Other Parts Discussed in Thread: DP83TC811
Hi
We use four of the DP83TC811R-Q1 PHYs on one of our boards.
We have found that, at power up, some or all of the PHYs enter what looks like the sleep state.
All we do at startup is bring the power supplies on and keep the reset low and enable high. After de-asserting the reset the PHYs are still in a sleep state. The INH pin is high and the SMI interface is not responding.
The PHYs are strapped to RMII slave, Normal operation, slave mode, managed mode. We have checked these in the registers when they are working and they are correct. We have however found that when the PHYs are in this sleep state, the strapping levels on the pins themselves are almost all wrong.
What we have found is that when we pull the wake pin high, the strapping and SMI interface works as normal. We typically leave the WAKE pin floating (internally pulled low).
According to the datasheet, the wake pin is ignored in slave mode, but for some reason they start up in this sleep mode regardless. We do not actively control the wake pin, but we would like to use the sleep function in master mode, so we cannot just keep the wake pin high.
Why does the PHY always start up in sleep mode, even in slave mode?
Our chips have the following text :
DP83TC811 A1R TI 884 ZLY7 G4
Thank you
Luke
