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| 型号： | ADT7467ARQ-REEL7 |
| 厂商： | ON Semiconductor |
| 文件页数： | 14/72页 |
| 文件大小： | 0K |
| 描述： | IC REMOTE THERMAL CTRLR 16-QSOP |
| 产品变化通告： | MFG CHG Notification ADI to ON Semi Product Obsolescence 11/Feb/2009 |
| 标准包装： | 1,000 |
| 系列： | dBCool® |
| 功能： | 风扇控制，温度监控器 |
| 传感器类型： | 内部和外部 |
| 感应温度： | -40°C ~ 120°C，外部传感器 |
| 精确度： | ±1.5°C |
| 拓扑： | ADC，比较器，风扇速度计数器，多路复用器，寄存器库 |
| 输出类型： | SMBus? |
| 输出警报： | 无 |
| 输出风扇： | 是 |
| 电源电压： | 3 V ~ 5.5 V |
| 工作温度： | -40°C ~ 120°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-QSOP |
| 包装： | 带卷 (TR) |
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ADT7467
D V BE + kT q
Temperature Measurement
A simple method of measuring temperature is to exploit
the negative temperature coefficient of a diode, measuring
the base-emitter voltage (V BE ) of a transistor operated at
constant current. Unfortunately, this technique requires
calibration to null the effect of the absolute value of V BE ,
which varies from each device.
The technique used in the ADT7467 is to measure the
change in V BE when the device is operated at three currents.
Previous devices have used only two operating currents, but
the use of a third current allows automatic cancellation of
resistances in series with the external temperature sensor.
Figure 23 shows the input signal conditioning used to
measure the output of an external temperature sensor. This
figure shows the external sensor as a substrate transistor, but
it could equally be a discrete transistor. If a discrete
transistor is used, the collector is not grounded and should
be linked to the base. To prevent ground noise from
interfering with the measurement, the more negative
terminal of the sensor is not referenced to ground but is
biased above ground by an internal diode at the D ? input. C1
can optionally be added as a noise filter (the recommended
maximum value is 1,000 pF). However, a better option in
noisy environments is to add a filter as described in the Noise
Filtering section.
Local Temperature Measurement
The ADT7467 contains an on-chip band gap temperature
sensor whose output is digitized by the on-chip 10-bit ADC.
The 8-bit MSB temperature data is stored in the local
temperature register (Address 0x26). Because both positive
and negative temperatures can be measured, the temperature
data is stored in Offset 64 format or twos complement
format, as shown in Table 7 and Table 8. Theoretically, the
temperature sensor and ADC can measure temperatures
from ? 128 ? C to +127 ? C (or ? 64 ? C to +191 ? C in the
extended temperature range) with a resolution of 0.25 ? C.
However, this exceeds the operating temperature range of
the device, preventing local temperature measurements
outside the ADT7467 operating temperature range.
Remote Temperature Measurement
The ADT7467 can measure the temperature of two remote
diode sensors or diode-connected transistors connected to
Pin 10 and Pin 11 or to Pin 12 and Pin 13.
The forward voltage of a diode or diode-connected
transistor operated at a constant current exhibits a negative
temperature coefficient of about ? 2 mV/ ? C. Unfortunately,
the absolute value of V BE varies from each device and thus
requires individual calibration; therefore, the technique is
unsuitable for mass production. The technique used in the
ADT7467 is to measure the change in V BE when the device
is operated at three currents. This is given by:
ln(N) (eq. 1)
where:
k is Boltzmann’s constant.
q is the charge on the carrier.
T is the absolute temperature in Kelvins.
N is the ratio of the two currents.
Figure 22 shows the input signal conditioning used to
measure the output of a remote temperature sensor. This
figure shows the external sensor as a substrate transistor
provided for temperature monitoring on some
microprocessors. It could also be a discrete transistor such
as a 2N3904/2N3906.
I
N2 ? I
N1 ? I
I BIAS
V DD
D+
V OUT+
REMOTE
SENSING
TRANSISTOR
D ?
LOW-PASS FILTER
f C = 65 kHz
Figure 22. Signal Conditioning for Remote Diode Temperature Sensors
To ADC
V OUT ?
If a discrete transistor is used, the collector is not grounded
and should be linked to the base. If a PNP transistor is used,
the base is connected to the D ? input and the emitter is
connected to the D+ input. If an NPN transistor is used, the
emitter is connected to the D ? input and the base is
connected to the D+ input. Figure 24 and Figure 25 show
how to connect the ADT7467 to an NPN or PNP transistor
for temperature measurement. To prevent ground noise from
interfering with the measurement, the more negative
terminal of the sensor is not referenced to ground but is
biased above ground by an internal diode at the D ? input.
To measure D V BE , the operating current through the
sensor is switched among three related currents. Shown in
Figure 22, N1 ? I and N2 ? I are different multiples of the
current I. The currents through the temperature diode are
switched between I and N1 ? I, resulting in D V BE1 ; then
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADT7467ARQZ | 功能描述:马达/运动/点火控制器和驱动器 FAN CNTRLR/INT MON RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
| ADT7467ARQZ | 制造商:Analog Devices 功能描述:Temperature Sensor IC |
| ADT7467ARQZ-R7 | 功能描述:板上安装温度传感器 RMT THRM MON FAN CTL 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 |
| ADT7467ARQZ-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 |
| ADT7467ARQZ-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 |
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