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较强的输入信号可直接驱动光耦的发光二极管,较弱的输入信号须经放大后才能驱动光耦。在光耦光敏三极管的集电极或发射极直接接负载电阻即可满足较小的负载要求:在光耦光敏三极管的发射极加三极管放大驱动,通过两只光电耦合器构成的推挽式电路以及通过增加光敏三极管基极正反馈,既达到较强的负载能力,提高了功率接口的抗干扰能力,克服了光耦的输出功率不足的缺点,又提高光耦的开关速度,克服了由于光耦自身存在的分布电容,对传输速度造成影响。最后给出了光耦合器在数字电路中应用示例。
Strong input signal can directly drive the optocoupler LED, the weaker the input signal to be amplified to drive the optocoupler. The optocoupler phototransistor collector or emitter directly connected to the load resistance to meet the smaller load requirements: optocoupler phototransistor emitter plus transistor amplifier driven by two optocoupler push-pull circuit and By increasing the positive feedback of phototransistor base, not only strong load capacity is achieved, but also the antijamming capability of the power interface is improved, the shortcoming of insufficient output power of the optocoupler is overcome, the switching speed of the optocoupler is also improved, Own distribution capacitance, the impact on the transmission speed. Finally, the application of optocouplers in digital circuits is given.