Optical coupling in the application of switching power supply
Optical coupling circuit in the main function is to realize the photoelectric conversion, isolation, avoid the mutual interference between the input and output situation.
In the process of different switching power supply design, optical coupling effect is also different, combined with TL431 is used, is the best way to reduce cost control switching power supply industry.
One, the basic parameters of the optical coupling optical coupling structure made up of three basic parts: the leds, pervious to light insulation, photoelectric triode.
By light-emitting diodes, through insulating layer to the photoelectric triode, and realize the current transmission, isolation characteristic.
Second, the optical coupling in the application of switch power supply, optical coupling features: has to signal transmissions, so as to realize the input and the output electrical isolation, i. e. , had no effect on the output signal of the input, with strong anti-interference ability, stable performance, high reliability, high transmission efficiency, etc. The is usually used with switching power supply control circuit.
Optical coupling in the typical application of switch power supply principle: sampling from the output end, gain error signal, and then transmit the signal through the transformation, isolation to the input PWM controller IC, by adjusting the size of the PWM duty cycle, high precision voltage regulator output.