> I must confess I had not read this far in the data sheet.  However, mine
> only shows an example of using the control pin as an input via an 80K
> resistor and makes no reference as to how this might alter the
> hysteresis.  Can you give me a URL reference to your data sheet?

This is the reference. Refer to figure 2 (internal schematic). Also the
the text: "The response node may also be used as the receiver input as
long as the designer realizes that he may not drive this node with a low
impedance source to a voltage greater than one diode above ground or less
than one diode below ground. This feature is demonstrated in Figure 13
where two receivers are slaved to the same line that must still meet the
EIA232D impedance requirement."

This means that you can use the 'response node' as input using a resistor
different from the original one (3k8). You can also use the normal input
with an additional series resistor, with the same effect. With Rext = 3k8
on the normal input the hysteresis should double (still asymmetrically).

Peter

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