LXT970A 데이터 시트보기 (PDF) - Intel
부품명
상세내역
제조사
LXT970A Datasheet PDF : 74 Pages
| |||
Dual-Speed Fast Ethernet Transceiver — LXT970A
Test Loopback
A test loopback function is provided for diagnostic testing of the LXT970A. During test loopback
the twisted-pair interface is disabled. Data transmitted by the MAC is internally looped back by
the LXT970A and returned to the MAC.
Test loopback is available for 100 Mbps and 10 Mbps operation. Loopback paths for the two modes
of operation are shown in Figure 6.
Test loopback is enabled by setting bit 0.14 = 1 (loopback), bit 0.8 = 1 (full-duplex), and bit 0.12 =
0 (disable auto-negotiation). The desired mode of operation for test loopback is set using bits 0.13
and 19.2 as shown in Table 10.
Table 10. Test Loopback Operation
Mode of Operation
Bit
19.2
0.13
10 Mbps Test Loopback
0
0
100 Mbps Test Loopback
1
1
1. Also set bit 0.14 = 1, bit 0.8 = 1, and 0.12 = 0 to enable Test
Loopback.
Figure 6. Loopback Paths
10 Mbps
Loopback
MII
Digital
Block
100 Mbps
Loopback
Analog
Block
FX
Driver
TX
Driver
Collision
The LXT970A asserts its collision signal, asynchronously to any clock, whenever the line state is
half-duplex and the transmitter and receiver are active at the same time. Table 11 summarizes the
conditions for assertion of carrier sense, collision, and data loopback signals.
Table 11. Carrier Sense, Loopback, and Collision Conditions
Speed & Duplex Condition
Carrier Sense
Operational
Loopback
Full-Duplex at 10 Mbps or 100 Mbps
Repeater Mode
100 Mbps, Half-Duplex
10 Mbps, Half-Duplex, 19.11 = 0
10 Mbps, Half-Duplex, 19.11 = 1
Receive only
Transmit or Receive
Transmit or Receive
Receive only
None
None
Yes
None
Collision
None
Transmit and Receive
Transmit and Receive
Transmit and Receive
Datasheet
23
Share Link: 