LAN8820 Datasheet, PDF (19/83 Pages) Microchip Technology – RGMII 10/100/1000 Ethernet Transceiver

LAN8820/LAN8820I
The various RGMII modes and their corresponding configuration settings are summarized in Figure 3-3.
FIGURE 3-3:
RGMII MODES OF OPERATION
Non-ID Mode (RGMII Specification)
(27.[9:8] = 00b, RGMII_ID_MODE = 0)
MAC
TXC _{PCB Trace Delay} TXC
TXD[3:0]
TXD[3:0]
RXD[3:0]
RXD[3:0]
RXC _{PCB Trace Delay} RXC
LAN8820/
LAN8820i
RGMII PHY TXC Delay: Disabled
RGMII PHY RXC Delay: Disabled
ID Mode (RGMII Specification)
(27.[9:8] = 01b)
ID
MAC
TXC
TXD[3:0]
RXD[3:0]
RXC
TXC
TXD[3:0]
RXD[3:0]
RXC
LAN8820/
LAN8820i
ID
RGMII PHY TXC Delay: Disabled
RGMII PHY RXC Delay: Enabled
MAC
Hybrid Mode
(27.[9:8] = 11b, RGMII_ID_MODE = 1)
TXC
TXD[3:0]
RXD[3:0]
RXC
TXC
TXD[3:0]
RXD[3:0]
RXC
ID
LAN8820/
LAN8820i
ID
RGMII PHY TXC Delay: Enabled
RGMII PHY RXC Delay: Enabled
Note:
Strapping RGMII_ID_MODE high sets the device into Hybrid Mode. In order to set the device into ID Mode,
the RGMII PHY TXC Delay Enable and RGMII PHY RXC Delay Enable bits of the Control / Status Indica-
tions Register (27.[9:8]) must be configured via software to 01b.
Timing information for the RGMII interface is provided in Section 5.5, "AC Specifications," on page 65. For additional
information on the RGMII interface, refer to the RGMII specification.
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DS00001871B-page 19