MMA8450QT Freescale Semiconductor, MMA8450QT Datasheet - Page 38

• Manufacturer Part Number: MMA8450QT
• Description: Board Mount Accelerometers 12bit 3-Axis FIFO HPF PL
• Manufacturer: Freescale Semiconductor

Specifications of MMA8450QT

• Sensing Axis: X, Y, Z
• Acceleration: 2 g, 4 g, 8 g
• Digital Output - Number Of Bits: 12 bit
• Supply Voltage (max): 1.89 V
• Supply Voltage (min): 1.71 V
• Supply Current: 3 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Shutdown: Yes
• Sensitivity: 0.976 mg/digit, 1.953 mg/digit, 3.906 mg/digit
• Package / Case: QFN-16
• Output Type: Digital
• Package Type: QFN
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3mm
• Product Height (mm): 1mm
• Product Length (mm): 3mm
• Mounting: Surface Mount
• Pin Count: 16
• Acceleration Range: ± 2g, ± 4g, ± 8g
• No. Of Axes: 3
• Ic Interface Type: I2C, Serial
• Sensor Case Style: QFN
• No. Of Pins: 16
• Supply Voltage Range: 1.71V To 1.89V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

0x31 - 0x33: PULSE_THSX, Y, Z Pulse Threshold for X, Y & Z Registers
of 0.258g/LSB at a fixed 8g acceleration range, thus the minimum resolution is always fixed at 0.258g/LSB irrespective of the
selected g range.
pulse detection procedure. The threshold value is expressed over 5-bits as an unsigned number.
Table 46. PULSE_THSY Description
Table 47. PULSE_THSZ Description
0x34: PULSE_TMLT Pulse Time Window 1 Register
selected axis exceeding the specified threshold and the end when the acceleration on the selected axis must go below the
specified threshold to be considered a valid pulse.
at the given power mode multiplied by 255. The time steps available are dependent on whether the device is in Normal Power
mode or in Low Power mode. Notice in the table below that the time step is twice as long in Low Power mode.
≥ 159 ms.
Table 45. PULSE_THSX Description
0x32 PULSE_THSY Register (Read/Write)
0x34 PULSE_TMLT Register (Read/Write)
Table 48. Time Step for PULSE Time Limit at ODR and Power Mode
38
MMA8450Q
0x31 PULSE_THSX Register (Read/Write)
0x33 PULSE_THSZ Register (Read/Write)
The pulse threshold can be set separately for the X, Y and Z axes. The threshold values range from 0 to 31 counts with steps
The PULSE_THSX, PULSE_THSY and PULSE_THSZ registers define the threshold which is used by the system to start the
The bits Tmlt7 through Tmlt0 define the maximum time interval that can elapse between the start of the acceleration on the
The minimum time step for the pulse time limit is defined in
Therefore an ODR setting of 400 Hz with normal power mode would result in a maximum pulse time limit of (0.625 ms * 255)
THSY4, THSY0
Tmlt7
THSZ4, THSZ0
Bit 7
Bit 7
Bit 7
Bit 7
THSX4, THSX0
0
0
0
Output Data Rate (Hz)
12.5
1.56
400
200
100
Tmlt6
50
Bit 6
Bit 6
Bit 6
Bit 6
0
0
0
Pulse Threshold on Y-axis. Default value: 0_0000.
Pulse Threshold on Z-axis. Default value: 0_0000.
Pulse Threshold on X-axis. Default value: 0_0000.
Tmlt5
Bit 5
Bit 5
Bit 5
Bit 5
0
0
0
THSZ4
THSX4
THSY4
Tmlt4
Bit 4
Bit 4
Bit 4
Bit 4
Step at Normal Mode
0.625 ms
Table
1.25 ms
2.5 ms
5 ms
5 ms
5 ms
48. Maximum time for a given ODR is the minimum time step
THSZ3
THSX3
THSY3
Tmlt3
Bit 3
Bit 3
Bit 3
Bit 3
THSZ2
THSX2
THSY2
Tmlt2
Bit 2
Bit 2
Bit 2
Bit 2
Step at Low Power Mode
THSZ1
THSX1
THSY1
Bit 1
Tmlt1
Bit 1
Bit 1
Bit 1
Freescale Semiconductor
1.25 ms
2.5 ms
5.0 ms
10 ms
10 ms
10 ms
THSZ0
THSX0
THSY0
Bit 0
Bit 0
Tmlt0
Bit 0
Bit 0
Sensors