MMA7261Q Freescale Semiconductor, MMA7261Q Datasheet - Page 4

• Manufacturer Part Number: MMA7261Q
• Description: SENSOR ACCEL 3-AXIS +/-2.5 16QFN
• Manufacturer: Freescale Semiconductor

Specifications of MMA7261Q

• Axis: X, Y, Z
• Acceleration Range: ±2.5g, 3.3g, 6.7g, 10g (Config)
• Sensitivity: 480mV/g, 360mV/g, 180mV/g, 120mV/g
• Voltage - Supply: 2.2 V ~ 3.6 V
• Output Type: Analog
• Bandwidth: 350Hz - X, 150Hz - Z
• Mounting Type: Surface Mount
• Package / Case: 16-QFN
• Sensing Axis: X, Y, Z
• Acceleration: 2.5 g, 3.3 g, 6.7 g, 10 g
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.2 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 20 C
• For Use With: RD3152MMA7260Q - BOARD REF 3-AXIS ACCELEROMETER
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Interface: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

integrated-circuit accelerometer.
capacitive sensing cells (g-cell) and a signal conditioning
ASIC contained in a single integrated circuit package. The
sensing elements are sealed hermetically at the wafer level
using a bulk micromachined cap wafer.
semiconductor materials (postillion) 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
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.
(Figure
distance between the beams changes and each capacitor's
value will change, (C = Aε/D). Where A is the area of the
beam, ε is the dielectric constant, and D is the distance
between the beams.
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.
4
MMA7261QT
The Freescale accelerometer is a surface-micromachined
The device consists of two surface micromachined
The g-cell is a mechanical structure formed from
As the beams attached to the central mass move, the
The g-cell beams form two back-to-back capacitors
The ASIC uses switched capacitor techniques to measure
Figure 3. Simplified Transducer Physical Model
3). As the center beam moves with acceleration, the
(Figure
Acceleration
3).
PRINCIPLE OF OPERATION
g-Select
sensitivities present in the device. Depending on the logic
input placed on pins 1 and 2, the device internal gain will be
changed allowing it to function with a 2.5g, 3.3g, 6.7g, or 10g
sensitivity
applications requiring different sensitivities for optimum
performance. The sensitivity can be changed at anytime
during the operation of the product. The g-Select1 and g-
Select2 pins can be left unconnected for applications
requiring only a 2.5g sensitivity as the device has an internal
pull-down to keep it at that sensitivity (480mV/g).
Sleep Mode
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 12
(Sleep Mode) will place the device in this mode and reduce
the current to 3uA typ. For lower power consumption, it is
recommended to set g-Select1 and g-Select2 to 2.5g mode.
By placing a high input signal on pin 12, the device will
resume to normal mode of operation.
Filtering
switched capacitor filters. 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
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.
Table 3. g-Select pin Descriptions
The g-Select feature allows for the selection among 4
The 3 axis accelerometer provides a Sleep Mode that is
The 3 axis accelerometer contains onboard single-pole
Ratiometricity simply means the output offset voltage and
g-Select2
0
0
1
1
(Table
3). This feature is ideal when a product has
g-Select1
SPECIAL FEATURES
0
1
0
1
g-Range
Freescale Semiconductor
2.5g
3.3g
6.7g
10g
Sensitivity
480mV/g
360mV/g
180mV/g
120mV/g
Sensors