BC548 Transistor: Pinout, Datasheet, and Equivalents

The BC548 is a general-purpose NPN bipolar junction transistor (BJT) widely used in low-voltage electronics. It is the 30V sibling to the popular BC547, making it ideal for standard 5V, 9V, and 12V circuits where high voltage handling is not required. This guide covers the pinout configuration, technical specifications, and how it compares to the BC547.

BC548 Pinout Diagram

The BC548 uses the industry-standard TO-92 package. The pin configuration is identical to the BC547 series.

BC548 Pinout: NPN BJT transistor, TO-92 package, 3-pin through-hole mount

BC548 TO-92 package pinout diagram
TO-92 Package View
NPN transistor schematic symbol
NPN Circuit Symbol
Pin No Pin Name Function
1 Collector (C) Current In
2 Base (B) Control / Bias
3 Emitter (E) Current Out (Ground)

BC548 Datasheet and Technical Specifications

Key electrical characteristics and maximum ratings for the BC548 transistor at 25°C ambient temperature.

View BC548 Datasheet (PDF)
Parameter Value Description
VCEO 30V Max Collector-Emitter Voltage
VCBO 30V Max Collector-Base Voltage
VEBO 5V Max Emitter-Base Voltage
IC 100mA Max Collector Current
Pd 625mW Max Power Dissipation
hFE 110-800 DC Current Gain (varies by variant)
fT 150MHz Transition Frequency (Min)
VCE(sat) 250mV Saturation Voltage
Temp Range -55°C to +150°C Operating Temperature
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Primary Usage: The BC548 is strictly for low-voltage applications (under 30V). For circuits operating near or above 30V, use the BC547 instead.

BC548 Equivalent and Replacement Transistors

The following NPN transistors share the TO-92 package and have similar or better voltage/current ratings, making them suitable replacements.

Part Number Manufacturer VCEO IC hFE
2N3904BU onsemi 40V 200mA 100
2SD1616A(RANGE:200-400) JSCJ 60V 1A 200
ZTX455 DIODES 140V 1A 100
ZTX694B DIODES 120V 500mA 400
ZTX450 DIODES 45V 1A 100
2N4401BU-HXY HXY MOSFET 40V 600mA 300
KTC3202-Y-HXY HXY MOSFET 40V 600mA 300
KSP8099TF-HXY HXY MOSFET 160V 600mA 200
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BC548 Variants: A, B, and C

Like the BC547, the BC548 is manufactured in three gain groups. The letter suffix determines the DC Current Gain (hFE) range.

Variant hFE Range Usage Case
BC548A 110 - 220 General Switching
BC548B 200 - 450 Signal Amplification (Most Common)
BC548C 420 - 800 High Gain Pre-Amplifiers
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If you're looking for the BC548CTA transistor produced by onsemi, please check out its datasheet and specifications here.

BC548 vs BC547: What's the Difference?

These two transistors are physically identical and often confused. The only difference is the breakdown voltage.

Specification BC548 BC547
Max Voltage (VCEO) 30V 45V
Max Current (IC) 100mA 100mA
Application 5V, 9V, 12V Circuits Up to 24V/36V Circuits
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Summary: You can always use a BC547 to replace a BC548. However, you should not use a BC548 to replace a BC547 if the circuit voltage exceeds 30V.

Common BC548 Applications

Due to its low cost and availability, the BC548 is used in basic educational and consumer electronics:

  • Relay Drivers: Switching small 5V/12V relays.
  • Sensor Circuits: Amplifying signals from LDRs or thermistors.
  • Audio Preamps: The 'B' and 'C' variants are excellent for microphone pre-amplifiers.
  • Logic Gates: Building basic NOT/AND gates in educational labs.

Frequently Asked Questions

Q: What is the PNP complement of BC548?
A: The PNP complement is the BC558. They are often used together in push-pull amplifier circuits.
Q: Can I use BC548 for Arduino projects?
A: Yes, absolutely. The BC548 is perfect for 5V Arduino logic to switch loads like LEDs or small fans (under 100mA).
Q: Is BC548 obsolete?
A: No, while it is an older design, it is still in active production by major manufacturers like OnSemi, Diotec, and CDIL.

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