- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄359176 > MMA1220D (飛思卡爾半導(dǎo)體(中國)有限公司) Low G Micromachined Accelerometer(小重力微電機(jī)加速計(jì)) PDF資料下載
參數(shù)資料
| 型號(hào)： | MMA1220D |
| 廠商： | 飛思卡爾半導(dǎo)體(中國)有限公司 |
| 英文描述： | Low G Micromachined Accelerometer(小重力微電機(jī)加速計(jì)) |
| 中文描述： | 低摹微加速度計(jì)（小重力微電機(jī)加速計(jì)） |
| 文件頁數(shù)： | 4/8頁 |
| 文件大?。?/td> | 156K |
| 代理商： | MMA1220D |
MMA1220D
4
Motorola Sensor Device Data
PRINCIPLE OF OPERATION
The Motorola 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 two
stationary plates with a moveable plate in-between. The center
plate can be deflected from its rest position by subjecting the
system to an acceleration (Figure 2).
When the center plate deflects, the distance from it to one
fixed plate will increase by the same amount that the distance
to the other plate decreases. The change in distance is a
measure of acceleration.
The g-cell plates form two back-to-back capacitors
(Figure 3). As the center plate moves with acceleration, the
distance between the plates changes and each capacitor's
value will change, (C = A
ε
/D). Where A is the area of the plate,
ε
is the dielectric constant, and D is the distance between the
plates.
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.
SPECIAL FEATURES
Filtering
The Motorola 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
Motorola 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 falling edge on the self-test
input pin, unless one (or more) of the fault conditions continues
to exist.
Acceleration
Figure 2. Transducer
Physical Model
Figure 3. Equivalent
Circuit Model
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MMA1220 | Low G Micromachined Accelerometer |
| MMA1250D | Low G Micromachined Accelerometer(小重力微電機(jī)加速計(jì)) |
| MMA1250EG | Low G Micromachined Accelerometer |
| MMA1260D | Low G Micromachined Accelerometer(小重力微電機(jī)加速計(jì)) |
| MMA1260EG | Low G Micromachined Accelerometer |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MMA1220DR2 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:Low G Micromachined Accelerometer |
| MMA1220EG | 功能描述:加速計(jì) - 板上安裝 LOW G Z-AXIS Acceleration Sensor 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 |
| MMA1220EGR2 | 功能描述:加速計(jì) - 板上安裝 LOW G Z-AXIS 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 |
| MMA1220KEG | 功能描述:加速計(jì) - 板上安裝 LOW G Z-AXIS 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 |
| MMA1220KEGR2 | 制造商:Freescale Semiconductor 功能描述:Accelerometer Single 制造商:Freescale Semiconductor 功能描述:MMA1220KEGR2 - Tape and Reel 制造商:Freescale Semiconductor 功能描述:IC ACCEL Z-AXIS 8G 250G 16SOIC 制造商:Freescale Semiconductor 功能描述:LOW G Z-AXIS |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。