Datasheet

TX_CLK
TX_EN
TXD[3:0]
CRS
RX_CLK
RX_DV
RXD[3:0]
T0361-01
t
1
TLK110
SLLS901D –DECEMBER 2011–REVISED JANUARY 2014 www.ti.com
9.7.21 100Mbs Loopback Timing
Table 9-21. 100Mbs Loopback Timing
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
100Mbs external loopback 241 242 243
100Mbs external loopback – fast RX_DV mode 201 202 203
t
1
TX_EN to RX_DV Loopback 100Mbs analog loopback 232 233 234 ns
100Mbs PCS Input loop back 120 121 122
100Mbs MII loop back 8 9 10
(1) Due to the nature of the descrambler function, all 100Base-TX Loopback modes cause an initial dead-time of up to 550 μs during
which time no data is present at the receive MII outputs. The 100Base-TX timing specified is based on device delays after the initial
550µs dead-time.
(2) Measurement is made from the first rising edge of TX_CLK after assertion of TX_EN.
(3) External loopback was measured using very short external cable (approximately 10cm).
(4) Since MII loopback introduce extreme short roundtrip delay, some hosts would use PCS Input loopback (Mainly in 100BT).
Figure 9-21. 100Mbs Loopback Timing
92 Electrical Specifications Copyright © 2011–2014, Texas Instruments Incorporated
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