2SA1943 PNP Power Transistor : Pin Configuration & Its Applications

The 2SA1943 is a semiconductor device that amplifies or switches electronic signals and electrical power. It is typically made of semiconductor material and has at least three terminals for connecting to an external circuit.
A voltage or current applied to one pair of terminals of the transistor controls the current through another pair of terminals. A transistor can amplify a signal because the controlled (output) power can be greater than the controlling (input) power. Some transistors are still packaged individually today, but many more are embedded in integrated circuits.

Now we know what is a PNP transistor but to understand how the 2SA1943 work and where to use it we need to take a short overview of what is a PNP power transistor.
The power transistor, as the name suggests, is intended to operate at high power levels. That is, it can withstand high voltage and current.
A power transistor has a completely different structure and construction than a signal transistor, but their characteristics and operation are nearly identical.

It operates in four regions based on the forward and reverses bias conditions of the power transistor.
1. Cut off region.
2. Active region.
3. Quasi saturation region.
4. Hard saturation region.
When an NPN power transistor is connected in reverse bias, the power transistor enters cut-off mode.
Case 1: The negative terminal of a power transistor is connected to the base, and the positive terminal is connected to the emitter.
Case 2: The collector is connected to the transistor’s negative terminal, and the positive terminal is connected to the transistor’s base terminal.
In this case, the output current to the transistor’s base IBE = 0 and the output current flowing through the collector to the emitter IC = IB = 0. A small amount of leakage current flows from collector to emitter through the transistor.
The transistor is said to be inactive when the collector-base region is reverse biassed and the base-emitter region is forward biased. When IB rises, IC rises as well.
The collector-base and base-emitter connections of a transistor are connected in a forward bias pattern during the quasi saturation stage. When the collector-base and base-emitter are connected in a forward bias pattern, a hard saturation condition is achieved.

Pin Configurations

1. Base – Controls the biasing of the transistor; used to turn the transistor ON or OFF.
2. Collector – Current flows in through collector, normally connected to load.
3. Emitter – Current Drains out through emitter, normally connected to ground.