EVAL-ADXL344Z Analog Devices, EVAL-ADXL344Z Datasheet - Page 10

• 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

ADXL344
THEORY OF OPERATION
The
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, which
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 with an
amplitude proportional to acceleration. Phase-sensitive de-
modulation 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 Mode
ADXL344
is a complete 3-axis acceleration measurement
V
Off
On
Off
On
S
V
Off
Off
On
On
DD I/O
Rev. 0 | Page 10 of 40
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
will create 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 will 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.
POWER SEQUENCING
Power can be applied to V
damaging the ADXL344. 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
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, any register can be written to or read from to configure
the part while the device is in standby mode. 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
ADXL344
can differ from V
S
does not create a conflict on the
or V
S
DD I/O
is greater than or equal to V
S
. In a dual-supply application,
DD I/O
S
, which must be present to
to accommodate the desired
in any sequence without
Data Sheet
DD I/O
DD I/O
can be
to be
DD I/O
.