ADT7468 Analog Devices, Inc., ADT7468 Datasheet - Page 55

• Manufacturer Part Number: ADT7468
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

range (OP − Hyst), because the temperature has not exceeded
the operating temperature.
Once the temperature exceeds the operating temperature, the
long cycle causes T
while the temperature remains above the operating
temperature. This takes place in addition to the decrease in T
that would occur due to the short cycle. In Figure 74, because
the temperature is increasing at a rate ≤0.25°C per short cycle,
no reduction in T
Once the temperature has fallen below the operating temp-
erature, T
to increase slowly, T
increases at a rate ≤0.25°C per cycle.
Increasing the T
When the temperature drops below the low temperature limit,
T
effect of running the fan slower and, therefore, quieter. The long
cycle diagram in Figure 74 shows the conditions that need to be
true for T
conditions and the reasons they need to be true.
MIN
can increase in the long cycle. Increasing T
MIN
MIN
stays the same. Even when the temperature starts
to increase. Here is a quick summary of those
MIN
MIN
MIN
MIN
takes place during the short cycle.
Cycle
to be reduced by 1°C every long cycle
stays the same, because the temperature
OPERATING
HIGH TEMP
LOW TEMP
THERM
POINT
LIMIT
LIMIT
LIMIT
T
MIN
Figure 74. Effect of Exceeding Operating Point Minus Hysteresis Temperature
HYSTERESIS
DECREASE HERE DUE TO
T1(n) – T1 (n – 1) = 0.5°C
EVERY SHORT CYCLE
SHORT CYCLE ONLY
DECREASES BY 1°C
OR 0.75°C = > T
MIN
ACTUAL
TEMP
has the
MIN
Rev. A | Page 55 of 84
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
T
•
•
•
•
MIN
The measured temperature has fallen below the low
temperature limit. This means the user must choose the
low limit carefully. It should not be so low that the temp-
erature never falls below it, because T
increase and the fans would run faster than necessary.
T
allowed to increase above the high temperature limit. As a
result, the high limit should be carefully chosen, because it
determines how high T
T
never be allowed to increase above the operating point
temperature, because the fans would not switch on until
the temperature rose above the operating point.
The temperature is above T
is turned off below T
can increase if
MIN
MIN
DUE TO ANY CYCLE, BECAUSE
MIN
NO CHANGE IN T
is below the high temperature limit. T
is below the operating point temperature. T
T1(n) – T1 (n – 1) ≤ 0.25°C
AND T1(n) < OP = > T
STAYS THE SAME
MIN
HERE
MIN
MIN
MIN
.
can go.
MIN
. The dynamic T
MIN
would never
MIN
ADT7468
is never
MIN
MIN
control
should