Freescale MMA845xQ series three-axis accelerometer development scheme

Freescale’s MMA845xQ series is an intelligent low-power three-axis capacitive micro-machined accelerometer with 12-bit resolution, power supply voltage 1.95V-3.6V, interface voltage 1.6V-3.6V, dynamic selectable full scale +/-2g /+/-4g/+/-8g, output data rate (ODR) is 1.56 Hz to 800 Hz, 12-bit and 8-bit digital output, I2C digital output interface, current consumption 6uA-160uA, mainly used for Electronic compass, static Orientation detection, drop detection for notebooks, e-books, etc., real-time orientation detection and job analysis, handheld device motion detection, vibration and vibration monitoring and user interface. This article introduces the main features and block diagrams of the MMA845xQ series, application block diagrams, and the MMA845xQ accelerometer development kit LFSTBEB845x Circuit diagram and MMA8451/2/3Q application circuit diagram.

The MMA8452Q is a smart low-power, three-axis, capacitive micromachined accelerometer with 12 bits of resolution. This accelerometer is packed with embedded functions with flexible user programmable options, configurable to two interrupt pins. Embedded interrupt functions allow for overall power savings relieving the host processor from continuously polling data.

The MMA8452Q has user selectable full scales of +/-2g/+/-4g/+/-8g with high-pass filter filtered data as well as non-filtered data available real-time. The device can be configured to generate inertial wakeup interrupt signals from any combination of the configurable embedded functions allowing the MMA8452Q to monitor events and remain in a low power mode during periods of inactivity. The MMA8452Q is available in a 3 mm by 3 mm by 1 mm QFN package.

Main features of MMA845xQ series:

.1.95V to 3.6V supply voltage

. 1.6V to 3.6V interface voltage

.+/-2g/+/-4g/+/-8g dynamically selectable full-scale

. Output Data Rates (ODR) from 1.56 Hz to 800 Hz

.99ug/√Hz noise

. 12-bit and 8-bit digital output

.I2C digital output interface

. Two programmable interrupt pins for six interrupt sources

.Three embedded channels of motion detection

. Freefall or Motion Detection: 1 channel

. Pulse Detection: 1 channel

.Transient Detection: 1 channel

.Orientation (Portrait/Landscape) detection with set hysteresis

. Automatic ODR change for Auto-WAKE and return to SLEEP

.High-Pass Filter Data available real-time


.RoHS compliant

.Current Consumption: 6uA-165uA

Typical applications of the MMA845xQ series:

.eCompass applications

.Static orientation detection (Portrait/Landscape, Up/Down, Left/Right, Back/Front position identification)

. Notebook, eReader and Laptop Tumble and Freefall Detection

. Real-time orientation detection (virtual reality and gaming 3D user position feedback)

. Real-time activity analysis (pedometer step counting, freefall drop detection for HDD, dead-reckoning GPS backup)

. Motion detection for portable product power saving (Auto-SLEEP and Auto-WAKE for cell phone, PDA, GPS, gaming)

. Shock and vibration monitoring (mechatronic compensation, shipping and warranty usage logging)

. User interface (menu scrolling by orientation change, pulse detection for button replacement)

Figure 1. MMA845xQ Family Block Diagram

Figure 2. MMA845xQ series application block diagram

MMA845xQ Accelerometer Development Kit

The Freescale MMA845xQ sensor toolbox accelerometer kit provides hardware and software for development and demonstration of the MMA845xQ family of accelerometers.

The MMA845xQ Accelerometer Development Kit includes:

The kit includes the following:

• MMA845xQ evaluation boards

• MMA8451Q accelerometer daughter board

• MMA8452Q accelerometer daughter board

• MMA8453Q accelerometer daughter board

The kit requires the LFSTBUSB USB-interface board to attach the kit to a personal computer. If you already have the RD3924MM450Q Sensor Toolbox, for the MMA8450Q accelerometer, the USB board is in that kit.

The MMA845xQ kit’s part number is LFSTBEB845x and the USB-interface board’s part number is LFSTBUSB.

Figure 3. MMA845xQ Accelerometer Development Kit Outline Drawing

Figure 4. LFSTBEB845x circuit diagram (1)

Figure 5. LFSTBEB845x circuit diagram (2)

Figure 6. LFSTBEB845x board layout

Figure 7. MMA8451Q circuit diagram

Figure 8. MMA8452Q circuit diagram

Figure 9. MMA8453Q circuit diagram
For details, see:
as well as

The Links:   DMF-50997 BSM150GT120DN2