EVAL-ADT7467EBZ ON Semiconductor, EVAL-ADT7467EBZ Datasheet - Page 53

• Manufacturer Part Number: EVAL-ADT7467EBZ
• Description: BOARD EVALUATION FOR ADT7467
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of EVAL-ADT7467EBZ

• Sensor Type: Temperature
• Sensing Range: -40°C ~ 120°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1.5°C
• Voltage - Supply: 3 V ~ 5.5 V
• Embedded: No
• Utilized Ic / Part: ADT7467
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 74 shows how T
ture is above T
T
operating point. Once the temperature rises above the low
temperature limit, T
Preventing T
T
to reach full scale (127°C), because the fan would never switch on.
As a result, T
•
•
•
MIN
MIN
OPERATING
HIGH TEMP
LOW TEMP
The lowest possible value for T
complement mode) or −64°C (Offset 64 mode).
T
If the temperature is below T
runs at minimum speed and dynamic T
disabled.
is below the high temperature limit and below the
is dynamically adjusted; therefore, it is undesirable for T
MIN
THERM
POINT
LIMIT
LIMIT
LIMIT
T
MIN
cannot exceed the high temperature limit.
Figure 74. Increasing T
MIN
MIN
HYSTERESIS
MIN
ACTUAL
is allowed to vary only within a specified range.
from Reaching Full Scale
TEMP
but below the low temperature limit, and how
MIN
MIN
remains fixed.
increases when the current tempera-
OPERATING
HIGH TEMP
LOW TEMP
MIN
MIN
THERM
for Quiet Operation
POINT
MIN
LIMIT
LIMIT
LIMIT
T
, the fan switches off or
Figure 73. Effect of Exceeding Operating Point Minus Hysteresis Temperature
MIN
is –127°C (twos
HYSTERESIS
DECREASE HERE DUE TO
T1(n) – T1 (n – 1) = 0.5°C
EVERY SHORT CYCLE
MIN
SHORT CYCLE ONLY
DECREASES BY 1°C
OR 0.75°C = > T
control is
ACTUAL
TEMP
Rev. 3 | Page 53 of 77 | www.onsemi.com
MIN
MIN
DECREASE HERE DUE TO
T1(n) – T1 (n – 1) ≤ 0.25°C
AND T1(n) > OP = > T
EVERY LONG CYCLE
DECREASES BY 1°C
LONG CYCLE ONLY
STEP 11: MONITORING THERM
Using the operating point limit ensures that the dynamic T
control mode operates in the best possible acoustic position and
that the temperature never exceeds the maximum operating
temperature. Using the operating point limit allows T
independent of system-level issues because of its self-corrective
nature. In PC design, the operating point for the chassis is usually
the worst-case internal chassis temperature.
The optimal operating point for the processor is determined by
monitoring the thermal monitor in the Intel Pentium 4 processor.
To do this, the PROCHOT output of the Pentium 4 is con-
nected to the THERM input of the ADT7467.
The operating point for the processor can be determined by
allowing the current temperature to be copied to the operating
point register when the PROCHOT output pulls the THERM
input low on the ADT7467. This reveals the maximum
temperature at which the Pentium 4 can run before clock
modulation occurs.
OPERATING
HIGH TEMP
LOW TEMP
Figure 75. T
THERM
POINT
LIMIT
LIMIT
LIMIT
DUE TO ANY CYCLE, BECAUSE
T
MIN
MIN
NO CHANGE IN T
T1(n) – T1 (n – 1) ≤ 0.25°C
AND T1(n) < OP = > T
STAYS THE SAME
MIN
HYSTERESIS
Adjustments Limited by the High Temperature Limit
ACTUAL
TEMP
MIN
HERE
MIN
T
FROM INCREASING
MIN
PREVENTED
ADT7467
MIN
to be
MIN