LXT972 Level One, LXT972 Datasheet - Page 41

• Manufacturer Part Number: LXT972
• Description: 3.3V Dual-Speed Fast Ethernet Transceiver Datasheet
• Manufacturer: Level One

Figure 24: 100BASE-TX Transmit Timing - 4B Mode
Table 26: 100BASE-TX Transmit Timing Parameters
TXD<3:0>, TX_EN, TX_ER setup to TX_CLK High
TXD<3:0>, TX_EN, TX_ER hold from TX_CLK High
TX_EN sampled to CRS asserted
TX_EN sampled to CRS de-asserted
TX_EN sampled to TPO out (Tx latency)
1. Typical values are at 25 °C and are for design aid only; not guaranteed and not subject to production testing.
2. BT is the duration of one bit as transferred to and from the MAC and is the reciprocal of the bit rate. 100BASE-T bit time = 10
TXD<3:0>
T X C L K
T X _ E N
Parameter
C R S
T P O
0ns
t3
t5
t2
t1
Sym
t1
t2
t3
t4
t5
Min
-
5.3
12
20
24
LXT972 Preliminary Test Specifications
0
4B Mode
Typ
–
–
–
–
–
1
t4
250ns
Max
5.7
24
28
–
–
Units
BT
BT
BT
ns
ns
2
Conditions
-8
s or 10 ns.
Test
–
–
–
–
–
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