NH82801FBM S L89K Intel, NH82801FBM S L89K Datasheet - Page 76

• Manufacturer Part Number: NH82801FBM S L89K
• Manufacturer: Intel

Specifications of NH82801FBM S L89K

• Lead Free Status / RoHS Status: Compliant

Signal Description
2.22.2
2.22.3
2.22.3.1
2.22.3.2
76
Figure 2-3. Example External RTC Circuit
External RTC Circuitry
To reduce RTC well power consumption, the ICH6 implements an internal oscillator circuit that is
sensitive to step voltage changes in VccRTC.
recommended to ensure correct operation of the ICH6 RTC.
NOTE: C1 and C2 depend on crystal load.
Power Sequencing Requirements
V5REF / Vcc3_3 Sequencing Requirements
V5REF is the reference voltage for 5 V tolerance on inputs to the ICH6. V5REF must be powered
up before Vcc3_3, or after Vcc3_3 within 0.7 V. Also, V5REF must power down after Vcc3_3, or
before Vcc3_3 within 0.7 V. The rule must be followed in order to ensure the safety of the ICH6. If
the rule is violated, internal diodes will attempt to draw power sufficient to damage the diodes from
the Vcc3_3 rail.
This rule also applies to V5REF_Sus and VccSus3_3. However, in most platforms, the VccSus3_3
rail is derived from the 5 VSB on the power supply through a voltage regulator and therefore, the
VccSus3_3 rail will always come up after the VccSus5 rail. As a result, V5REF_Sus (which is
derived directly from VccSus5) will always be powered up before VccSus3_3 and thus circuitry to
satisfy the sequence requirement is not needed. However, in platforms that do not derive the
VccSus3_3 rail from the VccSus5 rail, this rule must be observed in the platform design as
described above.
3.3 V/1.5 V Standby Power Sequencing Requirements
For platforms that use the integrated 1.5 V standby regulator, there are no power sequencing
requirements for associated 3.3 V/1.5 V (standby or core) rails of the ICH6.
For platforms that use an external 1.5 V standby regulator to power VccSus1_5 of the ICH6 (the
internal voltage regulator is disabled), the platform must ensure that VccSus3_3 ramps up before
VccSus1_5 or after VccSus1_5 within 0.7 V. VccSus1_5 must power down before VccSus3_3 or
after VccSus3_3 within 0.7 V.
VccSus3_3
Vbatt
1 KΩ
+
–
Schottky
(20% tolerance)
Diodes
1.0 µF
20 KΩ
32.768 kHz
Xtal
1 µF
(20% tolerance)
Intel
(5% tolerance)
Figure 2-3
®
15 pF
I/O Controller Hub 6 (ICH6) Family Datasheet
C1
shows an example schematic
(5% tolerance)
15 pF
C2
10 MΩ
R1
VCCRTC
RTCX1
RTCX2
RTCRST#