Datasheet
SLLS424G − JUNE 2000 − REVISED DECEMBER 2004
47
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
LPS
CTL0
LREQ
SYSCLK
D0−D7
CTL1
(1)
(2)
(3)
(4)
(high)
T
CLK_ACTIVE
7 Cycles
ISO
Figure 27. Interface Initialization, ISO High
The sequence of events for initialization of the PHY-LLC interface when the interface is in the nondifferentiated
mode of operation (ISO
terminal is high) is as follows:
1. LPS reasserted. After the interface has been in the reset or disabled state for at least the minimum
T
RESTORE
time, the LLC causes the interface to be initialized and restored to normal operation by
reasserting the LPS signal. In Figure 27, the interface is shown in the disabled state with SYSCLK low
inactive. However, the interface initialization sequence described here is also executed if the interface is
merely reset but not yet disabled.
2. SYSCLK activated. If the interface is disabled, the PHY reactivates its SYSCLK output when it detects that
LPS has been reasserted. If the PHY has entered a low-power state, it takes between 5.3 ms to 7.3 ms for
SYSCLK to be restored; if the PHY is not in a low-power state, SYSCLK is restored within 60 ns. The
SYSCLK output is a 50% duty cycle square wave with a frequency of 49.152 MHz ±100 ppm (period of
20.345 ns). During the first seven cycles of SYSCLK, the PHY continues to drive the CTL and D terminals
low. The LLC is also required to drive its CTL and D outputs low for one of the first six cycles of SYSCLK
but to otherwise place its CTL and D outputs in a high-impedance state. The LLC continues to drive its LREQ
output low during this time.
3. Receive indicated. Upon the eighth SYSCLK cycle following reassertion of LPS, the PHY asserts the
Receive state on the CTL lines and the data-on indication (all ones) on the D lines for one or more cycles.
4. Initialization complete. The PHY asserts the idle state on the CTL lines and logic 0 on the D lines. This
indicates that the PHY-LLC interface initialization is complete and normal operation may commence. The
PHY now accepts requests from the LLC via the LREQ line.