TLK105_16 Datasheet, PDF (19/104 Pages) Texas Instruments – TLK105 TLK106 Industrial Temp, Single Port 10/100Mbs Ethernet Physical Layer

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TLK105
TLK106
SLLSEB8C – AUGUST 2012 – REVISED APRIL 2016
In this mode, data transfers two bits at a time using the 50MHz RMII reference clock for both transmit and
receive. RMII mode uses the following pins:
SIGNAL
PIN
XI (RMII reference clock is 50MHz)
23
TXD_0
4
TXD_1
5
TX_EN
3
CRS_DV
27
RX_ER
28
RXD_0
30
RXD_1
31
Data on TXD [1:0] are latched at the PHY with reference to the reference-clock edges on the XI pin. Data
on RXD [1:0] are latched at the MAC with reference to the same reference clock edges on the XI pin. The
RMII operates at the same speed (50MHz) in both 10B-T and 100B-TX. In 10B-T the data is 10 times
slower than the reference clock, so transmit data is sampled every 10 clocks. Likewise, receive data is
generated on every 10th clock so that an attached MAC device can sample the data every 10 clocks.
In addition, RMII mode supplies an RX_DV signal which allows a simpler method of recovering receive
data without the need to separate RX_DV from the CRS_DV indication. RX_ER is also supported even
though not required by RMII spec (The TLK10x supports optional use of RX_ER and RX_DV in RMII as
an extra feature). RMII mode requires a 50MHz oscillator connected to the device XI pin.
The TLK10x supports a special mode called “RMII receive clock” mode. This mode, which is not part of
the RMII specification, allows synchronization of the MAC-PHY RX interface. In this mode, the PHY
generates a recovered 50MHz clock through the RX_CLK pin and synchronizes the RXD[1:0], CRS_DV,
RX_DV and RX_ER signals to this clock. Setting register 0x000A bit [0] is required to activate this mode.
Figure 4-2 describes the RMII signals connectivity between the TLK10x and any MAC device.
PHY
TX_EN
TXD[1:0]
RX_CLK
RX_DV
RX_ER
RXD[1:0]
CRS/RX_DV
TX_EN
TXD[1:0]
RX_CLK (optional)
RX_DV (optional)
RX_ER (optional)
RXD[1:0]
CRS/RX_DV
XI
MAC
50MHz
Clock Source
Copyright © 2016, Texas Instruments Incorporated
Figure 4-2. TLK10x RMII/MAC Connection
Copyright © 2012–2016, Texas Instruments Incorporated
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