Analog Devices’ ADXL362 is a micropower triaxial MEMS accelerometer with digital output, acceleration range of ±2/±4/±8 g, operating voltage 1.8V-3.3V, power consumption at 2V supply voltage and 100Hz output data rate The power consumption of the motion-triggered wake-up mode is 2μA, the power consumption of the motion-triggered wake-up mode is 300nA, the device provides 12-bit output resolution, 8-bit format data, and the resolution is 1 mg/LSB in the range of ±2 g, mainly used in hearing aids, home health care equipment , motion-enabled power switches, wireless sensors, and motion-enabled metering devices. This article introduces the main features of the ADXL362, the ADXL362 functional block diagram, and the main features and circuit diagram of the evaluation board EVAL-ADXL362Z.
ADXL362: Micropower 3-Axis MEMS Accelerometer: Digital Output, ±2/±4/±8 g Range
The ADXL362 is an ultra-low power 3-axis MEMS accelerometer that consumes less than 2 μA at a 100 Hz output data rate, and 300 nA in motion-triggered Wake-Up Mode.
Unlike accelerometers that use power duty cycling to achieve low power consumption, the ADXL362 does not alias input signals by undersampling; it samples the sensor’s full bandwidth at all data rates.
The ADXL362 always provides 12-bit output resolution; 8-bit formatted data is also provided for more efficient single-byte transfers when a lower resolution is sufficient. Measurement ranges of ±2 g, ±4 g, and ±8 g are available, with a resolution of 1 mg/LSB on the ±2 g range. For applications where a noise level lower than the ADXL362’s normal 550 μg/7Hz is desired, either of two lower noise modes (down to 175 μg/7Hz typ) may be selected at minimal increase in supply current.
In addition to its ultra-low power consumption, the ADXL362 has many features to enable true system-level power reduction.
It includes a deep multimode output FIFO, a built-in micropower temperature sensor, and several activity detection modes including adjustable-threshold sleep and wakeup operation that can run as low as 300 nA at a 6 Hz (approximate) measurement rate. A pin output is provided to directly control an external switch when activity is detected if desired. In addition, the ADXL362 has provisions for external control of sampling time and/or an external clock.
The ADXL362 operates on a wide 1.6 V to 3.6 V supply range, and can interface, if necessary, to a host operating on a separate, lower supply voltage. The ADXL362 is available in a 3 mm × 3.25 mm × 1.06 mm package.
ADXL362 main features:
Ultra low power
Power can be derived from coin cell battery
1.8 μA @ 100 Hz ODR, 2.0V supply
3.0 μA @ 400 Hz ODR, 2.0V supply
300nA motion-activated Wake-up Mode
10nA Standby Current
Built-in features for system-level power savings:
Adjustable-threshold sleep/wake modes for motion activation
Autonomous interrupt processing without need for microcontroller intervention, so the rest of the system can be turned off completely
Deep embedded FIFO minimizes host processor load
Awake state output enables implementation of standalone motion-activated switch High resolution of 1 mg/LSB
Low noise down to 175 μg/@Hz
Wide supply and I/O voltage ranges: 1.6 V to 3.6 V
Operates off 1.8V to 3.3V rails
Acceleration sample synchronization via external trigger
On-chip temperature sensor
SPI digital interface
Measurement ranges selectable via SPI command
Small and thin 3 mm × 3.25 mm × 1.06 mm package
Home healthcare devices
Motion-enabled power save switch
Motion-enabled metering devices
Figure 1. ADXL362 Functional Block Diagram
ADXL362 Evaluation Board EVAL-ADXL362Z
The EVAL-ADXL362Z is a simple breakout board that enables easy connection of an ADXL362 micropower, 3-axis, digital-output MEMS accelerometer into an existing system. Due to its small size, the EVAL-ADXL362Z has minimal effect on performance of the system and of the accelerometer, and thus it is ideal for evaluation of the ADXL362 in an existing system. Note that the ADXL362 must be communicated with digitally via SPI. No processor is included with the EVAL-ADXL362Z; firmware must be supplied externally by the user . Some sample firmware is available at the link below:
The EVAL-ADXL362Z-MLP is a complete system for real-time evaluation of the ADXL362 micropower, 3-axis, digital-ouptut MEMS accelerometer. This system is accompanied by a graphical user interface (GUI) that facilitates evaluation of parameters such as power consumption, temperature coefficient, noise, and more. The system consists of a motherboard and a satellite board. The sensor is housed in a socket on the satellite board, enabling evaluation of multiple parts using one evaluation system.
To order the complete system, order the EVAL-ADXL362Z-MLP. This kit includes a motherboard, satellite board, accelerometer, and cables. Additional satellite board kits can be ordered using the part number EVAL-ADXL362Z-S. Satellite kit orders include a satellite board and an accelerometer.
Figure 2. Outline Drawing of Evaluation Board EVAL-ADXL362Z
Figure 3. Circuit Diagram of Evaluation Board EVAL-ADXL362Z
Figure 4. Evaluation Board EVAL-ADXL362Z Satellite Board Circuit Diagram
For details, see:
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