TIP122 Darlington Transistor: Symbol, Features, Applications and More
19 October 2023
Ⅱ. Overview of TIP122 transistor
Ⅲ. Symbol and footprint of TIP122 transistor
Ⅳ. Technical parameters of TIP122 transistor
Ⅴ. What are the features of TIP122 transistor?
Ⅵ. Pin configuration of TIP122 transistor
Ⅶ. How does TIP122 transistor work?
Ⅷ. What are the applications of TIP122 transistor?
Ⅸ. Advantages and disadvantages of TIP122 Darlington transistor
A Darlington is a circuit consisting of two bipolar transistors in which the emitter of one transistor is connected to the base of the other so that the current flowing through them is further amplified. The collectors of the two transistors are connected together. Because of this configuration, the current gain is much higher than if each transistor were used individually. Usually, Darlington tubes are used to amplify small signals in high-sensitivity amplifier circuits, such as high-power switching circuits. In electronic circuit design, Darlington connection is often used in power amplifiers and regulated power supplies.
TIP122 is a Darlington pair NPN transistor, which consists of a pair of Darlington transistors. Its working principle is similar to that of ordinary NPN transistors. The TIP122 has a maximum collector current of 5 amps and can operate with voltages up to 100 volts. Its DC current gain (hFE) is usually in the range of 1000 to 5000, making it an electronic device with high amplification capabilities.
Replacement and equivalent:
• BC639
• BDT63
• KSB601
• MJF6388
• NTE263
• TIP132
• 2N3055
• It is a medium-power linear switching device commonly used in low-speed switching circuits.
• It has a relatively slow switching speed and is therefore more suitable for low-frequency switching and amplification applications.
• TIP122 is generally capable of handling higher voltages and currents. Normally, its operating current is several amps, which can effectively meet the requirements of various high-power applications.
• It has a high current gain, usually between 50 and 100. This means that only a very small base current is required to control a larger collector current, thereby achieving efficient signal amplification and current control.
• TIP122 has higher amplification and lower saturation voltage drop, allowing it to withstand higher operating voltages. Therefore, it performs well in some circuits that require high power.
The TIP122 transistor consists of 3 pins:
Pin 1 (Base): This pin controls the transistor bias.
Pin 2 (Collector): Current will flow through this pin.
Pin 3 (Transmitter): This pin is used to drain current.
It works basically the same as other triodes. It consists of two PN junctions forming a structure, in which one transistor is P-type (base) and the other is N-type (emitter), with an N-type region (collector) sandwiched between the two. When forward biased, there is a forward current at the collector, and the voltage change of the control electrode will also affect the size of the collector current.
Collection electrode (C): accepts load current
Emitter (E): controls the injection of electrons in its area through the base current, thereby producing a current amplification effect
Base (B): used to control electron injection in the merging region, thereby controlling the collector current
In practical applications, TIP122 transistors are usually used as switches or amplifiers. For example, in a lighting control circuit, TIP122 can be used to adjust the brightness of LED lights. When the control voltage is applied to the base, TIP122 begins to conduct, causing the LED to light up. When the control voltage is no longer applied, TIP122 turns off and the LED light stops emitting light.
In addition to this, TIP122 can also be used as a switch to drive a motor. In this case, the base of the TIP122 is connected to the output pin of a microcontroller or other logic circuit. When the output pin is high, TIP122 will conduct and the motor will start running. When the output pin is low, TIP122 will turn off and the motor will stop.
• Voltage regulator: It is often used to construct voltage regulator circuits. This circuit helps stabilize the output voltage so that it remains constant over a variety of environmental conditions.
• Power management: TIP122 can be used as a switch or adjustment tube in various power equipment such as power adapters and power switches to realize voltage adjustment or on-off control of the power supply.
• Lighting system: It is a chip that integrates an LED driver or lighting controller. By adjusting the base voltage, it can easily realize various functions such as light brightness adjustment and switch control, thereby meeting the application needs of various scenarios.
• Motor control: TIP122 can realize switching control of the motor by adjusting the base voltage, so that the motor can start or stop when needed. In applications such as motor drives, high current and voltage tolerance enable efficient control of high-power motors.
• Switch circuit: TIP122 can be used as a switch to control the on and off of high current loads. By applying an input signal (usually the output of a microcontroller) to the base, we can control the on and off states of the output circuit, thereby achieving a switching function.
1. Advantages
• Very sensitive to current
• Can do signal amplification for a long time
• Use fewer components to make the circuit
• The input impedance it provides is very high.
• It provides lower noise compared to phototransistors containing external amplifiers.
• It provides extremely high current gain compared to a single transistor.
• By using current sources of a few milliamps, designers can drive more power-based applications.
2. Disadvantages
• Slow switching speed
• It provides maximum power consumption due to high saturation voltage.
• At certain frequencies, this design can introduce phase shifts in the negative feedback circuit.
• The leakage current of the first transistor can be amplified by the second transistor.
• Once the transistor is in the saturation region, a voltage drop occurs outside the BE terminal.
Frequently Asked Questions
1. What does a TIP122 do?
TIP122 is a commonly used NPN Darlington transistor. That is widely used in electronic circuits for various applications. This transistor is designed to amplify low-level signals and can handle high currents and voltages.
2. What type of transistor is a TIP122?
TIP122 Transistor is an NPN Darlington transistor. The Darlington transistor means there are two transistors in one pack joined to increase gain at the output.
3. What is the operating temperature range of TIP122?
The operating temperature of TIP122 ranges from -65°C to 150 °C.
4. When is the TIP122 transistor commonly used?
The TIP122 is often used in applications where high-current switching is required, such as motor control, relay drivers, and power amplification.
5. What is the difference between TIP120 and TIP122?
TIP120 is a 60V 5A NPN Darlington with an Emitter-Base Voltage of 5V and Base Current (DC) of 120 mA. TIP121 and TIP122 are the 80V and 100V versions. The TIP122 will work as a replacement for the TIP120. TIP31 is a 40V 5A NPN.
