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| 型号： | ADT7473ARQZ-1REEL |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 温度/湿度传感器 |
| 英文描述： | DIGITAL TEMP SENSOR-SERIAL, 8BIT(s), 2.50Cel, RECTANGULAR, SURFACE MOUNT |
| 封装： | ROHS COMPLIANT, MO-137AB, QSOP-16 |
| 文件页数： | 26/72页 |
| 文件大小： | 1494K |
| 代理商： | ADT7473ARQZ-1REEL |
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ADT7473/ADT7473-1
Rev. C | Page 32 of 72
PROGRAMMING THE AUTOMATIC FAN SPEED CONTROL LOOP
To understand the automatic fan speed control loop, it is
strongly recommended to use the ADT7473/ADT7473-1
evaluation board and software while reading this section.
This section provides the system designer with an understand-
ing of the automatic fan control loop, and provides step-by-step
guidance on effectively evaluating and selecting critical system
parameters. To optimize the system characteristics, the designer
needs to consider the system configuration, including the
number of fans, where they are located, and what temperatures
are measured in the particular system.
The mechanical or thermal engineer who is tasked with the
system thermal characterization should also be involved at the
beginning of the process.
AUTOMATIC FAN CONTROL OVERVIEW
The ADT7473/ADT7473-1 can automatically control the speed
of fans based on the measured temperature. This is done
independently of CPU intervention once initial parameters are
set up.
The ADT7473/ADT7473-1 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
CPUs and other CPUs). These three temperature channels can
be used as the basis for automatic fan speed control to drive
fans using PWM.
Automatic fan speed control reduces acoustic noise by optimiz-
ing fan speed according to accurately measured temperature.
Reducing fan speed can also decrease system current consump-
tion. The automatic fan speed control mode is very flexible due
to the number of programmable parameters, including TMIN
and TRANGE. The TMIN and TRANGE 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 ADT7473/ADT7473-1. 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 ADT7473/
ADT7473-1 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, a designer can
decide to run the CPU fan when 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.
MUX
THERMAL CALIBRATION
0%
TMIN
TRANGE
THERMAL CALIBRATION
100%
0%
TMIN
TRANGE
THERMAL CALIBRATION
100%
0%
TMIN
TRANGE
REMOTE 1
TEMP
LOCAL
TEMP
REMOTE 2
TEMP
04
68
6-
04
6
TACHOMETER 1
MEASUREMENT
PWM
CONFIG
PWM
MIN
PWM1
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
PWM
GENERATOR
TACHOMETER 2
MEASUREMENT
PWM
CONFIG
PWM
MIN
PWM2
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
PWM
GENERATOR
TACHOMETER 3
AND 4
MEASUREMENT
PWM
CONFIG
PWM
MIN
PWM3
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
PWM
GENERATOR
100%
TACH1
TACH2
TACH3
Figure 49. Automatic Fan Control Block Diagram
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADT7473ARQZ-1REEL7 | 功能描述:IC THERM MON FAN CTRLR 16-QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热管理 系列:dBCool® 标准包装:1 系列:- 功能:温度监控系统（传感器） 传感器类型:内部和外部 感应温度:-40°C ~ 125°C，外部传感器 精确度:±2.5°C 本地（最大值），±5°C 远程（最大值） 拓扑:ADC，比较器，寄存器库 输出类型:2 线 SMBus? 输出警报:无 输出风扇:无 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:SOT-23-8 供应商设备封装:SOT-23-8 包装:Digi-Reel® 其它名称:296-22675-6 |
| ADT7473ARQZ-1RL | 功能描述:板上安装温度传感器 FAN CNTRLR/INT MON RoHS:否 制造商:Omron Electronics 输出类型:Digital 配置: 准确性:+/- 1.5 C, +/- 3 C 温度阈值: 数字输出 - 总线接口:2-Wire, I2C, SMBus 电源电压-最大:5.5 V 电源电压-最小:4.5 V 最大工作温度:+ 50 C 最小工作温度:0 C 关闭: 安装风格: 封装 / 箱体: 设备功能:Temperature and Humidity Sensor |
| ADT7473ARQZ-REEL | 功能描述:板上安装温度传感器 FAN CNTRLR/INT MON RoHS:否 制造商:Omron Electronics 输出类型:Digital 配置: 准确性:+/- 1.5 C, +/- 3 C 温度阈值: 数字输出 - 总线接口:2-Wire, I2C, SMBus 电源电压-最大:5.5 V 电源电压-最小:4.5 V 最大工作温度:+ 50 C 最小工作温度:0 C 关闭: 安装风格: 封装 / 箱体: 设备功能:Temperature and Humidity Sensor |
| ADT7473ARQZ-REEL7 | 功能描述:IC REMOTE THERMAL CTRLR 16QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热管理 系列:dBCool® 标准包装:1 系列:- 功能:温度监控系统（传感器） 传感器类型:内部和外部 感应温度:-40°C ~ 125°C，外部传感器 精确度:±2.5°C 本地（最大值），±5°C 远程（最大值） 拓扑:ADC，比较器，寄存器库 输出类型:2 线 SMBus? 输出警报:无 输出风扇:无 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:SOT-23-8 供应商设备封装:SOT-23-8 包装:Digi-Reel® 其它名称:296-22675-6 |
| ADT7473ARQZ-RL7 | 功能描述:板上安装温度传感器 FAN CNTRLR/INT MON RoHS:否 制造商:Omron Electronics 输出类型:Digital 配置: 准确性:+/- 1.5 C, +/- 3 C 温度阈值: 数字输出 - 总线接口:2-Wire, I2C, SMBus 电源电压-最大:5.5 V 电源电压-最小:4.5 V 最大工作温度:+ 50 C 最小工作温度:0 C 关闭: 安装风格: 封装 / 箱体: 设备功能:Temperature and Humidity Sensor |
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