LAN8810I-AKZE Datasheet, PDF (28/100 Pages) Microchip Technology – GMII 10/100/1000 Ethernet Transceiver with HP Auto-MDIX Support

GMII 10/100/1000 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
3.7 Power-Down modes
3.7.1
3.7.2
3.7.3
The device supports 3 power-down modes:
 General Power-Down
 Energy Detect Power-Down
 Hardware Power-Down
General Power-Down
This power-down mode is controlled by the Power Down bit of the Basic Control Register. In this mode,
the entire device is powered-down except for the serial management interface and MACCLK output.
The device remains in the general power-down mode while Power Down is set. When Power Down is
cleared, the device powers up and is automatically reset (via a Power-Down Reset). Additionally
setting the MACCLKDIS bit of the Extended Mode Control/Status Register will disable the MACCLK
pin output and power-down the PLL. For maximum power savings, auto-negotiation should be disabled
before enabling the general power-down mode.
Energy Detect Power-Down
This power-down mode is controlled by the EDPWRDOWN bit of the 10/100 Mode Control/Status
Register. In this mode, when no energy is present on the line, nothing is transmitted and the device
is powered-down except for the management interface, MACCLK, the SQUELCH circuit and the
ENERGYON logic.
The ENERGYON bit in the 10/100 Mode Control/Status Register is asserted when there is valid energy
from the line (100BASE-TX, 10BASE-T, or Auto-Negotiation signals) and the PHY powers-up. It
automatically resets itself into the previous state prior to power-down, and stays in active mode as long
as energy exists on the line. If the ENGERGYON interrupt is enabled (INT7_EN of the Interrupt Mask
Register), IRQ is asserted.
Note: The first and possibly second packet to activate ENERGYON may be lost.
Hardware Power-Down
This power-down mode is controlled by the HPD pin. In this mode, the entire device is powered-down
except for the serial management interface. The HPD_MODE configuration strap selects whether the
PLL will be shut down when in hardware power-down mode. To exit the hardware power-down mode,
the HPD pin must be deasserted, followed by the deassertion of the Power Down bit in the Basic
Control Register. If the hardware power-down mode is set to shut down the PLL, a software reset must
also be issued.
Note: The device will wake-up in the hardware power-down mode if the HPD pin is asserted during
hardware reset.
Note: For additional information on the HPD_MODE configuration strap, refer to Section 3.8.1.1,
"Configuration Straps," on page 29.
Revision 1.0 (02-06-13)
28
DATASHEET
SMSC LAN8810/LAN8810i