| 摘要 |
<p>PURPOSE: To provide a window comparator which does not present a vibrational phenomenon and can reliably discriminate whether or not it is outside of a voltage level range by providing hysteresis characteristics in a comparator to set the upper limit and the lower limit with simple circuit constitution. CONSTITUTION: A window comparator is composed of a first hysteresis circuit H1 to compare a detecting signal with a threshold value Vth1 of the upper limit and a second hysteresis circuit H2 to compare the detecting signal with a threshold value Vth2 of the lower limit, and the first hysteresis circuit H1 has hysteresis characteristics to reduce the threshold value Vth1 when voltage of an input signal exceeds its threshold value Vth1, and the second hysteresis circuit H2 has hysteresis characteristics to raise the threshold value Vth 2 when the voltage does not reach its threshole value Vth2. Both the first and the second hysteresis circuits H1 and H2 are open collector output, and these output terminals 3 are connected to each other, and are constituted by being connected to a constant voltage source Vdd through a pull-up resistance Ru.</p> |
