W83977F-A Datasheet, PDF (110/182 Pages) Winbond – WINBOND I/O

W83977F-A/ W83977G-A/ W83977AF-A/ W83977AG-A
UF
The update-ended interrupt flag bit is set after the end of each update cycle. This bit is cleared by a
RESET or when this bit is read.
Bit 3 - Bit 0
These bits are reserved and all read "0".
9.3.4 Register D (Read only)
BIT
7
6
5
4
3
2
1
0
NAME
VRT
0
0
0
0
0
0
0
VRT
The valid RAM and time bit. A "0" appears on this bit when the external battery is removed or at low-
voltage during power-failure situation, indicating the data integrity of the real time clock, "On-Now"
logic, and storage registers is not guaranteed. This bit can only be set by reading this register, and is
not affected by a RESET.
9.4 "On-Now" Control
The "On-Now" Control function is built in RTC. It enables the PC to be powered on automatically
from triggers of various events, and to be powered off in an orderly controlled fashion.
The "On-Now" works at all times even when the system power is switch-off or disconnected. It
detects several external events to control system power supply On/Off properly (e.g. telephone ring,
panel switch-off). It also controls the signal ( PSCTRL ) to turn the power supply on or off.
9.5 Power-On Events
The "On-Now" Control turns on power supply when one of the following events occurs:
• Panel Switch "turned on"
• Telephone is ringing
• Ring-In detection signal comes from a modem
• Keyboard/Mouse is stroked/moved
• Power-wake-up input goes from high to low.
• PSCTRL active when power returns after a power-failure occurs.
(Note: Panel-Switch has a debounce circuit which is clocked by RTC 32.768KHz oscillator. The "On-Now" control will not
function properly if this oscillator fails to work and PC can not be powered-on consequently)
9.6 Power-Off Events
• Panel Switch "turned off"
• Power-off under software control
• Power-failure event
• Override Power off: Panel switch is pushed for at least 4 seconds, then the system will be forced
to turn off immediately
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