EVAL-ADXL344Z Analog Devices, EVAL-ADXL344Z Datasheet - Page 33

• Manufacturer Part Number: EVAL-ADXL344Z
• Description: Daughter Cards & OEM Boards EB
• Manufacturer: Analog Devices
• Series: ADXL344r

Specifications of EVAL-ADXL344Z

• Rohs: yes
• Product: Breakout Boards
• Description/function: 3 axis accelerometer evaluation board
• Interface Type: I2C, SPI
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Voltage: 1.7 V to 2.75 V
• Factory Pack Quantity: 1
• For Use With: ADXL344

Data Sheet
NOISE PERFORMANCE
The specification of noise shown in Table 1 corresponds to the
typical noise performance of the ADXL344 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
For data rates greater than 100 Hz, the noise increases approxi-
mately 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
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
Figure 43 shows the typical Allan deviation for the ADXL344.
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 44 shows the typical noise performance trend of the
ADXL344
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 42,
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 42. Noise vs. Output Data Rate for Normal and Low Power Modes,
ADXL344
7
6
5
4
3
2
1
0
over supply voltage. The performance is normalized
3.13 6.25 12.50 25
is equivalent to the noise at 100 Hz ODR in LSBs.
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
ADXL344
100
200
400
ADXL344
is shown in Figure 42.
S
800
= 2.6 V. The x-axis
1600
is constant
3200
Rev. 0 | Page 33 of 40
OPERATION AT VOLTAGES OTHER THAN 2.6 V
The
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
ADXL344
150
140
130
120
110
100
10k
100
90
1k
10
S
0.01
1.6
= 1.8 V operation as it is at V
Figure 44. Normalized Noise vs. Supply Voltage
is tested and specified at a supply voltage of
1.8
0.1
Figure 43. Allan Deviation
X-AXIS
Y-AXIS
Z-AXIS
SUPPLY VOLTAGE, V
AVERAGING PERIOD,
2.0
1
10
2.2
S
= 1.8 V, the offset of the x- and
S
= 2.6 V. Sensitivity on the
S
100
S
= 2.6 V operation. Simple
2.4
S
(V)
S
= 2.6 V operation. The
(s)
= 2.6 V operation to
S
as high as 2.75 V
1k
2.6
X-AXIS
Y-AXIS
Z-AXIS
ADXL344
10k
2.8