The 2SA1943 is a high power PNP transistor originally from Toshiba. Due to its high current gain and collector current it is very commonly used in High power audio circuits or AF amplifiers. But now the Transistor is absolute from Toshiba and it has been replaced with TTA1943, but still the good old 2SA1943 can still be found in the market since it is still being cloned by other manufacturers.
USES OF 2SA1943 Transistor
The 2SA1943 is mainly used in amplifier designs. Most amplifiers employ a push-pull circuit similar to that of Class B amplifier, which requires an NPN and PNP transistors. The 2SA1943 is a PNP Transistor and it also has its complementary 2SE5200 which is a NPN type transistor. Both of these transistors are often used together to design high power Amplifiers.
Since the Transistors work with high switching frequency and high collector current, they tend to heat up very fast, hence they are always used along with a heat sink. Note that the heat sink will also act as the collector pin of the transistor and hence heat sink should be isolated from the rest of the circuit.
These transistors are commonly used to build Stereo systems that are rated for 200W or above, they can respond to frequency from 5Hz to 100kHz and has a very good sensitivity of 0.75Vrms. They have very less signal to noise ratio and less total harmonic distortion making it ideal for audio applications.
click here to download the pdf of the datasheet