Overview: TOP414G internal structure and working principle Project Touch Panel,Interactive Panel Capacitive Touch,Mounted Flat Panel Touch Screen,Touch Flat Panel ESEN Optoelectronics Technology Co., Ltd, , https://www.esenlcd.com
The application of modern electronic technology is rapidly developing, and the requirements for electronic instruments and equipment are more secure and reliable, and the functions are constantly increasing. The degree of automation is getting higher and higher in use. In terms of volume, it is becoming smaller and smaller. This makes it even more important to use a switching regulator with many advantages. Therefore, switching power supply has been widely used in computer, communication, aerospace, color TV, etc., and has played a huge role [1]. The -48V to 5VSTB solution uses the most typical single-ended flyback mode in medium and small power switching power supplies. The DC/DC conversion in the circuit uses POWERINT's wide-range input three-pin PWM switch TOP414G, which has a maximum operating frequency of 132KHz. The maximum duty cycle is 70%. 
The internal functional block diagram of the TOP414G is shown in Figure 1. A high-voltage MOS switch tube (the MOS tube on the right side of Figure 1) is integrated inside. The working principle is to adjust the conduction and cut-off time of the high-power MOS tube through the internal control circuit through the feedback signal (IFB) sampled by the Control pin (duty) Ratio), thereby controlling the output of its drain to achieve the purpose of stabilizing the output voltage of the circuit. Here is its pin definition:
C pin: error amplification and feedback current input pin, used to adjust the duty cycle of the internal MOS switch tube. S pin: the source of the internal MOS switch tube, which is the reference ground of the DC/DC pre-stage circuit.
D pin: The drain of the internal MOS switch, which provides internal bias current to the chip when the circuit is started. After the circuit is stabilized, the bias current is provided by the Vc of the Control pin and used as the internal current sampling pin. Primary flow restriction.
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