External Rtc Circuitry; Example External Rtc Circuit - Intel 6 SERIES CHIPSET - DATASHEET 01-2011 Datasheet

Signal Description
Table 2-27. Functional Strap Definitions (Sheet 5 of 5)
Signal
SATA2GP/GPIO36
SATA3GP/GPIO37
NOTE: See
2.28

External RTC Circuitry

The PCH implements an internal oscillator circuit that is sensitive to step voltage
changes in VccRTC.
correct operation of the PCH RTC.
Figure 2-2.

Example External RTC Circuit

VccDSW3_3
(see note 3)
1 K 
Vbatt
NOTES:
1. The exact capacitor values for C1 and C2 must be based on the crystal maker
recommendations.
2. Reference designators are arbitrarily assigned.
3. For platforms not supporting Deep S4/S5, the VccDSW3_3 pins will be connected to the
VccSus3_3 pins.
4. Vbatt is voltage provided by the RTC battery (such as coin cell).
5. VccRTC, RTCX1, RTCX2, RTCRST#, and SRTCRST# are PCH pins.
6. VccRTC powers PCH RTC well.
7. RTCX1 is the input to the internal oscillator.
8. RTCX2 is the amplified feedback for the external crystal.
Datasheet
When
Usage
Sampled
Rising edge of
Reserved
PWROK
Rising edge of
Reserved
PWROK
Section 3.1 for full details on pull-up/pull-down resistors.
Figure 2-2 shows an example schematic recommended to ensure
Schottky Diodes
20 K 20 K
1.0 uF 1.0 uF
This signal has a weak internal pull-down.
NOTES:
1. The internal pull-down is disabled after
PLTRST# deasserts.
2. This signal should not be pulled high
when strap is sampled.
This signal has a weak internal pull-down.
NOTES:
1. The internal pull-down is disabled after
PLTRST# deasserts.
2. This signal should not be pulled high
when strap is sampled.
1uF
32.768 KHz
Xtal
C1 C2
§ §
Comment
VCCRTC
0.1uF
RTCX2
R1
10M
RTCX1
RTCRST#
SRTCRST#
91