7.4.3.2 Non-Inverting Comparator With Hysteresis

A noninverting comparator with hysteresis requires a two resistor network, and a voltage reference (V_REF) at the inverting input. When V_IN is low, the output is also low. For the output to switch from low to high, V_IN must rise up to V_IN1 where V_IN1 is calculated by:

Equation 4.

As soon as V_O switches to V_CC, V_A steps to a value greater than V_REF which is given by:

Equation 5.

To make the comparator switch back to its low state, V_IN must equal V_REF before V_A will again equal V_REF. V_IN2 can be calculated by:

Equation 6.

The hysteresis of this circuit is the difference between V_IN1 and V_IN2.

Figure 20. Noninverting Comparator With Hysteresis

Figure 21. Noninverting Comparator Thresholds