MMA8452QR1 Freescale Semiconductor, MMA8452QR1 Datasheet - Page 35

• 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

Table 33. TRANSIENT_THS Description
0x1F TRANSIENT_THS Register
TRANSIENT_THS register corresponds to a g value which is compared against the values of High Pass Filtered Data. If the High
Pass Filtered acceleration value exceeds the threshold limit an event flag is raised and the interrupt is generated if enabled.
scale at 2g or 4g this function will still operate up to 8g. If the Low Noise bit is set in Register 0x2A the maximum threshold to be
reached is 4g.
0x20 TRANSIENT_COUNT
unsigned value of high pass filtered data is greater than the user specified value of TRANSIENT_THS.
Table 34. TRANSIENT_COUNT Description
Sensors
Freescale Semiconductor
0x1F TRANSIENT_THS Register (Read/Write)
0x20 TRANSIENT_COUNT Register (Read/Write)
Table 35. TRANSIENT_COUNT Relationship with the ODR
The Transient Threshold register sets the threshold limit for the detection of the transient acceleration. The value in the
The threshold THS[6:0] is a 7-bit unsigned number, 0.063g/LSB. The maximum threshold is 8g. Even if the part is set to full
The TRANSIENT_COUNT sets the minimum number of debounce counts continuously matching the condition where the
The time step for the transient detection debounce counter is set by the value of the system ODR and the Oversampling mode.
DBCNTM
ODR (Hz)
THS[6:0]
DBCNTM
12.5
6.25
1.56
Bit 7
Bit 7
800
400
200
100
50
D7
D[7:0]
Debounce counter mode selection. Default value: 0. 0: increments or decrements debounce; 1: increments or clears counter.
Transient Threshold: Default value: 000_0000.
Normal
0.319
0.638
1.28
2.55
5.1
5.1
5.1
5.1
THS6
Bit 6
Bit 6
Count value. Default value: 0000_0000.
D6
LPLN
Max Time Range (s)
0.319
0.638
1.28
2.55
20.4
20.4
20.4
5.1
THS5
Bit 5
Bit 5
D5
HighRes
0.319
0.638
0.638
0.638
0.638
0.638
0.638
0.638
THS4
Bit 4
Bit 4
D4
0.319
0.638
1.28
2.55
20.4
40.8
40.8
5.1
LP
THS3
Bit 3
Bit 3
D3
Normal
1.25
2.5
10
20
20
20
20
5
THS2
LPLN
Bit 2
Bit 2
1.25
2.5
D2
10
20
80
80
80
5
Time Step (ms)
HighRes
1.25
THS1
2.5
2.5
2.5
2.5
2.5
2.5
2.5
Bit 1
Bit 1
D1
MMA8452Q
THS0
1.25
160
160
Bit 0
Bit 0
LP
2.5
10
20
80
D0
5
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