ADXL345BCCZ-RL7 Analog Devices Inc, ADXL345BCCZ-RL7 Datasheet - Page 13

• Manufacturer Part Number: ADXL345BCCZ-RL7
• Description: Digital Output Three-Axis XL 1500pc RL
• Manufacturer: Analog Devices Inc
• Series: iMEMS®r

Specifications of ADXL345BCCZ-RL7

• Design Resources: Sensing Low-g Acceleration Using ADXL345 Digital Accelerometer Connected to ADuC7024 (CN0133)
• Axis: X, Y, Z
• Acceleration Range: ±2g, 4g, 8g, 16g
• Sensitivity: 256LSB/g, 128LSB/g, 64LSB/g, 32LSB/g
• Voltage - Supply: 2 V ~ 3.6 V
• Output Type: Digital
• Bandwidth: 6.25Hz ~ 3.2kHz Selectable
• Interface: I²C, SPI
• Mounting Type: Surface Mount
• Package / Case: 14-LGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADXL345Z - BOARD EVALUATION FOR ADXL345EVAL-ADXL345Z-S - BOARD SATELLITE FOR ADXL345Z-MEVAL-ADXL345Z-M - BOARD EVAL FOR ADXL345
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADXL345BCCZ-RL7TR

THEORY OF OPERATION
The ADXL345 is a complete 3-axis acceleration measurement
system with a selectable measurement range of ±2 g, ±4 g, ±8 g,
or ±16 g. It measures both dynamic acceleration resulting from
motion or shock and static acceleration, such as gravity, that
allows the device to be used as a tilt sensor.
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 forces due to applied acceleration.
Deflection of the structure is measured using differential capacitors
that consist of independent fixed plates and plates attached to the
moving mass. Acceleration deflects the proof mass and unbalances
the differential capacitor, resulting in a sensor output whose ampli-
tude is proportional to acceleration. Phase-sensitive demodulation
is used to determine the magnitude and polarity of the acceleration.
Table 6. Power Sequencing
Condition
Power Off
Bus Disabled
Bus Enabled
Standby or Measurement
V
Off
On
Off
On
S
V
Off
Off
On
On
DD I/O
Description
The device is completely off, but there is a potential for a communication bus conflict.
The device is on in standby mode, but communication is unavailable and creates a conflict on
the communication bus. The duration of this state should be minimized during power-up to
prevent a conflict.
No functions are available, but the device does not create a conflict on the communication bus.
At power-up, the device is in standby mode, awaiting a command to enter measurement
mode, and all sensor functions are off. After the device is instructed to enter measurement
mode, all sensor functions are available.
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POWER SEQUENCING
Power can be applied to V
damaging the ADXL345. All possible power-on modes are
summarized in Table 6. The interface voltage level is set with
the interface supply voltage, V
ensure that the ADXL345 does not create a conflict on the
communication bus. For single-supply operation, V
the same as the main supply, V
however, V
interface voltage, as long as V
After V
consumption is minimized and the device waits for V
applied and for the command to enter measurement mode to be
received. (This command can be initiated by setting the measure
bit (Bit D3) in the POWER_CTL register (Address 0x2D).) In
addition, while the device is in standby mode, any register can be
written to or read from to configure the part. It is recommended
to configure the device in standby mode and then to enable
measurement mode. Clearing the measure bit returns the
device to the standby mode.
S
is applied, the device enters standby mode, where power
DD I/O
can differ from V
S
or V
S
is greater than or equal to V
DD I/O
S
. In a dual-supply application,
DD I/O
S
to accommodate the desired
, which must be present to
in any sequence without
ADXL345
DD I/O
DD I/O
DD I/O
can be
to be
.