ICS1893BY-10 Data Sheet - Release
Chapter 6 Functional Blocks
– Enabled (bit 18.0 is logic 0), the Link Monitor Function continues to report its link as valid as long as
it continues to detect any of the following:
• ISO/IEC-defined, Normal Link Pulses (NLPs)
• Any valid data followed by a valid IDL
• Valid, the Link Monitor Function declares the link as invalid if it receives neither data nor NLPs (that is,
the link shows either no activity or inconsistent activity) for more than 81 to 83 ms. In this case the Link
Monitor Function sets the Link Status bit to logic zero.
Note:
1. An ICS1893BY-10 receives ‘valid data’ when its Twisted-Pair Receiver phase-locked loop can acquire
lock and extract the receive clock from the incoming data stream for a minimum of three consecutive bit
times.
2. When a link is invalid and the Link Monitor Function detects the presence of data, the ICS1893BY-10
does not transition the link to the valid state until after the reception of the present packet is complete.
3. Enabling or disabling the Smart Squelch Function affects the Link Monitor function.
4. A transition from the invalid state to the valid state does not automatically update the latching-low Link
Status bit.
6.5.6 10Base-T Operation: Smart Squelch
The Smart Squelch Function imposes more stringent requirements on the Link Monitor Function regarding
the definition of a valid link, thereby providing a level of insurance that spurious noise is not mistaken for a
valid link during cable installation.
An STA can control the execution of the ICS1893BY-10 Smart Squelch Function using bit 18.0 (the Smart
Squelch Inhibit bit in the 10Base-T Operations Register). When bit 18.0 is logic:
• Zero (the default), an ICS1893BY-10 enables its Smart Squelch Function. In this case, the Link Monitor
must confirm the presence of both data and a valid IDL at the end of the packet before declaring a link
valid.
• One, an ICS1893BY-10 disables or inhibits its Smart Squelch Function. In this case, the Link Monitor
does not have to confirm the presence of an IDL to declare a link valid (that is, the reception of any data
is sufficient).
In 10Base-T mode, an ICS1893BY-10 appends an IDL to the end of each packet during data transmission.
The receiving PHY (that is, the remote link partner) sees this IDL and removes it from the data stream.
6.5.7 10Base-T Operation: Carrier Detection
The ICS1893BY-10 has a 10Base-T Carrier Detection Function that establishes the state of its Carrier
Sense signal (CRS), based upon the state of its Transmit and Receive state machines. These functions
indicate whether the ICS1893BY-10 is (1) transmitting data, (2) receiving data, or (3) in a collision state
(that is, the ICS1893BY-10 is both transmitting and receiving data on its twisted-pair medium, as defined in
the ISO/IEC 8802-3 standard). When the ICS1893BY-10 is configured for:
• Half-duplex operations, the ICS1893BY-10 asserts its CRS signal when either transmitting or receiving
data.
• Full-duplex operations (or when it is in Repeater mode), the ICS1893BY-10 asserts its CRS signal only
when it is receiving data.
ICS1893BY-10 Rev A 3/24/04
March, 2004
Copyright © 2004, Integrated Circuit Systems, Inc.
All rights reserved.
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ICSI [ INTEGRATED CIRCUIT SOLUTION INC ]
