I347-AT4 Datasheet, PDF (46/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

I347-AT4—Device Functionality
3.10.5
Pulse Amplitude and Pulse Width
The transmitted pulse amplitude and pulse width can be adjusted via registers
28_5.9:8 and 28_5.11:10, respectively. They should normally be set to full amplitude
and full pulse width.
3.10.6
Drop Link
When register 28_5.12 is set to 0b the circuit waits 1.5 seconds to break the link before
starting cable tester. When set to 1b this delay is bypassed.
3.10.7
3.11
Cable Test with Link Up
The following status requires the PHY to link up with a link partner.
• Register 20_5 reports the pair skew of each pair of wires relative to each other.
• Register 21_5.3:0 reports the polarity of each pair of wires.
• Register 21_5.6:5 reports the crossover status.
• Register 20_5 and 21_5 are not valid unless register 21_5.6 is set to 1b.
Data Terminal Equipment (DTE) Detect
The I347-AT4 supports the DTE power function. The DTE power function is used to
detect if a link partner requires power supplied by the I347-AT4.
The DTE power function is enabled by writing to register 26_0.8. When DTE is enabled,
the I347-AT4 first monitors for any activity transmitted by the link partner. If the link
partner is active, then the link partner has power and power from the POE PSE device is
not required. If there is no activity coming from the link partner, DTE power engages,
and special pulses are sent to detect if the link partner requires DTE power. If the link
partner has a low pass filter (or similar fixture) installed, the link partner is detected as
requiring DTE power.
The DTE power status register (Register 17_0.2) immediately comes up as soon as the
link partner is detected as a device requiring DTE power. Register 19_0.2 is a stray bit
that reports the DTE power status has changed states.
If a link partner that requires DTE power is unplugged, the DTE power status (register
17_0.2) drops after a user-controlled delay (default is 20 seconds - Register 26_0.7:4)
to avoid DTE power status register drop during the link partner powering up (for most
applications), since the low pass filter (or similar fixture) is removed during power up.
If DTE power status drop is desired to be reported immediately, write register 26_0.7:4
to 0x0000.
A detailed description of the register bits used for DTE power detection for the I347-
AT4 are listed in Table 15.
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