BC547A-AP Equivalent & Substitute Parts

Part Overview

The BC547A-AP is a small-signal NPN bipolar junction transistor manufactured by Micro Commercial Co, rated for 45V collector-emitter breakdown voltage and 100mA maximum collector current. This device is classified as obsolete, necessitating identification of active equivalent alternatives for ongoing production and maintenance applications. The BC547A-AP operates across a wide temperature range from -55°C to 150°C and is housed in a TO-92 through-hole package suitable for conventional PCB assembly methods.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Maximum Collector Current (Ic)	100	mA
Collector-Emitter Breakdown Voltage (Max)	45	V
Maximum Power Dissipation	625	mW
Transition Frequency	300	MHz
DC Current Gain (hFE Min @ 2mA, 5V)	110	—
Operating Temperature Range	-55 to 150	°C
Package Type	TO-92	—
Mounting Type	Through Hole	—

Substitute Part Grouping Explanation

Substitution eligibility for the BC547A-AP is determined by strict equivalence across the following electrical and mechanical parameters:

Critical Matching Parameters:

Transistor polarity: NPN configuration
Maximum collector current: 100mA
Collector-emitter breakdown voltage: 45V
Package type: TO-92 through-hole
Transition frequency: 300MHz
DC current gain minimum: 110 @ 2mA, 5V

The identified substitute parts BC547ATA (Fairchild Semiconductor) and BC550CTA (onsemi) satisfy all critical electrical parameters. Both devices maintain identical maximum ratings for collector current, breakdown voltage, and transition frequency. Both are packaged in TO-92-3 configuration with through-hole mounting compatibility. The primary distinction between substitutes relates to power dissipation rating and product status, with both alternatives currently in active production status.

Parameter Comparison

Parameter	BC547A-AP (Main)	BC547ATA (Substitute)	BC550CTA (Substitute)
Manufacturer	Micro Commercial Co	Fairchild Semiconductor	onsemi
Product Status	Obsolete	Active	Active
Transistor Type	NPN	NPN	NPN
Ic (Max)	100 mA	100 mA	100 mA
Vce Breakdown (Max)	45 V	45 V	45 V
Vce Saturation @ 5mA, 100mA	300 mV	600 mV	600 mV
hFE (Min) @ 2mA, 5V	110	110	420
Power (Max)	625 mW	500 mW	500 mW
Frequency - Transition	300 MHz	300 MHz	300 MHz
Operating Temperature (Max)	150°C	150°C	150°C
Package / Case	TO-92-3	TO-92-3	TO-92-3
Mounting Type	Through Hole	Through Hole	Through Hole
RoHS Status	ROHS3 Compliant	Not specified	ROHS3 Compliant
REACH Status	REACH Unaffected	Not specified	REACH Unaffected

Engineering Selection Recommendations

BC547ATA (Fairchild Semiconductor) provides direct electrical equivalence to the BC547A-AP with identical DC current gain specification (110 minimum @ 2mA, 5V). This substitute maintains the same collector current and breakdown voltage ratings. The BC547ATA is currently in active production status, ensuring long-term availability. Compliance documentation for RoHS and REACH status is not specified in available data.

BC550CTA (onsemi) satisfies all critical electrical parameters with identical maximum ratings for collector current, breakdown voltage, and transition frequency. The BC550CTA exhibits higher DC current gain (420 minimum @ 2mA, 5V) compared to the BC547A-AP specification. This device is actively produced and carries ROHS3 compliance and REACH Unaffected certification, matching the regulatory status of the original part. The higher current gain may require circuit design verification in applications with tight gain tolerance requirements.

Both substitute parts operate within the same temperature range and are packaged identically in TO-92-3 through-hole configuration. Selection between BC547ATA and BC550CTA depends on circuit gain requirements and regulatory compliance documentation needs.

Frequently Asked Questions (FAQ)

Q: Can BC547ATA and BC550CTA be used interchangeably with BC547A-AP?

A: Both parts satisfy the critical electrical parameters: 100mA collector current, 45V breakdown voltage, 300MHz transition frequency, and TO-92 through-hole packaging. The primary difference is DC current gain specification. BC547ATA matches the original 110 minimum gain, while BC550CTA specifies 420 minimum gain. Circuit applications with gain-dependent biasing networks may require design adjustment when substituting BC550CTA.

Q: What is the significance of the Vce saturation difference between the main part and substitutes?

A: The BC547A-AP specifies 300mV maximum saturation voltage, while both substitutes specify 600mV. In switching applications operating at saturation, the BC550CTA and BC547ATA will exhibit approximately twice the saturation voltage drop. Applications requiring minimal saturation voltage may experience performance changes.

Q: Are the substitute parts suitable for new production designs?

A: Both BC547ATA and BC550CTA are in active production status, making them suitable for new designs. The BC547A-AP is obsolete and should not be specified for new production. BC550CTA carries explicit ROHS3 and REACH compliance certifications, while BC547ATA compliance status is not documented.

Q: Does the lower power rating of the substitutes affect compatibility?

A: The BC547A-AP is rated for 625mW maximum power dissipation, while both substitutes are rated for 500mW. Applications operating below 500mW are fully compatible. Designs requiring power dissipation between 500mW and 625mW require thermal analysis to confirm substitute suitability.

Q: Are there package or pinout differences between these parts?

A: All three devices use identical TO-92-3 through-hole packaging with standard NPN pinout configuration (Emitter, Base, Collector). No PCB layout modifications are required for substitution.

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