For remote wake up, the initial state of the system is TC10 sleep. Core voltages to the PHY and MAC are turned off but the VSLEEP of the PHY is present. At some time, wake-up pulses (WUP) are received on the MDI lines. The PHY recevies the message and if its a valid sequence then the PHY wakes up and drives INH pin HIGH. INH pin is used as enable input to voltage regulator (e.g. LDO). Voltage regulators turns on and supplies power to a power management device. The power management device then supplies power to the PHY, MAC, and any other devices on the system. The whole system powers up and becomes operational.
DP83TC812-Q1support wake forwarding feature. When the device received Wake-Up Requests (WUR) or Wake-Up Pulses (MDI) on the MDI then the PHY will transmit an 40µs high pulse on the WAKE pin. This can be used to wake-up any other PHYs on the system that are in TC-10 sleep.
For local wake, it is assumed that some portion of the system is already active and the PHY is in TC10 sleep. As a example, the system might have micro-controller in active mode to control the WAKE pin of the PHY. When the MCU wants to wake up the PHY from TC10 sleep, it raises the WAKE pin to 3.3V to send a wake pulse (min. 40μs). The PHY wakes up and drives INH pin HIGH. INH pin is used as enable input to voltage regulator (e.g. LDO). Voltage regulators turns on and supplies power to a power management device. The power management device then supplies power to the PHY. Any other device on the system that depends on the PHY wake up can now be powered up and the system becomes operational.
When the PHY is in normal operational mode and the MAC needs to put it in TC10 sleep, it initiates the TC10 sleep process via SMI on the PHY. DP83TC812-Q1 then sends LPS signals on MDI to the link partner. If the link partner also agrees to enter TC10 sleep, the host PHY enters TC10 sleep. It then releases the INH pin and it gets pulled low through the external pull down resistor. Voltage regulator that uses INH pin as enable input will be turned off. PHY, MAC, and any other devices that are dependent on the voltage regulator will be turned off. The PHY will still have VSLEEP voltage present and continue to stay in TC10 sleep.