VSC8221 datasheet(48/138 Pages) MICROSEMI

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VSC8221

Data Sheet

VMDS-10106 Revision 4.1

December 2006

48 of 48

15.2 Low-Power State

in the low-power state, all major digital blocks are powered down. However the following functionality is provided:

• SMi interface (MDC/MODDEF1, MDiO/MODDEF2, MDiNT)

• CLKOUT and CLKOUTMiCRO

in this state, the PHY monitors the media interface pins for signal energy. The PHY comes out of the low power state and

transitions to the Normal operating state when signal energy is detected on the media. This happens when the PHY is

connected to one of the following:

• Auto-negotiation capable link partner

• Auto-negotiation incapable (blind/forced) 100BTX only link partner

• Auto-negotiation incapable (blind/forced) 10BT only link partner

• Another PHY in enhanced ActiPHY LP wakeup state

in the absence of signal energy on the media pins, the PHY will transition from the low power state to the LP Wake up state

periodically based on the programmable sleep timer. Two register bits (Mii Register bits 28.1:0) are provided to program the

value of the sleep timer. The sleep timer can be programmed to 2'b00 (1sec), 2'b01 (2sec), 2'b10 (3sec), or 2'b11 (4sec). The

default value is 2 seconds. The actual sleep time duration is randomized by -80ms to +60ms to prevent two PHYs in Enhanced

ActiPHY mode from entering a lock-up state.

15.3 LP Wake-Up State

in this state, the PHY attempts to wake up the link partner. One complete FLP (Fast link Pulse) is sent on both pairs A and B of

the CAT5 media. in this state, the following functionality is provided:

• SMi interface (MDC/MODDEF1, MDiO/MODDEF2, MDiNT)

• CLKOUT and CLKOUTMiCRO

After sending signal energy on the relevant media, the PHY returns to the Low power state.

15.4 Normal Operating State

in this state, the PHY establishes a link with a link partner. When the media is unplugged or the link partner is powered down,

the PHY waits for the duration programmed through a link status timeout timer and then enters the low power state. The Link

Status Timeout timer can be programmed to 2'b00 (1sec), 2'b01 (2sec), 2'b10 (3sec) or 2'b11 (4sec). The default value for this

timer is 2 seconds.

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