**ADXL213AE-REEL: A Comprehensive Technical Overview of the Low Power ±2 g Dual-Axis Accelerometer**

The **ADXL213AE-REEL** from Analog Devices is a low-power, low-noise, complete dual-axis accelerometer featuring a precision-tuned **MEMS (Micro-Electro-Mechanical Systems)** sensor on a single monolithic IC. This device is engineered to measure both static (e.g., tilt) and dynamic (e.g., motion, shock, vibration) acceleration with a full-scale range of **±2 g**. Its combination of low power consumption, small form factor, and analog output makes it an ideal solution for a vast array of portable, battery-powered applications, including industrial instrumentation, medical devices, and consumer electronics.

**Key Architectural Features and Operating Principles**

At the heart of the ADXL213AE is a surface-micromachined polysilicon sensor structure built on a silicon wafer. This structure behaves like a set of differential capacitors. Under acceleration, the sensor's movable plates deflect from their neutral position, unbalancing the differential capacitor. This imbalance is detected by a precision signal conditioner, which outputs a voltage proportional to the acceleration. The device measures acceleration on two orthogonal axes (X and Y), providing simultaneous dual-axis sensing.

A defining characteristic of the ADXL213AE is its **pulse width modulation (PWM)** output. Instead of a traditional analog voltage, the acceleration data is encoded in the duty cycle of a fixed-frequency square wave. The output is a digital pulse train whose duty cycle (T1/T2) is linearly proportional to acceleration. A 0 g acceleration typically corresponds to a 50% duty cycle. This PWM interface is highly immune to noise and can be easily measured by a low-cost microcontroller's timer/capture pin without the need for an external analog-to-digital converter (ADC), simplifying system design.

**Critical Performance Specifications and Advantages**

* **Low Power Operation:** The device consumes a mere **350 μA** at a 3 V supply, making it exceptionally suitable for power-sensitive, always-on applications.

* **Low Noise Density:** With a noise floor of approximately **170 μg/√Hz**, the ADXL213AE can resolve minute levels of acceleration, which is critical for high-precision tilt sensing and vibration analysis.

* **User-Selectable Bandwidth:** A significant design flexibility is offered through external capacitors (CX and CY) that set the bandwidth of the internal low-pass filters. This allows designers to tailor the measurement bandwidth from 0.5 Hz to 2.5 kHz, optimizing the trade-off between noise (lower bandwidth) and response speed (higher bandwidth).

* **Single-Supply Operation:** The accelerometer functions from a **2.7 V to 5.25 V** supply, ensuring compatibility with common lithium-ion batteries and standard 3.3 V/5 V logic systems.

* **Robust Design:** It can withstand non-operational shocks up to 3500 g, ensuring high reliability in harsh environments.

**Application Spectrum**

The versatile nature of the ADXL213AE-REEL enables its use in diverse fields:

* **Tilt Sensing:** Used in construction tools and game controllers to measure orientation.

* **Motion and Shock Detection:** Employed in asset tracking, security systems, and for detecting drops in portable devices.

* **Vibration Monitoring:** Ideal for predictive maintenance in industrial equipment.

* **Portable and Battery-Powered Devices:** Its low power consumption is perfect for handheld medical diagnostics, wearable devices, and remote sensors.

**ICGOODFIND**

The **ADXL213AE-REEL** stands out as a highly integrated, efficient, and flexible solution for dual-axis acceleration measurement. Its innovative **PWM output**, exceptionally **low power consumption**, and **user-configurable bandwidth** provide designers with a powerful tool to create robust and precise motion-sensing systems without compromising on battery life or system complexity. It remains a compelling choice for engineering applications demanding reliable performance from a proven MEMS technology.

**Keywords:**

1. **MEMS Accelerometer**

2. **Low Power**

3. **PWM Output**

4. **Dual-Axis**

5. **±2 g Range**