Platform Design Checklist
R
318
Intel
®
855PM Chipset Platform Design Guide
Figure 159 External Circuitry for the RTC
32.768 kHz
Xtal
0.047uF
10M
Ω
VCCRTC
RTCX2
RTCX1
VBIAS
Vbatt
1uF
1k
Ω
3.3V Sus
10M
Ω
C1
C2
C3
R1
R2
Notes
Reference Designators Arbitrarily Assigned
3.3V Sus is Active Whenever System Plugged In
Vbatt is Voltage Provided By Battery
VBIAS, VCCRTC, RTCX1, and RTCX2 are ICH4-M pins
VBIAS is used to bias the ICH4 Internal Oscillator
VCCRTC powers the RTC well of the ICH4-M
RTCX1 is the Input to the Internal Oscillator
RTCX2 is the feedback for the external crystal