PC87307VUL National Semiconductor, PC87307VUL Datasheet - Page 55

• Manufacturer Part Number: PC87307VUL
• Description: PC87307/PC97307 Plug and Play Compatible and PC97 Compliant SuperI/O
• Manufacturer: National Semiconductor

Bit 7 - Interrupt Request Flag (IRQF)
4.2.4
This register indicates the validity of the RTC RAM data.
Bits 6-0 - Reserved
Bit 7 - Valid RAM and Time (VRT)
WARNING:
7
0
This read-only bit is the inverse of the value on the IRQ
output signal of the RTC/APC.
0 - IRQ is inactive (high).
1 - IRQ is active (low) and any of the following condi-
These bits are reserved and are always 0.
The VRT bit senses the voltage that feeds this logical
device (V
was too low since the last time this bit was read. If it was
too low, the RTC and RAM data are not valid.
This read-only bit is set to 1 when this register is read.
0 - The voltage that feeds the APC/RTC logical device
1 - The RTC and RAM data are valid.
If V
may reset this bit.
VRT
6
0
0
tions exists: both PIE and PF are 1; both AIE and
AF are 1; both UIE and UF are 1. (PIE, AIE and
UIE are bits 6, 5 and 4, respectively of the CRB
register.)
was too low.
CCH
RTC Control Register D (CRD), Index 0Dh
5
0
0
ramps down at a rate exceeding 1 V/msec, it
CCH
4
0
0
FIGURE 4-8. CRD Bitmap
3
0
0
or V
Real-Time Clock (RTC) and Advanced Power Control (APC) (Logical Device 2)
2
0
0
Reserved
BAT
1
0
0
) and indicates whether or not it
0
0
0
Power-Up
Reset
Required
RTC Control
Register D
Index 0Dh
(CRD)
55
4.3 APC OVERVIEW
Advanced Power Supply Control (APC) is implemented
within the RTC logical device. It enables the PC to power up
automatically, as required by specific conditions, or to pow-
er down in an orderly, controlled manner, replacing the
physical power supply On/Off switch.
The APC device is powered at all times that external AC
power or battery backup power are connected to the RTC
device. This is true even though the PC may be switched off
or disconnected from the external AC power outlet, in which
case the APC device is active but does not activate system
power. The APC device powers up the entire PC system
upon the occurrence of various events (including the power-
on switch event).
WARNING:
The APC function produces the ONCTL signal to activate
the system power supply, and the Power-Off Request
(POR) interrupt request signal when there is a request for
power off.
ONCTL: The ONCTL signal physically activates or deacti-
vates the system power supply.
The ONCTL value depends on the following:
POR: The APC generates a Power-Off Request (POR) in-
terrupt request signal when the power switch is manually
toggled to turn the power off. This enables a software con-
trolled exit procedure (analogous to the autoexec.bat
startup procedure in DOS operating systems) with automat-
ic activation of preprogrammed features such as system
status backup, system activity logging, file closing and
backup, remote communications termination, print comple-
tion, etc.
Table 4-4 shows the registers used for Automatic Power
Supply Control (APC) in the part.
4.3.1
The APC function enables users to tailor system response
to power up, power down, power failure and battery opera-
tion situations.
User-selectable parameters include:
•
•
•
•
•
•
The APC device does not function if the 32.768 KHz os-
cillator is not running.
External events
Programmable parameter settings
The system state when an external event occurs
The state of the system power supply.
Enabling various external events to wake up the sys-
tem. See “Power Up” on page 58.
Wake-up time for an automatic system wake-up. See
“Predetermined Wake-Up” on page 60.
Index
40h
41h
42h
47h
User Selectable Parameters
TABLE 4-4. APC Control Register List
Mnemonic
APCR1
APCR2
APSR
RLR
APC Control Register 1
APC Control Register 2
APC Status Register
RAM Lock Register
Description
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