2SA1943 PNP Power Transistor : Pin Configuration & Its Applications

The high power 2SA1943 PNP power transistor is originally designed by Toshiba to use commonly in AF amplifiers or audio circuits based on high power due to maximum collector current & current gain. At present, this transistor has been used by replacing it with TTA1943 transistor, however, it is found in different applications because of being cloned by other different manufacturers around the world.


This 2SA1943 PNP power transistor is simply used to switch or change electronic signals as well as electrical power. This article discusses an overview of the 2SA1943 PNP power transistor and its working with applications

What is 2SA1943 PNP Power Transistor?

The 2SA1943 PNP power transistor plays a key role in designing amplifiers. Generally, most of the amplifiers use a push-pull circuit which is the same as a Class B amplifier. This amplifier can be built with two transistors like PNP and NPN where the 2SA1943 transistor is PNP type and 2SE5200 transistor is NPN type. So the combination of two transistors is used together frequently to design amplifiers with high power.

2SA1943 PNP Power Transistor
2SA1943 PNP Power Transistor

This power transistor is designed with a semiconductor material generally with as a minimum of three terminals which are used for connecting an external circuit. Once current or voltage is applied to one pair of terminals in this transistor, then it controls the flow of current in the other pair of terminals because the output power is higher than the input power.

When these transistors work with high collector current and maximum switching frequency then they get heat very quickly. So better to use a heat sink to avoid this heat problem. These PNP power transistors are used to design stereo systems with 200W or above of power, frequency ranges from 5Hz to 100 kHz & 0.75Vrms of sensitivity. The less signal to noise ratio and total harmonic distortion will make this transistor to use in audio-based applications.

Pin Configuration

The pin configuration of the 2SA1943 PNP power transistor & its symbol are shown below. This PNP power transistor includes three terminals which are discussed below.

2SA1943 PNP Transistor Pin Configuration
2SA1943 PNP Transistor Pin Configuration
  • Pin1 (Base): The transistor biasing is possible through this terminal by turning ON or OFF this transistor
  • Pin2 (Collector): The current supplies through this terminal which is connected to load normally
  • Pin3 (Emitter): The flow of current drains out using this terminal which is connected to GND normally.

Features & Specifications

The features and specifications of the 2SA1943 transistor include the following.

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  • Package is To-264
  • Mount type is Through Hole
  • Number of terminals – 3
  • Polarity is PNP with medium power
  • Process technology is advanced
  • The error voltage is less
  • Switching speed is very fast
  • Full-voltage based operation
  • It handles with high current and high power
  • DC Current Gain or hFE ranges from 55 – 160
  • Collector current or IC is 15A
  • Collector to emitter voltage or VCE is 230Volts
  • Collector to base voltage or VCB is 230Volts
  • Emitter to base voltage or VBE is 5Volts
  • The substitution frequency is 30 MHZ.
  • Operating & storing temperature range is -55 to +150 °C

Complementary NPN transistors are TTC5200, 2SE5200, 2SA1962, 2SA2151A-O, KTA1962A, KTA1943, 2SA2151A-Y, 2SA2151A-P, FJA4213, KTA1943A, KTA1962, , FJL4215, KTA1943, MJW1302AG or MJW1302. Equivalent PNP transistor is TTA1943. Transistors from same family are TTA1943, TTC5200, 2SA1943N & 2SC5200N.

Sometimes, the marking of the 2SA1943 PNP power transistor does not contain the prefix like 2S”, so this transistor may be marked like “A1943”.

How to use 2SA1943 PNP Power Transistor?

The amplifier circuit using three transistors is shown below. The required components to build this circuit mainly includes three transistors like 2SC5200 (NPN), 2SA1943 (PNP) & BD139 (NPN), two D1&D2 diodes like Diode 1N4007, Electrolytic capacitors like C1 is 2.200uF to 63V, C2 is 4.7uF to 25V, Resistors like R1 & R2 are .22 ohms with 5W, 1 K Ohm resistor, 100K resistor, potentiometer 10K ohm, connecting wires, etc.

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The designing of this circuit is very simple by using three transistors that can drive a 600W RMS Subwoofer speaker. The testing of this circuit can be done through two stages wherein the first stage, a non-symmetrical power supply with 24V is used and in the second stage, 30V with non-symmetrical power is used.

Amplifier Circuit using 2SA1943 PNP Power Transistor
Amplifier Circuit using 2SA1943 PNP Power Transistor

The primary stage is known as the pre-amplification stage which is simultaneously used to enhance the output stage. h stage can be formed by a BD139 transistor with medium power, which supports up to 80 volts, 1.5A of current, and 12.5Watts of power.


The second stage is known as the power stage, which can be formed through both NPN and PNP complementary transistors like 2SC5200 & 2SA1943 with high fidelity, 100W of power & supports 15 Amps of collector current. If we want to use 20Volts or above to any amplifier circuit, so need to use a power transistor with a heat sink and continuously use the amplifier, then they will heat up.

Where to use/Applications

The applications of the 2SA1943 PNP power transistor include the following.

  • The 2SA1943 PNP power transistor plays a major role in designing amplifiers
  • Most of the amplifiers use a push-pull circuit which is alike to a Class B amplifier which uses both the PNP & NPN transistors. Here, the NPN transistor is 2SE5200 whereas NPN is 2SA1943.
  • So, in high power amplifiers, both the 2SE5200 & 2sa1943 transistors are used together frequently.
  • These transistors are used in Stereo systems.
  • This transistor is used in audio frequency amplifiers
  • AF or RF circuits
  • Used in less slew rate devices
  • Used in Push-Pull configuration based circuits
  • High current switching loads upto 15A
  • It can be used as a medium power switches
  • It is used in switching circuits where a high current is necessary.
  • Used as an intermediate Power switch.

Please refer to this link to know more about the 2SA1943 PNP power transistor datasheet

Thus, the 2sa1943 transistor is designed by Toshiba which consumes high power and high gain current, so used in AF amplifiers and audio circuits. The main difference between 2SA1943 & 2SC5200 transistors is; 2SA1943 is a PNP transistor and it is complementary to NPN 2SC5200 where 2SC5200 NPN transistor has collector to emitter terminal voltage is 230V. Here is a question for you, what are the main drawbacks of the 2SA1943 PNP power transistor?

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