First, create an equation for V
T that covers both output voltages when the output is high or low.
Equation 5. Equation 6. The hysteresis voltage in this network is equal to the difference in the two threshold voltage equations.
Equation 7. Equation 8. Equation 9. Equation 10. Note that these equations do not take into account the effects of the internal hysteresis and offset voltage of the comparator. Design parameters will need to be adjusted accordingly. Select a value for R2. Plug in given values for V
REF, V
T1, V
T2, Q, and
Q, and solve for R1. For the given example, R2 = 50 kΩ, and R1 is solved as = 8.3 kΩ.