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參數(shù)資料
| 型號： | MMA2301DR2 |
| 廠商： | 飛思卡爾半導(dǎo)體(中國)有限公司 |
| 英文描述： | Surface Mount Micromachined Accelerometer |
| 中文描述： | 表面貼裝微加速度計 |
| 文件頁數(shù)： | 4/10頁 |
| 文件大?。?/td> | 275K |
| 代理商： | MMA2301DR2 |
Sensors
4
Freescale Semiconductor
MMA2301D
PRINCIPLE OF OPERATION
The Freescale Semiconductor, Inc. accelerometer is a
surface-micromachined integrated-circuit accelerometer.
The device consists of a surface micromachined
capacitive sensing cell (g-cell) and a CMOS signal
conditioning ASIC contained in a single integrated circuit
package. The sensing element is sealed hermetically at the
wafer level using a bulk micromachined
cap
wafer.
The g-cell is a mechanical structure formed from
semiconductor materials (polysilicon) using semiconductor
processes (masking and etching). It can be modeled as a set
of beams attached to a movable central mass that move
between fixed beams. The movable beams can be deflected
from their rest position by subjecting the system to an
acceleration(
Figure 3
).
As the beams attached to the central mass move, the
distance from them to the fixed beams on one side will
increase by the same amount that the distance to the fixed
beams on the other side decreases. The change in distance
is a measure of acceleration.
The g-cell plates form two back-to-back capacitors
(
Figure 3
). As the central mass moves with acceleration, the
distance between the beams change and each capacitor's
value will change, (C = NA
ε
/D). Where A is the area of the
facing side of the beam,
ε
is the dielectric constant, D is the
distance between the beams, and N is the number of beams.
The CMOS ASIC uses switched capacitor techniques to
measure the g-cell capacitors and extract the acceleration
data from the difference between the two capacitors. The
ASIC also signal conditions and filters (switched capacitor)
the signal, providing a high level output voltage that is
ratiometric and proportional to acceleration.
Figure 3. Simplified Transducer Physical Model versus
Transducer Physical Model
SPECIAL FEATURES
Filtering
The accelerometers contain an onboard 4-pole switched
capacitor filter. A Bessel implementation is used because it
provides a maximally flat delay response (linear phase) thus
preserving pulse shape integrity. Because the filter is realized
using switched capacitor techniques, there is no requirement
for external passive components (resistors and capacitors) to
set the cut-off frequency.
Self-Test
The sensor provides a self-test feature that allows the
verification of the mechanical and electrical integrity of the
accelerometer at any time before or after installation. This
feature is critical in applications such as automotive airbag
systems where system integrity must be ensured over the life
of the vehicle. A fourth
plate
is used in the g-cell as a self-test
plate. When the user applies a logic high input to the self-test
pin, a calibrated potential is applied across the self-test plate
and the moveable plate. The resulting electrostatic force
(Fe =
1
/
2
AV
2
/d
2
) causes the center plate to deflect. The
resultant deflection is measured by the accelerometer's
control ASIC and a proportional output voltage results. This
procedure assures that both the mechanical (g-cell) and
electronic sections of the accelerometer are functioning.
Ratiometricity
Ratiometricity simply means that the output offset voltage
and sensitivity will scale linearly with applied supply voltage.
That is, as you increase supply voltage the sensitivity and
offset increase linearly; as supply voltage decreases, offset
and sensitivity decrease linearly. This is a key feature when
interfacing to a microcontroller or an A/D converter because
it provides system level cancellation of supply induced errors
in the analog to digital conversion process.
Status
Freescale accelerometers include fault detection circuitry
and a fault latch. The Status pin is an output from the fault
latch, OR'd with self-test, and is set high whenever one (or
more) of the following events occur:
Supply voltage falls below the Low Voltage Detect (LVD)
voltage threshold
Clock oscillator falls below the clock monitor minimum
frequency
Parity of the EPROM bits becomes odd in number.
The fault latch can be reset by a rising edge on the self-test
input pin, unless one (or more) of the fault conditions
continues to exist.
Acceleration
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MMA2301EG | Surface Mount Micromachined Accelerometer |
| MMA2301EGR2 | Surface Mount Micromachined Accelerometer |
| MMA3201EG | Surface Mount Micromachined Accelerometer |
| MMA3201EGR2 | Surface Mount Micromachined Accelerometer |
| MMA3202_06 | Surface Mount Micromachined Accelerometer |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MMA2301EG | 功能描述:加速計 - 板上安裝 X-AXIS 200G NOMINAL RoHS:否 制造商:Murata 傳感軸:Double 加速:12 g 靈敏度: 封裝 / 箱體: 輸出類型:Analog 數(shù)字輸出 - 位數(shù):11 bit 電源電壓-最大:5.25 V 電源電壓-最小:4.75 V 電源電流:4 mA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C |
| MMA2301EG | 制造商:Freescale Semiconductor 功能描述:ACCELERATION SENSOR X AXIS 200G 制造商:Freescale Semiconductor 功能描述:ACCELERATION SENSOR, X AXIS, 200G |
| MMA2301EGR2 | 功能描述:加速計 - 板上安裝 X-AXIS 200G NOMINAL RoHS:否 制造商:Murata 傳感軸:Double 加速:12 g 靈敏度: 封裝 / 箱體: 輸出類型:Analog 數(shù)字輸出 - 位數(shù):11 bit 電源電壓-最大:5.25 V 電源電壓-最小:4.75 V 電源電流:4 mA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C |
| MMA2301KEG | 功能描述:SENSOR ACCEL X-AX +/-200G 16SOIC RoHS:是 類別:傳感器，轉(zhuǎn)換器 >> 加速計 系列:MMA 標準包裝:1 系列:SCA1000 軸:X，Y 加速范圍:±1.7g 靈敏度:1.2V/g 電源電壓:4.75 V ~ 5.25 V 輸出類型:數(shù)字 帶寬:50±30Hz 接口:SPI 安裝類型:表面貼裝 封裝/外殼:12-SMD 供應(yīng)商設(shè)備封裝:12-SMD 其它名稱:551-1007-1 |
| MMA2301KEG_12 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Surface Mount Micromachined Accelerometer |
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