I'm using the ICL 7673 circuit from datasheet "without external PNP transistors".

Please help with deciding Rf and Rs resistor values for 0.5V hysteresis.

Any help is much appreciated.

Please see picture below. enter image description here

You can see below ( a simplified version) showing that this circuit is actually quite different from a regular hysteresis circuit.

Regular hysteresis = comparator + positive feedback resistor network

ICL 7673 hysteresis = comparator + positive feedback resistor network + switch

So this hysteresis circuit works only for the condition Vs > Vp

enter image description here


1 Answer 1


I solved the problem. Design the hysteresis network (assuming Vs+Hys>Vp).

I needed 0.5V Hysteresis. So, I designed the circuit for 0.5V drop across Rs. The catch in the design is I needed to design the Rf to sink enough current into the Sbar internal FET so the FET will operate in saturation always.

The best part of this circuit is the hysteresis circuit is selectively connected or disconnected by the Sbar FET.


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