
9.0 System Wake-Up Control (SWC)
(Continued)
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Revision1.2
P
9.3.11
This register controls the power-On process and the way the PC8741x device resumes operation after Power Fail. It is reset
by hardware to 87h.
Power Well:V
PP
Location:
All Banks
, Offset 09h
Type:
Varies per bit
Power On Control Register (PWONCTL)
Bit
7
6
5
4
3
2
1
0
Name
WAS
_PFAIL
LAST
_ONCTL
RESUME_MD
LEGACY
_PWBT
1
0
1. This bit is powered from the V
DD
well and is reset either by V
DD
power-up reset or by hardware reset.
CRBAR_TOUT
Reset
1
0
0
0
1
1
1
Bit
Type
Description
7
R/W1C
WAS_PFAIL (Was Power Fail Status).
Indicates that the device has woken up from a Power Fail
condition (V
DD
and V
SB
off). This bit is set by V
SB
Power-Up reset. Writing ‘1’ clears this bit; writing ‘0’
is ignored.
0: Inactive
1: Wake-up from Power Fail (default)
6
RO
LAST_ONCTL (Last Value of ONCTL).
This bit reflects the last value of the ONCTL signal when the
previous Power Fail condition (V
DD
and V
SB
off) occurred. Writing to this bit is ignored.
0: ONCTL inactive - V
DD
power Off (default)
1: ONCTL active - V
DD
power On
5-4
R/W
RESUME_MD (Resume Mode Control).
These bits control the power state to which the PC8741x
device resumes after waking-up from a Power Fail condition (i.e., when V
DD
and V
SB
are off). Table 49
shows the behavior of the ONCTL and PWBTOUT signals in all four Resume modes.
3
R/W
LEGACY_PWBT (Legacy Power Button).
This bit allows the Power button to set ONCTL to inactive
level (V
DD
power supply Off).
0: ACPI-compliant Power button - V
DD
power turned off by sleep state (written into SLP_TYPx field or
decoded from SLPS3 and SLPS5) or by a Power Button Override condition (default)
1: Legacy Power button - V
DD
power turned off by pressing the Power button (PWBTIN) when the V
DD
power is on
2-0
R/W
CRBAR_TOUT (Crowbar Timeout Configuration).
This field controls the timeout value for the
Crowbar function (the time between the activation of ONCTL and its deactivation as a result of V
DD
remaining off). After the Crowbar timeout, the PC8741x device waits another second before it accepts
a new Power button event.
Bits
2 1 0
Timeout (Seconds)
0 0 0:
0.5
0 0 1:
1
0 1 0:
2
0 1 1:
3
1 0 0:
6
1 0 1:
10
1 1 0:
15
1 1 1:
20 (default)