BC548A Equivalent & Substitute Parts

Part Overview

The BC548A is a small-signal NPN bipolar junction transistor (BJT) manufactured by onsemi, housed in a TO-92-3 through-hole package. This device is rated for 30 V collector-emitter breakdown voltage, 100 mA maximum collector current, and 500 mW power dissipation. The BC548A is classified as obsolete, making identification of active equivalent parts essential for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	100	mA
Voltage - Collector Emitter Breakdown (Max)	30	V
Vce Saturation (Max) @ Ib, Ic	600 mV @ 5 mA, 100 mA	—
Current - Collector Cutoff (Max)	15	nA (ICBO)
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)	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the BC548A is determined by strict equivalence across all critical electrical and mechanical parameters. The following parameters establish the substitution criteria:

Transistor Type: NPN configuration
Current Rating: 100 mA maximum collector current
Voltage Rating: 30 V collector-emitter breakdown voltage
Saturation Characteristics: 600 mV Vce(sat) @ 5 mA, 100 mA
Leakage Current: 15 nA maximum collector cutoff current
Current Gain: Minimum 110 hFE @ 2 mA, 5 V
Power Dissipation: 500 mW maximum
Frequency Response: 300 MHz transition frequency
Package: TO-92-3 through-hole configuration
Temperature Rating: 150°C maximum junction temperature

The BC548BU meets all specified parameters and is classified as an active product, providing direct parametric equivalence to the obsolete BC548A.

Parameter Comparison

Parameter	BC548A (onsemi)	BC548BU (Fairchild Semiconductor)	Match
Transistor Type	NPN	NPN	✓
Current - Collector (Ic) (Max)	100 mA	100 mA	✓
Voltage - Collector Emitter Breakdown (Max)	30 V	30 V	✓
Vce Saturation (Max) @ Ib, Ic	600 mV @ 5 mA, 100 mA	600 mV @ 5 mA, 100 mA	✓
Current - Collector Cutoff (Max)	15 nA (ICBO)	15 nA (ICBO)	✓
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-92-3	✓
Product Status	Obsolete	Active	—

Engineering Selection Recommendations

The BC548BU manufactured by Fairchild Semiconductor is a direct parametric equivalent to the BC548A. All electrical specifications, mechanical dimensions, and thermal ratings are identical. The BC548BU holds active product status, ensuring continued availability and supply chain reliability.

The BC548A is classified as obsolete, which restricts procurement options and may result in extended lead times or unavailable inventory. Selection of the BC548BU eliminates obsolescence risk while maintaining full electrical and mechanical compatibility.

Both parts carry identical ECCN (EAR99) and HTSUS (8541.21.0075) classifications, confirming regulatory equivalence for export and trade purposes.

Frequently Asked Questions (FAQ)

Q: Can the BC548BU be used as a direct replacement for the BC548A in existing designs?

A: Yes. The BC548BU is a parametric equivalent with identical electrical specifications, current ratings, voltage ratings, gain characteristics, and TO-92-3 package configuration. No circuit modifications are required.

Q: What is the primary advantage of switching from BC548A to BC548BU?

A: The BC548BU is an active product with established supply chain availability, whereas the BC548A is obsolete. This transition eliminates procurement delays and ensures long-term component availability.

Q: Are there any differences in thermal or environmental performance between these parts?

A: No. Both parts are rated for 150°C maximum junction temperature, identical power dissipation limits, and equivalent leakage current specifications.

Q: Does the TO-92-3 package remain the same for both parts?

A: Yes. Both the BC548A and BC548BU use the TO-92-3 (TO-226AA) through-hole package, ensuring mechanical compatibility with existing PCB layouts and footprints.

Q: Are there compliance or regulatory differences between the BC548A and BC548BU?

A: No. Both parts share identical ECCN and HTSUS classifications, confirming regulatory equivalence for all jurisdictions.

Q: What is the minimum DC current gain for both parts?

A: Both parts guarantee a minimum DC current gain (hFE) of 110 when measured at 2 mA collector current and 5 V collector-emitter voltage.

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