Hello,
I would like to ask the "RXDET" functions for DS80PCI810.
According to the DataSheet.
When it is in "F" mode.
PCIe detection occurs; termination is Hi-Z until Rx detection; once detected input termination is 50 Ω
Q1: What is the input termination is Hi-Z?
Q2: What is the input termination is in 50 Ohm?
And
Q3: Where does the RX begin to detect?
The input termination part means Re-driver's TX or Re-driver's RX side?
Thanks a lot.
Hi Chih-Wei,
Please see answers to questions below:
1. For RXDET, if the input termination is Hi-Z, that is equivalent to a switch being disconnected that would otherwise provide a path from the input differential lines via 50-ohm resistor to VDD (2.5 V). When the inputs are Hi-Z, the channel is inactive (see circled section in functional block diagram below)
2. When the input termination is 50-ohm, this indicates that the differential channels are active, with a 50-ohm resistor to VDD. In this case, the channel is active.
3. The RXDET feature checks for whether there is a proper load termination after the DS80PCI810. This is done by periodic pulses being emitted from the DS80PCI810 Tx to determine whether the line is being loaded correctly and not being left as an open-circuit (no connect). When a load is detected, the input termination (50-ohm to VDD) is connected at the DS80PCI810 input (Rx-side) to make the channel active. Otherwise, the channel will remain inactive in order not to propagate noise through an unused channel with no end-point device connected.
Regards,
Michael
