Hi, I'm currently using SN74AVC2T245 with VCCA = 1.8V and VCCB support voltage like 1.2V, 1.5V, 1.8V, 2.5V, 3.3V. I have attached the schematic as below:
When I drive signal from port A to port B, I noticed that the different VCCB is affecting my VCCA SI. This make no sense to me as my VCCA and VCCB are from different power source.
From my experiment and the screenshots below, it looks like when VCCB = 3.3V, the SI at port A is the worst. While 1.2V is giving the best SI.
Port A Signal When VCCB = 3.3V,
Port A Signal When VCCB = 2.5V,
Port A Signal When VCCB = 1.8V,
Port A Signal When VCCB = 1.2V,
Would SN74AVC2T245 change its internal impedance when VCCB is switching, and thus affecting my SI? Else, what could be the reason?
Looking forward for the reply.