Built using advanced MEMS technology, ADXL345 3-Axis digital accelerometer provides accurate digital output for detecting tilt, motion, vibration, shock, and free-fall events. This article will discuss the ADXL345 pin configuration, block diagram, variants, technical specifications, features, application circuit, axis sensitivity, and more.

Catalog

ADXL345 3-Axis Digital Accelerometer Basic

The ADXL345 3-Axis Digital Accelerometer is a compact motion sensor that measures acceleration in three directions: X, Y, and Z. It uses MEMS technology to detect both movement and tilt, allowing electronic systems to understand changes in position and motion. Because it outputs digital data, it can easily connect to microcontrollers through I2C or SPI communication interfaces.

This sensor can detect static acceleration such as gravity for tilt measurement, as well as dynamic acceleration caused by vibration, shock, or sudden movement. Its small size and low power consumption make it ideal for portable devices, robotics, industrial monitoring, and embedded system projects.

With built-in motion detection features and flexible configuration options, the ADXL345 is widely used in smart devices and control systems. If you are interested in purchasing the ADXL345 3-Axis Digital Accelerometer, feel free to contact us for pricing and availability.

ADXL345 Digital Accelerometer CAD Models

ADXL345 Pinout Description

Alternatives & Equivalent Model

• ADXL343

• ADXL346

• ADXL335

• ADXL377

• LIS3DH

• LIS2DH12

• MPU6050

• BMA280

• MMA8452Q

• KXTJ3-1057

ADXL345 Block Diagram

The ADXL345 block diagram shows how motion is measured and converted into digital output data. The process starts at the 3-axis sensor, which detects acceleration along the X, Y, and Z axes. The tiny mechanical sensing structure responds to movement or gravity, and the signal is sent to the sensor electronics, where it is conditioned and prepared for conversion.

Next, the signal passes through the ADC (Analog-to-Digital Converter), which changes the analog acceleration signal into digital data. The digital output is then processed by a digital filter to remove noise and improve measurement accuracy. This helps ensure stable and reliable acceleration readings.

The processed data can be stored temporarily in the built-in 32-level FIFO buffer, reducing the need for constant communication with the microcontroller. The control and interrupt logic block manages motion detection features such as tap, activity, inactivity, and free-fall, and sends alerts through INT1 or INT2 pins.

Finally, the serial I/O interface (SPI or I²C) allows the microcontroller to read acceleration data and configure the device. The power management block controls energy usage to maintain low power consumption.

ADXL345 Different Variants

ADXL345 Technical Specifications

ADXL345 Wide Features

• Ultra-Low Power Operation – Consumes as low as 23 µA in measurement mode and 0.1 µA in standby mode (typical at 2.5 V), ideal for battery-powered devices.

• Automatic Power Scaling with Bandwidth – Power consumption adjusts automatically based on selected bandwidth to optimize efficiency.

• User-Selectable Resolution – Supports fixed 10-bit resolution or full-resolution mode.

• Full-Resolution Mode (Up to 13-bit at ±16 g) – Resolution increases with measurement range while maintaining consistent scale factor across all ranges.

• Selectable Measurement Ranges – Programmable ±2 g, ±4 g, ±8 g, and ±16 g ranges via serial command.

• Embedded FIFO Memory (32-Level Buffer) – Stores data internally to reduce microcontroller workload and improve power efficiency.

• Single Tap and Double Tap Detection – Detects tap gestures in any direction.

• Activity and Inactivity Detection – Monitors motion or lack of motion using programmable thresholds.

• Free-Fall Detection – Identifies sudden drop events.

• Flexible Interrupt Mapping – Motion events can be assigned to either interrupt output pin.

• SPI Interface (3-Wire and 4-Wire) – Supports flexible high-speed digital communication.

• I²C Digital Interface – Compatible with standard two-wire communication systems.

• Adjustable Bandwidth – Bandwidth can be selected via serial commands to match application needs.

• Wide Supply Voltage Range (2.0 V to 3.6 V) – Suitable for low-voltage systems.

• I/O Voltage Range (1.7 V to Vs) – Supports flexible logic level compatibility.

• Wide Operating Temperature Range (–40°C to +85°C) – Reliable in industrial environments.

• High Shock Survival (10,000 g) – Designed to withstand extreme mechanical shock.

• Pb-Free / RoHS Compliant – Environmentally compliant materials.

• Compact LGA Package (3 mm × 5 mm × 1 mm) – Small and thin design for space-constrained applications.

ADXL345 Application Circuit

The ADXL345 application circuit shows how the accelerometer is connected to a microcontroller for proper operation. The VS pin is connected to the main power supply, while VDD I/O powers the digital communication interface. Small external capacitors (CS and CIO) are placed close to these supply pins to stabilize the voltage and reduce noise, ensuring accurate acceleration measurements.

The GND pin connects to the system ground to complete the power circuit. Communication with the microcontroller is handled through either SPI (3-wire or 4-wire) or I²C interface. The SCL/SCLK, SDA/SDI/SDIO, and SDO/ALT ADDRESS pins are used for data and clock signals. The CS pin selects SPI mode; if tied high, the device operates in I²C mode.

The INT1 and INT2 pins provide interrupt outputs. These allow the sensor to signal events such as motion, tap detection, or free-fall directly to the microcontroller without continuous polling, improving system efficiency and reducing power consumption.

ADXL345 Axes of Acceleration Sensitivity

The ADXL345 measures acceleration along three perpendicular axes labeled X, Y, and Z. These axes define the sensor’s direction of sensitivity. When acceleration occurs along one of these axes, the corresponding output value increases or decreases depending on the direction of motion. Positive acceleration along an axis produces a positive reading, while acceleration in the opposite direction produces a negative reading.

The diagram also shows how gravity affects the output when the device is stationary. Since gravity equals approximately 1 g, placing the sensor flat with the top side facing upward results in about +1 g on the Z-axis and 0 g on the X and Y axes. If the device is flipped upside down, the Z-axis reads about −1 g. Similarly, rotating the device so that one side points downward shifts the 1 g reading to the corresponding X or Y axis.

This orientation response allows the ADXL345 to detect tilt, inclination, and position relative to gravity.

ADXL345 Applications & Uses

• Tilt sensing

• Motion detection

• Free-fall detection

• Tap and double-tap detection

• Vibration monitoring

• Wearable devices

• Gaming controllers

• Robotics systems

• Smartphones and tablets

• Drone and UAV stabilization

• Shock detection systems

• Data logging systems

Comparison: ADXL345 vs MPU6050

Mechanical Dimensions

Manufacturer

Analog Devices manufactures the ADXL345 using advanced MEMS (Micro-Electro-Mechanical Systems) fabrication technology combined with precision CMOS signal processing. The company integrates the microscopic mechanical sensing structure and analog-to-digital circuitry on a single chip to ensure high accuracy, low noise, and stable performance. With strong expertise in wafer-level manufacturing, packaging, and calibration, Analog Devices maintains tight quality control and high reliability standards for industrial and consumer applications.