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参数资料
| 型号： | MPX5006 |
| 厂商： | Motorola, Inc. |
| 英文描述： | Pressure Sensor(压力传感器) |
| 中文描述： | 压力传感器（压力传感器） |
| 文件页数： | 3/4页 |
| 文件大小： | 65K |
| 代理商： | MPX5006 |
3
Motorola Sensor Device Data
IMPROVEMENT ON OFFSET ERROR
In the following calculations, we will illustrate how auto–zero
will improve the offset error contribution. We will use the
MPX5006 interfaced to an 8–bit A/D as an example. When
auto–zero is performed, the offset errors are reduced and the
resulting offset errors are replaced with the error (due to
resolution) of the A/D.We can categorize the offset error
contributions into temperature and calibration errors.
Temperature Coefficient of Offset Error
The offset error due to temperature is due to Temperature
Coefficient of Offset, or TCO. This parameter is the rate of
change of the offset when the sensor is subject to
temperature. It is defined as:
TCO = (
VOFF/
T).
The MPX5006 has a temperature coefficient of offset
(normalized with the span at 25
°
C) of:
TCO = (
VOFF/
T)/VFS@25
°
C = 0.06% FS/
°
C.
As an example, if the sensor is subjected to temperature
range between 10
°
C and 60
°
C, the error due to TCO is:
TCO = (0.06% FS/C)*(60
°
C
10
°
C) =
3.0% FS.
Offset Calibration Errors
Even though the offset is laser trimmed, offset can shift due
to packaging stresses, aging and external mechanical
stresses due to mounting and orientation. This results in offset
calibration error. For example, the MPX5006 data sheet
shows this as:
VOFF MIN = 0.100 V,
VOFF TYPICAL = 0.225 V and VOFF MAX = 0.430 V.
We can then calculate the offset calibration error with
respect to the full scale span as:
VOFF MIN,MAX =
(VOFF TYPICAL
VOFF MIN,MAX)/VFS.
This results in the following offset calibration error,
VOFF MIN = 2.7% FS and
VOFF MAX = 4.5% FS.
A/D Error
As mentioned above, we can reduce offset errors
(calibration and TCO) when we perform auto–zero. These
errors are replaced with the A/D error (due to its resolution),
OFFSETAUTOZERO =
TCO +
OFFSET =
A/D.
Typically, a sensor is interfaced to an 8–bit A/D. With the A/D
reference tied to VRH = 5 V and VRL = 0 V, the A/D can resolve
19.6 mV/bit. For example, the MXP5006 has a sensitivity of
7.5 mV/mmH20, the resolution is therefore,
A/DRESOLUTION = 19.6 mV/bit)/(7.5 mV/mmH20)
= 2.6 mmH20/bit.
Assuming +/
1 LSB error, the error due to digitization and
the resulting offset error is,
A/D =
OFFSETAUTOZERO = 2.6 mmH20/612 mmH20
= +/
0.4% FS.
It can be seen that with increasing A/D resolution, offset
errors can be further reduced. For example, with a 10–bit A/D,
the resulting offset error contribution is only 0.1% FS when
auto–zero is performed.
If auto–zero is to be performed only once and offset
correction data is stored in non–volatile memory, the TCO
offset error and calibration error will not be corrected ifthe
sensor later experiences a wide temperature range or later
experience an offset shift. However, if auto–zero is performed
atthe operating temperature, TCO error will be compensated
although subsequent offset calibration error will not be
compensated. It is therefore best to auto–zero as often as
possible in order to dynamically compensate the system for
offset errors.
CONCLUSION
Auto–zero can be used to reduce offset errors in a sensor
system. This technique can easily be implemented when an
integrated pressure sensor is interfaced to an A/D and a
microcontroller. With a few lines of code, the offset errors are
effectively reduced; the resulting offset error reduction is
limited only by the resolution of the A/D.
相关PDF资料 |
PDF描述 |
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| MPX5050GVSX | OPERATING OVERVIEW INTEGRATED PRESSURE SENSOR 0 to 50 kPa (0 to 7.25 psi) 0.2 to 4.7 Volts Output |
| MPX5050GP1 | Sensor |
| MPX5050GVP | OPERATING OVERVIEW INTEGRATED PRESSURE SENSOR 0 to 50 kPa (0 to 7.25 psi) 0.2 to 4.7 Volts Output |
| MPX5050GVS | OPERATING OVERVIEW INTEGRATED PRESSURE SENSOR 0 to 50 kPa (0 to 7.25 psi) 0.2 to 4.7 Volts Output |
| MPX5050GSX | OPERATING OVERVIEW INTEGRATED PRESSURE SENSOR 0 to 50 kPa (0 to 7.25 psi) 0.2 to 4.7 Volts Output |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MPX5010 | 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, Temperature Compensated and Calibrated |
| MPX5010_09 | 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, Temperature Compensated and Calibrated |
| MPX5010D | 功能描述:板上安装压力/力传感器 PRES SEN INTEG 10KPA RoHS:否 制造商:Honeywell 工作压力:0 bar to 4 bar 压力类型:Gage 准确性:+ / - 0.25 % 输出类型:Digital 安装风格:Through Hole 工作电源电压:5 V 封装 / 箱体:SIP 端口类型:Dual Radial Barbed, Same sides |
| MPX5010D | 制造商:Freescale Semiconductor 功能描述:Pressure Sensors IC |
| MPX5010DP | 功能描述:板上安装压力/力传感器 PRES SEN INTEG 10KPA RoHS:否 制造商:Honeywell 工作压力:0 bar to 4 bar 压力类型:Gage 准确性:+ / - 0.25 % 输出类型:Digital 安装风格:Through Hole 工作电源电压:5 V 封装 / 箱体:SIP 端口类型:Dual Radial Barbed, Same sides |
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