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Jiangsu Aisikai Electric Co.,Ltd.(CE, CCC, ISO9001)

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Light switch power supply decoupling

Switching power supply is the use of modern power electronic technology, control switch tube opened and shut off time ratio, to maintain stable output voltage of a power supply, switching power supply with the characteristics of small, light weight and high efficiency are widely used almost all of the electronic equipment. In switching power supply voltage regulator is usually USES the negative feedback, through to the output voltage sampling comparison, to adjust the duty ratios of the switch tube to achieve the objective of the voltage regulator


Package content


The input power, as a general rule, be high pressure, output is generally low pressure, in order to ensure safety, proposed to the output feedback signal through the linear optical coupling isolation is coupled to the input of pulse width modulation.


Common can be used for the linear output transistor switching power supply decoupling are: light TLP785, TLP185, TLP291, PC817, PS2801, etc.


Application of the principle


Output voltage sampling done by R3 and R4, TL431 reference pole between R3 and R4, output is 5 V, the reference TL431 is 2.5 V, cathode current stability, when the power supply voltage changes, such as the rise and the TL431 reference voltage is greater than 2.5 V, the cathodic current increases, at the same time, the optical coupling of the LED current is added, because use the linear optical coupling, therefore, the output current of light coupling has increased, TOP414G C current increase after duty ratio is reduced, so as to make the output voltage is reduced, and at the same time light coupling LED current, when reduced to 5 V output voltage of the following, TL431 reference voltage is lower than 2.5 V, cathode current is zero, light coupling does not work, TOP414G C, no current, his duty ratio will rise in order to improve the output voltage, thus to realize the feedback voltage stability.


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    Update time:12/24/2015 10:15:08 AM  【Print this page】  【Close