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Revision 1.0

1.4.15 Power and Ground

1.5

INTERNAL PULL-UP AND PULL-DOWN RESISTORS

The signals listed in Table 3 have internal pull-up (PU) and/or pull-down (PD) resistors. The internal resistors are optional

for those signals indicated as “Programmable”. See Section 2.3 on page 25 for the values of each resistor type.

Signal

Pin(s)

I/O Buffer Type

Description

11, 43, 68,

93, 115

I

GND

Ground. Serves for both on-chip logic, output drivers and back-up battery

circuit.

69, 116

I

PWR

Digital 3.3V Power Supply. Serves as power supply for the legacy

peripherals and the LPC Interface.

12, 40, 92

I

PWR

Standby Digital 3.3V Power Supply. Used for the SMBus and X-Bus

interfaces, the GPIO ports and the clock generator. When active, it also

powers the RTC and the SWC.

70

I/O

PWR

On-Chip Core Power Converter Filter. Used by the on-chip core power

converter which powers the core logic of all the device modules. An external

1

µF ceramic filter capacitor must be connected between this pin and V

41

I

to the SWC registers, the RTC and the 32 KHz crystal oscillator. The pin is

connected to the internal logic through a series resistor for UL-compliant

protection.

Table 3. Internal Pull-Up and Pull-Down Resistors

Signal

Pin(s)

Power Well

Type

Comments

Keyboard and Mouse Controller (KBC)

P12, P16, P17

121, 75, 66

SMBus (SMB) Interface

SMBCLK

47

SMBDAT

46

Programmable1

SMBALERT35

Programmable1

Health Monitoring and Control (HMC)

LMPCIF

82

THRMTRIP1,

THRMTRIP2

21,

22

VRMTHRM

83

System Wake-Up Control (SWC)

PWBTIN

36

SLBTIN

35

PWBTOUT

49

SIOSMI

37

SIOSCI

38