Sensors

2

Freescale Semiconductor

MMA8451Q

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. Landscape/Portrait Orientation .................................................................................................................... 7

Figure 4. Application Diagram ..................................................................................................................................... 7

Table 1. Pin Description .............................................................................................................................................. 8

1.3

Soldering Information .................................................................................................................................................. 8

2

Mechanical and Electrical Specifications ......................................................................................................................... 9

2.1

Mechanical Characteristics ......................................................................................................................................... 9

Table 2. Mechanical Characteristics ........................................................................................................................... 9

2.2

Electrical Characteristics ........................................................................................................................................... 10

Table 3. Electrical Characteristics............................................................................................................................. 10

2.3

I2C Interface Characteristic ....................................................................................................................................... 11

Table 4. I2C Slave Timing Values ............................................................................................................................. 11

Figure 5. I2C Slave Timing Diagram ......................................................................................................................... 12

2.4

Absolute Maximum Ratings ...................................................................................................................................... 12

Table 5. Maximum Ratings ....................................................................................................................................... 12

Table 6. ESD and Latch-Up Protection Characteristics ............................................................................................ 12

3

Terminology ...................................................................................................................................................................... 13

3.1

Sensitivity .................................................................................................................................................................. 13

3.2

Zero-g Offset ............................................................................................................................................................. 13

3.3

Self-Test .................................................................................................................................................................... 13

4

Modes of Operation .......................................................................................................................................................... 13

Figure 6. MMA8451Q Mode Transition Diagram ...................................................................................................... 13

Table 7. Mode of Operation Description ................................................................................................................... 13

5

Functionality ...................................................................................................................................................................... 14

5.1

Device Calibration ..................................................................................................................................................... 14

5.2

8-bit or 14-bit Data .................................................................................................................................................... 14

5.3

Internal FIFO Data Buffer .......................................................................................................................................... 14

5.4

Low Power Modes vs. High Resolution Modes ......................................................................................................... 15

5.5

Auto-WAKE/SLEEP Mode ........................................................................................................................................ 15

5.6

Freefall and Motion Detection ................................................................................................................................... 15

5.6.1

Freefall Detection ........................................................................................................................................... 15

5.6.2

Motion Detection ............................................................................................................................................ 15

5.7

Transient Detection ................................................................................................................................................... 16

5.8

Tap Detection ............................................................................................................................................................ 16

5.9

Orientation Detection ................................................................................................................................................ 16

Figure 7. Landscape/Portrait Orientation .................................................................................................................. 16

Figure 8. Illustration of Landscape to Portrait Transition .......................................................................................... 17

Figure 9. Illustration of Portrait to Landscape Transition .......................................................................................... 17

Figure 10. Illustration of Z-Tilt Angle Lockout Transition ........................................................................................... 17

5.10 Interrupt Register Configurations .............................................................................................................................. 18

Figure 11. System Interrupt Generation Block Diagram ........................................................................................... 18

5.11 Serial I2C Interface .................................................................................................................................................... 18

Table 8. Serial Interface Pin Description ................................................................................................................... 18

5.11.1 I2C Operation ................................................................................................................................................. 19

Table 9. I2C Address Selection Table ....................................................................................................................... 19

Single Byte Read ......................................................................................................................................................... 19

Multiple Byte Read ....................................................................................................................................................... 19

Single Byte Write ......................................................................................................................................................... 19

Multiple Byte Write ....................................................................................................................................................... 20

Table 10. I2C Device Address Sequence ................................................................................................................. 20

Figure 12. I2C Timing Diagram ................................................................................................................................. 20