Thermtrip# Signal; Platform Environment Control Interface (Peci); Introduction - Intel Core i7 Extreme Edition Datasheet

Thermal Specifications
external source (e.g., a voltage regulator) to activate the TCC. The ability to activate
the TCC via PROCHOT# can provide a means for thermal protection of system
components.
As an output, PROCHOT# (Processor Hot) will go active when the processor
temperature monitoring sensor detects that one or more cores has reached its
maximum safe operating temperature. This indicates that the processor Thermal
Control Circuit (TCC) has been activated, if enabled. As an input, assertion of
PROCHOT# by the system will activate the TCC for all cores. TCC activation when
PROCHOT# is asserted by the system will result in the processor immediately
transitioning to the minimum frequency and corresponding voltage (using Freq/VID
control). Clock modulation is not activated in this case. The TCC will remain active until
the system de-asserts PROCHOT#.
Use of PROCHOT# in bi-directional mode can allow VR thermal designs to target
maximum sustained current instead of maximum current. Systems should still provide
proper cooling for the VR, and rely on PROCHOT# only as a backup in case of system
cooling failure. The system thermal design should allow the power delivery circuitry to
operate within its temperature specification even while the processor is operating at its
Thermal Design Power.
6.2.3

THERMTRIP# Signal

Regardless of whether or not Adaptive Thermal Monitor is enabled, in the event of a
catastrophic cooling failure, the processor will automatically shut down when the silicon
has reached an elevated temperature (refer to the THERMTRIP# definition in
Table 5-1). THERMTRIP# activation is independent of processor activity. The
temperature at which THERMTRIP# asserts is not user configurable and is not software
visible.
6.3

Platform Environment Control Interface (PECI)

6.3.1

Introduction

The Platform Environment Control Interface (PECI) is a one-wire interface that provides
a communication channel between Intel processor and chipset components to external
monitoring devices. The processor implements a PECI interface to allow communication
of processor thermal and other information to other devices on the platform. The
processor provides a digital thermal sensor (DTS) for fan speed control. The DTS is
calibrated at the factory to provide a digital representation of relative processor
temperature. Instantaneous temperature readings from the DTS are available via the
IA32_THERM_STATUS MSR; averaged DTS values are read via the PECI interface.
The PECI physical layer is a self-clocked one-wire bus that begins each bit with a
driven, rising edge from an idle level near zero volts. The duration of the signal driven
high depends on whether the bit value is a logic '0' or logic '1'. PECI also includes
variable data transfer rate established with every message. The single wire interface
provides low board routing overhead for the multiple load connections in the congested
routing area near the processor and chipset components. Bus speed, error checking,
and low protocol overhead provides adequate link bandwidth and reliability to transfer
critical device operating conditions and configuration information.
Datasheet 85