ADXL150 Analog Devices, Inc., ADXL150 Datasheet - Page 4

• Manufacturer Part Number: ADXL150
• Description: 65 G To 650 G, Low Noise, Low Power , Single/dual Axis Imems? Accelerometers
• Manufacturer: Analog Devices, Inc.

GLOSSARY OF TERMS
Acceleration: Change in velocity per unit time.
Acceleration Vector: Vector describing the net acceleration
acting upon the ADXL150/ADXL250.
g: A unit of acceleration equal to the average force of gravity
occurring at the earth’s surface. A g is approximately equal to
32.17 feet/s
Nonlinearity: The maximum deviation of the ADXL150/
ADXL250 output voltage from a best fit straight line fitted to a
plot of acceleration vs. output voltage, calculated as a % of the
full-scale output voltage (at 50 g).
Resonant Frequency: The natural frequency of vibration of
the ADXL150/ADXL250 sensor’s central plate (or “beam”). At
its resonant frequency of 24 kHz, the ADXL150/ADXL250’s
moving center plate has a slight peak in its frequency response.
Sensitivity: The output voltage change per g unit of accelera-
tion applied, specified at the V
Total Alignment Error: Net misalignment of the ADXL150/
ADXL250’s on-chip sensor and the measurement axis of the
application. This error includes errors due to sensor die align-
ment to the package, and any misalignment due to installation
of the sensor package in a circuit board or module.
Transverse Acceleration: Any acceleration applied 90 to the
axis of sensitivity.
Transverse Sensitivity Error: The percent of a transverse
acceleration that appears at V
Transverse Axis: The axis perpendicular (90 ) to the axis of
sensitivity.
ADXL150/ADXL250
2
or 9.807 meters/s
OUT
2
OUT
.
.
pin in mV/g.
–4–
Zero g Bias Level: The output voltage of the ADXL150/
ADXL250 when there is no acceleration (or gravity) acting
upon the axis of sensitivity. The output offset is the difference
between the actual zero g bias level and (V
Polarity of the Acceleration Output
The polarity of the ADXL150/ADXL250 output is shown in
Figure 1. When its sensitive axis is oriented to the earth’s gravity
(and held in place), it will experience an acceleration of +1 g.
This corresponds to a change of approximately +38 mV at the
output pin. Note that the polarity will be reversed if the package
is rotated 180 . The figure shows the ADXL250 oriented so that
its “X” axis measures +1 g. If the package is rotated 90 clock-
wise (Pin 14 up, Pin 1 down), the ADXL250’s “Y” axis will now
measure +1 g.
Acceleration Vectors
The ADXL150/ADXL250 is a sensor designed to measure
accelerations that result from an applied force. It responds to
the component of acceleration on its sensitive X axis (ADXL150)
or on both the “X” and “Y” axis (ADXL250).
Figure 2. Output Polarity
14
8
ADXL150
A
X
1
7
14
8
S
ADXL250
/2).
A
X
A
Y
1
7
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