where vol u201c voltage out low u201d represents the voltage that an output drives the signal to when driving out a 0 value and iol u201c current out low u201d represents the amount of current a driver supplies when driving out a 0 value to reach 0 5v with an iol of 4 ma the driver must have a resistance to ground of less than 125 ohm at 125 ohm a driver would pull down a 3530 ohm load to 188 mv assume though that the voltage is only pulled to 0 3v before it is released so that the shortest time that pdiag may take to reach a high value with a 40 conductor cable from 0 2 to 0 8v is 13 u03bcs it is also important to know how long it will take to discharge the capacitor when a device asserts pdiag the maximum time to discharge the capacitor down to 0 3v would depend on the maximum resistance to ground as stated above the driver itself may have 125 ohm maximum in combination with the 3530 ohm pull up the lowest level that the signal could reach is 188 mv assuming this were 200 mv the exponential curve will be to a minimum of 200 mv this would be equivalent to a curve from 5 3 to 0v these numbers show that.