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| 型号： | ADT7467ARQ-REEL |
| 厂商： | ON Semiconductor |
| 文件页数： | 15/72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： | 2,500 |
| 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
they are switched between I and N2 ? I, resulting in D V BE2 .
The temperature can then be calculated using the two D V BE
measurements. This method can also cancel the effect of
series resistance on the temperature measurement.
The resulting D V BE waveforms are passed through a
65 kHz low-pass filter to remove noise and then sent to a
Figure 23 shows a low-pass R-C-R filter with the following
values:
R = 100 W , C = 1 nF
This filtering reduces both common-mode noise and
differential noise.
chopper-stabilized amplifier that amplifies and rectifies the
waveform to produce a dc voltage proportional to D V BE .
The ADC digitizes this voltage, and a temperature
measurement is produced. To reduce the effects of noise,
digital filtering is performed by averaging the results of 16
REMOTE
TEMPERATURE
SENSOR
100 W
100 W
1 nF
D+
D ?
measurement cycles.
The results of remote temperature measurements are
stored in 10-bit twos complement format, as listed in
Table 7. The extra resolution for the temperature
measurements is held in the Extended Resolution Register 2
(0x77). This produces temperature readings with a
resolution of 0.25 ? C.
Series Resistance Cancellation
Parasitic resistance to the ADT7467 D+ and D ? inputs
(seen in series with the remote diode) is caused by a variety
of factors, including PCB track resistance and track length.
This series resistance appears as a temperature offset in the
remote sensor ’s temperature measurement. This error
typically causes a 0.5 ? C offset per 1 W of parasitic resistance
in series with the remote diode.
The ADT7467 automatically cancels the effect of this
series resistance on the temperature reading, providing a
more accurate result without the need for user
characterization of this resistance. The ADT7467 is
designed to automatically cancel, typically up to 3 k W of
resistance. By using an advanced temperature measurement
method, this is transparent to the user. This feature allows
resistances to be added to the sensor path to produce a filter,
allowing the part to be used in noisy environments. See the
Noise Filtering section for details.
Noise Filtering
For temperature sensors operating in noisy environments,
previous practice involved placing a capacitor across the D+
and D ? pins to help combat the effects of noise. However,
large capacitances affect the accuracy of the temperature
measurement, leading to a recommended maximum
capacitor value of 1,000 pF. A capacitor of this value
reduces the noise but does not eliminate it, making use of the
sensor difficult in a very noisy environment.
The ADT7467 has a major advantage over other devices
for eliminating the effects of noise on the external sensor.
Using the series resistance cancellation feature, a filter can
be constructed between the external temperature sensor and
the device. The effect of filter resistance seen in series with
the remote sensor is automatically canceled from the
temperature result.
The construction of a filter allows the ADT7467 and the
remote temperature sensor to operate in noisy environments.
Figure 23. Filter Between Remote Sensor and
ADT7467
Factors Affecting Diode Accuracy
Remote Sensing Diode
The ADT7467 is designed to work with either substrate
transistors built into processors or discrete transistors.
Substrate transistors are generally PNP types with the
collector connected to the substrate. Discrete types can be
either PNP or NPN transistors connected as a diode
(base-shorted to the collector). If an NPN transistor is used,
the collector and base are connected to D+ and the emitter
is connected to D ? . If a PNP transistor is used, the collector
and base are connected to D ? and the emitter is connected to
D+.
To reduce the error due to variations in both substrate and
discrete transistors, a number of factors should be taken into
consideration:
? The ideality factor, n f , of the transistor is a measure of
the deviation of the thermal diode from ideal behavior.
The ADT7467 is trimmed for an n f value of 1.008. Use
the following equation to calculate the error introduced
at a temperature, T ( ? C), when using a transistor whose
n f does not equal 1.008. See the processor ’s data sheet
for the n f values.
D T = ( n f ? 1.008)/1.008 ? (273.15 K + T )
? To correct for this error, the user can write the D T value
to the offset register, and the ADT7467 automatically
adds it to or subtracts it from the temperature
measurement.
? Some CPU manufacturers specify the high and low
current levels of the substrate transistors. The high
current level of the ADT7467, I HIGH , is 96 m A, and the
low level current, I LOW , is 6 m A. If the ADT7467
current levels do not match the current levels specified
by the CPU manufacturer, it may be necessary to
remove an offset. The CPU’s data sheet should provide
information relating to n f to compensate for differences.
An offset can be programmed to the offset register. It is
important to note that if more than one offset must be
considered, the algebraic sum of these offsets must be
programmed to the offset register.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADT7467ARQ-REEL7 | 功能描述:IC REMOTE THERMAL CTRLR 16-QSOP RoHS:否 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 |
| 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 |
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