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參數(shù)資料
| 型號： | MMA7330L |
| 廠商： | 飛思卡爾半導體(中國)有限公司 |
| 英文描述： | 【4g - 16g Three Axis Low-g Micromachined Accelerometer |
| 中文描述： | 【4克-一六克三三軸低g加速度計 |
| 文件頁數(shù)： | 4/10頁 |
| 文件大?。?/td> | 240K |
| 代理商： | MMA7330L |
Sensors
4
Freescale Semiconductor
MMA7330L
PRINCIPLE OF OPERATION
The Freescale accelerometer is a surface-micromachined
integrated-circuit accelerometer.
The device consists of a surface micromachined
capacitive sensing cell (g-cell) and a signal conditioning ASIC
contained in a single 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 beams form two back-to-back capacitors
(
Figure 3
). As the center beam moves with acceleration, the
distance between the beams changes and each capacitor's
value will change, (C = A
ε
/D). Where A is the area of the
beam,
ε
is the dielectric constant, and D is the distance
between the beams.
The 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
SPECIAL FEATURES
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 hard disk drive
protection where system integrity must be ensured over the
life of the product. Customers can use self test to verify the
solderability to confirm that the part was mounted to the PCB
correctly. When the self test function is initiated, an
electrostatic force is applied to each axis to cause it to deflect.
The x- and y-axis are deflected slightly while the z-axis is
trimmed to deflect 1g. This procedure assures that both the
mechanical (g-cell) and electronic sections of the
accelerometer are functioning.
g-Select
The g-Select feature allows for the selection between two
sensitivities. Depending on the logic input placed on pin 10,
the device internal gain will be changed allowing it to function
with a 4g or 16g sensitivity (
Table 3
). This feature is ideal
when a product has applications requiring two different
sensitivities for optimum performance. The sensitivity can be
changed at anytime during the operation of the product. The
g-Select pin can be left unconnected for applications
requiring only a 4g sensitivity as the device has an internal
pull-down to keep it at that sensitivity (308mV/g)).
Sleep Mode
The 3 axis accelerometer provides a Sleep Mode that is
ideal for battery operated products. When Sleep Mode is
active, the device outputs are turned off, providing significant
reduction of operating current. A low input signal on pin 7
(Sleep Mode) will place the device in this mode and reduce
the current to 3
μ
A typ. For lower power consumption, it is
recommended to set g-Select to 4g mode. By placing a high
input signal on pin 7, the device will resume to normal mode
of operation.
Filtering
The 3 axis accelerometer contains an onboard single-pole
switched capacitor filter. 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.
Ratiometricity
Ratiometricity simply means the output offset voltage and
sensitivity will scale linearly with applied supply voltage. That
is, as supply voltage is increased, 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.
Acceleration
Table 3. g-Select Pin Description
g-Select
g-Range
Sensitivity
0
4g
308 mV/g
1
16g
77 mV/g
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MMA7340L | 【3g - 12g Three Axis Low-g Micromachined Accelerometer |
| MMA7360L | 【1.5g-6g Three Axis Low-g Micromachined Accelerometer |
| MMA7450L | 【2g/【4g/【8g Three Axis Low-g Digital Output Accelerometer |
| MMA7455L | Three Axis Low-g Digital Output Accelerometer |
| MMBD4148T | 0.15 A, 75 V, SILICON, SIGNAL DIODE |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MMA7330L_0708 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:【4g - 16g Three Axis Low-g Micromachined Accelerometer |
| MMA7330LR1 | 功能描述:加速計 - 板上安裝 4G YXZ LGA 14 LDS 7 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 |
| MMA7330LR2 | 功能描述:加速計 - 板上安裝 4GXYZ LGA 14 LEAD3X5 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 |
| MMA7330LT | 功能描述:加速計 - 板上安裝 4g-16g XYZ 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 |
| MMA7331L | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:【4g, 【12g Three Axis Low-g Micromachined Accelerometer |
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