3X38FTR Datasheet, PDF (29/64 Pages) Agere Systems – OCTAL-FET (Fast Ethernet Transceiver) for 10Base-T/100Base-TX/FX

Preliminary Data Sheet
September 2000
3X38FTR 208-Pin SQFP
OCTAL-FET for 10Base-T/100Base-TX/FX
Functional Description (continued)
Loopback
During normal operation, RTXD[1:0] and RTXEN will
not be looped back to RCRS_DV and RRXD[1:0].
When in isolate mode, the specified port on the 3X38
does not respond to packet data present at the
RTXD[1:0] and RTXEN inputs, and presents a high
impedance on the RCRS_DV, RRXER, and RRXD[1:0]
outputs. The 3X38 will continue to respond to all man-
agement transactions while the port is in isolate mode.
RMII/SMII Interface
RMII Isolate Mode
The 3X38 also implements an RMII isolate mode that is
controlled by bit 10 of each one of the eight control reg-
isters (register 0h). At reset, the 3X38 will initialize this
bit to 0. Setting the bit to a 1 will put the port into RMII
isolate mode.
Serial Media Independent Interface (SMII)
The SMII allows a further reduction in the number of
signals that are required to interface a PHY to a MAC.
There are two global signals, RMCLK and SSYNC, and
two per-port signals, SRXD and STXD. All signals are
synchronous to the 125 MHz clock.
MULTI-MAC
STXD0
SRXD0
STXD[1—6]
SRXD[1—6]
STAD7
SRXD7
SSYNC[3:0]
SSYNC[4:7]
CLOCK
3X38
PORT 0
PORT [1—6]
PORT 7
125 MHz
REFERENCE CLOCK
Figure 9. SMII Connection Diagram
5-7507(F).b
1
2
3
4
5
6
7
8
9
10
11
SMII_CLK
SYNC
RXD
CRS RX_DV RXD0 RXD1 RXD2 RXD3 RXD4 RXD5 RXD6 RXD7
Figure 10. Receive Sequence Diagram
5-7507(F)
Lucent Technologies Inc.
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