BC549 Transistor: Pinout, Equivalent and Difference

BC549 is a general purpose NPN transistor, it is most common in hobby circuits and switching circuit. in this post i’m sharing the pinout configuration, proper replacement of the transistor and comparison between the BC549 and BC547 transistor. This transistor is very sensitive so it can able amplify the small input signal to large current.

BC549 Transistor Pinout

If you are holding the flat surface of this transistor in front, the left side pin is collector, center pin is base and right side pin is emitter. The detailed pinout configuration is given below in a table,

Pin Number	Pin Name
1	Collector
2	Base
3	Emitter

Table 1: BC549 Transistor pinout configuration

BC549 Transistor Specifications

Parameter	Symbol	Value / Range	Unit
Collector-Base Voltage	VCBO	30	V
Collector-Emitter Voltage	VCEO	30	V
Emitter-Base Voltage	VEBO	5	V
Collector Current (DC)	IC	100	mA
Peak Collector Current	ICM	200	mA
Peak Base Current	IBM	200	mA
Total Power Dissipation	Ptot	500 (at ≤25 °C ambient)	mW
Junction Temperature	Tj	150	°C
Operating Temperature	Tamb	-65 to +150	°C
Thermal Resistance (Junction-Ambient)	Rth j-a	250	K/W
DC Current Gain (hFE)	hFE	420 – 800 (at IC = 2 mA, VCE = 5 V)	–
Collector-Emitter Saturation Voltage	VCEsat	Max 600 (at IC = 100 mA, IB = 5 mA)	mV
Base-Emitter Saturation Voltage	VBEsat	Max 900 (at IC = 100 mA, IB = 5 mA)	mV
Transition Frequency	fT	100	MHz
Noise Figure	F	Max 4 (at IC = 200 µA)	dB
Package Type	–	TO-92 (SOT54)	–

Table 2: Transistor specifications

Equivalent Transistor for BC549

BC547
BC548
2N2222
2N3904
BC337

Difference Between BC549 vs BC547

Parameter	BC549	BC547	Difference
Maximum Collector Emitter Voltage (VCEO)	30V	50V	BC547 can handle higher voltages
Maximum Collector-Base Voltage (VCBO)	30V	50V	BC547 again rated for higher voltage
Maximum Collector Current (IC)	100 mA	100 mA	Same for both
Power Dissipation (Ptot)	500 mW	500 mW	Same for both
DC Current Gain (hFE)	200-800	110-800	Similar ranges (depends on grade: A/B/C)
Noise Figure	Low (≈ 2-4 dB)	Higher than BC549	BC549 is designed for low-noise operation
Transition Frequency (fT)	100 MHz	150 MHz	BC547 may offer slightly higher speed
Package Type	TO-92	TO-92	Same
Application Focus	Low-noise audio, RF stages	General-purpose switching, amplification	Use BC549 where low noise matters