Datasheet

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    
SGLS122C − JULY 2002 − REVISED JUNE 2008
45
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
interface reset and disable (continued)
The sequence of events for resetting the PHY-LLC interface when it is in the nondifferentiated mode of operation
(ISO
terminal is high) is as follows:1
a. Normal operation. Interface is operating normally, with LPS asserted, SYSCLK active, status and
packet data reception and transmission via the CTL and D lines, and request activity via the LREQ line.
In Figure 23, the LPS signal is shown as a non-pulsed level signal. However, it is permissible to use
a pulsed signal for LPS in a direct connection between the PHY and LLC; a pulsed signal is required
when using an isolation barrier (whether of the TI bus holder type or Annex J type).
b. LPS deasserted. The LLC deasserts the LPS signal and, within 1 µs, terminates any request or interface
bus activity, places its CTL and D outputs into a high-impedance state, and drives its LREQ output low.
c. Interface reset. After T
LPS_RESET
time, the PHY determines that LPS is inactive, terminates any
interface bus activity, and drives its CTL and D outputs low. The PHY-LLC interface is now in the reset
state.
d. Interface restored. After the minimum T
RESTORE
time, the LLC may again assert LPS active. When LPS
is asserted, the interface initializes as described below.
If the LLC continues to keep the LPS signal deasserted, it requests that the interface be disabled. The PHY
disables the interface when it observes that LPS has been deasserted for T
LPS_DISABLE
. When the interface
is disabled, the PHY sets its CTL and D outputs as stated above for interface reset, but also stops SYSCLK
activity. The interface is also placed into the disabled condition upon a hardware reset of the PHY. The timing
for interface disable is shown in Figure 24 and Figure 25.
When the interface is disabled, the PHY enters a low-power state if none of its ports is active.
SYSCLK
ISO
(low)
(a) (c)
(b)
CTL0, CTL1
D0 − D7
LREQ
LPS
(d)
T
LPS_RESET
T
LPS_DISABLE
T
LPSL
T
LPSH
Figure 25. Interface Disable, ISO Low