82562EZ Datasheet, PDF (20/40 Pages) Intel Corporation – 82562EZ 10/100 Mbps Platform LAN Connect (PLC)

82562EZ — Networking Silicon
4.4
Dynamic Reduced Power & Auto Plugging Detection
The 82562EZ can be configured to support a dynamic reduced power mode. This mode reduces power
consumption of the 82562EZ when LAN activity is not present. The reduced power mode decreases power
consumption from 300 mW to about 50 mW and is based on automatic detection of cable plugging. If the 82562EZ
is configured to support dynamic power reduction, it enters the reduced power mode whenever a cable is not
connected to the device. In reduced power mode, the 82562EZ shuts off the link circuits, except the circuit used for
the automatic plugging detection. On the LAN Connect side, the entire interface remains active, including full
access to all MII Management Interface (MMI) registers. In this mode, the 82562EZ switches to the 10 Mbps speed
interface
(5 MHz for LAN Connect). Thus, the reduced power mode is fully transparent to driver.
4.4.1
Auto Plugging Detection
The 82562EZ senses the link all the time. If it detects loss of any link activity for more than 6.6 seconds, it indicates
to the Media Access Controller (MAC) an “unplugged state” by resetting the SQL LAN Connect control bit. If the
82562EZ is in reduced power mode and link activity is detected, the 82562EZ notifies the MAC (in less than 1
second) that it is in a “plugged state” by setting the SQL LAN Connect control bit. Link activity detection is based
on energy detection.
4.4.2
Dynamic Reduced Power
The 82562EZ can be configured to support dynamic reduced power. In the dynamic reduced power mode, the
82562EZ transitions to reduced power mode when an unplugged state is detected. The 82562EZ will only return to
full power if the reduced power bit on the LAN Connect is reset and a plugged state is detected. However, if the
82562EZ is not configured to support dynamic reduced power, the 82562EZ operates according to the LAN
Connect power-down bit (in other words, the 82562EZ will operate in reduced power mode only if the LAN
Connect power-down bit is set).
4.4.3
Configuration
The dynamic reduced power mode is configured through bit 13 of register 16. The default value is disabled (0). The
status of the 82562EZ can be read through bits 10:9 of register 16. When the 82562EZ is in reduced power mode,
these two bits are set to 1b.
Table 3. Register 16 (10 Hexadecimal): PLC Status, Control and Address Data
Bit
13
Name
Dynamic Reduced Power Down
10
100BASE-TX Power Down
9
10BASE-T Power Down
Description
Read/Write
0 = Automatic reduced power down
enabled
1 = Automatic reduced power down
disabled (default)
Read/Write
The 100BASE-TX Power Down bit indicates
the power state.
0 = Normal operation (default)
1 = Power down
Read Only
The 10BASE-T Power Down bit indicates the
power state.
0 = Normal operation (default)
1 = Power down
Read Only
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Datasheet