FLLXT971ABC.A4-834926 Cortina Systems Inc, FLLXT971ABC.A4-834926 Datasheet - Page 26

• Manufacturer Part Number: FLLXT971ABC.A4-834926
• Manufacturer: Cortina Systems Inc

Specifications of FLLXT971ABC.A4-834926

• Lead Free Status / RoHS Status: Not Compliant

LXT971A PHY
Datasheet
249414, Revision 5.2
13 September 2007
5.2.1.2
5.2.1.3
Cortina Systems
Only a transformer, RJ-45 connector, load resistor and bypass capacitors are required to
complete this interface. On the transmit side, the LXT971A PHY has an active internal
termination and does not require external termination resistors. Cortina’s waveshaping
technology shapes the outgoing signal to help reduce the need for external EMI filters.
Four slew rate settings allow the designer to match the output waveform to the magnetic
characteristics. On the receive side, the internal impedance is high enough that it has no
practical effect on the external termination circuit. (For the slew rate settings, see
Table 62, Transmit Control Register - Address 30, Hex 1E, on page
Fiber Interface
The LXT971A PHY fiber port is designed to interface with common industry-standard fiber
modules. It incorporates an LVPECL interface that complies with the ANSI X3.166
standard for seamless integration.
Fiber mode is selected through register bit 16.0 by the following two methods:
Remote Fault Detection and Reporting
The LXT971A PHY supports two remote fault detection and reporting mechanisms.
Remote Fault Detection. register bit 4.13 in the Auto-Negotiation Advertisement Register
is reserved for Remote Fault indications. It is typically used when re-starting the auto-
negotiation sequence to indicate to the link partner that the link is down because the
advertising device detected a local fault.
When the LXT971A PHY receives a Remote Fault indication from its partner during auto-
negotiation, the following occurs:
100BASE-FX Far-End Fault Indication. The LXT971A PHY independently detects signal
faults from the local fiber PHYs through the SD/TP_L pin. The LXT971A PHY also uses
register bit 1.4 to report Remote Fault indications received from its link partner. The
LXT971A PHY ORs both fault conditions to set bit 1.4 to ‘1’. register bit 1.4 is set once and
clears to ‘0’ when it is read. In fiber operations, the far-end fault detection process requires
idles to establish link. Link does not establish if a far-end fault pattern is the initial signal
detected.
Either fault condition causes the LXT971A PHY to drop the link unless Forced Link Pass
is selected by setting register bit 16.14 to ‘1’. A ‘link is down’ condition is then reported
with interrupts and status bits.
In response to locally detected signal faults (that is, the SD/TP_L pin is activated by the
local fiber PHY), the affected port can transmit the far-end fault code if the fault code
transmission is enabled by register bit 16.2.
®
1. Drive the SD input to a value greater than 600 mV during power-up and reset states
2. Configure register bit 16.0 = 1 through the MDIO interface.
• “Remote Fault” refers to a MAC-to-MAC communication function that is transparent to
• “Far-End Fault” is an optional PMA-layer function that may be embedded within PHY
• register bit 5.13 in the Link Partner Base Page Ability Register is set.
• Remote Fault register bit 1.4 in the MII Status Register is set to pass this information
LXT971A Single-Port 10/100 Mbps PHY Transceiver
(all LVPECL signaling levels from a fiber PHY are acceptable).
PHY layer devices. It is used only during auto-negotiation, and is applicable only to
twisted-pair links.
devices.
to the local controller.
5.2 Network Media / Protocol
93.)
Support
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