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Data Reception

Receiver Clock Select Mode

K28.5

DXX.X

DXX.X

DXX.X

K28.5

DXX.X

RBC0

RBC1

SYNC

RD(0-9)

K28.5

DXX.X

DXX.X

DXX.X

K28.5

DXX.X

RBC0

SYNC

RD(0-9)

TLK1201ARCP, TLK1201AIRCP

ETHERNET TRANSCEIVERS

SLLS580D – FEBRUARY 2004 – REVISED SEPTEMBER 2007

The receiver portion deserializes the differential serial data. The serial data is retimed based on an interpolated

clock generated from the reference clock. The serial data is then aligned to the 10-bit word boundaries and

presented to the protocol controller along with receive byte clocks (RBC0 and RBC1).

There are two modes of operation for the parallel bus: 1) the 10-bit (TBI) mode and 2) 5-bit (DDR) mode. When

in TBI mode, there are two user-selectable clock modes that are controlled by the RBCMODE terminal: 1)

full-rate clock on RBC0 and 2) half-rate clocks on RBC0 and RBC1. When in the DDR mode, only a full-rate

clock is available on RBC0; see Table 1.

Table 1. Mode Selection

RECEIVE BYTE CLOCK

MODESEL

RBCMODE

MODE

TLK1201A

TLK1201AI

0

0

TBI half-rate

30–65 MHz

30–65 MHz

0

1

TBI full-rate

60–130 MHz

60–130 MHz

1

0

DDR

60–130 MHz

60–130 MHz

1

1

DDR

60–130 MHz

60–130 MHz

In the half-rate mode, two receive byte clocks (RBC0 and RBC1) are 180 degrees out of phase and operate at

one-half the data rate. The clocks are generated by dividing down the recovered clock. The received data is

output with respect to the two receive byte clocks (RBC0 and RBC1) allowing a protocol device to clock the

parallel bytes using the RBC0 and RBC1 rising edges. The outputs to the protocol device, byte 0 of the received

data is valid on the rising edge of RBC1. See the timing diagram shown in Figure 2.

Figure 2. Synchronous Timing Characteristics Waveforms (TBI Half-Rate Mode)

In the normal-rate mode, only RBC0 is used and operates at full data rate (that is, 1.25-Gbps data rate produces

a 125-MHz clock). The received data is output with respect to the rising edge of RBC0. RBC1 is low in this

mode. See the timing diagram shown in Figure 3.

Figure 3. Synchronous Timing Characteristics Waveforms (TBI Full-Rate Mode)

In the double data rate mode, the receiver presents the data on both the rising and falling edges of RBC0. RBC1

is low impedance. The data is clocked bit 0 first, and aligned to the rising edge of RBC0. See the timing diagram

shown in Figure 4.

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