ADXL321EB Analog Devices Inc, ADXL321EB Datasheet - Page 13

• Manufacturer Part Number: ADXL321EB
• Description: Evaluation Board
• Manufacturer: Analog Devices Inc
• Series: iMEMS®r

Specifications of ADXL321EB

• Silicon Manufacturer: Analog Devices
• Application Sub Type: Accelerometer - Dual-Axis
• Kit Application Type: Sensing - Motion / Vibration / Shock
• Silicon Core Number: ADXL321
• Kit Contents: Board
• Supply Voltage Max: 6V
• Sensor Type: Accelerometer, 2 Axis
• Sensing Range: ±18g
• Interface: Analog
• Sensitivity: 57mV/g
• Voltage - Supply: 2.4 V ~ 6 V
• Embedded: No
• Utilized Ic / Part: ADXL321
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: Q2215334; Q2758648

Peak-to-peak noise values give the best estimate of the
uncertainty in a single measurement. Table 7 gives the typical
noise output of the ADXL321 for various C
Table 7. Filter Capacitor Selection (C
Bandwidth
(Hz)
10
50
100
500
USE WITH OPERATING VOLTAGES OTHER THAN 3 V
The ADXL321 is tested and specified at V
can be powered with V
that some performance parameters change as the supply voltage
is varied.
The ADXL321 output is ratiometric, so the sensitivity (or scale
factor) varies proportionally to supply voltage. At V
sensitivity is typically 100 mV/g. At V
typically 45 mV/g.
The zero g bias output is also ratiometric, so the zero g output is
nominally equal to V
The output noise is not ratiometric but is absolute in volts;
therefore, the noise density decreases as the supply voltage
increases. This is because the scale factor (mV/g) increases
while the noise voltage remains constant. At V
density is typically 190 μg/√Hz, while at V
density is typically 400 μg/√Hz,
Self-test response in g is roughly proportional to the square of
the supply voltage. However, when ratiometricity of sensitivity
is factored in with supply voltage, the self-test response in volts
is roughly proportional to the cube of the supply voltage. For
example, at V
approximately 80 mV. At V
approximately 8 mV.
The supply current decreases as the supply voltage decreases.
Typical current consumption at V
current consumption at V
S
= 5 V, the self-test response for the ADXL321 is
C
(μF)
0.47
0.1
0.047
0.01
X
, C
S
/2 at all supply voltages.
Y
S
as low as 2.4 V or as high as 6 V. Note
S
S
= 2.4 V is 350 μA.
= 2.4 V, the self-test response is
RMS Noise
(mg)
1.3
2.9
4
9.1
S
= 5 V is 750 μA, and typical
S
X
= 2.4 V, the sensitivity is
, C
S
S
Y
= 3 V; however, it
X
= 2.4 V, the noise
)
and C
S
Peak-to-Peak
Noise Estimate
(mg)
7.8
17.4
24
54.6
= 5 V, the noise
Y
S
values.
= 5 V, the
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USE AS A DUAL-AXIS TILT SENSOR
An accelerometer is most sensitive to tilt when its sensitive axis
is perpendicular to the force of gravity (that is, when it is
parallel to the earth’s surface). At this orientation, its sensitivity
to changes in tilt is highest. When the accelerometer is oriented
on axis to gravity (near its +1 g or −1 g reading), the change in
output acceleration per degree of tilt is negligible. When the
accelerometer is perpendicular to gravity, its output changes
nearly 17.5 mg per degree of tilt. At 45°, its output changes at
only 12.2 mg per degree of tilt, and resolution declines.
Converting Acceleration to Tilt
When the accelerometer is oriented so both its X-axis and
Y-axis are parallel to the earth’s surface, it can be used as a 2-
axis tilt sensor with both a roll axis and pitch axis. Once the
output signal from the accelerometer has been converted to an
acceleration that varies between −1 g and +1 g, the output tilt in
degrees is calculated as
Be sure to account for overranges. It is possible for the
accelerometers to output a signal greater than ±1 g due to
vibration, shock, or other accelerations.
PITCH = arcsine(A
ROLL = arcsine(A
Y
/1 g)
X
/1 g)
ADXL321