Datasheet

PHY MAC

TXD[1:0]

TX_EN

TXD[1:0]

RX_ER (optional)

RXD[1:0]

RX_DV (optional)

RX_DV

RX_ER

RXD[1:0]

CRS/RX_DV

50MHz

Clock Source

RX_CLK (optional)

RX_CLK

TLK110

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SLLS901D –DECEMBER 2011–REVISED JANUARY 2014

Figure 4-2 describes the RMII signals connectivity between the TLK110 and any MAC device.

Figure 4-2. TLK110 RMII/MAC Connection

RMII function includes a programmable elastic buffer to adjust for the frequency differences between the

reference clock and the recovered receive clock. The programmable elastic buffer minimizes internal

propagation delay based on expected maximum packet size and clock accuracy.

Table 4-1 indicates how to program the buffer FIFO based on the expected max packet size and clock

accuracy. It assumes that the RMII reference clock and the far-end transmitter clock have the same

accuracy.

Table 4-1. Recommended RMII Packet Sizes

Recommended packet size at Recommended packet size at

Start Threshold RBR[1:0] Latency Tolerance

±50ppm ±100ppm

1(4-bits) 2 bits 2400 bytes 1200 bytes

2(8-bits) 6 bits 7200 bytes 3600 bytes

3(12-bits) 10 bits 12000 bytes 6000 bytes

0(16-bits) 14 bits 16800 bytes 8400 bytes

4.3 Serial Management Interface

The Serial Management Interface (SMI), provides access to the TLK110 internal register space for status

information and configuration. The SMI is compatible with IEEE802.3-2002 clause 22. The implemented

additional visibility and controllability of the TLK110 device.

The SMI includes the MDC management clock input and the management MDIO data pin. The MDC clock

is sourced by the external management entity, also called Station (STA), and can run at a maximum clock

rate of 25MHz. MDC is not expected to be continuous, and can be turned off by the external management

entity when the bus is idle.

The MDIO is sourced by the external management entity and by the PHY. The data on the MDIO pin is

latched on the rising edge of the MDC clock. The MDIO pin requires a pull-up resistor (2.2k Ω) which,

during IDLE and turnaround, pulls MDIO high.

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