307013-003 Datasheet, PDF (78/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

Signal Description
Table 2-23. Functional Strap Definitions (Sheet 3 of 3)
Signal
Usage
When
Sampled
Comment
LINKALERT#
(Desktop
and Mobile
Only)
REQ[4:1]#
SATALED#
(Desktop
and Mobile
Only)
SPKR
TP3
Reserved
XOR Chain
Selection
Reserved
No Reboot
XOR Chain
Entrance
This signal requires an external pull-up resistor.
Rising Edge of
PWROK
See Chapter 25 for functionality information.
This signal has a weak internal pull-up enabled only
when PLTRST# is asserted.
NOTE: This signal should not be pulled low.
Rising Edge of
PWROK
The signal has a weak internal pull-down. If the
signal is sampled high, this indicates that the
system is strapped to the “No Reboot” mode (ICH7
will disable the TCO Timer system reboot feature).
The status of this strap is readable via the NO
REBOOT bit (Chipset Config Registers:Offset
3410h:bit 5).
Rising Edge of
PWROK
See Chapter 25 for functionality information. This
signal has a weak internal pull-up.
NOTE: This signal should not be pulled low unless
using XOR Chain testing.
NOTE: See Section 3.1for full details on pull-up/pull-down resistors.
2.24.2 External RTC Circuitry
To reduce RTC well power consumption, the ICH7 implements an internal oscillator
circuit that is sensitive to step voltage changes in VccRTC. Figure 2-4 shows an
example schematic recommended to ensure correct operation of the ICH7 RTC.
Figure 2-4. Example External RTC Circuit
VccSus3_3
1 KΩ
Vbatt
+
–
Schottky
Diodes
20 KΩ
1 µF
(20% tolerance)
1 µF
(20% tolerance)
32.768 kHz
Xtal
C1
15 pF
(5% tolerance)
C2
15 pF
(5% tolerance)
VCCRTC
R1
10 MΩ
RTCX2
RTCX1
NOTE: C1 and C2 depend on crystal load.
§
78
RTCRST#
Intel ^® ICH7 Family Datasheet