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參數(shù)資料
| 型號(hào)： | ADM1031ARQZ-R7 |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | DIGITAL TEMP SENSOR-SERIAL, 11BIT(s), 3Cel, RECTANGULAR, SURFACE MOUNT |
| 封裝： | LEAD FREE, QSOP-16 |
| 文件頁數(shù)： | 14/30頁 |
| 文件大?。?/td> | 299K |
| 代理商： | ADM1031ARQZ-R7 |
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ADM1031
http://onsemi.com
21
Figure 34 shows how a 3wire fan can be driven using
PWM control.
Figure 34. Interfacing the ADM1031 to a 3Wire Fan
+V
5.0 V OR 12 V
FAN
Q1
NDT3055L
ADM1031
PWM_OUT
TACH/AIN
TACH
10kW
TYPICAL
10kΩ
TYPICAL
3.3 V
The NDT3055L ntype MOSFET was chosen since it has
3.3 V gate drive, low onresistance, and can handle 3.5 A of
current. Other MOSFETs can be substituted based on the
system’s fan drive requirements.
Figure 35 shows how a 2wire fan can be connected to the
ADM1031. This circuit allows the speed of the 2wire fan
to be measured even though the fan has no dedicated Tach
signal. A series RSENSE resistor in the fan circuit converts
the fan commutation pulses into a voltage. This is accoupled
into the ADM1031 through the 0.01
mF capacitor. Onchip
signal conditioning allows accurate monitoring of fan speed.
For typical notebook fans drawing approximately 170 mA,
a 2
W RSENSE value is suitable. For fans such as desktop or
server fans that draw more current, RSENSE can be reduced.
The smaller RSENSE is, the better, since more voltage is
developed across the fan, and the fan then spins faster.
Figure 35. Interfacing the ADM1031 to a 2Wire Fan
+V
5.0 V OR 12 V
FAN
ADM1031
TACH/AIN
PWM_OUT
TACH
10kW
TYPICAL
0.01μF
3.3 V
Q1
NDT3055L
RSENSE
(2W TYPICAL)
Figure 36 shows a typical plot of the sensing waveform at
the TACH/AIN pin. The most important thing is that the
negativegoing spikes are more than 250 mV in amplitude.
This is the case for most fans when RSENSE = 2 W. The value
of RSENSE can be reduced as long as the voltage spikes at the
TACH/AIN pin are greater than 250 mV. This allows fan
speed to be reliably determined.
Figure 36. Fan Speed Sensing Waveform at
TACH/AIN Pin
Fan Speed Measurement
The fan counter does not count the fan tach output pulses
directly, because the fan speed can be less than 1000 RPM
and it would take several seconds to accumulate a
reasonably large and accurate count. Instead, the period of
the fan revolution is measured by gating an onchip
11.25 kHz oscillator into the input of an 8bit counter. The
fan speed measuring circuit is initialized on the rising edge
of a PWM high output if fan speed measurement is enabled
(Bit 2 and Bit 3 of Configuration Register 2 = 1). It then starts
counting on the rising edge of the second tach pulse and
counts for two fan tach periods, until the rising edge of the
fourth tach pulse, or until the counter overranges if the fan
tach period is too long. The measurement cycle repeats until
monitoring is disabled. The fan speed measurement is stored
in the fan speed reading register at address 0
×08, 0×09. The
fan speed count is given by:
Count = (f
× 60)/R × N
where:
f = 11.25 kHz
R = fan speed in RPM.
N = speed range (either 1, 2, 4, or 8)
The frequency of the oscillator can be adjusted to suit the
expected running speed of the fan by varying N, the speed
range. The oscillator frequency is set by Bit 7 and Bit 6 of
Fan Characteristics Register 1 (0
×20) and Fan
Characteristics Register 2 (0
×21) as shown in Table 11.
Figure 37 shows how the fan measurements relate to the
PWM_OUT pulse trains.
Table 11. Oscillator Frequencies
Bit 7
Bit 6
N
Oscillator Frequency (kHz)
0
1
11.25
0
1
2
5.625
1
0
4
2.812
1
8
1.406
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| ADM1031ARQZ-REEL | 功能描述:板上安裝溫度傳感器 2 CH TDM PWM FAN CTRL IC 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 |
| ADM1031ARQZ-REEL7 | 功能描述:IC SENSOR 2TEMP/FAN CTRL 16QSOP 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 |
| ADM1032 | 制造商:AD 制造商全稱:Analog Devices 功能描述:+-1C Remote and Local System Temperature Monitor |
| ADM1032_12 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:1C Remote and Local System Temperature Monitor Supports SMBus Alert |
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