MMA1260D Freescale Semiconductor, MMA1260D Datasheet - Page 4
Manufacturer Part Number
SENSOR ACCEL Z-AX +/-1.5G 16SOIC
Specifications of MMA1260D
Voltage - Supply
4.75 V ~ 5.25 V
Package / Case
16-SOIC (0.300", 7.50mm Width)
For Use With
RD1986MMA2260D - KIT SENSOR ACCEL MMA2260D TRIAX
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
micromachined integrated--circuit accelerometer.
tive 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 us-
ing a bulk micromachined “cap’’ wafer.
ductor materials (polysilicon) using semiconductor pro-
cesses (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 sub-
jecting the system to an acceleration (Figure 2).
fixed plate will increase by the same amount that the dis-
tance to the other plate decreases. The change in distance is
a measure of acceleration.
ure 3). As the center plate moves with acceleration, the dis-
tance between the plates changes and each capacitor’s
value will change, (C = Aε/D). Where A is the area of the
plate, ε is the dielectric constant, and D is the distance be-
tween the plates.
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 ratio-
metric and proportional to acceleration.
The Freescale Semiconductor accelerometer is a surface--
The device consists of a surface micromachined capaci-
The g--cell is a mechanical structure formed from semicon-
When the center plate deflects, the distance from it to one
The g--cell plates form two back--to--back capacitors (Fig-
The CMOS ASIC uses switched capacitor techniques to
Figure 2. Transducer
PRINCIPLE OF OPERATION
Figure 3. Equivalent
onboard 2--pole switched capacitor filter. A Bessel imple-
mentation is used because it provides a maximally flat delay
response (linear phase) thus preserving pulse shape integri-
ty. 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 fre-
ification of the mechanical and electrical integrity of the ac-
celerometer at any time before or after installation. 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 cali-
brated potential is applied across the self--test plate and
the moveable plate. The resulting electrostatic force
sultant deflection is measured by the accelerometer’s control
ASIC and a proportional output voltage results. This proce-
dure assures that both the mechanical (g--cell) and electronic
sections of the accelerometer are functioning.
detection circuitry and a fault latch. The Status pin is an out-
put from the fault latch, OR’d with self--test, and is set high
whenever the following event occurs:
• Parity of the EPROM bits becomes odd in number.
test input pin, unless one (or more) of the fault conditions
continues to exist.
The Freescale Semiconductor accelerometers contain an
The sensor provides a self--test feature that allows the ver-
Freescale Semiconductor accelerometers include fault
The fault latch can be reset by a rising edge on the self--
) causes the center plate to deflect. The re-
Sensor Device Data