MMA8450QT Freescale Semiconductor, MMA8450QT Datasheet - Page 36

• 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

Table 41. TRANSIENT_COUNT Description
0x2D: TRANSIENT_THS Transient Threshold Register
TRANSIENT_THS register corresponds to a g value which is compared against the values of OUT_X_DELTA, OUT_Y_DELTA,
and OUT_Z_DELTA. If the acceleration exceeds the threshold limit an event flag is raised and an interrupt is generated if
interrupts are enabled.
Table 40. TRANSIENT_THS Description
of 0 to 127.
Therefore:
0x2E: TRANSIENT_COUNT Transient Debounce Register
unsigned value of OUT_X_DELTA or OUT_Y_DELTA or OUT_Z_DELTA register is greater than the user specified value of
TRANSIENT_THS.
Table 42. TRANSIENT_COUNT Relationship with the ODR
Table 39. TRANSIENT_SRC Description
36
0x2D TRANSIENT_THS Register (Read/Write)
0x2E TRANSIENT_COUNT Register (Read/Write)
MMA8450Q
The TRANSIENT_THS register sets the threshold limit for the high pass filtered acceleration. The value in the
The minimum threshold resolution is dependent on the selected acceleration g range and the threshold register has a range
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.
An ODR of 100 Hz and a TRANSIENT_COUNT value of 15 would result in a debounce response time of 150 ms.
DBCNTM
THS[6:0]
DBCNTM
•
•
•
•
YTRANSE
XTRANSE
ZTRANSE
Bit 7
Bit 7
D[7-0]
D7
If the selected acceleration g range is 8g mode (FS = 11), the minimum threshold resolution is 0.063g/LSB. The maximum
is 8g.
If the selected acceleration g range is 4g mode (FS = 10), the minimum threshold resolution is 0.0315g/LSB. The
maximum is 4g.
If the selected acceleration g range is 2g mode (FS = 01), the minimum threshold resolution is 0.01575g/LSB. The
maximum is 2g.
The DBCNTM bit behaves in the same manner described previously for the Motion/Freefall 1.
EA
Output Data Rate (Hz)
Debounce counter mode selection. Default value: 0. 0: increments or decrements debounce; 1: increments or clears counter
Transient Threshold: Default value: 000_0000
Count value. Default value: 0000_0000.
Event Active Flag. Default value: 0.
0: No event flag asserted; 1: one or more event flag has been asserted.
Z transient event. Default value: 0.
0: No Z event detected, 1: Z event detected
Y transient event. Default value: 0.
0: No Y event detected, 1: Y event detected
X transient event. Default value: 0.
0: No X event detected, 1: X event detected
12.5
1.56
400
200
100
50
THS6
Bit 6
Bit 6
D6
THS5
Bit 5
Bit 5
D5
THS4
Bit 4
Bit 4
D4
640 ms
2.5 ms
10 ms
20 ms
80 ms
Step
5 ms
THS3
Bit 3
Bit 3
D3
THS2
Bit 2
Bit 2
D2
Duration Range
2.5 ms – 0.637s
640 ms – 163s
5 ms – 1.275s
10 ms – 2.55s
80 ms – 20.4s
20 ms – 5.1s
THS1
Bit 1
Bit 1
Freescale Semiconductor
D1
THS0
Bit 0
Bit 0
D0
Sensors