BC557_D11Z Equivalent & Substitute Parts

Part Overview

The BC557_D11Z is a small-signal PNP bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 100 mA, collector-emitter breakdown voltage of 45 V, and a transition frequency of 150 MHz. The BC557_D11Z is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement continuity. Substitute parts must maintain electrical and mechanical compatibility across all critical performance parameters to ensure direct replacement capability in existing circuit designs.

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)	15	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	110 @ 2 mA, 5 V	—
Power - Max	500	mW
Frequency - Transition	150	MHz
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the BC557_D11Z is determined by strict equivalence across all electrical and mechanical parameters. The primary substitution criterion is functional compatibility, which requires matching specifications in the following areas:

Electrical Parameters:

Transistor polarity (PNP)
Maximum collector current (100 mA)
Collector-emitter breakdown voltage (45 V)
Saturation voltage characteristics (650 mV @ 5 mA, 100 mA)
Collector cutoff current (15 nA maximum)
DC current gain minimum (110 @ 2 mA, 5 V)
Maximum power dissipation (500 mW)
Transition frequency (150 MHz)
Maximum junction temperature (150°C)

Mechanical Parameters:

Through-hole mounting configuration
TO-92-3 package format with formed leads

The BC557ATA, manufactured by Fairchild Semiconductor, meets all specified electrical and mechanical parameters and qualifies as a direct substitute. This part maintains active product status, ensuring ongoing availability and supply chain reliability.

Parameter Comparison

Parameter	BC557_D11Z (onsemi)	BC557ATA (Fairchild Semiconductor)	Match Status
Transistor Type	PNP	PNP	Equivalent
Current - Collector (Ic) (Max)	100 mA	100 mA	Equivalent
Voltage - Collector Emitter Breakdown (Max)	45 V	45 V	Equivalent
Vce Saturation (Max) @ Ib, Ic	650 mV @ 5 mA, 100 mA	650 mV @ 5 mA, 100 mA	Equivalent
Current - Collector Cutoff (Max)	15 nA	15 nA	Equivalent
DC Current Gain (hFE) (Min) @ Ic, Vce	110 @ 2 mA, 5 V	110 @ 2 mA, 5 V	Equivalent
Power - Max	500 mW	500 mW	Equivalent
Frequency - Transition	150 MHz	150 MHz	Equivalent
Operating Temperature (TJ)	150°C	150°C	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Package / Case	TO-92-3	TO-92-3	Equivalent

Engineering Selection Recommendations

The BC557ATA is the qualified substitute for the BC557_D11Z based on complete electrical and mechanical parameter equivalence. The BC557ATA maintains active product status with Fairchild Semiconductor, providing superior supply chain continuity compared to the obsolete BC557_D11Z. Both parts carry identical ECCN (EAR99) and HTSUS (8541.21.0075) classifications, ensuring regulatory compliance consistency.

Selection of the BC557ATA eliminates obsolescence risk while preserving all functional characteristics required for direct circuit replacement. The through-hole TO-92-3 package format ensures mechanical compatibility with existing printed circuit board layouts and assembly processes.

Frequently Asked Questions (FAQ)

Q: Can the BC557ATA be used as a direct replacement for the BC557_D11Z in existing designs?

A: Yes. The BC557ATA meets all electrical and mechanical specifications of the BC557_D11Z, including collector current, breakdown voltage, saturation characteristics, current gain, power dissipation, transition frequency, and package format. Direct substitution is supported without circuit modification.

Q: What is the primary advantage of selecting the BC557ATA over the BC557_D11Z?

A: The BC557ATA maintains active product status, ensuring reliable long-term availability and supply chain support. The BC557_D11Z is classified as obsolete, creating procurement risk and potential discontinuation.

Q: Are the package dimensions and pin configurations identical between these parts?

A: Yes. Both the BC557_D11Z and BC557ATA use the TO-92-3 package format with formed leads, ensuring identical mechanical compatibility, pin spacing, and printed circuit board footprint requirements.

Q: Do these parts share the same regulatory classifications?

A: Yes. Both parts carry identical ECCN (EAR99) and HTSUS (8541.21.0075) classifications, maintaining regulatory compliance consistency across substitution.

Q: What parameters determine substitution eligibility for PNP bipolar transistors in this category?

A: Substitution eligibility is determined by equivalence across transistor polarity, maximum collector current, collector-emitter breakdown voltage, saturation voltage, collector cutoff current, DC current gain, maximum power dissipation, transition frequency, operating temperature range, and package format. All parameters must match the original specification.

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