参数资料
| 型号： | ADT7468ZEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 37/81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
AUTOMATIC FAN CONTROL OVERVIEW
The ADT7468 can automatically control the speed of fans based
upon the measured temperature. This is done independently of
CPU intervention once initial parameters are set up.
The ADT7468 has a local temperature sensor and two remote
temperature channels that can be connected to a CPU on-chip
thermal diode (available on Intel Pentium class and other
CPUs). These three temperature channels can be used as the
basis for automatic fan speed control to drive fans using pulse-
width modulation (PWM).
Automatic fan speed control reduces acoustic noise by
optimizing fan speed according to accurately measured
temperature. Reducing fan speed can also decrease system
current consumption. The automatic fan speed control mode is
very flexible, owing to the number of programmable para-
meters, including T MIN and T RANGE . The T MIN and T RANGE values
for a temperature channel and, therefore, for a given fan are
critical, because they define the thermal characteristics of the
system. The thermal validation of the system is one of the most
important steps in the design process, so these values should be
selected carefully.
Figure 49 gives a top level overview of the automatic fan control
circuitry on the ADT7468. From a systems-level perspective, up
to three system temperatures can be monitored and used to
control three PWM outputs. The three PWM outputs can be
used to control up to four fans. The ADT7468 allows the speed
of four fans to be monitored. Each temperature channel has a
thermal calibration block, allowing the designer to individually
configure the thermal characteristics of each temperature
channel. For example, one can decide to run the CPU fan when
the CPU temperature increases above 60°C and a chassis fan
when the local temperature increases above 45°C. At this stage,
the designer has not assigned these thermal calibration settings
to a particular fan drive (PWM) channel. The right side of
Figure 49 shows controls that are fan-specific. The designer has
individual control over parameters such as minimum PWM
duty cycle, fan speed failure thresholds, and even ramp control
of the PWM outputs. Automatic fan control, then, ultimately
allows graceful fan speed changes that are less perceptible to the
system user.
THERMAL CALIBRATION
100%
PWM
MIN
PWM
CONFIG
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
PWM
GENERATOR
PWM1
REMOTE 1
TEMP
T MIN T RANGE
THERMAL CALIBRATION
0%
100%
PWM
MIN
TACHOMETER 1
MEASUREMENT
PWM
CONFIG
TACH1
RAMP
MUX
CONTROL
(ACOUSTIC
PWM
GENERATOR
PWM2
ENHANCEMENT)
LOCAL
TEMP
T MIN T RANGE
THERMAL CALIBRATION
0%
100%
PWM
MIN
TACHOMETER 2
MEASUREMENT
RAMP
PWM
CONFIG
TACH2
CONTROL
(ACOUSTIC
ENHANCEMENT)
PWM
GENERATOR
PWM3
REMOTE 2
T MIN
T RANGE
0%
TACHOMETER 3
AND 4
MEASUREMENT
TACH3
TEMP
Figure 49. Automatic Fan Control Block Diagram
Rev. 3 | Page 37 of 81 | www.onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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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