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參數(shù)資料
| 型號(hào)： | ADT7476ARQZ-REEL7 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | DIGITAL TEMP SENSOR-SERIAL, 10BIT(s), 2.50Cel, RECTANGULAR, SURFACE MOUNT |
| 封裝： | ROHS COMPLIANT, MO-137AE, QSOP-24 |
| 文件頁數(shù)： | 31/72頁 |
| 文件大?。?/td> | 5219K |
| 代理商： | ADT7476ARQZ-REEL7 |
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ADT7476
Rev. B | Page 37 of 72
PROGRAMMING THE AUTOMATIC FAN SPEED CONTROL LOOP
To understand the automatic fan speed control loop, use the
ADT7476 evaluation board and software while reading this
section. This section provides the system designer with an
understanding 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 give
some thought to system configuration, including the number of
fans, where they are located, and what temperatures are being
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 system develop-
ment process.
MANUAL FAN CONTROL OVERVIEW
In unusual circumstances, it can be necessary to manually
control the speed of the fans. Because the ADT7476 has an
SMBus interface, a system can read back all necessary voltage,
fan speed, and temperature information and use this informa-
tion to control the speed of the fans by writing to the PWM
current duty cycle registers (0x30, 0x31, and 0x32) of the
appropriate fan. Bits [7:5] of the PWMx configuration registers
(0x5C, 0x5D, 0x5E) are used to set up fans for manual control.
THERM OPERATION IN MANUAL MODE
In manual mode, if the temperature increases above the pro-
grammed THERM temperature limit, the fans automatically
speed up to maximum PWM or100% PWM, whichever way the
appropriate fan channel is configured.
AUTOMATIC FAN CONTROL OVERVIEW
The ADT7476 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 ADT7476 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 optimizing
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
owing 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 47 gives a top-level overview of the automatic fan control
circuitry on the ADT7476. 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 ADT7476 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, the designer can decide to run the CPU
fan when CPU temperature increases above 60°C and run 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 47 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.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADT7476EBZEVB | 功能描述:BOARD EVALUATION FOR ADT7476 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 過時(shí)/停產(chǎn)零件編號(hào) 系列:dBCool® 標(biāo)準(zhǔn)包裝:1 系列:- 傳感器類型:CMOS 成像，彩色（RGB） 傳感范圍:WVGA 接口:I²C 靈敏度:60 fps 電源電壓:5.7 V ~ 6.3 V 嵌入式:否 已供物品:成像器板 已用 IC / 零件:KAC-00401 相關(guān)產(chǎn)品:4H2099-ND - SENSOR IMAGE WVGA COLOR 48-PQFP4H2094-ND - SENSOR IMAGE WVGA MONO 48-PQFP |
| ADT7481 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dual Channel Temperature Sensor and Over Temperature Alarm |
| ADT7481ARMZ | 功能描述:板上安裝溫度傳感器 2 CH TEMP SNSR/ALARM 2 WIRE SMBUS INTRFCE RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| ADT7481ARMZ-001 | 功能描述:板上安裝溫度傳感器 2 CH TEMP SNSR/ALARM 2 WIRE SMBUS INTRFCE RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| ADT7481ARMZ-1 | 功能描述:IC SENSOR TEMP 2CH ALARM 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 功能:溫度監(jiān)控系統(tǒng)（傳感器） 傳感器類型:內(nèi)部和外部 感應(yīng)溫度:-40°C ~ 125°C，外部傳感器 精確度:±2.5°C 本地（最大值），±5°C 遠(yuǎn)程（最大值） 拓?fù)?ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報(bào):無 輸出風(fēng)扇:無 電源電壓:2.7 V ~ 5.5 V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-8 供應(yīng)商設(shè)備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
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