DocID022203 Rev 4

5/13

ST33TPM12LPC

Pin and signal description

Table 1. Pin descriptions

Signal

Type

Description

VPS

Input

3.3V Power supply. This pin must be connected to 3.3V DC power rail

supplied by the motherboard.

GND

Input

GND has to be connected to the main motherboard ground.

LAD[3:0]

Bidir

LPC Multiplexed Command, Address and Data (see LPC Spec)

LCLK

Input

Clock Same clock as PCI clock on the host (typically 33 MHz, but may be

as low as 10 MHz). Same clock phase with typical PCI skew. (see LPC

Spec)

LFRAME

Input

Frame indicates start of a new cycle, termination of broken cycle (see LPC

Spec)

LPCPD

Input

Power Down indicates that the peripheral should prepare for power to be

removed from the LPC i/F devices. Actual power removal is system

dependent (see LPC Spec)

LRESET

Input

Reset used to re-initialize the device

PP

Input

Physical Presence, active high, internal pull-down. Used to indicate

Physical Presence to the TPM.

SERIRQ

Bidir

Serialized IRQ is used by TPM to handle interrupt support (see LPC

Spec)

VNC

-

Vendor-controlled No Connect: internal pull-up implemented. Can be

left unconnected. Must not be tied to GND.