If the input current increase is not possible, then the gain of the transistor will need to be increased. So, the load current is equal to the i/p current and the gain of the transistor. So, a particular transistor cannot supply ample current to the load. The amount of i/p current to switch on a transistor is low in certain applications. So the current available to drive the load is 100 times greater than the i/p of the transistor. For a normal transistor the current gain would be normally around 100. The current gain of every transistor varies. Load current=i/p current X transistor gain When the Darlington transistor is switched ON, then the current supplies through the load to the circuit Working of a Darlington Pair Transistor What is Current Gain?Ĭurrent gain is the most important characteristic of a transistor and it is indicated with hFE. The below Darlington circuit is built with two transistors shown in the circuit diagram. For instance, the following circuit is explained below. PNP and NPN Darlington Transistors Working of a Darlington TransistorĪ Darlington transistor acts as a single transistor with high current gain, it means that a small amount of current is used from a microcontroller or a sensor to run a larger load. The max CE voltage of Darlington transistor is 450V and power dissipation can be in the range of 200mW to 250mW. The common values of max CE voltage are 30V, 60V, 80V & 100V. Darlington transistors are classified into different types by Power Dissipation, Max CE Voltage, Polarity, Min DC Current Gain and Type of Packaging. So, the i/p transistor amplifies the current even further amplifies by the o/p transistor. In this transistor, the emitter of the i/p transistor is connected to the o/p of the base of the transistor and the collectors of the transistor are wired together. This transistor is also called as a Darlington pair, contains of two BJTs that are connected to deliver a high current gain from a low base current. Darlington Transistor Darlington Transistor
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