NH82801HBM S LB9A Intel, NH82801HBM S LB9A Datasheet - Page 249

• Manufacturer Part Number: NH82801HBM S LB9A
• Description: CONTROLLER HUB, ICH8M, I/O, 82801HBM
• Manufacturer: Intel

Specifications of NH82801HBM S LB9A

• Power Dissipation Pd: 2.4W
• Digital Ic Case Style: BGA
• No. Of Pins: 676
• Pci Bus Type: I/O Controller Hub
• Pci Express Base Spec: PCIe 1.1
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Functional Description
5.24
Note:
5.24.1
5.24.2
5.25
Intel
®
ICH8 Family Datasheet
Intel
The ICH8 implements three PWM and 4 TACH signals for fan speed control.
Intel
including an appropriate (G)MCH with ME, ME Firmware, and system BIOS support.
PWM Outputs
This signal is driven as open-drain. An external pull-up resistor is integrated into the
fan to provide the rising edge of the PWM output signal. The PWM output is driven low
during reset, which represents 0% duty cycle to the fans. After reset de-assertion, the
PWM output will continue to be driven low until one of the following occurs:
Note that if a PWM output will be programmed to inverted polarity for a particular fan,
then the low voltage driven during reset represents 100% duty cycle to the fan.
TACH Inputs
This signal is driven as an open-collector or open-drain output from the fan. An
external pull-up is expected to be implemented on the motherboard to provide the
rising edge of the TACH input. This signal has analog hysteresis and digital filtering due
to the potentially slow rise and fall times. This signal has a weak internal pull-up
resistor to keep the input buffer from floating if the TACH input is not connected to a
fan.
Thermal Sensors
ICH8 integrates two thermal sensors that monitor the temperature within its die. The
thermal sensors are used for Intel Quiet System Technology. The AFSC firmware can
internally access the temperature measured by the sensors and use the data as a
factor to determine how to control the fans.
The ICH8 thermal sensors also provide the capability to protect the ICH8 under a
catastrophic thermal situation. When the sensors are enabled and correctly
programmed by the system BIOS, the ICH8 will shut down the system when the ICH8
thermal limit is reached. Refer to the Thermal Memory Mapped Configuration Registers
(Section 20.2) for more information on the catastrophic settings.
• The internal PWM control register is programmed to a non-zero value by the AFSC
• The watchdog timer expires (enabled and set at 4 seconds by default).
• The polarity of the signal is inverted by the Intel Quiet System Technology firmware
firmware
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Quiet System Technology functionality requires a correctly configured system,
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Quiet System Technology (Desktop Only)
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