TLK3114SA_13 Datasheet, PDF (38/66 Pages) Texas Instruments – 10-Gbps XAUI Transceiver

3.23 Device Configuration
The TLK3114SA device has four operational configurations controlled by two configuration terminals, CONFIG0 and
CONFIG1. These configurations are listed in Table 3−10 and controlled by the MDIO interface (see Table 3−18).
When the device is put in a certain mode, unused circuit blocks are powered down to conserve the system power.
CONFIG0
Low
Low
High
High
CONFIG1
Low
High
Low
High
Table 3−10. Device Configuration
CONFIGURATION
Full-duplex transceiver mode—normal operation (default after reset).
Transmit-only mode—data on high-speed data inputs is ignored. Receive data bus is in a high-impedance
state.
Receive-only mode—high-speed data outputs are in a high-impedance state. Data on the transmit data
bus is ignored.
Repeater mode—recovered serial data and clock are sent back out the transmit serial output.
While transceiver, transmit-only, and receive-only modes are straightforward, the repeater mode of operation is
shown in Figure 3−18. The received serial data is recovered by the extracted clock and is then sent back out on the
transmit serial output. The data eye opens both vertically and horizontally.
RXxP
RXxN
Recovered Clock
DQ
Deserializer
TXxP
TXxN
DQ
Serializer
CONFIG0
CONFIG1
Mode
Selection
Repeater
Mode
Figure 3−18. Repeater-Mode Block Diagram
TX PLL
3.24 PRBS Generator
The TLK3114SA device has a built-in 2⁷−1 PRBS self-test function available on each channel. The PRBS data pattern
represents a worst case data recovery task compared to any 8-b/10-b data pattern combination and is, therefore, a
sufficient test for the link and jitter tolerance. The self-test function is enabled by asserting the PRBSEN terminal or
setting bit 2 (PRBS enable) of MDIO channel configuration registers 16−20, 4.32768−4.32772, or 5.32768−5.32772.
When the self-test function is enabled, PRBS is generated and fed into the 10-bit parallel-to-serial converter input
register. Data on the transmit data bus is ignored during the PRBS test mode. The PRBS pattern is then fed through
the transmit circuitry as if it were normal data and sent out to the transmitter. The output can be sent to a BERT (bit
error rate tester), the receiver of another TLK3114SA channel, or can be looped back to the receive input of the same
channel. Since the PRBS is not really random but a predetermined sequence of 1s and 0s, the data can be captured
and checked for errors by a BERT.
3−19