参数资料
| 型号： | ADT7468ZEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 55/81页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR ADT7468 |
| 标准包装： | 1 |
| 其它名称： | EVAL-ADT7468EB EVAL-ADT7468EB-ND |
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ADT7468
Once the temperature exceeds the operating temperature, the
long cycle causes T MIN to be reduced by 1°C every long cycle
T MIN can increase if
while the temperature remains above the operating
temperature. This takes place in addition to the decrease in T MIN
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 MIN takes place during the short cycle.
Once the temperature has fallen below the operating temp-
erature, T MIN stays the same. Even when the temperature starts
to increase slowly, T MIN stays the same, because the temperature
increases at a rate ≤0.25°C per cycle.
Increasing the T MIN Cycle
When the temperature drops below the low temperature limit,
T MIN can increase in the long cycle. Increasing T MIN has the
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 MIN to increase. Here is a quick summary of those
conditions and the reasons they need to be true.
THERM
LIMIT
HIGH TEMP
LIMIT
OPERATING
POINT
HYSTERESIS
ACTUAL
TEMP
T MIN
LOW TEMP
LIMIT
?
?
?
?
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 MIN would never
increase and the fans would run faster than necessary.
T MIN is below the high temperature limit. T MIN is never
allowed to increase above the high temperature limit. As a
result, the high limit should be carefully chosen, because it
determines how high T MIN can go.
T MIN is below the operating point temperature. T MIN should
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 MIN . The dynamic T MIN control
is turned off below T MIN .
NO CHANGE IN T MIN HERE
DUE TO ANY CYCLE, BECAUSE
T1(n) – T1 (n – 1) ≤ 0.25°C
AND T1(n) < OP = > T MIN
STAYS THE SAME
DECREASE HERE DUE TO
SHORT CYCLE ONLY
T1(n) – T1 (n – 1) = 0.5°C
OR 0.75°C = > T MIN
DECREASES BY 1°C
EVERY SHORT CYCLE
DECREASE HERE DUE TO
LONG CYCLE ONLY
T1(n) – T1 (n – 1) ≤ 0.25°C
AND T1(n) > OP = > T MIN
DECREASES BY 1°C
EVERY LONG CYCLE
Figure 74. Effect of Exceeding Operating Point Minus Hysteresis Temperature
Figure 75 shows how T MIN increases when the current tempera-
ture is above T MIN and below the low temperature limit, and
T MIN is below the high temperature limit and below the
THERM
LIMIT
HIGH TEMP
LIMIT
operating point. Once the temperature rises above the low
OPERATING
POINT
HYSTERESIS
temperature limit, T MIN stays the same.
ACTUAL
LOW TEMP
TEMP
LIMIT
T MIN
Figure 75. Increasing T MIN for Quieter Operation
Rev. 3 | Page 55 of 81 | www.onsemi.com
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相关代理商/技术参数 |
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|---|---|
| ADT7470 | 制造商:AD 制造商全称:Analog Devices 功能描述:Temperature Sensor Hub and Fan Controller |
| ADT7470_13 | 制造商:AD 制造商全称:Analog Devices 功能描述:Temperature Sensor Hub and Fan Controller |
| ADT7470ARQ | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP |
| ADT7470ARQ-REEL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| ADT7470ARQ-REEL7 | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP T/R |
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