I'm trying to redesign a project which has an m128 @ 5V connected via SPI directly to a 3,3V dataflash and only SO(data out) is currently converted to 5V via a tranzistor.
That way, the circuit works ok because Dataflash has 5V tolerant inputs.
This relative new IC from TI, TXB0104, seems ideal for SPI signal level shifting, yet doesn't work for me.
DC signals are being translated ok, but CLK and other fast changing signals are shown as discharging spikes on my scope. There is a TPS76333 regulator with all needed capacitors as 3,3V source and it should be strong enough.
Do you think that the ringing on AVR's SPI signals could cause this?