MMA1210D Freescale Semiconductor, MMA1210D Datasheet - Page 4

• Manufacturer Part Number: MMA1210D
• Description: SENSOR ACCEL Z-AX +/-100G 16SOIC
• Manufacturer: Freescale Semiconductor

Specifications of MMA1210D

• Axis: Z
• Acceleration Range: ±112.5g
• Sensitivity: 20mV/g
• Voltage - Supply: 4.75 V ~ 5.25 V
• Output Type: Analog
• Bandwidth: 400Hz
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.50mm Width)
• Sensing Axis: Z
• Acceleration: 100 g
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PRINCIPLE OF OPERATION
integrated-circuit accelerometer.
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.
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).
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.
3). As the center plate moves with acceleration, the distance
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 between 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 ratiometric and
proportional to acceleration.
SPECIAL FEATURES
Filtering
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.
MMA1210D
4
Figure 2. Transducer
The Motorola accelerometer is a surface-micromachined
The device consists of a surface micromachined capacitive
The g-cell is a mechanical structure formed from
When the center plate deflects, the distance from it to one
The g-cell plates form two back-to-back capacitors (Figure
The CMOS ASIC uses switched capacitor techniques to
The Motorola accelerometers contain an onboard 4-pole
Physical Model
Acceleration
Figure 3. Equivalent
Circuit Model
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
Self-Test
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 =
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
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
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:
•
•
•
input pin, unless one (or more) of the fault conditions continues
to exist.
The sensor provides a self-test feature that allows the
Ratiometricity simply means that the output offset voltage
Motorola accelerometers include fault detection circuitry and
The fault latch can be reset by a rising edge on the self-test
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.
1
/
2
AV
2
/d
2
) causes the center plate to deflect. The
Motorola Sensor Device Data