What is the NPN Darlington transistor switch configuration?

What is the NPN Darlington transistor switch configuration?

The above NPN Darlington transistor switch configuration shows the Collectors of the two transistors connected together with the Emitter of the first transistor connected to the Base terminal of the second transistor therefore, the Emitter current of the first transistor becomes the Base current of the second transistor switching it “ON”.

Is a transistor an open switch or closed switch?

If the transistor is operated in the saturation region then it acts as closed switch and when it is operated in the cut off region then it behaves as an open switch. The transistor operates as a Single Pole Single Throw (SPST) solid state switch. When a zero input signal applied to the base of the transistor, it acts as an open switch.

What is the VCE of a transistor with no resistance?

In “theory,” at this point the collector/emitter voltage drop (VCE(sat)) should be zero if the transistor was working like an SPST mechanical switch. Remember, a mechanical switch has no voltage drop when flipped to the on state because there’s no resistance between the contacts.

Can a bipolar transistor be used as a switch?

Similarly, for PNP transistors, the emitter potential must be –ve with respect to the base of the transistor. Then we can define the “cut-off region” or “OFF mode” when using a bipolar transistor as a switch as being, both junctions reverse biased, IC = 0, and VB < 0.7v.

What is the difference between single bipolar and Darlington transistors?

One difference to consider when using Darlington transistors over the conventional single bipolar types when using the transistor as a switch is that the Base-Emitter input voltage ( VBE ) needs to be higher at approx 1.4v for silicon devices, due to the series connection of the two PN junctions.

Can a bipolar junction transistor be used as a switch?

The Bipolar Junction Transistor (BJT) as a Switch. Chapter 4 – Bipolar Junction Transistors. Bipolar junction transistors (Also known as BJTs) can be used as an amplifier, filter, rectifier, oscillator, or even a switch, which we cover an example in the first section.

What is the beta value of a Darlington transistor?

The overall current gain Beta (β) or hfe value of a Darlington device is the product of the two individual gains of the transistors and is given as: So Darlington Transistors with very high β values and high Collector currents are possible compared to a single transistor switch.