ICS1893CF datasheet(36/126 Pages) ICST

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ICS1893CF, Rev. F, 03/01/07

Mar. 2007

Chapter 6 Functional Blocks

ICS1893CF Data Sheet - Release

When the 10Base-T link is:

• Invalid, and the Smart Squelch function is:

– Disabled (bit 18.0 is logic one), the Link Monitor Function must detect at least one of the following

events before transitioning its link from the invalid state to the valid state:

• More than seven, ISO/IEC-defined, Normal Link Pulses (NLPs)

• Any valid data

– Enabled (bit 18.0 is logic zero), the Link Monitor Function must detect at least one of the following

events before transitioning its link from the invalid state to the valid state:

• More than seven, ISO/IEC-defined, Normal Link Pulses (NLPs)

• Any valid data followed by a valid IDL

• Valid, and the Smart Squelch function is:

– Disabled (bit 18.0 is logic one), 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

– Enabled (bit 18.0 is logic zero), 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 ICS1893CF 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 ICS1893CF 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 ICS1893CF 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 ICS1893CF 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 ICS1893CF 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 ICS1893CF appends an IDL to the end of each packet during data transmission.

The receiving PHY (the remote link partner) sees this IDL and removes it from the data stream.

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