Darlington Field Effect Transistor

China Supplier of Darlington FETs
The Darlington field effect tube is two triodes connected together, and the polarity only recognizes the front triode. The specific connection method is as follows, taking two triodes of the same polarity as an example. The collector of the front triode is connected to the collector of the back triode, and the emitter of the front triode is connected to the base of the back triode. The power of the front triode is generally smaller than that of the back triode, and the base of the front triode is the base of the Darlington tube. The emitter of the triode at the back is the emitter of the Darlington tube. The usage is the same as that of the triode, and the magnification is the product of the magnification of the two triodes.

Principle of Darlington Composite Tube

Darlington tube is also called composite tube. He connected two triodes in series to form an equivalent new triode. The magnification of this equivalent triode is the product of the original two, so it is characterized by a very high magnification. The role of the Darlington tube is generally to amplify very small signals in highly sensitive amplifying circuits, such as high-power switching circuits. In electronic circuit design, Darlington connection is often used in power amplifiers and regulated power supplies.
Under the correct applied voltage, each transistor works in the amplification region.
The collector current or emitter current of the first element is used as the base current of the second element, and the real current direction is the same.
The type of equivalent transistor is the type of the first original.

Darlington transistor circuit

Darlington circuit has four connection methods: NPN+NPN, PNP+PNP, NPN+PNP, PNP+NPN
The first two are homopolar connections, and the latter two are heteropolar connections. Homopolar connection of NPN+NPN: B1 is B, C1C2 is C, E1B2 is connected together, then E2 is E; The heteropolar connection method takes NPN+PNP as an example: set the triodes of the first triode T1 as C1, B1, E1, and the triodes of the next triode T2 as C2, B2, E2. Then the connection method of Darlington tube should be: C1 connects B2, E1 connects C2. The corresponding relationship between the pins of the equivalent triode CBE is: C=E2, B=B1, E=E1 (namely C2). (Note: The polarity of the equivalent triode CBE is the same as T1, which is NPN type.) The connection method of PNP+NPN is similar to this.

NPN PNP
Homopolar Darlington Transistor
NPN PNP is equivalent to a triode
Heteropolar Darlington Transistor