Calculating hysteresis

[anishkgt]

Hello all,

I starting to learn about opamps, comparators to begin with. I want to add a 5mV hysteresis for Low threshold of 1.5v and High threshold of 2.5v. The circuit is to charge supercaps. I got the resistor vlaues with playing around with the LTSpice simulator.

Would appreciate if anyone could share the calculation of this circuit including the Hysteresis.

[Wimberleytech]

Are you hoping for 5mV of hysteresis, or 500mV?  Post your LTSpice file.
Calculating the hysteresis is pretty simple.  You have to solve two cases: 1) when the output is high, and 2) when the output is low.  In each case calculate what Vin must be in order for the non-inverting input voltage to be 1.3 volts.

[anishkgt]

Thank you !

From reading couple of app notes of TI i know its all about the Hth and Lth. but can't find anything that explains in simple english. Yes its 500mV not 5mv, sorry !