In the datasheet, there is an Equation for an external pulldown resistor for VOH. Is there an equation for an external pullup resistor for VOH? Also, does a Tina/Spice model exist for this device?
Hello Roy,
There is no equation for a pull-up resistor because this will not effect Voh. The main consideration with adding a pull-up resistor is that this will increase the amount of current that your device will have to sink in order to pull the output down to 0V.
You can simply calculate the equivalent parallel resistance with the external pull-up resistor and the internal 40k pull-up resistor and then determine the current that will flow through that resistor using Ohm's Law. Do this for both A side and B side, assuming you have pull-ups on both sides, and then sum the two current values and this will approximate the amount of current that your driver will have to sink in order to pull the line low.
We have an Ibis model, you can find it at the bottom of this page:
