ptmsl said:
It is like that any voltage within the limits you mentioned is interpreted as logic 0 or 1. The only problem with using open collector outputs is that you have to make sure that the low voltage is under 0.4V. If you can produce voltages outside the 0.4 to 2.4V region your circuit will work. Be careful to use the output from an IC that can go close to the supply rails.
Hi,
Open collector outputs does not normally have problems with the low level output(0). The selection of pullup resistor may cause some problem for the high level(1). If you use a resistor value too high, the timing of the signal may suffer, depending on the switching frequency. A TTL input draws current both high and low, less to high. The resistor chosen, must overcome both this current and the capacitance in question to make the switching flank steep enough. If you have more than one input to drive, everything adds up, resulting in a lower resistor value needed.
TOK