BC638 transistor

BC638 transistor
BC638 transistor

BC638 specification

  • BC638 is an epitaxial silicon PNP transistor device
  • Collector to emitter voltage (VER) is -60V
  • Collector to emitter voltage (VES) is -60V
  • Collector to emitter voltage (VEO) is -60V
  • Emitter to base voltage is –5V
  • Collector current is -1A
  • Pulsed collector current is -1.5A
  • Base current is -100mA
  • Power dissipation is 1W
  • DC current gain is 25 to 160hFE
  • Current gain-bandwidth transition frequency (FT) is 100MHz
  • Junction temperature is between -65 to 150℃
  • Thermal resistance, junction to ambient is 125℃/W
  • Collector to emitter saturation voltage (VCE (SAT)) is -0.5V
  • Output capacitance is 9pF
  • HIGH transition frequency

BC638 Pinout

BC638 Pinout
BC638 Pinout
Pin Number Pin Name Description
1 Emitter  Current flows through the emitter terminal
2 Collector Current flow through the collector 
3 Base Base terminal is used to trigger the transistor


BC638 package

The BC638 PNP transistor had a TO-92 package, it is a three-terminal transistor package.

TO-92 package is made with epoxy/plastic material which provides higher temperature capacity and compactness.

The shape and size of the TO-92 package support the BC638 transistor used in small circuits.

BC638 PNP transistor electrical specification description/application

In this section, we try to explain the electrical specifications of the BC638 PNP transistor. This description will help to know more about this device for the application.

Voltage specs

The voltage specs of BC638 transistor are collector to emitter VER is -60V, VES is -60V and VEO is -60V, emitter to base voltage is -5V, this is the terminal voltage specifications.

The collector to emitter saturation voltage is -0.5V, which is the individual voltage value of both terminals, normally it is less than the base voltage.

The overall voltage of the BC638 transistor shows that it is a general purpose multiple application transistor devices.

Current specs

The collector current value is -1A, and the current value indicates the load capacity of the device.

The current values of the BC638 transistor show that they had more switching applications.

Dissipation specs

The power dissipation of the BC638 PNP transistor is 500Mw, it is the product of the voltage and current at the transistor.

Current gain specs

The DC gain value of BC638 PNP transistor is 1W, this value is very important for applications like amplifiers and regulators.

Transition frequency

The transition frequency value of the BC638 PNP transistor is 100MHz, this shows the frequency range of the transistor device.

Junction temperature/ storage temperature

 The junction temperature/ storage temperature of -65 to 150℃.

Thermal resistance

The thermal resistance of junction to ambient value is 125℃/W

Output capacitance

The output capacitance of the BC638 transistor is 9pF

BC638 transistor DATASHEET

If you need the datasheet in pdf please click this link

BC638 equivalent

The transistor devices such as BC640, KSA931, BC557, BC559, BC107, and BC108 are the equivalent transistors of BC638. Each of these transistors has a similar set of electrical specifications.

Before the replacement process of this transistor, we need to check and verify the electrical specifications such as current, voltage, and PINOUT details.

BC638 PNP complementary pair

The BC637 NPN transistor is the complementary pair of the BC638 transistor, all of the specifications are the same and opposite, so we can use it in complementary pair circuit applications.

BC638 vs BC557

We listed the electrical specifications of BC638 and BC557 transistor

Collector to emitter voltage (VCEO)-60V-45V
Collector to emitter voltage
Collector to emitter-60V
Collector to base voltage (VCB)--50V
Emitter to base voltage (VEB)-5V-5V
Collector to emitter saturation voltage (VCE (SAT))-0.5V0.30 to 0.65V
Collector current (IC)-1A-100mA
Power dissipation1W500mW
Junction temperature (TJ)-65 to +150°C-65 to +150°C
Thermal resistance125℃/W250℃/W
Transition frequency (FT)100MHz150MHz
Gain (hFE)25 to 160hFE75 to 800hFE
Output capacitance9pF6dB

Both of these transistors’ electrical specifications show that voltage specifications are almost identical for these two transistors, other than that every electrical spec is different and double that of the BC638 transistor.

BC638 applications

  • Amplifier circuit
  • Switching applications
  • Signal amplifier
  • Lighting systems
  • Microphone preamp circuit

Characteristics curves of BC638 PNP transistor

static characteristics of the BC638
static characteristics of the BC638

The figure shows the static characteristics of the BC638 transistor, the graph plots with collector current vs collector to emitter voltage.

The characteristics curves plot at different base current values, at the initial stage it increases a slight curve and becomes constant with respect to voltage value.

DC current gain characteristics of the BC638
DC current gain characteristics of the BC638

The figure shows the DC current gain characteristics of the BC638 transistor, the graph plots with dc current gain vs collector current.

At constant collector to an emitter voltage value, the DC gain increases from a higher value and becomes constant, and decreases at the end.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *