The dual audio power amplifier integrated circuit is composed of two fully symmetrical OTL power amplifying circuits. When VCC=12V, it can output 2*4.5W audio power (RL=4 ohms). The power supply voltage range is wide, and 7~16V can work normally. The voltage balance of the circuit has high channel balance, the blasting noise level at the time of starting is low, and the high frequency compensation capacitor is set inside the circuit, which improves the stability of the high frequency and reduces the number of external components. In addition, the ripple filter terminal 6 pin can also be used as a squelch terminal. Bi Directions Thyristor (Triac) Bi Directions Thyristor (Triac) is equivalent to the antiparallel connection of two unidirectional thyristors, but only one control pole. Bi Directions Thyristor,Electronic Components Triac,Power Thyristor For Inverter,Silicon Power Bipolar Transistors YANGZHOU POSITIONING TECH CO., LTD. , https://www.cnpositioning.com
The XG536 ​​is available in a single in-line 12-pin plastic package. This circuit is interchangeable with BA536 produced by Japan Dongjiang Electric Co., Ltd. Domestically produced by Sichuan New Optoelectronics Factory. The main electrical parameters of XG536 ​​are as follows: Vcc=12v, RL=4Ω, RNF=120Ω; output power: 4.5W; quiescent current: 40mA; closed loop voltage gain: 45dB; harmonic distortion: 0.3%; output noise voltage 0.7mV; Output impedance: 100Ω. An example of the application of the XG536 ​​for stereo power amplification is shown in Figure 7-73.
The role of several components and the choice of 1C1 and C11 for the bootstrap capacitor. The recommended value is 100μ, the capacity is small, the low-frequency rated power will be reduced, and the distortion will increase. 2C2 and C12 are output coupling capacitors. The recommended value is 1000μ, and the capacity is small, which also reduces the power at the low end and increases the distortion. 3C3 and C13 are input coupling capacitors. The recommended value is 2.2μ. If the capacitance is too large or too small, it is easy to cause noise. 4RNF has no feedback resistor. The main decision is the size of the closed loop gain. 5C5 is the national filter capacitor. The recommended value is 47μ. If the capacitance is too small, the ripple suppression ratio will be deteriorated. If the capacity is too large, the startup time will be increased, and the startup blasting sound can be reduced. 6C6 and C16 are damping capacitors. Polyester film capacitors are recommended. 
Bidirectional thyristors are made of N-P-N-P-N five-layer semiconductor materials, and three electrodes are also derived from the outside. Its structure is shown in the figure. Bi-directional thyristor volt-ampere characteristic curve Since the forward and reverse characteristics of the bidirectional thyristor are symmetrical, it can be turned on in any direction and is an ideal AC switching device.