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| 型号： | TMPSNSRD-TCPL1 |
| 厂商： | Microchip Technology |
| 文件页数： | 9/30页 |
| 文件大小： | 0K |
| 描述： | BOARD RTD REFERENCE DESIGN |
| 产品培训模块： | MCP3901 Analog Front End |
| 标准包装： | 1 |
| 传感器类型： | 温度，热电偶 |
| 嵌入式： | 否 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MCP3421，MCP9804 |
| 产品目录页面： | 672 (CN2011-ZH PDF) |
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Wheatstone Bridge
Bridge Sensor Circuit
Sensors for temperature, pressure, load or other phys-
ical excitation quantities are most often configured in a
Wheatstone bridge configuration. The bridge can have
anywhere from one to all four elements reacting to the
physical excitation, and should be used in a ratiometeric
configuration when possible, with the system reference
driving both the sensor and the ADC voltage reference. By
using the same reference for both the sensor excitation and
ADC, the variation in the reference can be cancelled out.
Furthermore, the output voltage from the bridge sensor is
proportional to the excitation voltage. Therefore, the ADC
that is using the external reference is more popular than
the ADC that is using internal reference, for the ratiometric
configuration.
One example sensor from GE NovaSensor is an absolute
pressure sensor, shown below, a four element varying
bridge. This example uses the MCP355X family of delta
sigma ADCs. When designing with the MCP355X family
of 22-bit delta-sigma ADCs, the initial step should be to
evaluate the sensor performance and then determine what
steps (if any) should be used to increase the overall system
resolution when using the MCP355X . In many situations, the
MCP355X devices can be used to directly digitize the sensor
output, eliminating any need for external signal conditioning
circuitry.
Using the absolute pressure sensor as our Wheatstone
bridge example, the NPP-301 device has a typical full
scale output of 60 mV when excited with a 3V battery. The
pressure range for this device is 100 kPa. The MCP3551
has a output noise speci?cation of 2.5 μV RMS .
The following equation is a ?rst order approximation of the
relationship between pressure in pascals (P) and altitude (h),
in meters.
h
log(P) ≈ 5 –
15500
Using 60 mV as the full scale range and 2.5 μV as the
resolution, the resulting resolution from direct digitization in
meters is 0.64 meters or approximately 2 feet.
It should be noted that this is only used as an example for
discussion; temperature effects and the error from a ?rst
order approximation must be included in ?nal system design.
Example of Wheatstone Bridge Sensor Configuration with High Resolution Delta-Sigma ADC
0.1 μF 1.0 μF
To V DD
NPP-301
R 1
R 2
R 3
2
3
1 8
V REF V DD
V IN+
SCK
MCP3551 SDO
V IN- CS
V SS
SPI
5, 6, 7
MCU
R 4
4
Altimeter Watch
?V ~ [(?R 2 + ?R 4 ) - (?R 1 +?R 3 )]/4R * V DD
With R 1 = R 2 = R 3 = R 4 = R
Signal Chain Design Guide
9
相关PDF资料 |
PDF描述 |
|---|---|
| TMPSNSRD-RTD2 | BOARD RTD REFERENCE DESIGN |
| IR2183PBF | IC DRIVER HALF BRIDGE 8DIP |
| IR21814SPBF | IC DRIVER HIGH/LOW SIDE 14SOIC |
| IR1167BSTRPBF | IC SMART SECONDARY DRIVER 8-SOIC |
| IR21814PBF | IC DRIVER HIGH/LOW SIDE 14DIP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| TMPSNS-RTD1 | 功能描述:开发板和工具包 - PIC / DSPIC RTD Temp Sensor Demo Brd RoHS:否 制造商:Microchip Technology 产品:Starter Kits 工具用于评估:chipKIT 核心:Uno32 接口类型: 工作电源电压: |
| TMPT2369ALT | 制造商:ALL 功能描述:ALLEGRO NXC7D |
| TMPT2SU1 | 制造商:Red Lion Controls 功能描述:THERMOCOUPLE TEMP PROBE, TYPE T, 400?F 制造商:Red Lion Controls 功能描述:TYPE T 400DEG F |
| TMPT3906LT | 制造商:ALL 功能描述:ALLEGRO S9K3A |
| TMPT5089LT | 制造商:Allegro MicroSystems LLC 功能描述:Bipolar Junction Transistor, NPN Type, TO-236 |
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