RD3172MMA7455L Freescale Semiconductor, RD3172MMA7455L Datasheet - Page 8
![EVAL BOARD FOR MMA7455L](/photos/28/40/284048/rd3172mma7455l_sml.jpg)
RD3172MMA7455L
Manufacturer Part Number
RD3172MMA7455L
Description
EVAL BOARD FOR MMA7455L
Manufacturer
Freescale Semiconductor
Series
ZSTAR3r
Datasheets
1.RD3172MMA7455L.pdf
(35 pages)
2.RD3172MMA7455L.pdf
(2 pages)
3.RD3172MMA7455L.pdf
(100 pages)
Specifications of RD3172MMA7455L
Design Resources
ZSTAR3 Schematic
Sensor Type
Accelerometer, 3 Axis
Sensing Range
±2g, 4g, 8g
Interface
RF
Sensitivity
16, 32, 64 LSB/g
Voltage - Supply
3V
Embedded
Yes, MCU, 16-Bit
Utilized Ic / Part
MMA7455
Acceleration
5000 g
Sensing Axis
Triple Axis
Output Type
Digital
Interface Type
I2C, SPI
Operating Voltage
3.6 L
Operating Current
490 uA
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
For Use With/related Products
MMA7455L
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
RD3172MMA7455L
Manufacturer:
Freescale Semiconductor
Quantity:
135
Note: The response time is between 10% of full scale V
*The bandwidth for detecting interrupts in level and pulse is 600Hz which is changed from measurement mode.
PRINCIPLE OF OPERATION
The Freescale accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface mi-
cromachined 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
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 accel-
eration. The g-cell beams form two back-to-back capacitors
between the beams changes and each capacitor's value will change, (C = A
electric 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 differ-
ence between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a digital
output that is proportional to acceleration.
Table 4. Function Parameters for Detection
–40°C < T
8
MMA7455L
Level Detection
Pulse Detection
Detection Threshold Range
Pulse detection range (Adjustable range)
Time step for pulse detection
Threshold range for pulses
Detection levels for threshold
Latency timer (Adjustable range)
Time Window (Adjustable range)
Bandwidth for detecting interrupt*
Time step for latency timer and time window
A
< 85°C, 2.4 V < AV
Characteristic
DD
< 3.6 V, unless otherwise specified
Figure 3. Simplified Transducer Physical Model
DD
input voltage and 90% of the final operating output voltage.
Acceleration
(Figure
(Figure
3).
3). As the center beam moves with acceleration, the distance
Symbol
ε
/D). Where A is the area of the beam,
Min
0.5
—
—
—
—
0
0
1
1
Typ
127
600
0.5
—
—
—
—
—
1
Freescale Semiconductor
Max
127
150
250
FS
FS
—
—
—
—
ε
is the di-
Counts
Unit
Sensors
ms
ms
ms
ms
ms
Hz
g
g