BC550ATA Equivalent & Substitute Parts

Part Overview

The BC550ATA is an NPN bipolar junction transistor (BJT) manufactured by onsemi, designed for small-signal amplification and switching applications. This device features a maximum collector current of 100 mA, collector-emitter breakdown voltage of 45 V, and a transition frequency of 300 MHz. The BC550ATA is housed in a TO-92-3 through-hole package with a maximum power dissipation of 500 mW.

The BC550ATA is classified as obsolete. Locating equivalent substitute parts is necessary to support ongoing production requirements, maintenance operations, and design continuity where this component was originally specified.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	100	mA
Voltage - Collector Emitter Breakdown (Max)	45	V
Vce Saturation (Max) @ Ib, Ic	600 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	300	MHz
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—

Substitute Part Grouping Explanation

Substitution of the BC550ATA is determined by electrical and mechanical parameter equivalence. The following criteria establish valid substitution:

Electrical Parameters (Critical):

Transistor type: NPN
Maximum collector current: 100 mA
Collector-emitter breakdown voltage: 45 V
Vce saturation: 600 mV @ 5 mA, 100 mA
Collector cutoff current: 15 nA
DC current gain (hFE): minimum 110 @ 2 mA, 5 V
Maximum power dissipation: 500 mW
Transition frequency: 300 MHz
Maximum operating temperature: 150 °C

Mechanical Parameters (Critical):

Mounting type: Through Hole
Package: TO-92-3 (TO-226AA) with formed leads

Substitute parts must match all electrical specifications and the through-hole TO-92-3 package configuration to ensure direct functional and physical compatibility.

Parameter Comparison

Parameter	BC550ATA (onsemi)	BC547ATA (Fairchild Semiconductor)
Transistor Type	NPN	NPN
Current - Collector (Ic) (Max)	100 mA	100 mA
Voltage - Collector Emitter Breakdown (Max)	45 V	45 V
Vce Saturation (Max) @ Ib, Ic	600 mV @ 5 mA, 100 mA	600 mV @ 5 mA, 100 mA
Current - Collector Cutoff (Max)	15 nA	15 nA
DC Current Gain (hFE) (Min) @ Ic, Vce	110 @ 2 mA, 5 V	110 @ 2 mA, 5 V
Power - Max	500 mW	500 mW
Frequency - Transition	300 MHz	300 MHz
Operating Temperature (TJ)	150 °C	150 °C
Mounting Type	Through Hole	Through Hole
Package / Case	TO-92-3 (TO-226AA)	TO-92-3 (TO-226AA)

Engineering Selection Recommendations

The BC547ATA manufactured by Fairchild Semiconductor is a parametric equivalent to the BC550ATA. All electrical specifications, including collector current, breakdown voltage, saturation characteristics, current gain, power dissipation, and transition frequency, are identical. The package configuration and mounting type are also equivalent.

The BC547ATA carries an active product status, ensuring ongoing availability and supply chain continuity. Both devices comply with ECCN EAR99 and HTSUS 8541.21.0075 classifications.

Selection of the BC547ATA as a substitute for the obsolete BC550ATA is supported by complete electrical and mechanical parameter equivalence. No design modifications or circuit adjustments are required for direct substitution in applications originally specified for the BC550ATA.

Frequently Asked Questions (FAQ)

Q: Can the BC547ATA be used as a direct replacement for the BC550ATA?

A: Yes. The BC547ATA meets all electrical and mechanical specifications of the BC550ATA. Both devices are NPN transistors with identical maximum ratings, gain characteristics, and TO-92-3 package configuration. Direct substitution is supported without circuit modification.

Q: Are there differences in the package or pin configuration?

A: No. Both the BC550ATA and BC547ATA use the TO-92-3 (TO-226AA) through-hole package with formed leads. Pin assignments and physical dimensions are identical, enabling direct board-level replacement.

Q: What is the primary reason for substitution?

A: The BC550ATA is classified as obsolete. The BC547ATA is an active product with established supply availability, making it the appropriate choice for new production and ongoing support.

Q: Are there any compliance or certification differences?

A: Both devices share identical ECCN and HTSUS classifications. No compliance barriers exist for substitution.

Q: Will circuit performance change with this substitution?

A: No. Electrical performance remains unchanged. All critical parameters—collector current, breakdown voltage, gain, saturation characteristics, and frequency response—are identical between the two devices.

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