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OPA698设计施密特

在VERY HIGH-SPEED SCHMITT TRIGGER 章节
门槛计算公式怎么来的,R1、R2、R3为什么是并联

  • 施密特触发器, 可以通过正反馈来实现, 你可以调整偏置和反馈量来调节触发点电压。至于电阻怎么计算,那只是中学物理题了
  • 您好,按照Figure 15的电路,列式子为I1=I2+I3:

    (Vref-Vin)/R1=[(Vref-Vin)/R1+Vin/R3]
    然后进行推导,计算得到:
    Vin=( Vref*R2*R3 +Vout*R1*R3)/(R1+R2+R3)
    然后分子分母同时除以R1*R2*R3得到:

    Vin=[(Vref/R1 )+(Vout/R2)]*{ R1*R2*R3/[R1+R2+R3]}
    =(Vref/R1 )+(Vout/R2)*(R1//R2//R3)

    即为阈值电压Vhh,Vhl=【(Vref/R1 )+(Vout/R2)】*(R1//R2//R3)