参数资料
| 型号： | ADT7468ZEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 49/81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
Increasing or decreasing PWM MIN changes the effective T RANGE ,
although the fan control still follows the same PWM duty cycle
fan actually runs at about 45% fan speed when the temperature
exceeds T MIN .
to temperature slope. The effective T RANGE for different PWM MIN
values can be calculated using Equation 2:
100
90
2°C
2.5°C
3.33°C
T MAX = T MIN + ( Max DC ? Min DC ) × T RANGE /170
where:
(2)
80
70
60
4°C
5°C
6.67°C
8°C
( Max DC ? Min DC ) × T RANGE /170 is the effective T RANGE value.
See the Note on Fan Speed and PWM Duty Cycle.
Figure 65 shows PWM duty cycle versus temperature for each
T RANGE setting. The lower graph shows how each T RANGE setting
50
40
30
20
10
10°C
13.3°C
16°C
20°C
26.6°C
32°C
40°C
53.3°C
affects fan speed versus temperature. As can be seen from the
graph, the effect on fan speed is nonlinear.
0
0
20
40 60 80
TEMPERATURE ABOVE T MIN
100
120
80°C
100
90
80
70
60
50
40
30
20
10
0
0
20
40 60 80
TEMPERATURE ABOVE T MIN
100
120
2°C
2.5°C
3.33°C
4°C
5°C
6.67°C
8°C
10°C
13.3°C
16°C
20°C
26.6°C
32°C
40°C
53.3°C
80°C
100
90
80
70
60
50
40
30
20
10
0
0
20
40 60 80
TEMPERATURE ABOVE T MIN
100
120
2°C
2.5°C
3.33°C
4°C
5°C
6.67°C
8°C
10°C
13.3°C
16°C
20°C
26.6°C
32°C
40°C
53.3°C
80°C
100
2°C
90
80
70
60
50
40
30
20
2.5°C
3.33°C
4°C
5°C
6.67°C
8°C
10°C
13.3°C
16°C
20°C
26.6°C
32°C
Figure 66. T RANGE and % Fan Speed Slopes with PWM MIN = 20%
Example: Determining T RANGE for Each Temperature Channel
The following example shows how the different T MIN and T RANGE
settings can be applied to three different thermal zones. In this
example, the following T RANGE values apply:
T RANGE = 80°C for ambient temperature
T RANGE = 53.3°C for CPU temperature
T RANGE = 40°C for VRM temperature
10
0
0
20
40 60 80
100
120
40°C
53.3°C
80°C
This example uses the MUX configuration described in Step 2,
with the ADT7468 connected as shown in Figure 57. Both CPU
TEMPERATURE ABOVE T MIN
Figure 65. T RANGE vs. Actual Fan Speed Profile
The graphs in Figure 65 assume that the fan starts from 0%
PWM duty cycle. Clearly, the minimum PWM duty cycle,
PWM MIN , needs to be factored in to see how the loop actually
performs in the system. Figure 66 shows how T RANGE is affected
temperature and VRM temperature drive the CPU fan
connected to PWM1. Ambient temperature drives the front
chassis fan and rear chassis fan connected to PWM2 and
PWM3. The front chassis fan is configured to run at PWM MIN =
20%. The rear chassis fan is configured to run at PWM MIN =
30%. The CPU fan is configured to run at PWM MIN = 10%.
when the PWM MIN value is set to 20%. It can be seen that the
Rev. 3 | Page 49 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 |
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| ADT7470ARQ | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP |
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