BC558 transistor

BC558 transistor
BC558 transistor

BC558 specification

  • BC558 is a general-purpose PNP transistor device
  • Collector to emitter voltage is -30V
  • Collector to base voltage is -30V
  • Emitter to base voltage is –5V
  • Collector current is -100mA
  • Power dissipation is 500mW
  • DC current gain is 125 to 800hFE
  • Current gain-bandwidth transition frequency (FT) is 100MHz
  • Junction temperature is between -65 to 150℃
  • Thermal resistance, junction to ambient is 250℃/W
  • Collector to emitter saturation voltage (VCE (SAT)) is -60 to -650mV
  • Noise figure is 2 to 10dB
  • Low current
  • Low voltage
  • AF driver stages
  • Low power output stages

BC558 Pinout

BC558 Pinout
BC558 Pinout
Pin Number Pin Name Description
1 Collector Current flows through the emitter terminal
2 Base Base terminal is the trigger for the transistor
3 Emitter Current flow through the collector 


BC558 transistor package

The BC558 PNP general purpose transistor has a TO-92 package, it is a low-power transistor device.

TO-92 package is made of epoxy/plastic material, which makes the transistor more heat resistant and compact.  

BC558 PNP transistor electrical specification description/application

In this section, we try to explain the electrical specifications of the BC558 PNP transistor, this detailed explanation will help us know more about this device for the replacement process.

Voltage specs

The voltage specs of BC558 PNP transistor are collector to base voltage is -30V, collector to emitter -30V, and emitter to base voltage is -5V, this is the terminal voltage values.

The collector to emitter saturation voltage value is -60 to -650mV, it is the switching voltage of this transistor.

The voltage specifications of the BC558 PNP transistor indicate that it is a low voltage device which having project-based applications.

Current specs

The collector current value of the BC558 PNP transistor is -100mA, and the current value of the device shows the load capacity.

Dissipation specs

The power dissipation of the BC558 PNP transistor is 500mW, the TO-92 package provides a moderate range of dissipation.

Current gain specs

The DC current gain value of the BC558 PNP transistor is 125 to 800Hfe, the gain value mainly indicates the amplification capacity of the device.

Transition frequency

The bandwidth transition frequency value of the BC558 PNP transistor is 100MHz, it is the frequency range of the transistor.

Junction temperature/ storage temperature

 The junction temperature/ storage temperature of -65 to 150℃, and the heat capacity of the transistor are mainly dependent on the case.

Thermal resistance

The thermal resistance of junction to ambient value is 250K/W

Noise figure

The noise figure value of BC558 transistor is 2 to 10dB

BC558 transistor DATASHEET

If you need the datasheet in pdf please click this link

BC558 equivalent

The transistors BC557, BC560, 2N3906, BC338, A1015, BC556, BC157, and BD140 are the equivalent devices of the BC558 transistor. Each of these transistors has similar electrical specifications.

Before the replacement, we need to verify the voltage and PINOUT details, because at the circuit level both these specs will become more dangerous.

BC558 PNP complementary pair

The BC558 PNP transistor has BC548 NPN transistor complementary pair, each of these transistor devices has a similar and opposite set of electrical specifications.

SMD versions of BC558 transistor

The BC858 (SOT-23), BC858 (SOT-323), and BC859W (SOT-323) are the SMD version transistor device of BC558, the power dissipation specs of these transistors are different from BC558.

BC558 vs BC557

In the table, we listed the electrical specifications of BC558 vs BC557 transistor, this comparison will help us to know about the device.

Collector to base voltage (VCB)     -30V   -50V
Collector to emitter voltage (VCE)-30V-45V
Emitter to base voltage (VEB)-5V-5V
Collector to emitter saturation voltage (VCE (SAT))-60 to -650mV0.30 to 0.65V
Collector current (IC)-100mA-100mA
Power dissipation500mW500mW
Junction temperature (TJ)-65 to +150°C-65 to +150°C
Transition frequency (FT)100MHz150MHz
Gain (hFE)125 to 800hFE75 to 800hFE
Noise figure2 to 10dB10dB

BC558 applications

  • Signal amplifier
  • Preamp circuit
  • Relay driver circuit
  • Motor controller
  • Buffer circuit
  • H-bridge circuit
  • Multi-vibrator circuit
  • Current mirror circuit
  • Comparator
  • Oscillator circuit

Characteristics curves of BC558 PNP transistor

DC current gain characteristics of the BC558
DC current gain characteristics of the BC558

The figure shows the DC current gain characteristics of the BC558 transistor, the graph plots with DC current gain vs collector current.

At constant collector to emitter voltage, the gain value starts from the maximum value and becomes constant, then dip at the end.  

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