TLK3101 Datasheet, PDF (13/24 Pages) Texas Instruments – 2.5 Gbps to 3.125 Gbps TRANSCEIVER

TLK3101
2.5 Gbps to 3.125 Gbps TRANSCEIVER
SCAS649A – AUGUST 2000 – REVISED FEBRUARY 2001
Terminal Functions (Continued)
signal (continued)
TERMINAL
NAME
NO.
PREM
56
RX_ER/
29
PRBS_PASS
RX_DV/
30
LOS
TX_EN
20
TX_ER
22
† _{Hi-Z on power-up}
‡ _{Internal pull-down}
TYPE
DESCRIPTION
Input^‡ Preemphasis control. Selects the amount of preemphasis to be added to the high speed data output drivers.
Left low or unconnected, 5% of pre-emphasis is added. Pulled high, 20% of preemphasis is added.
Output^†
Receive error. When RX_ER and RX_DV/LOS are asserted, indicates that an error was detected
somewhere in the frame presently being output on the receive data bus. When RX_ER is asserted and
RX_DV/LOS is deasserted, indicates that carrier extension data is being presented. RX_ER goes to high
impedance state during power-on reset.
Output^†
When PRBSEN= low (deasserted), this pin is used to indicate receive error (RX_ER). When PRBSEN = high
(asserted), this pin indicates status of the PRBS test results (high=pass).
Receive data valid. RX_DV/LOS is output by the transceiver to indicate that recovered and decoded data is
being output on the receive data bus. RX_DV/LOS is asserted continuously from the first recovered word of
the frame through the final recovered word and is deasserted prior to the first rising edge of RX_CLK that
follows the final word. RX_DV/LOS is in high-impedance state during power-on reset.
Input^‡
Input^‡
If, during normal operation, the differential signal amplitude on the serial receive pins is below 200 mV,
RX_DV/LOS is asserted high along with RX_ER and the receive data bus to indicate a loss of signal
condition. If the device is in power-down mode, RX_DV/LOS is the output of the signal detect circuit and is
asserted low when a loss of signal condition is detected.
Transmit enable. TX_EN in combination with TX_ER indicates the protocol device is presenting data on the
transmit data bus for transmission. TX_EN must be high with the first word of the preamble and remain
asserted while all words to be transmitted are presented on the transmit data bus. TX_EN must be negated
prior to the first rising edge of GTX_CLK following the final word of a frame.
Transmit error coding. When TX_ER and TX_EN are high, indicates that the transceiver generates an error
somewhere in the frame presently being transferred. When TX_ER is asserted and TX_EN is deasserted,
indicates the protocol device is presenting carrier extension data. When TX_ER is deasserted with TX_EN
asserted, indicates that normal data is being presented.
test
TERMINAL
NAME
NO.
ENABLE
24
LOOPEN
21
PRBSEN
26
TESTEN
27
‡ _{Internal pulldown}
§ _{Internal pullup}
TYPE
DESCRIPTION
Input^§
Input^‡
Input^‡
Input^‡
Device enable. When this pin is held low, the device is placed in power-down mode. Only the signal detect
circuit on the serial receive pair is active. When asserted high, the transceiver goes into power-on reset
before beginning normal operation.
Loop enable. When LOOPEN is high, the internal loopback path is activated. The transmitted serial data is
directly routed internally to the inputs of the receiver. This provides a self-test capability in conjunction with
the protocol device. The DOUTTXP and DOUTTXN outputs are held in a high-impedance state during the
loopback test. LOOPEN is held low during standard operational state with external serial outputs and inputs
active.
PRBS test enable. When asserted high results of pseudorandom bit stream (PRBS) tests can be monitored
on the RX_ER/PRBS_PASS pin. A high on PRBS_PASS indicates that valid PRBS is being received.
Test mode enable. This pin should be left unconnected or tied low.
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