SNLA404 December 2022 DP83TC811R-Q1 , DP83TC811S-Q1 , DP83TC812R-Q1 , DP83TC812S-Q1 , DP83TG720R-Q1 , DP83TG720S-Q1
Texas Instruments' 100Base-T1 (DP83TC811, DP83TC812) and 1000Base-T1 (DP83TG720) Automotive Ethernet physical layers (PHYs) are designed such that same PCB board can be used for either transceiver. While the hardware changes needed to make the swap are listed in the DP83TC811, DP83TG720 Rollover Document application note, there are also necessarily changes to be accounted for in software. This application note acts as a reference guide to point out the appropriate timing flowchart for these devices and distinguish between the necessary timing specifications of each device.
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Ethernet PHYs have their own timing requirements as dictated in their respective data sheets. It is important that these requirements are met from a power supply standpoint to be able to supply the PHY appropriately as well as from a microcontroller standpoint to know exactly when a PHY is available for normal communication as well as register access for any programming needs for the system. Also, each PHY has an optimized register configuration which is loaded after the power-up sequence is complete.
Even after the PHY is configured and linked-up with the remote link partner, systems can choose to continue with status or health checks of the link using various PHY registers. Details of the required sequence to control and poll the PHY is described in this document.