Figure 159 External Circuitry For The Rtc - Intel 855PM Design Manual

Platform Design Checklist

Figure 159 External Circuitry for the RTC

3.3V Sus
1k Ω
Vbatt
Notes
Reference Designators Arbitrarily Assigned
3.3V Sus is Active Whenever System Plugged In
Vbatt is Voltage Provided By Battery
318
1uF
32.768 kHz
Xtal
C3
C1
0.047uF
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
®
Intel 855PM Chipset Platform Design Guide
VCCRTC
RTCX2
R1
10M Ω
RTCX1
R2
C2
10M Ω
VBIAS
R