MEMS Safety & Security

The ADXL251 is a dual-axis, integrated satellite sensor with user selectable g ranges, compliant to the PSI5 Version 2.1 airbag substandard, and backwards compliant to PSI5 Version 1.3. The ADXL251 (x-axis/y-axis) enables low cost solutions for front impact and side impact airbags, as well as satellite sensor and electronic control unit (ECU) main sensor applications. Acceleration data is sent to the control module via a digital, 2-wire current loop PSI5 bus. Communication via the SPI bus is also available for ECU applications.

The device uses an ECC protected one time programmable (OTP) memory. The sensor g range is configurable to provide full-scale measurement of ±60 g, ±120 g, ±240 g, or ±480 g acceleration. The user can program each axis independently with multiple g ranges in different time slots. In PSI5 mode, there are four programmable time slots available. The device transmits 16-bit or 10-bit acceleration data to the control module, and can be configured to include either a 1-bit parity check, or a 3-bit cyclic redundancy check (CRC).

The ADXL251 is available in a 4 mm × 4 mm LFCSP package and is specified to operate over the full automotive temperature range, −40°C to +125°C.

Applications

• Front impact crash sensing
• Side impact crash sensing

The ADXC1501 is a yaw rate gyroscope and three-axis accelerometer combined in a single package. It is designed for electronic stability control (ESC) and other high performance applications that require yaw rate and acceleration signals simultaneously. An internal temperature sensor compensates offset and sensitivity performance, providing excellent stability over the −40°C to +105°C temperature range.

A digital serial port interface (SPI) transmits the yaw rate and acceleration data to a host microcontroller. A 4-bit cyclical redundancy check (CRC) provides fault coverage for the transmitted SPI data, and internal fault detection routines ensure the integrity of all reported yaw rates and acceleration data. A fully integrated electromechanical continuous self-test (CST) routine provides run-time diagnostic capability for assessing the health of each MEMS element.

An advanced gyroscope sensor design rejects the linear acceleration effects of shock and vibration, enabling the ADXC1501 to operate in harsh environments. The accelerometer signal chain is designed to prevent overload conditions from occurring in these same harsh environments.

The ADXC1501 is designed to operate at either 3.3 V or 5 V. At less than 16 mA current consumption, the ADXC1501 can be used in energy sensitive applications.

Applications

• Electronic stability control
• Chassis control

The ADXRS910 is a high performance in-plane gyroscope, designed for automotive rollover detection applications. The ADXRS910 also has an internal temperature sensor that is used to compensate offset and sensitivity performance, providing excellent stability over the −40°C to +105°C temperature range.

The gyroscope provides a full-scale range of ±300°/sec with a sensitivity of 80 LSB/°/sec. Its resonating disk sensor structure enables angular rate measurement around an in-plane axis. The −3 dB filter corner frequency can be selected to be 27.6 Hz, 51.3 Hz, 109 Hz, or 196.8 Hz. The sensor data output from the device is a 16-bit, twos complement word contained in a 32-bit SPI transaction. SPI communications are compatible up to 10 MHz.

The ADXRS910 is available in a 16-lead inverted SOIC package. The ADXRS910 is specified to operate at 3.3 V and 5 V, with less than 20 mA of current consumption. Its specifications are valid over the −40°C to +105°C temperature range.

Applications

• Rollover detection

The ADXL313 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement up to ±4g. Digital output data is formatted as 16-bit twos complement and is accessible through either a serial port interface (SPI) (3-wire or 4-wire) or I²C digital interface.

The ADXL313 is well suited for car alarm or black box applications. It measures the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion or shock. Its high resolution (1024 LSB/g) and low noise (150 μg/√Hz) enable resolution of inclination changes of as little as 0.1°. A built-in FIFO facilitates using oversampling techniques to improve resolution to as little as 0.025° of inclination.

Several built-in sensing functions are provided. Activity and inactivity sensing detects the presence or absence of motion and whether the acceleration on any axis exceeds a user-set level. These functions can be mapped to interrupt output pins. An integrated 32-level FIFO can be used to store data to minimize host processor intervention, resulting in reduced system power consumption.

Low power modes enable intelligent motion-based power management with threshold sensing and active acceleration measurement at extremely low power dissipation.

The ADXL313 is supplied in a small, thin 5 mm × 5 mm × 1.45 mm, 32-lead LFCSP package and is pin compatible with the ADXL312 accelerometer device.

APPLICATIONS

• Car alarms
• Hill start aid (HSA) systems
• Electronic parking brakes
• Data recorders (black boxes)