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韩国LG公司CF—21G 20K彩电开关电源所采用的核心元件是日本三根电子公司新产品SRT—S5707厚膜集成电路,和我国大屏幕彩电现在流行采用的STH—S6708/6709厚膜集成块相比较,又有其独特之处:连稳压取样放大部分电路也集成在IC内部,使IC外围电路元件进一步减少。 (一)开关电源剖析图1为该机开关电源电路,它属于脉冲变压器耦合、并联型、他激式开关稳压电路。 STR—S5707集成电路各引脚功能:①脚为IC内部开关管V1的集电极;②脚为开关管的发射极,也是IC内部电路的接地端;③脚为开关管的基极;④脚为IC内部激励器向开关管b极输入的反向截止电流,使开关管的截止过程加快进行;⑤脚为过流保护信号输入端,当有过流现象时,该脚输入过流信号电压,使IC内部保护电路动作,使振荡器停止工作;⑥脚为反馈端,当暂停信号输入时,使IC内部振荡器工作减弱,开
South Korea’s LG company CF-21G 20K color TV switching power supply core components used in Japan’s three electronics company new product SRT-S5707 thick film integrated circuits, and China’s large-screen color TV now popular STH-S6708 / 6709 thick film manifold compared , But also has its unique features: Even the constant voltage sampling amplification part of the circuit is also integrated in the IC, the IC peripheral circuit components to further reduce. (A) Analysis of switching power supply Figure 1 for the aircraft switching power supply circuit, which belongs to the pulse transformer coupling, parallel type, he excited switching regulator circuit. STR-S5707 integrated circuit pin function: ① feet for the IC’s internal collector V1 collector; ② feet for the emitter of the switch, but also the IC’s internal circuit ground; ③ feet for the switch base; ④ feet For the IC internal b-type switch to the switch input reverse blocking current, the switch to cut off the process to speed up; ⑤ foot over-current protection signal input, when there is an over-current phenomenon, the foot input over-current signal voltage , The IC internal protection circuit action, the oscillator to stop working; ⑥ feet for the feedback side, when the suspension of signal input, the IC oscillator to weaken the internal work, open