Thermal Management
66
Datasheet
5.2.2.1.3
Catastrophic Trip Point
This trip point is set at the temperature at which the integrated graphics and memory
controller must be shut down immediately without any software support. This trip point
may be programmed to generate an interrupt, enable throttling, or immediately shut
down the system (via Halt or via THERMTRIP# assertion). Crossing a trip point in either
direction may generate several types of interrupts.
5.2.2.1.4
Recommended Programming for Available Trip Points
See the integrated graphics and memory controller BIOS Specification for
recommended Trip Point programming. Aux Trip Points (0, 1, 2, 3) should be
programmed for software and firmware control via interrupts. HOT Trip Point should be
set to throttle integrated graphics and memory controller to avoid T
j,max
of 100°C.
Catastrophic Trip Point should be set to halt operation to avoid maximum Tj of 130°C.
Note:
Crossing a trip point in either direction may generate several types of interrupts. Each
trip point has a register that can be programmed to select the type of interrupt to be
generated. Crossing a trip point is implemented as edge detection on each trip point to
generate the interrupts. Either edge (i.e., crossing the trip point in either direction)
generates the interrupt.
5.2.2.1.5
Thermal Sensor Accuracy (T
accuracy
)
The error associated with DTS measurement will not exceed ±5°C within the operating
range. Integrated graphics and memory controller may not operate above T
j,max
spec.
This value is based on product characterization and is not guaranteed by manufacturing
test.
Software has the ability to program the T
cat
, T
hot
, and T
aux
trip points, but these trip
points should be selected with consideration for the thermal sensor accuracy and the
quality of the platform thermal solution. Overly conservative (unnecessarily low)
temperature settings may unnecessarily degrade performance due to frequent
throttling, while overly aggressive (dangerously high) temperature settings may fail to
protect the part against permanent thermal damage.
5.2.2.1.6
Hysteresis Operation
Hysteresis provides a small amount of positive feedback to the thermal sensor circuit to
prevent a trip point from flipping back and forth rapidly when the temperature is right
at the trip point. The digital hysteresis offset is programmable via processor registers.
5.2.2.2
Memory Thermal Throttling Options
The integrated graphics and memory controller has two, independent mechanisms that
cause system memory throttling:
TDP Controller: The TDP Controller is the main mechanism for limiting MCH power by
limiting memory bandwidth. Utilized as a thermal throttling mechanism, this feature is
triggered by the Hot temperature trip point of the Graphics and Memory Controller