series tolerance band. Circuit designs should not depend on specific hFE values but rather use biasing networks that accommodate the specified minimum gain range.

Q: Can these parts be used in surface-mount applications?

A: No. All parts, including the main BC557C-AP and all substitutes, are through-hole mounted devices in TO-92-3 package configuration. They are not suitable for surface-mount assembly. Surface-mount alternatives would require different package types (such as SOT-23) and separate component selection.

Q: What is the operating temperature range for the substitute parts?

A: The substitute parts are rated for maximum junction temperature of 150°C. The BC557C-AP specifies operating temperature range of -55°C to 150°C. Substitute parts meet the upper temperature limit. For applications requiring operation below -55°C, specific low-temperature performance data should be obtained from the respective manufacturers.

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