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參數資料
| 型號： | ADT7460 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | dB COOL?? Remote Thermal Controller and Fan Controller |
| 中文描述： | 分貝很酷吧？？遠程熱控制器和風扇控制器 |
| 文件頁數： | 24/48頁 |
| 文件大小： | 695K |
| 代理商： | ADT7460 |
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REV. 0
–24–
ADT7460
Driving 2-Wire Fans
Figure 32 shows how a 2-wire fan may be connected to the
ADT7460. This circuit allows the speed of a 2-wire fan to be
measured, even though the fan has no dedicated TACH signal.
A series resistor, R
SENSE
, in the fan circuit converts the fan commu-
tation pulses into a voltage. This is ac-coupled into the ADT7460
through the 0.01
μ
F capacitor. On-chip signal conditioning
allows accurate monitoring of fan speed. The value of R
SENSE
chosen depends upon the programmed input threshold and the
current drawn by the fan. For fans drawing approximately 200 mA,
a 2
R
SENSE
value is suitable when the threshold is programmed as
40 mV. For fans that draw more current, such as larger desktop
or server fans, R
SENSE
may be reduced for the same programmed
threshold. The smaller the threshold programmed the better,
since more voltage will be developed across the fan and the fan
will spin faster. Figure 33 shows a typical plot of the sensing
waveform at a TACH/AIN pin. The most important thing is that
the voltage spikes (either negative going or positive going) are
more than 40 mV in amplitude. This allows fan speed to be
reliably determined.
ADT7460
TACH/AIN
PWM
10k
TYPICAL
3.3V
+V
Q1
NDT3055L
5V OR
12V FAN
R
SENSE
2
TYPICAL
0.01 F
1N4148
Figure 32. Driving a 2-Wire Fan
Figure 33. Fan Speed Sensing Waveform at
TACH/AIN Pin
LAYING OUT 2-WIRE AND 3-WIRE FANS
Figure 34 shows how to lay out a common circuit arrangement
for 2-wire and 3-wire fans. Some components will not be popu-
lated, depending on whether a 2-wire or 3-wire fan is being used.
3.3V OR 5V
TACH/AIN
PWM
12V OR 5V
Q1
MMBT2222
R4
R5
R3
C1
R2
R1
FOR 3-WIRE FANS:
POPULATE R1, R2, R3
R4 = 0
C1 = UNPOPULATED
FOR 2-WIRE FANS:
POPULATE R4, C1
R1, R2, R3 UNPOPULATED
1N4148
Figure 34. Planning for 2-Wire or 3-Wire Fans on a PCB
TACH Inputs
Pins 4, 6, 7, and 9 are open-drain TACH inputs intended for
fan speed measurement.
Signal conditioning in the ADT7460 accommodates the slow rise
and fall times typical of fan tachometer outputs. The maximum
input signal range is 0 V to 5 V, even where V
CC
is less than 5 V.
In the event that these inputs are supplied from fan outputs that
exceed 0 V to 5 V, either resistive attenuation of the fan signal
or diode clamping must be included to keep inputs within an
acceptable range.
Figures 35a to 35d show circuits for most common fan
TACH outputs.
If the fan TACH output has a resistive pull-up to
V
CC
, it can
be connected directly to the fan input, as shown in Figure 35a.
12V
ADT7460
FAN SPEED
COUNTER
TACH
TACH
OUTPUT
PULL-UP
4.7k
TYP
V
CC
Figure 35a. Fan with TACH Pull-Up to +V
CC
If the fan output has a resistive pull-up to 12 V (or other voltage
greater than 5 V), the fan output can be clamped with a Zener
diode, as shown in Figure 35b. The Zener diode voltage should
be chosen so that it is greater than V
IH
of the TACH input but
less than 5 V, allowing for the voltage tolerance of the Zener. A
value of between 3 V and 5 V is suitable.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADT7460ARQ | 功能描述:IC REMOTE THRML/FAN CTRLR 16QSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱管理 系列:dBCool® 標準包裝:1 系列:- 功能:溫度監控系統（傳感器） 傳感器類型:內部和外部 感應溫度:-40°C ~ 125°C，外部傳感器 精確度:±2.5°C 本地（最大值），±5°C 遠程（最大值） 拓撲:ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報:無 輸出風扇: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 供應商設備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
| ADT7460ARQ-REEL | 功能描述:IC SENSOR TEMP FAN-CTRL 16QSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱管理 系列:dBCool® 標準包裝:1 系列:- 功能:溫度監控系統（傳感器） 傳感器類型:內部和外部 感應溫度:-40°C ~ 125°C，外部傳感器 精確度:±2.5°C 本地（最大值），±5°C 遠程（最大值） 拓撲:ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報:無 輸出風扇: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 供應商設備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
| ADT7460ARQ-REEL7 | 功能描述:IC SENSOR TEMP FAN-CTRL 16QSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱管理 系列:dBCool® 標準包裝:1 系列:- 功能:溫度監控系統（傳感器） 傳感器類型:內部和外部 感應溫度:-40°C ~ 125°C，外部傳感器 精確度:±2.5°C 本地（最大值），±5°C 遠程（最大值） 拓撲:ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報:無 輸出風扇: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 供應商設備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
| ADT7460ARQZ | 功能描述:馬達/運動/點火控制器和驅動器 THERMAL MGMT CNTRLR IC RoHS:否 制造商:STMicroelectronics 產品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| ADT7460ARQZ-R7 | 制造商:ON Semiconductor 功能描述:Temp Sensor Digital Serial (3-Wire) 16-Pin QSOP T/R |
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