Sensors

Freescale Semiconductor

2

MMA8450Q

Contents

Application Notes for Reference ............................................................................................................................................... 6

1

Block Diagram and Pin Description .................................................................................................................................. 6

1.1

Block Diagram ............................................................................................................................................................. 6

Figure 1. Block Diagram .............................................................................................................................................. 6

1.2

Pin Description ............................................................................................................................................................ 6

Figure 2. Direction of the Detectable Accelerations .................................................................................................... 6

Figure 3. Application Diagram ..................................................................................................................................... 7

Table 1. Pin Description .............................................................................................................................................. 7

1.3

Soldering Information .................................................................................................................................................. 7

2

Mechanical and Electrical Specifications ......................................................................................................................... 8

2.1

Mechanical Characteristics ......................................................................................................................................... 8

Table 2. Mechanical Characteristics ........................................................................................................................... 8

2.2

Electrical Characteristics ............................................................................................................................................. 9

Table 3. Electrical Characteristics @ VDD = 1.8 V, T = 25°C unless otherwise noted. ............................................. 9

2.3

I2C Interface Characteristic ....................................................................................................................................... 10

Figure 4. I2C Slave Timing Diagram .......................................................................................................................... 11

2.4

Absolute Maximum Ratings ....................................................................................................................................... 11

Table 5. Maximum Ratings ........................................................................................................................................ 11

Table 6. ESD and Latch-Up Protection Characteristics ............................................................................................11

3

Terminology ....................................................................................................................................................................... 12

3.1

Sensitivity .................................................................................................................................................................. 12

3.2

Zero-g Offset ............................................................................................................................................................. 12

3.3

Self-Test ....................................................................................................................................................................12

4

Modes of Operation ........................................................................................................................................................... 12

Figure 5. MMA8450Q Mode Transition Diagram ....................................................................................................... 12

Table 7. Mode of Operation Description .................................................................................................................... 12

5

Functionality ...................................................................................................................................................................... 13

5.1

Device Calibration ..................................................................................................................................................... 13

5.2

8-bit or 12-bit Data ..................................................................................................................................................... 13

5.3

Internal FIFO Data Buffer .......................................................................................................................................... 13

5.4

Low Power Mode ....................................................................................................................................................... 13

5.5

Auto-Wake/Sleep Mode ............................................................................................................................................ 14

5.6

Freefall and Motion Detection ................................................................................................................................... 14

5.6.1

Freefall Detection ........................................................................................................................................... 14

5.6.2

Motion Detection ............................................................................................................................................ 14

5.7

Transient Detection ................................................................................................................................................... 14

5.8

Orientation Detection ................................................................................................................................................. 15

Figure 6. Illustration of Landscape-to-Portrait Transition ......................................................................................... 15

Figure 7. Illustration of Portrait-to-Landscape Transition .......................................................................................... 15

Figure 8. Illustration of Z-Tilt Angle Lockout Transition ............................................................................................. 15

Figure 9. Landscape/Portrait Orientation .................................................................................................................. 16

5.9

Interrupt Register Configurations .............................................................................................................................. 16

Figure 10. System Interrupt Generation Block Diagram ............................................................................................16

5.10 Serial I2C Interface .................................................................................................................................................... 17

Table 8. Serial Interface Pin Description ................................................................................................................... 17

5.10.1

Single Byte Read ......................................................................................................................................................... 17

Multiple Byte Read ....................................................................................................................................................... 18

Single Byte Write .......................................................................................................................................................... 18

Multiple Byte Write ....................................................................................................................................................... 18

Table 10. I2C device Address Sequence .................................................................................................................. 18