KSP2222A Transistor : Pin Configuration & Its Applications

The function of the KSP2222A transistor is similar to the BC547 NPN transistor with a variation in collector current and the power dissipation properties. This transistor allows the continuous collector current IC of the maximum of 600 milli Amps with a power dissipation of 625 mW.

It is widely used to drive the circuit’s heavy loads when compared to BC547 transistors. The open collector-to-emitter VCEO is 40 Volts. This is the best KSP2222A NPN transistor to switch loads with a high current. This article gives a brief description of the KSP2222A transistor with a circuit diagram.

What is the KSP2222A Transistor?

The KSP2222A transistor is a 3-pin Bi-polar junction NPN transistor. When the base terminal or pin is connected to the ground, the emitter and collector terminals of the NPN transistor are opened and go to reverse biased conditions. When the input voltage signal is applied to the base terminal, the transistor is forward biased and starts conducting.

The capacity of the transistor to amplify the voltage signal is determined from its gain, which has a value of 100 to 300. The current allowed by the collector terminal is a maximum of 600 mA. So, multiple loads that consume more than 600 mA cannot be connected. For transistor biasing, the input supply given to the base terminal is limited to 5 mA, that is base current IB.

The fully biased NPN transistor allows the maximum current of 600 mA flow over the collector terminal and emitter terminal. This is called the saturation region, which allows a maximum typical voltage of 40 V and 600 mV across the collector-to-emitter (VCE) or base-to-emitter (VBE) terminals. By removing the base current IB, the transistor goes to reverse biased condition and it is in fully OFF condition. This is called the cut-off region.

Pin Configuration/Pin Diagram

This is a 3-terminal Bi-polar NPN transistor. The KSP2222A transistor pin configuration/pin diagram is illustrated below. The equivalent schematic symbol of the KSP2222A transistor is shown in the figure below. It is designed in the To-92 package with 3 leads or terminals pointing downwards as shown below.

Schematic Symbol
Schematic Symbol

When the base terminal of the transistor is connected to the ground, then it is reverse biased and no current flows through the collector and emitter terminals and are open. When the base terminal of the transistor is connected to the input supply, then it is forward biased (closed) and allows the current flow through the collector and emitter terminals.

KSP2222A Transistor Pin Out
KSP2222A Transistor Pin Out
  • Pin-1 (Emitter): The current is drained out through this terminal
  • Pin-2 (Base): The transistor biasing is controlled by this pin
  • Pin-3 (Collector): The input current flows through this terminal.


The following are the KSP2222A Transistor specifications

  • This is a Bi-polar NPN high current transistor and manufactured in To-92 package type.
  • The range of DC current gain (hFE) is between 100 to 300
  • The maximum Emitter-to-Base Voltage (VBE) is 6 Volts
  • The maximum collector current (IC) is 600 milliAmps (continuous)
  • The maximum Collector-to-Emitter Voltage (VCE) is 40 Volts
  • The maximum Base Current IB is 5 milliAmps
  • The maximum Collector-to-Base Voltage is 75 Volts
  • The total power dissipation at the collector terminal is 0.625 Watts
  • The maximum noise figure is 4 dB
  • The transition frequency range is of maximum 300 MHz
  • The range of storage junction and operating temperature is -55°C to +150°C

Circuit Diagram/How to Use

The KSP2222A is an NPN bipolar general-purpose transistor used in various applications and it is an equivalent and direct substitute to the 2N2222A transistor. The properties of both NPN transistors are the same with a difference in collector current Ic and the Collector-to-emitter voltage VBE.

In general, this transistor is used as an amplifier and switch. The circuit diagram/how to use the KSP2222A transistor as an amplifier and switch is illustrated below.

KSP2222A Transistor Working as a Switch

The basic and default function of the transistor is to work as a Switch. It controls the switch with the help of electrical signals and it is just like a mechanical switch. Consider an example with a circuit diagram shown in the figure below, to switch ON and OFF the motor or load by using the KSP2222A NPN transistor.

Transistor as a Switch
Transistor as a Switch

Here, the base resistor R1 is used to drive the NPN transistor with a limited base current. This helps to avoid transistor damage. The R2 resistor is connected to the motor, which limits the current flowing through the collector terminal.

The KSP2222A NPN transistor starts conducting only when the voltage across the emitter and base terminals reaches and exceeds the threshold voltage, that is 6 Volts. The resistor used in the circuit design should be selected based on the application.

KSP2222A Transistor Working as an Amplifier

Generally, transistors are most widely used as amplifiers because their gain (hfe) is used in amplifying the current or voltage. The circuit diagram of a common emitter (CE) amplifier by using the KSP2222A transistor is shown below. Even though there are different amplifier circuits, the CE mode amplifier is commonly used to amplify the voltage signal with a low-frequency range (for example audio signals).

In the above circuit, the base pin and the emitter pin of the NPN transistor are connected to the same voltage (that is supply voltage) and they are connected to the ground with two resistors R3 and R4. The input voltage is applied to the base terminal to bias the NPN transistor. The resistors R6 & R4 form a potential divider network. and for filtering, C1 & C2 capacitors are used.

Transistor as an Amplifier
Transistor as an Amplifier

The values of the capacitors and the resistors used in the circuit are assumed based on the type of application and NPN transistor used. The main disadvantage of this amplifier circuit is, it is not suitable for high-frequency voltage signals. In such cases, op-amps (a group of transistors packed together) are used for amplification very quickly and easily.

Where to Use/Applications

The applications of KSP2222A transistor are,

  • Used as an NPN transistor for general purposes.
  • Used to switch high current loads of up to 600 mA.
  • Used to control the speed of motors
  • Used in Darlington pair.
  • Used in several applications of switching
  • Used in rectifier and inverter circuits.

Alternative KSP2222A Transistor

BC636, BC549, BC639, BC547, 2N3045, 2N2369, 2N3906, 2N3904 and 2SC5200 are the alternative KSP2222A Transistors.

The 2N2222A Transistor is the equivalent or complementary of the KSP2222A Transistor.

The replacement or equivalent of various NPN transistors like MPSW01AG, MPS651G, NTE123AP, MPS2222AG, MPSW01A, 2SC1008, BC538, BC547, MPS650, MPS651, MPS650G, P2N2223AG, 2N4401, PN2222A, PN2219A, KN2222A, P2N2222A, KSC1008, MPS2222A, KTN2222A, ZTX450 or PN4033.

Thus, this is all about an overview of the KSP2222A transistor datasheet – definition, pin configuration/pin diagram, specifications, circuit diagram/how to use, where to use/applications, and its alternatives. Here is a question for you, “What is an advantage of using the KSP2222A transistor instead of 2N2222A transistor?”.