FW82801E Intel, FW82801E Datasheet - Page 51

• Manufacturer Part Number: FW82801E
• Description: Communications I/O Controller Hub
• Manufacturer: Intel

3.3.4
3.4
3.4.1
Advance Information Datasheet
Figure 8. Example V5REF Sequencing Circuit
Table 29. 82801E C-ICH Power Planes
V5REF is the reference voltage for 5 V tolerance on inputs to the 82801E C-ICH. V5REF must
power up before or simultaneous to Vcc3_3, and must power down after or simultaneous to
Vcc3_3. Refer to Figure 8 for an example circuit schematic that may be used to ensure proper
V5REF sequencing.
Power Planes and Pin States
Power Planes
V5REF/Vcc3_3 Sequencing Requirements
Processor Interface
(1.3 ~ 2.5 V)
Main Logic
Main I/O
(3.3 V)
(1.8 V)
Plane
RTC
Vcc3_3: Powered by the main power supply.
Vcc1_8: Powered by the main power supply.
V_CPU_IO: Powered by the main power supply via processor voltage regulator.
VccRTC: When other power is available (from the main supply), external diode
coupling will provide power to reduce the drain on the RTC battery. Assumed to operate
from 3.3 V down to 2.0 V.
VCC Supply
To System
(3.3V)
Schottky
Diode
5VREF
Description
1 uF
1k
To System
5V Supply
Intel
®
82801E C-ICH
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