LAN83C183 Datasheet, PDF (46/113 Pages) SMSC Corporation – FAST ETHERNET PHYSICAL LAYER DEVICE

2.1 MEDIA INTERFACE SIGNALS
REXT
Transmit Current Set
I/O
An external resistor connected between the REXT pin and GND sets
the output current for the TP and FX
transmit outputs.
SD/FXDISn
I
FX Signal Detect Input/FX Interface Disable
When this pin is not tied to GND, the FX interface is enabled and this
pin becomes an ECL signal detect input. The voltage on SD_THR
determines the trip point for this ECL input.
When this pin is tied to GND, the FX interface is disabled and the TP
interface is enabled.
SD_THR
Signal Detect Input Threshold Level Set
I
The voltage on this pin determines the ECL threshold level (trip point)
for the SD input pin so that the device can directly interface to both
3.3 V and 5 V fiber optic transceivers. Typically, this pin is either tied
to GND (for 3.3 V operation) or to an external voltage divider (for 5
V operation).
TPO+/FXI-
Twisted-Pair Transmit Output (Positive), or
Fiber Optic Receive Input (Negative)
I/O
The TPO+/FXI- pin is shared for the twisted-pair and fiber optic sig-
nals. It functions as the positive signal in the twisted-pair output or
the negative signal in the fiber optic input.
TPO-/FXI+
Twisted-Pair Transmit Output (Negative), or
Fiber Optic Receive Input (Positive)
I/O
The TPO-/FXI+ pin is shared for the twisted-pair and fiber optic sig-
nals. It functions as the negative signal in the twisted-pair output or
the positive signal in the fiber optic input.
TPI+/FXO-
Twisted-Pair Receive Input (Positive), or
Fiber Optic Transmit Output (Negative)
I/O
The TPI+/FXO- pin is shared for the twisted-pair and fiber optic sig-
nals. It functions as the positive signal in the twisted-pair input or the
negative signal in the fiber optic output.
TPI-/FXO+
Twisted-Pair Receive Input (Negative), or
Fiber Optic Output (Positive)
I/O
The TPI-/FXO+ pin is shared for the twisted-pair and fiber optic sig-
nals. It functions as the negative signal in the twisted-pair input or the
positive signal in the fiber optic output.
SMSC DS – LAN83C183
46
Rev. 12/14/2000