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IDT Power Management
Notes
PES4T4 User Manual
WAKEN Signal as an Input
The WAKEN signal may be configured as an input to make use of the PES4T4's ability to translate
WAKEN input to Beacon transmission (on the upstream link). To enable this feature, the following must be
true:
– The WAKEDIR bit in the SWCTL register must be 0x0.
– The WAKEEN bit in the WAKEUP register is set.
– The BCONEN bit in the WAKEUP register is set.
– Auxiliary power is ON.
– Auxiliary power consumption is enabled (APWREN bit is set in the Switch Control register).
– The PMEE bit in the PMCSR register of the upstream port is set.
On receiving WAKEN signal, the PES4T4 propagates transmission of the in-band beacon signal on the
upstream link until a break in electrical idle is detected in this link.
WAKEN Signal as an Output
The WAKEN signal may be configured as an output when it is desired that the PES4T4 initiate the
wakeup protocol by asserting this signal. In order to enable the WAKEN signal as an output, the following
must be true:
– The WAKEDIR bit in the SWCTL register must be 0x1.
– The WAKEEN bit in the WAKEUP register is set.
– Auxiliary power is ON
– Auxiliary power consumption is enabled (APWREN bit is set in Switch Control register)
– PMEE bit in the PMCSR register in the associated downstream port is set.
WAKEN and Beacon Disabled
When both the WAKEN and Beacon signalling mechanisms are disabled, the PES4T4 wakeup protocol
mechanism is disabled.
Auxiliary Power Implementation
Switch System States
The PES4T4 system states are determined by the main power and auxiliary power supply ON/OFF state
as shown in Figure 7.2.
Any State
Device OFF
Main Power Off
Auxiliary Power Off
Device ON
Main Power ON
Figure 7.2 PES4T4 System States
7 - 5
Active Standby
Main Power Off
Auxiliary Power ON
Aux Pwr Enabled
Inactive Standby
Main Power Off
Auxiliary Power ON
Aux Pwr Disabled
February 1, 2011
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