– Copied from customer query –
When using the gigablox nano at reduced speeds 10M/100M, does the IC also automatically slow down the rise/fall times? I’d like to reduce the EMI on my board and gigabit spec for rise/fall times are 10x faster than 100base spec
Unfortunately the chip does not specify this in the datasheet, but it’s highly likely it will adapt it’s rise/fall time to meet the specification of 100BASE-Tx or 1000BASE-T.
As per google…
“The rise time of 100BASE-TX is between 3.0 ns and 5.0 ns”
I can’t find a source for what the rise/fall time of 1000BASE-T is, but given that the clock frequency of 1000BASE-T is 125MHz, then the period would be 8 ns. Thus we can assume that 1000BASE-T can’t use the same rise time as 100BASE-TX (5 ns is nearly all of the 8 ns period), so it’s pretty safe to assume that the 1000BASE-T rise time is probably less than 1ns.
Thus I would imagine, as per spec, the ethernet driver will slow down the rise time between 100BASE-TX and 1000BASE-T.
