NetBurner Community Forum

Hello all, <MOD5272>
I'm designing a mixed voltage board where all but one of the components is a 5V device. I'm going to use a '164245 dual supply buffer for the 5V side of the board, but I was wondering, do I absolutely have to buffer the data bus for the other component? I know on my Dev-Kit 1.12 board they do, but in my final design I won't be using the dev board, and the data bus will just go to a CPLD on the 3.3V side, and just the buffer on the other side. Should that be OK, or do I really have to buffer everything? Note, I will never try to read from the bus, just write to it.
Thanks,
Dan B.

If you are only connecting to one device, and that device is very close to the processor, you are "probably" ok, meaning there is still some risk but it is low. A bigger issue may be your cpld driving the databus on power-up when it is not initialized. Buffers are cheap, I would go the safe route since it eliminates the problem.