Other Parts Discussed in Thread: TMUX1134
Hi,
We designed a PCB with SN74AXC4T774 to convert SPI4 signals from/to 3V3(=VCCB) to/from 1V2(=VCCA) domain.
Based on SN74AXC4T774 datasheet, we would have expected MISO signal not to be delayed by more than 12ns and SCLK/CSn/MOSI signals not to be delayed by more than 7 ns.
But looking with scope we observe up to 15ns propagation delay through SN74AXC4T774 part.
In other words, when it comes to sampling MISO, we have up to 30ns delay for MISO in 3V3 domain compared to falling edge of SCLK. This is not compatible with a SPI frequency of 12MHz which is our requirement.
So can you please confirm propagation delay through SN74AXC4T774, that it is supposed to work with SPI at 12MHz ? And above all, can you please provide guidance about how to reduce this propagation delay ?
Thanks,
Julie