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7300 Series contains Digital Thermal Sensors (DTS) distributed throughout the die.
These sensors are implemented as analog-to-digital converters calibrated at the factory
for reasonable accuracy to provide a digital representation of relative processor
temperature. PECI provides an interface to relay the highest DTS temperature within a
die to external management devices for thermal/fan speed control.
2.11.2.1
DC Characteristics
A PECI device interface operates at a nominal voltage set by V
electrical specifications shown in
from a V
TT
PECI devices will operate at the V
system. For specific nominal V
Table 2-15. PECI DC Electrical Limits
Symbol
V
in
V
hysteresis
V
n
V
p
I
source
I
sink
I
leak+
I
leak-
C
bus
V
noise
Note:
1.
V
supplies the PECI interface. PECI behavior does not affect V
TT
2.
The leakage specification applies to powered devices on the PECI bus.
3.
One node is counted for each client and one node for the system host. Extended trace lengths might
appear as additional nodes.
2.11.2.2
Input Device Hysteresis
The input buffers in both client and host models must use a Schmitt-triggered input
design for improved noise immunity. Use
36
Table 2-15
interface supply. V
nominal levels will vary between processor families. All
TT
TT
levels, refer to
TT
Definition and Conditions
Input Voltage Range
Hysteresis
Negative-edge threshold voltage
Positive-edge threshold voltage
High level output source
(V
= 0.75 * V
)
OH
TT
Low level output sink
(V
= 0.25 * V
)
OL
TT
High impedance state leakage to V
(V
= V
)
leak
OL
High impedance leakage to GND
(V
= V
)
leak
OH
Bus capacitance
Signal noise immunity above 300 MHz
is used with devices normally operating
level determined by the processor installed in the
Table
2-11.
Min
-0.150
0.1 * V
TT
0.275 * V
TT
0.550 * V
TT
-6.0
0.5
TT
N/A
N/A
N/A
0.1 * V
TT
min/max specifications.
TT
Figure 2-9
as a guide for input buffer design.
Electrical Specifications
. The set of DC
TT
Max
Units
Notes
V
V
TT
N/A
V
0.500 * V
V
TT
0.762 * V
V
TT
N/A
mA
1.0
mA
50
µA
2
10
µA
2
10
pF
3
N/A
V
p-p
Document Number: 318080-002
1
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