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BC559 General Purpose PNP Transistor

TheBC559transistor is ageneral-purpose PNP transistor. This transistor also comes with many different versions, if you are using this transistor as an amplifier make sure you check the gain of the transistor from the datasheet that can be found below. The Collector−Emitter Voltage(VCEO) of this device is -30V, the Collector−Base Voltage(VCBO) is -30V, and the Emitter−Base Voltage(VEBO) is -5V. Moreover, this device has a continuous collector current of -100Madc and can operate with 150°C. Additionally, thegain-bandwidthproduct of this transistor is very high so it can be used in many high-frequency applications.

When this transistor is in a biased condition, it can allow a maximum current of -100mA across CE(Collector-Emitter) Junction, this state of the transistor is called the饱和状态,and driving a load that consumes more current than -100mA may damage the device in this condition. As you already may know, a transistor is acurrent-controlled deviceso when the base current is removed the transistor becomes fully off, in this stage the transistor is working in itsCut-off Regionand the Base Emitter voltage could be around -660 mV.

BC559 Pinout Configuration

Pin Number

Pin Name




Electrons Emitted from Emitter Collected by the Collector



Controls the biasing of the transistor



Electrons emitted from the emitter into the first PN junction

Basic Overview and Features

  • Switching and Amplifier
  • High−Voltage: BC556, VCEO = -65V
  • Low−Noise: BC556, BC559
  • Complement to BC546, BC547, BC548, BC549, and BC559
  • These are Pb−Free Devices
  • Available in TO-92 Package

Note:Complete technical information can be found in theBC559 Datasheet,linked at the bottom of this page.

BC559 Equivalent Transistor


Basic Working of a Transistor

The BC559 transistor is a general-purpose PNP transistor. APNP transistoris made up of a doped N-Type material that is sanduzied in between two P-Type materials. In a PNP transistorhole are themajority charge carrierthat means the holes are emitted by the collector which is collected by the emitter, the main difference between the NPN and PNP transistor is that in an NPN transistor the flow of electrons is from collector to emitter, but in a PNP transistor the electrons run from emitter to collector, as a result, a PNP transistor turns on when there is a low or 0V on the base of the transistor. Whereas, an NPN transistor is on when a positive or high signal is applied.

How to use BC559 Transistor

晶体管是电流控制环vices so to turn them on/off a little current is needed. For the BC556 Transistor, this current is less than 2mA, as BC556 is a PNP transistor that means it will be on when the base is connected to the ground, and it will be off when a positive voltage is applied to the base of the transistor.

The simulated circuit below shows how this transistor behaves when the base of the basic circuit is connected to the ground and when it's connected to 5V of the power supply.

BC559 Transistor Circuit Diagram


  • Build simple audio circuits
  • General-purpose amplifier
  • Driver Modules like Relay Driver, LED driver, etc.
  • Amplifier modules like Audio amplifiers, signal Amplifiers, etc.
  • Darlington pair

2D Model and Dimensions

If you are designing a PCB or Perf board with this component then the following picture from the Datasheet will be useful to know its package type and dimensions.

BC559 Dimensions

Component Datasheet

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