MMA8452QR1 Freescale Semiconductor, MMA8452QR1 Datasheet - Page 13

• Manufacturer Part Number: MMA8452QR1
• Description: Board Mount Accelerometers LOW G 3-AXIS 12BT EX VLT
• Manufacturer: Freescale Semiconductor

Specifications of MMA8452QR1

• Sensing Axis: X, Y, Z
• Acceleration: 2 g, 4 g, 8 g
• Digital Output - Number Of Bits: 8 bit, 12 bit
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 1.95 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Digital Output - Bus Interface: I2C
• Shutdown: Yes
• Sensitivity: 256 count/g, 512 count/g, 1024 count/g
• Package / Case: QFN-16
• Output Type: Digital
• Rohs Compliant: Yes
• Peak Reflow Compatible (260 C): Yes
• Acceleration Range: ± 2g, ± 4g, ± 8g
• No. Of Axes: 3
• Ic Interface Type: I2C
• Sensor Case Style: QFN
• No. Of Pins: 16
• Supply Voltage Range: 1.95V To 3.6V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3
3.1
512 counts/g and in 8g mode the sensitivity is 256 counts/g.
3.2
sensor stationary on a horizontal surface will measure 0g in X-axis and 0g in Y-axis whereas the Z-axis will measure 1g. The output
is ideally in the middle of the dynamic range of the sensor (content of OUT Registers 0x00, data expressed as 2's complement
number). A deviation from ideal value in this case is called Zero-g offset. Offset is to some extent a result of stress on the MEMS
sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to
extensive mechanical stress.
3.3
actuation force is applied to the sensor, simulating a small acceleration. In this case the sensor outputs will exhibit a change in
their DC levels which are related to the selected full scale through the device sensitivity. When Self-T est is activated, the device
output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor and by the electrostatic
test-force.
4
transitioning from STANDBY to ACTIVE. These are all noted in the device memory map register table. The SLEEP and WAKE
modes are ACTIVE modes. For more information on how to use the SLEEP and WAKE modes and how to transition between
these modes please refer to the functionality section of this document.
Table 7. Mode of Operation Description
Sensors
Freescale Semiconductor
(WAKE/SLEEP)
The sensitivity is represented in counts/g. In 2g mode the sensitivity is 1024 counts/g. In 4g mode the sensitivity is
Zero-g Offset (TyOff) describes the deviation of an actual output signal from the ideal output signal if the sensor is stationary. A
Self-T est checks the transducer functionality without external mechanical stimulus. When Self-T est is activated, an electrostatic
All register contents are preserved when transitioning from ACTIVE to STANDBY mode. Some registers are reset when
STANDBY
ACTIVE
Mode
OFF
Terminology
Sensitivity
Zero-g Offset
Self-Test
Modes of Operation
Powered Down
I
MMA8452Q is possible
I
MMA8452Q is possible
OFF
2
2
C communication with
C communication with
I
2
C Bus State
Figure 6. MMA8452Q Mode Transition Diagram
<1.8 V
VDD
ON
ON
STANDBY
VDDIO Can be > VDD
VDDIO = High
VDD = High
ACTIVE bit is cleared
VDDIO = High
VDD = High
ACTIVE bit is set
VDDIO
SLEEP
The device is powered off. All analog and digital blocks
are shutdown. I
Only digital blocks are enabled.
Analog subsystem is disabled. Internal clocks disabled.
All blocks are enabled (digital, analog).
2
Function Description
C bus inhibited.
ACTIVE
WAKE
MMA8452Q
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