EVAL-ADXL330Z Analog Devices Inc, EVAL-ADXL330Z Datasheet - Page 11

• Manufacturer Part Number: EVAL-ADXL330Z
• Description: Three-Axis Accelerometer Evaluation Board
• Manufacturer: Analog Devices Inc
• Series: iMEMS®r

Specifications of EVAL-ADXL330Z

• Silicon Manufacturer: Analog Devices
• Application Sub Type: Accelerometer - Three-Axis
• Kit Application Type: Sensing - Motion / Vibration / Shock
• Silicon Core Number: ADXL330
• Sensor Type: Accelerometer, 3 Axis
• Sensing Range: ±3.6g
• Interface: Analog
• Sensitivity: 300mV/g
• Voltage - Supply: 1.8 V ~ 3.6 V
• Embedded: No
• Utilized Ic / Part: ADXL330
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: Q2904641

THEORY OF OPERATION
The ADXL330 is a complete 3-axis acceleration measurement
system on a single monolithic IC. The ADXL330 has a measure-
ment range of ±3 g minimum. It contains a polysilicon surface
micromachined sensor and signal conditioning circuitry to
implement an open-loop acceleration measurement architecture.
The output signals are analog voltages that are proportional to
acceleration. The accelerometer can measure the static accelera-
tion of gravity in tilt sensing applications as well as dynamic
acceleration resulting from motion, shock, or vibration.
The sensor is a polysilicon surface micromachined structure
built on top of a silicon wafer. Polysilicon springs suspend the
structure over the surface of the wafer and provide a resistance
against acceleration forces. Deflection of the structure is meas-
ured using a differential capacitor that consists of independent
fixed plates and plates attached to the moving mass. The fixed
plates are driven by 180° out-of-phase square waves. Acceleration
deflects the moving mass and unbalances the differential
capacitor resulting in a sensor output whose amplitude is
proportional to acceleration. Phase-sensitive demodulation
techniques are then used to determine the magnitude and
direction of the acceleration.
The demodulator output is amplified and brought off-chip
through a 32 kΩ resistor. The user then sets the signal band-
width of the device by adding a capacitor. This filtering improves
measurement resolution and helps prevent aliasing.
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MECHANICAL SENSOR
The ADXL330 uses a single structure for sensing the X, Y, and
Z axes. As a result, the three axes sense directions are highly
orthogonal with little cross axis sensitivity. Mechanical mis-
alignment of the sensor die to the package is the chief source
of cross axis sensitivity. Mechanical misalignment can, of
course, be calibrated out at the system level.
PERFORMANCE
Rather than using additional temperature compensation
circuitry, innovative design techniques ensure high
performance is built-in to the ADXL330. As a result, there is
neither quantization error nor nonmonotonic behavior, and
temperature hysteresis is very low (typically less than 3 mg over
the −25°C to +70°C temperature range).
Figure 14, Figure 15, and Figure 16 show the zero g output
performance of eight parts (X-, Y-, and Z-axis) soldered to a
PCB over a −25°C to +70°C temperature range.
Figure 26, Figure 27, and Figure 28 demonstrate the typical
sensitivity shift over temperature for supply voltages of 3 V. This
is typically better than ±1% over the −25°C to +70°C
temperature range.
ADXL330