EVAL-ADXL346Z Analog Devices Inc, EVAL-ADXL346Z Datasheet - Page 35

no-image

EVAL-ADXL346Z

Manufacturer Part Number
EVAL-ADXL346Z
Description
Inertial Sensor Evaluation System
Manufacturer
Analog Devices Inc
Datasheets

Specifications of EVAL-ADXL346Z

Silicon Manufacturer
Analog Devices
Silicon Core Number
ADXL346
Kit Application Type
Sensing - Motion / Vibration / Shock
Application Sub Type
Accelerometer
Silicon Family Name
IMEMS
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
NOISE PERFORMANCE
The specification of noise shown in Table 1 corresponds to the
typical noise performance of the ADXL346 in normal power opera-
tion with an output data rate of 100 Hz (LOW_POWER bit = 0,
rate = 0x0A in the BW_RATE register, Address 0x2C). For normal
power operation at data rates below 100 Hz, the noise of the
ADXL346 is equivalent to the noise at 100 Hz ODR in LSBs. For
data rates greater than 100 Hz, the noise increases approximately by
a factor of √2 per doubling of the data rate. For example, at 400 Hz
ODR, the noise on the x- and y-axes is typically less than 2 LSB
rms, and the noise on the z-axis is typically less than 3 LSB rms.
For low power operation (LOW_POWER bit = 1 in the BW_RATE
register, Address 0x2C), the noise of the ADXL346 is constant
for all valid data rates shown in Table 8. This value is typically
less than 2.83 LSB rms for the x- and y-axes and typically less
than 4.25 LSB rms for the z-axis.
The trend of noise performance for both normal power and low
power modes of operation of the ADXL346 is shown in Figure 53.
Figure 54 shows the typical Allan deviation for the ADXL346.
The 1/f corner of the device, as shown in this figure, is very low,
allowing absolute resolution of approximately 100 μg (assuming
that there is sufficient integration time). The figure also shows
that the noise density is 420 μg/√Hz for the x- and y-axes and
530 μg/√Hz for the z-axis.
Figure 55 shows the typical noise performance trend of the
ADXL346 over supply voltage. The performance is normalized
to the tested and specified supply voltage, V
offers the best noise performance over supply voltage, increasing by
typically less than 25% from nominal at a supply voltage of 1.8 V.
The performance of the y- and z-axes is comparable, with both
axes increasing by typically less than 35% when operating with a
supply voltage of 1.8 V. It should be noted, as shown in Figure 53,
that the noise on the z-axis is typically higher than that on the
y-axis; therefore, although the noise on the z- and y-axes change
roughly the same in percentage over supply voltage, the magnitude
of change on the z-axis is greater than the magnitude of change
on the y-axis.
Figure 53. Noise vs. Output Data Rate for Normal and Low Power Modes,
7
6
5
4
3
2
1
0
3.13 6.25 12.50 25
X-AXIS, NORMAL POWER
Y-AXIS, NORMAL POWER
Z-AXIS, NORMAL POWER
X-AXIS, LOW POWER
Y-AXIS, LOW POWER
Z-AXIS, LOW POWER
Full Resolution (256 LSB/g)
OUTPUT DATA RATE (Hz)
50
100
200
400
S
= 2.6 V. The x-axis
800
1600
3200
Rev. A | Page 35 of 40
OPERATION AT VOLTAGES OTHER THAN 2.6 V
The ADXL346 is tested and specified at a supply voltage of
V
or as low as 1.7 V. Some performance parameters change as the
supply voltage changes, including the offset, sensitivity, noise,
self-test, and supply current.
Due to minuscule changes in the electrostatic forces as supply
voltage is varied, the offset and sensitivity change slightly. When
operating at a supply voltage of V
y-axes is typically 25 mg higher than at V
z-axis is typically 20 mg lower when operating at a supply voltage
of 1.8 V than when operating at V
x- and y-axes typically shifts from a nominal 256 LSB/g (full-
resolution or ±2 g, 10-bit operation) at V
250 LSB/g when operating with a supply voltage of 1.8 V. The z-axis
sensitivity is unaffected by a change in supply voltage and is the
same at V
linear interpolation can be used to determine typical shifts in
offset and sensitivity at other supply voltages.
S
= 2.6 V; however, it can be powered with a V
150
140
130
120
110
100
90
10k
100
1k
10
1.6
S
0.01
= 1.8 V operation as it is at V
Figure 55. Normalized Noise vs. Supply Voltage
1.8
0.1
Figure 54. Allan Deviation
X-AXIS
Y-AXIS
Z-AXIS
SUPPLY VOLTAGE, V
AVERAGING PERIOD,
2.0
1
S
2.2
10
= 1.8 V, the offset of the x- and
S
= 2.6 V. Sensitivity on the
S
= 2.6 V operation. Simple
S
100
S
S
2.4
= 2.6 V operation. The
(V)
= 2.6 V operation to
(s)
S
as high as 2.75 V
1k
2.6
X-AXIS
Y-AXIS
Z-AXIS
ADXL346
10k
2.8

Related parts for EVAL-ADXL346Z