EVAL-ADXL345Z-DB Analog Devices Inc, EVAL-ADXL345Z-DB Datasheet - Page 22

• Manufacturer Part Number: EVAL-ADXL345Z-DB
• Description: BOARD EVAL FOR ADXL345
• Manufacturer: Analog Devices Inc
• Series: iMEMS®r

Specifications of EVAL-ADXL345Z-DB

• Sensor Type: Accelerometer, 3 Axis
• Sensing Range: ±2g, 4g, 8g, 16g
• Interface: I²C, SPI
• Sensitivity: 256LSB/g, 128LSB/g, 64LSB/g, 32LSB/g
• Voltage - Supply: 2 V ~ 3.6 V
• Embedded: No
• Utilized Ic / Part: ADXL345
• Silicon Manufacturer: Analog Devices
• Application Sub Type: Accelerometer - Three-Axis
• Kit Application Type: Sensing - Motion / Vibration / Shock
• Silicon Core Number: ADXL345
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADXL345
SELF-TEST
The ADXL345 incorporates a self-test feature that effectively
tests its mechanical and electronic systems simultaneously.
When the self-test function is enabled (via the SELF_TEST bit
in the DATA_FORMAT register, Address 0x31), an electrostatic
force is exerted on the mechanical sensor. This electrostatic force
moves the mechanical sensing element in the same manner as
acceleration, and it is additive to the acceleration experienced
by the device. This added electrostatic force results in an output
change in the x-, y-, and z-axes. Because the electrostatic force
is proportional to V
effect is shown in Figure 42. The scale factors shown in Table 14
can be used to adjust the expected self-test output limits for
different supply voltages, V
also exhibits a bimodal behavior. However, the limits shown in
Table 1 and Table 15 to Table 18 are valid for both potential self-
test values due to bimodality. Use of the self-test feature at data
rates less than 100 Hz or at 1600 Hz may yield values outside
these limits. Therefore, the part must be in normal power operation
(LOW_POWER bit = 0 in BW_RATE register, Address 0x2C)
and be placed into a data rate of 100 Hz through 800 Hz or 3200 Hz
for the self-test function to operate correctly.
–2
–4
–6
Figure 42. Self-Test Output Change Limits vs. Supply Voltage
6
4
2
0
X HIGH
X LOW
Y HIGH
Y LOW
Z HIGH
Z LOW
2.0
S
2
, the output change varies with V
2.5
S
. The self-test feature of the ADXL345
V
S
(V)
3.3
3.6
S
. This
Rev. B | Page 22 of 40
Table 14. Self-Test Output Scale Factors for Different Supply
Voltages, V
Supply Voltage, V
2.00
2.50
3.30
3.60
Table 15. Self-Test Output in LSB for ±2 g, 10-Bit or Full
Resolution (T
Axis
X
Y
Z
Table 16. Self-Test Output in LSB for ±4 g, 10-Bit Resolution
(T
Axis
X
Y
Z
Table 17. Self-Test Output in LSB for ±8 g, 10-Bit Resolution
(T
Axis
X
Y
Z
Table 18. Self-Test Output in LSB for ±16 g, 10-Bit Resolution
(T
Axis
X
Y
Z
A
A
A
= 25°C, V
= 25°C, V
= 25°C, V
S
S
S
S
A
= 2.5 V, V
= 2.5 V, V
= 2.5 V, V
= 25°C, V
Min
50
−540
75
Min
25
−270
38
Min
12
−135
19
6
Min
−67
10
S
(V)
DD I/O
DD I/O
DD I/O
S
= 2.5 V, V
= 1.8 V)
= 1.8 V)
= 1.8 V)
X-Axis, Y-Axis
0.64
1.00
1.77
2.11
Max
540
−540
875
Max
270
−25
438
Max
135
−12
219
Max
67
−6
110
DD I/O
= 1.8 V)
Unit
LSB
LSB
LSB
Unit
LSB
LSB
LSB
Unit
LSB
LSB
LSB
Z-Axis
0.8
1.00
1.47
1.69
Unit
LSB
LSB
LSB