Hello all,
I've developed a PCCard that provides a parallel interface for connecting some measuring equipment to notebooks. The problem is that when the notebook is turned off while the external equipment is still running, the PCCard gets some power via the parallel interface inputs. This power propagates via the VCC pins of the inputbuffers of my card into the notebook. Some notebook models won't power on again in this situation and I will first have to remove the PCCard (or disconnect the external device).
Does anyone know if there is a family of logic circuits which can avoid this? Since the PCCard is operating at 3.3V and the external signals are 5 V it additionally has to translate down the input voltage.
Thank you, Manfred